Design and hierarchical assemblies of nanomaterials (nanoparticles, carbon materials, molecules) towards energy, sensing, electronic, catalysis and detection applications

Resume : In recent decades, considerable research effort has been devoted globally to the development of new and renewable energy devices. For this, ordered mesoporous materials have attracted much attention as electrode material due to their interconnected pores, controllable pore sizes and structures, and controllable pore wall chemical compositions. Compared with hard templated method, block copolymer self-assembly allows a one-pot simple process rather than tedious multistep procedures to prepare ordered mesoporous materials. In this talk, the simple process for large pore sized ordered mesoporous will be presented. Ordered large-pore (> 30 nm) mesoporous carbon/silica composites with highly dispersed intermetallic PtPb nanocatalysts were prepared for use as anode catalyst in direct formic acid fuel cells. N, P-co-doped ordered mesoporous carbon with a large pore size and precisely controlled doping-site position produced 70% of the maximum power density of Pt/C. Hybrid supercapacitor using ordered mesoporous Nb2O5-C anode and MSP-20 cathode exhibits excellent energy and power densities with advanced cycle life. Hierarchically porous oxide materials have immense potential for application in catalysis, separation and energy devices. However, these materials have been synthesized using multiple templates and the associated complicated steps hampered widespread application of such materials. Our research group developed a simple one-pot strategy for the synthesis of inorganic oxide materials with multiscale porosity.

Resume : Recently, supercapcitors (SCs) classified as electric double-layer capacitor (EDLC) and pseudocapacitor is receiving attention due to high power density, high electric conductivity and cycle stability. Although reduced graphene oxide (rGO) have been studied as an EDLC materials, actual specific surface area is lower than theoretical value because of restacking. To solve these problems, 3 dimensional (3D) and hybrid graphene based SCs have been developed. Transition-metal sulfides studied as pseudocapacitors are being recently studied because of richer redox reaction sites and high electrical conductivity than transition-metal oxides. In particular, manganese cobalt sulfide has high specific capacitance and excellent energy density due to high redox reaction. In this study, we successfully synthesized 3D structure MnCo2S4@rGO for hybrid supercapacitor electrode material through two-step process with chemical precipitation method and anion exchange. The morphology of precursor and MnCo2S4@rGO was analyzed by FE-SEM. The crystallinity of sample was confirmed by XRD. rGO were confirmed by Raman spectroscopy. And the components of as-prepared precusor were measured by FT-IR spectra.

Resume : A new process to obtain spherical porous granules (SPGs) is presented, namely self-organized formation only by one-step heat-treatment. Commercial MgCO3 (basic) (i.e., hydromagnesite), -Fe2O3 and Nb2O5 powders of Mg:Fe:Nb = 1:1:1 in mole fraction were wet-ball milled, and were heat-treated in air at 800-1350°C. When the samples were heated at more than 1100°C, most of the samples became SPGs with the 3-D network structure. The main constituent phase of porous spheres was pseudobrookite-type MgFeNbO5. The formation mechanism of SPGs was discussed by using SEM observation and high-temperature XRD analysis. Using the uniformly porous structure, the SPGs can be potential materials for energy storage.

Resume : Lithium-ion batteries (LIBs) are prime candidates to meet future energy storage demands, following further innovations to improve their efficacy, sustainability, and safety. An air-stable solid polymer electrolyte (ASPE) that possesses the conductivity on the order of a conventional liquid electrolyte with low volatility and mechanical properties of a solid, would enable flexible and non-toxic membranes for use in LIBs. ASPEs possess an inherent safety advantage over traditional liquid carbonate electrolytes due to their low flammability, and they eliminate the potential for leakage of toxic organics and other reduction products from the battery. In this work, we report on our progress towards the goal of the development of a solid-state battery utilizing an ASPE. The electrochemical properties of an ASPE using a poly(ethylene oxide) (PEO) polymer matrix in the presence of lithium bis(trifluorosulfonyl) imide (LiTFSI) in water solution with a room temperature ionic conductivity of ~1 mS/cm are presented. These homogenous, mechanically stable films were fabricated via a hot-pressing method and incorporated into lithium titanate/ASPE/lithium cobalt oxide (or lithium iron phosphate) test cells where the cycling performance and rate capability were assessed. Overvoltage studies were performed along with intermittent impedance spectroscopy to determine time-dependent anode/ASPE stability and SEI film growth.

Resume : Third generation solar cells is aimed at increasing efficiency by improving the solar spectrum capture. According to Marti and Luque [1], intermediate band cell concept could overtake the 31% theoretical efficiency of simple junction photovoltaic cells established by Shockley and Queisser [2] in 1961. For several years, the ‘Institut des Matériaux Jean Rouxel’ of Nantes worked on hybrid photosensitive sols and gels based on titanium oxides [3]. Those nanoparticles, either in solution or deposited as a film, present the characteristic of an intermediate band material, due to their photosensitive properties. To obtain those specific functionalities, several parameters have to be controlled during the synthesis. A sol-gel method is used, with a particular attention to the control of the solvent hydrolysis, thanks to Infra-Red and Raman analyses. Once deposited as thin films, the photosensitive properties can be studied by Infra-Red spectrometry and XPS measurements. As UV illumination is a mean to generate the intermediate band inside the material, studies were carried out as a function of time under UV illumination, by recording XPS and Infra-Red spectra. To complete those data, a mathematical method is further applied, the vectorial method [4]. In order to quantify and understand the chemical changes observed, vectorial method was applied to the set of spectra. Initially developed for XPS measurements, this method allows working without any a priori chemical hypothesis, by following the evolution of species involved in the hydrolysis mechanism. [1] Luque, A., Marti, A., Physical Review Letters, 28, 78, (1997) [2] Shockley, W., Queisser, H.J., Journal of Applied Physics, 32, 510 (1961) [3] Cottineau T., Brohan L., Pregelj M., Cevc P., Richard-Plouet M., Arčon D., Advanced Functional Materials, 18, 2602 (2008) [4] Baltrusaitis, J. et al. Applied Surface Science. 326, 151 (2015)

Resume : New catalytic materials have been extensively developed since the last decades for application in several research fields including sensors, drug delivery, light-weight/high mechanical strength composites and catalysis. In this presentation, we will discuss about last developments on the use of bio-sourced precursors for the synthesis of a new class of hierarchical materials for subsequence applications as metal-free in catalysis and as high energy and high power density supercapacitors. The first part of this contribution describes a straightforward and environmentally benign methodology for the preparation of highly N-doped (N@C) starting from non-toxic, raw and abundant organic building blocks. A shape-adaptable, highly N-doped mesoporous carbon phase is suitably grown as a truly metal-free ‘‘catalytic clothing’’ at the surface of macroscopically shaped supports, i.e. pellets, foam, monolith. The as-synthesized metal-free N@C catalysts were used as metal-free catalysts in two model and fundamental catalytic transformations: (1) the liquid-phase electrochemical oxygen reduction reaction in an alkaline environment and (2) the high temperature gas-phase H2S partial oxidation to elemental sulfur. For both processes, the N@C composites appear as ideal catalyst candidates capable of offering high (and to some extent better) catalytic performance and long-term stability compared to the classical state-of-the-art metal-based systems (including platinum-group metals– PGMs). The second part of this contribution deals with the synthesis of high specific surface area (> 2000 m2/g) hierarchical porous carbon-based material for use as high performance supercapacitor which displaying both high energy and power density, i.e. 26 W. h/kg at a power density of 700 W/kg and 18 W. h/kg at 10000 W/kg in an aqueous electrolyte medium, for replacing batteries in the electrochemical energy storage field. The material also displays an extremely high stability as a function of cycling tests, i.e. > 10,000 cycles, thanks to the high stability of the carbon electrode. It is expected that by combining innovative synthesis strategies, advanced characterization techniques, chemical engineering investigations significant progress will be at hand for developing new carbon-based composites with outstanding performances for several potential fields of application.

Resume : Extreme nanowires (ENs) represent the ultimate class of crystalline materials: They are the smallest possible periodic materials. With atom-wide motifs repeated in 1D, they offer a unique perspective into the Physics and Chemistry of low-dimensional systems. Single-walled carbon nanotubes (SWCNTs) provide ideal environments for the creation of such materials. Here we report the observation of Te ENs grown inside ultra-narrow SWCNTs with diameters between 0.7nm and 1.1nm. Through state-of-the-art imaging techniques and high-precision, high-throughput ab initio calculations, we unambiguously determine the competing structures of encapsulated Te as a function of the encapsulating diameters. From 1-atom-wide Peierls-distorted linear chains -- the ultimate ENs, Te morphs into zigzag chains and then gives rise to helical structures that are the 1D analogues of bulk Te. The pitch of the encapsulated Te coils varies non-monotonically with the diameter of the encapsulating SWCNTs.

Resume : Conventional adhesives show a decrease in the adhesion force with increasing temperature due to the thermally-induced viscoelastic thinning and/or structural decomposition. Here, we report the counter-intuitive behavior of carbon nanotube (CNT) dry adhesives that showed a temperature-enhanced adhesion strength by over six fold up to 143 N/cm2 (the highest adhesion strength among all known dry adhesives) over a temperature range of -196 ~ 1000˚C. This unusual adhesion behavior leads to thermally enhanced electrical and thermal transports through the CNT dry adhesive, allowing for the CNT dry adhesives to be used as conductive double-sided sticky tapes for efficient electrical/thermal managements. With a superb thermal stability, our CNT adhesives were demonstrated to sustain many temperature transition cycles over an extremely wide operation temperature, ranging from -196 to 1000˚C. Our experimental observations were rationalized by a newly-discovered “nano-interlock” adhesion mechanism, which could be applied to the development of various new dry adhesives of novel features [1]. [1] Xu, M. et al. Carbon nanotube dry adhesives with temperatureenhanced adhesion over a large temperature range. Nat. Commun. 7, 13450 doi: 10.1038/ncomms13450 (2016).

Resume : Click reactions largely crossed the borders of organic synthetic chemistry and are now at the forefront of many interdisciplinary studies at the interfaces between chemistry, physics and biology. As part of this research, our group is involved in a research program on the development of clickable fullerene building blocks and their application to the preparation of a large variety of new advanced materials and bioactive compounds. Importantly, the introduction of the click chemistry concept in fullerene chemistry allowed us to produce compounds that would be hardly accessible by using the classical tools of fullerene chemistry. In this paper, we will summarize our ongoing progresses in this particular field.

Resume : Harvest, conversion and guiding of light is one of the influential achievements of science to date, resulting in developments of telescopes, lasers, microscopes and optical communication fibres to name but a few. Correspondingly, the realisation of such critical processes, with high efficiencies and on nanoscales, is one the most critical challenges of today, having clear implications for future technologies including, but not limited to, integrated photonic circuitry. Light-activated systems found in nature are prime examples of such nanoscale control of light, where it is achieved through careful structuring of components to yield complexes where efficient energy transfer is achieved in a cascaded and more-over, directional manner, with nanoscale precision. In man-made systems, cascaded energy transfer has been previously observed in layer-by-layer stacks of semiconductor quantum dots (QDs), where the diameter of QDs in each layer was gradually increased across subsequent layers. These works showed that the cascaded transfer of energy can be extremely efficient, however, they lacked in the dimensional confinement of energy flow. Here, such gradient principle is employed to achieve nanoscale control over the flow of energy. This is achieved by using nanosized assemblies of semiconductor quantum dots, which are fabricated using a novel combinatory technique involving an amalgamation of top-down and bottom-up methods.

Resume : In this presentation I will the most recent results of our group on synthesis and functionalisation of nanoparticles (Au nanorods, Au nanoworms, high magnetic moment iron oxide nanoparticles, as well as novel structure of magnetic core@shell) for biomedical applications such as photo- and magnetic induced hyperthermia cancer treatment. We are currently studying the nucleation and growth of nanoparticles, and the kinetic studies in batch to translate to microfluidic flow synthesis for manufacturing of reproducibile and scale up the syntheses for industrial use in collaboration with various industrial partners as well as clinicians in the hospitals. Fig 1. Fine tuning Au nanorods and their optical properties. Ref: 1. Pallares, R. M., Bosman, M., Thanh, N.T.K. *, and Su, X. (2016) Plasmonic multi-logic gate platform based on sequence-specific binding of estrogen receptors and gold nanorods. Nanoscale. 8: 19919–20126. Front cover. 2. Thanh, N. T. K. (2016) Preface of Theme issue ”Multifunctional nanostructures for diagnosis and therapy of diseases’. Interface Focus, 6: 20160077. 3. Baber, R., Mazzei, L., Thanh, N. T. K., Gavriilidis, A. (2016) Synthesis of silver nanoparticles using microfluidic impinging jet reactors. Journal of Flow Chemistry. 6: 268-278. 4. Pallares, R. M., Lim, S. H., Thanh, N.T.K.*, and Su, X. (2016) Growth of Anisotropic Gold Nanoparticles in Photoresponsive Fluid and Application to UV Exposure Sensing and Erythema Prediction. Nanomedicine. 11: 2845-

Resume : The use of optically tunable Fe3O4-Au nanoparticles for hyperthermia studies is an attractive option based on plasmonic heating of gold nanoparticles, induced through the application of an external magnetic field, in order to enhance their light absorption in the VIS-NIR region.In this presentation, we report the synthesis, by the polyol process, of hybrid gold-magnetic nanoparticles (NPs) containing gold cores of about 80 nm in size decorated with less than 10 nm thickened magnetic CoxFe3-xO4 shell. The structure and the microstructure of the produced composites are investigated and correlated to their magnetic and optical properties. Their characterization as stable aqueous colloids is also checked. Interestingly, the NPs show a superparamagnetic behavior with a blocking temperature close to room temperature, making them valuable as contrast agents for Magnetic Resonance Imaging (MRI), and a strong plasmonic absorption shifted around 630 nm, an encouraging feature for using them as heating dyes by an excitation at the red visible light. Additionally, excited by an ac magnetic field of 400 kHz, they are able to heat up to 48 °C in 350 s leading to the conclusion that these NPs can be also very promising for magnetic hyperthermia therapy. The specific absorption rate (SAR) inferred from these measurements are quite high and reaches a value of 92 W per gram of iron.

Resume : Iron oxide magnetic nanoparticles (IONPs) are extensively studied from a fundamental point of view for the new properties generated by their size, shape and composition but also because of their broad range of applications (biomedical, spintronic, magnetodielectric, energy, magnetic memories). Depending on the intended application, the magnetic properties of NPs must be “adapted” and then NPs with given size, composition and shape have to be designed. Therefore, a lot of efforts are put in the development of synthesis methods able to tune easily and in reproducible way the size, shape and composition of NPs but especially their shape which would add a supplementary magnetic anisotropy energy. The most suitable synthesis method to control the NPs shape is the thermal decomposition (TD) where an iron precursor is heated in a high boiling point solvent in presence of ligands. Nevertheless, the control of the shape is not so trivial and the current strategy involves the addition of chelating ligands and the precise control of reaction parameters (heating rate, nature of solvent …). However one parameter is frequently forgotten: the iron precursor itself. The effect of the precursor structure and stability on the outcome of the synthesis remains an open question. To answer this question, different iron stearates have been synthesized by varying the nature of the synthesis atmosphere, the iron oxidation degree and the hydration rate. Their structure and their thermal stability have been investigated by TGA, infrared spectroscopy and XRD as function of temperature. The effect of precursor synthesis parameters has been related to their decomposition kinetics and to NPs characteristics. The influence of ligands on the shape of NPs has been achieved by varying the different iron precursor structures: it has allowed to determine the precursor structures the most suitable to tune the shape of NPs in a reproducible way. Such study permitted thus the synthesis of several anisotropic shapes such as cubes, octopods and plates. The effect of the shape on magnetic hyperthermia and MRI properties has been investigated for designing NPs promising for theranostic biomedical applications.

Resume : Student: Uriel Marie-Sainte Supervisors: Dr. Iain E. Dunlop & Dr. Theoni K. Georgiou Imperial College London Abstract: The ability of nanoparticles to bind to specific cells has widely attracted scientists as they offer numerous possibilities in targeting specific cancerous cells. By incorporating gold nanoparticles into polymer micelles, promising results are observed with these kinds of nanoparticles. Firstly, the focus has been put into gold nanoparticles because, not only they are non-toxic when its size is greater than 2nm, but they also have alluring optical and electronic properties that change with different shapes and sizes. The optical property that is the most interesting in our case is light absorption. Using photothermal therapy (PPT), gold nanoparticles can produce enough heat to kill cancerous cells. Secondly, seven polymers with different types of architecture and compositions have been synthesized and characterised, and they displayed remarkable resistance to biofouling and off-target binding. The studies are therefore focused on their synthesis with gold nanoparticles. Then, the seven nanoparticles are compared to understand how the architecture of the polymers can affect their properties (stability, heating capacity by NIR, etc.). Key words: gold nanoparticles, micelles, photothermal therapy, polymers.

Resume : For the past several years, our research has been directed towards the preparation of various uniform nanoparticles through solventless processes. (I) A general method, termed as a “wrap/bake/peel process”, was developed for nanostructural transformation [1]. Depending on the heat treatment conditions, spindle shaped hollow nanocapsules of either hematite or magnetite were able to be produced. (II) Self-assembled uniform-sized ferrite nanocrystals embedded carbon nanosheets were synthesized simultaneously through a single heating procedure using metal-oleate complex as the precursor for both ferrite and carbon [2]. As a demonstration of the ferrite/carbon nanocomposite as electrode material for Li-ion battery, electrochemical experiments were carried out in a coin type cell assembly. The nanocomposite electrodes exhibited large power capability with good cycling stability. (III) A transformation of hydrophobic iron oxide nanoparticles to hydrophilic and biocompatible maghemite nanocrystals by controlled heat treatment followed by dextran coating was reported. Through the process, highly crystalline bare maghemite nanoparticles with high magnetization were produced. In vivo MR imaging using these nanoparticles showed significant signal enhancement. (IV) Uniform hollow carbon with mesoporous shell was synthesized by coating its outer shell with silica to prevent aggregation during its high-temperature heat treatment [3]. The as-prepared hollow carbon exhibited a high surface area and formed stable dispersion in aqueous solution after the pegylation process. The drug-loading and drug-release properties of the material were also investigated. REFERENCES [1] Piao Y., Kim J., Na H. B., Kim D., Baek, J. S., Ko M. K., Lee J. H., Shokouhimehr M., Hyeon T.* (2008) “Wrap-bake-peel process for nanostructural transformation from beta-FeOOH nanorods to biocompatible iron oxide nanocapsules”, Nature Materials, 7, 242-247. [2] Jang B., Park M., Chae O. B., Park S., Kim Y., Oh S. M., Piao Y.*, Hyeon T.* (2012) “Direct Synthesis of Self-Assembled Ferrite/Carbon Hybrid Nanosheets for High Performance Lithium-Ion Battery Anodes”, J. Am. Chem. Soc., 134, 15010-15015. [3] Quan B., Nam G.-E., Choi H. J., Piao Y.* (2013) “Synthesis of monodisperse hollow carbon nanocapsules through protective silica shells”, Chemistry - An Asian Journal, 8, 765-770.

Resume : We will report a new strategy to generate multiple hollow nanocapsules1,2. The process is based on the observation of droplets in macroscopically miscible water/solvent mixtures, the so called "ouzo effect". Various nanoparticles comes to stabilized this interface, as in the case of Pickering emulsions. After addition of a crosslinking polymer and removal of the solvent core, hollow nanocapsules of diameter ca 100nm are obtained. This novel strategy does not require the use of block copolymers. In contrast, most methods reporting the formation of hybrid nanocapsules incorporates nanoparticles into block-copolymer polymersomes or use nanoparticles tethered with block-copolymers. This new type of nanocapsules were coined Hybridosomes® and were characterized by a full set of techniques including Nanoparticles Tracking Analysis, Scanning and Transmission electronic microscopy, liquid atomic force microscopy. Hybridosomes® were prepared from various nanoparticles such as QD, gold nanoparticles, SPION, UCNP and mixtures of different type of particles. The encapsulation of a fluorescent dye was also demonstrated opening the way to cargo release. Thus, nanocapsules with multiple properties (magnetic, plasmonic, fluorescent etc.) are easily obtained. Interestingely magnetic Hybridosomes® enable Magnetic Resonance Imaging contrast enhancement in vivo. The high versatility of these multifunctional platforms may have many other interests for multimodal imaging and theranostic application. A second application developed was the self construction of nanostructured film by electroclick chemistry. The surface of Hybridosomes® were functionalized via the polymer and engaged in an electrochemically assisted click reaction on a functionalized electrode thus generating a covalent nanostructured film. Both surface coverage and thickness could be tuned. Thanks to the high versatility of Hybridosomes®, film composition can easily be tuned with various combination of nanocapsules thus creating films with different functionalities. Finally a similar strategy was also applied to metal clusters leading to a new type of nano assemblies with promising application in catalysis. [1] Sciortino et al., ChemNanoMat. 2016, 2, 796-799. [2] Patent FR1562860

Resume : Nanoscale zero-valent iron particles (nZVI) are transforming many research fields, from biomedicine to environmental remediation.[1] NZVI particles are synthesized at laboratory scale by chemical synthesis methods.[2] However, they suffer from serious drawbacks for large-scale production due to the need to apply surfactans to control the size, aggregation and colloidal stability of synthesized nanoparticles, which requires multiple purification processes; thus increasing the production costs and waste production. Large-scale synthesis of dried nZVI particles is also achieved by mechanical grinding of granular bulk iron.[2] However, this method suffers from severe aggregation of nanoparticles and poor size and shape control. In order to overcome these limitations, the direct synthesis of nZVI particles by Liquid-Assisted Pulsed Laser Ablation (LA-PLA) of iron plates submerged in different liquids is explored here. Results showed that irradiation of iron plates in water with ns laser pulses yielded maghemite/magnetite nanoparticles embedded in an amorphous hematite matrix; whereas fs laser pulses produced nZVI particles. The use of organic solvents yielded nZVI particles, regardless of the width of the laser pulse. Moreover, laser fluence and pulse accumulation played a significant role on the control of size and polydispersity of these nanoparticles. [1] Lohse SE, Murphy CJ. J. Am. Chem. Soc. 2012, 134: 15607. [2] Stefaniuk, M., Oleszczuk, P., Sik, Y. Chem. Eng. J. 2016, 287: 618.

Resume : In recent years, ordered magnetic nanodot arrays have aroused particular interest due to their potential applications in various emerging devices and technologies such as spin torque nano-oscillators [1] and magnetic data storage [2]. The fabrication of patterned magnetic nanodot arrays with tailored properties (i.e morphology, structure and magnetic behavior) is becoming a major challenge for many researchers. In fact, this bit patterned media has recently been proposed to be among the future storage technologies. Such new promising technology would revolutionize the magnetic recording devices if the nanodot was in a single domain state [3]. However, the magnetization direction of a nanoparticle usually oscillates (thermally unblocked) at room temperature, leading to a paramagnetic behavior with a vanishing average remanent magnetization. This phenomenon, called superparamagnetism, must be bypassed for practical applications [4]. To this end, increased efforts must be directed toward an enhancement of the nanoparticles magnetic anisotropy in order to increase the thermal stability (or the magnetization relaxation time). One of the preferred methods is to use nanostructured magnetic alloys, however in order to overcome this limit, Co50Pt50 ordered alloy nanoparticles have recently attracted increased interest. In fact, after annealing treatments, this alloy could exhibit the L10 type ordered structure with magnetocrystalline anisotropy as high as 106 to 107 J/m3 [5]. Therefore, with such candidates, one can expect to form nanomagnetic units with stable magnetization at either room temperature or above and reach ultra-high storage density without experiencing thermal instabilities. In this work, we investigated a new approach based on the direct deposition of functionalized nanoparticles (i.e with predetermined and original properties) onto patterned substrates. Contrary to atomic deposition, where dense dots can be achieved, the present approach based on the deposition of preformed nanoparticles allows the formation of nanodots composed of a random packing of incident nanoparticles (i.e nanostrutured dots). We have focused on the elaboration and characterization of nanostructured magnetic dot arrays prepared by depositing Co50Pt50 nanoparticles preformed in the gas phase on Si substrates patterned by electron beam lithography (EBL). Annealing at 650 °C transforms the structure of deposited Co50Pt50 nanoparticles from the chemically disordered A1 phase to the chemically ordered L10 phase. The magnetic properties of the sub-50nm nanostructured Co50Pt50 dots before and after annealing were investigated using magnetic force microscopy (MFM) and vibrating sample magnetometer (VSM). All nanostructured dots were in a single domain state with the easy axis perpendicular to the plane. The VSM measurements have indicated a correlated super-spin glass state (CSSG) collective behavior with the approach to saturation slightly slower prior to annealing. Consequently, the magnetic properties are mainly governed by a correlated super-spin glass state with strong inter-dot dipolar interactions. References [1] R. A. van Mourik, T. Phung, S. S. P. Parkin, and B. Koopmans, Phys. Rev. B 93, 014435 (2016). [2] T. R Albrecht, H. Arora, V. Ayanoor-Vitikkate et al., IEEE Trans. Magn. 51(5), 1 (2015). [3] C. Vogler, C. Abert, F. Bruckner, D. Suess, and D. Praetorius, Appl. Phys. Lett. 108, 102406.1 (2016). [4] S. Kralj, and D. Makovec, ACS Nano 9(10), 9700 (2015). [5] P. Andreazza, V. Pierron-Bohnes, F. Tournus, C.Andreazza-Vignolle, V. Dupuis, Surf. Sci. Rep. 70(2), 188 (2015).

Resume : The remarkable properties of carbon nanotubes have made them an attractive platform for many current and future industrial applications1. Thus far, two component system made of single wall carbon nanotube SWNT/surfactant has been extensively studied in order to produce highly stable SWNT dispersion considering attraction of the hydrophobic part of the surfactant to SWNT sidewall. Additionally, SWNT/surfactant systems demonstrate near-IR photoluminescence (PL) with the PL quantum yield less than 1% 2 . Many research efforts have been paid recently for brightening of PL via encapsulation of organic materials inside the nanotubes3, 4, covalent incorporation of sp3 defects5, embedding luminescent local states 6 and development of macro-molecular complexes of SWNTs with dyes7. In this work, we have studied the interaction of the dioxaborine cyanine dye (DOB-719) with the SWNT dispersed in water using anionic surfactants with a purpose to increase the intensity of photoluminescent signal to SWNTs using absorption and PL spectroscopy. Our results show the DOB-719 is associated with the SWNT micellar to form nano-structured complex via Coulomb attraction. As a result, new optical features are revealed due to the resonance energy transfer (RET) from the dye to the SWNT. In the mixture of DOB-719 with the SWNT, the new absorption peak has emerged being 50 nm red shifted in comparison to the absorption peak of neat DOB-719 8. The new PL peaks featuring the RET have appeared at the excitation wavelength 735 nm. Additionally, the emission wavelength of the PL peaks for the mixture are strongly red shifted (up to 40 nm) in comparison with the peaks of the neat nanotubes for all the SWNT chiralities evidencing strong dielectric screening of the formed complexes. The development of the new peaks at the excitation wavelength 735 nm can be used for efficient PL detection of the SWNT in aqueous environment. References: 1. De Volder, M. F. L.; Tawfick, S. H.; Baughman, R. H.; Hart, A. J. Science 2013, 339, (6119), 535-539. 2. Tan, P. H.; Rozhin, A. G.; Hasan, T.; Hu, P.; Scardaci, V.; Milne, W. I.; Ferrari, A. C. Physical Review Letters 2007, 99, (13), 137402. 3. Yanagi, K.; Iakoubovskii, K.; Kazaoui, S.; Minami, N.; Maniwa, Y.; Miyata, Y.; Kataura, H. Physical Review B 2006, 74, (15), 155420. 4. Yanagi, K.; Iakoubovskii, K.; Matsui, H.; Matsuzaki, H.; Okamoto, H.; Miyata, Y.; Maniwa, Y.; Kazaoui, S.; Minami, N.; Kataura, H. J Am Chem Soc 2007, 129, (16), 4992-7. 5. Piao, Y.; Meany, B.; Powell, L. R.; Valley, N.; Kwon, H.; Schatz, G. C.; Wang, Y. Nature chemistry 2013, 5, (10), 840-845. 6. Miyauchi, Y.; Iwamura, M.; Mouri, S.; Kawazoe, T.; Ohtsu, M.; Matsuda, K. Nat Photon 2013, 7, (9), 715-719. 7. Lutsyk, P.; Arif, R.; Hruby, J.; Bukivskyi, A.; Vinijchuk, O.; Shandura, M.; Yakubovskyi, V.; Kovtun, Y.; Rance, G. A.; Fay, M.; Piryatinski, Y.; Kachkovsky, O.; Verbitsky, A.; Rozhin, A. Light Sci Appl 2016, 5, e16028. 8. Shandura, M. P.; Kovtun, Y. P.; Yakubovskyi, V. P.; Piryatinski, Y. P.; Lutsyk, P. M.; Perminov, R. J.; Arif, R. N.; Verbitsky, A. B.; Rozhin, A. Sensor Letters 2014, 12, (9), 1361-1367.

Resume : Transition metal-based and heteroatom-doped carbon materials are regarded as promising replacement for commercial Pt/C catalysts in oxygen reduction reactions for polymer-electrolyte-membrane fuel cells and metal-air batteries. However, these materials usually suffer from complicated fabrication as well as purification processes and inhomogeneous distribution of the doped heteroatom. Herein, we report a facile and scalable method of in situ precipitating the self-degraded iron ions on the wall of nitrogen and sulfur containing pyrrole nanotube, followed by carbonization and acid leaching to form the Fe, N, S tri-doped carbon nanotube. This material, with its N content higher than 17%, was used as nonprecious metal catalysts for the oxygen reduction reaction and showed outstanding electrocatalytic performance and exceptional methanol tolerance durability comparable to the state of the art Pt/C catalyst in alkaline media.

Resume : Aerogels assembled from colloidal nanocrystals (NCs) are of enormous scientific and technological interest owing to their ultralow density, high surface area and large open interconnected pores. The aerogels built from the nano building blocks (NBBs) can inherit the properties and functions from the parent NBBs while maintaining the aerogel properties, which frequently leads to amplification of the inherent properties and results in features that are unique to the aerogels. This presentation will report our recent progress on the in-situ shape engineering of the NBBs for hierarchical multimetallic aerogels. Different from the conventional metallic aerogels which are derived from solid NBBs, the hierarchical aerogels are built from two sorts of structures: one with nanoscale morphology (from the NBBs) and one with a macroscale porous structure (aerogel nature). By facilely controlling the chemical composition, we tuned the NBBs from hollow nanospheres to dendritic nanocrystals. The resulting hierarchical aerogels exhibit a remarkable electrocatalytic activity which is 10.6 and 7.6-fold higher than the state-of-the-art Pd/C and Pt/C catalysts, respectively, taking the ethanol oxidation reaction as an example. With the aid of time-dependent transmission electron microscopy and molecular dynamics simulations, a composition-dependent structural growth mechanism was revealed in terms of nanowelding of the particulate reaction intermediates. References 1. B. Cai, D. Wen, W. Liu, A. K. Herrmann, A. Benad, A. Eychmüller, Angew. Chem. Int. Ed. 2015, 54, 13101. 2. B. Cai, A. Dianat, R. Hübner, W. Liu, D. Wen, A. Benad, L. Sonntag, T. Gemming, G. Cuniberti, A. Eychmüller, Adv. Mater., 2017, 1605254.

Resume : Understanding the binding mechanism for aromatic molecules on transition-metal surfaces, especially with defects such as vacancies, steps, and kinks, is a major challenge in designing functional interfaces for organic devices. One important parameter in organic device performance is the barrier of charge carrier injection. In case of the metallic electrode, tuning the electronic interface potential or the work function (WF) for electronic level alignment is crucial. Here, we use the screened vdW and many-body dispersion (MBD) methods, coupled with density functional theory calculations, to systematically study the interactions of benzene with a variety of stepped surfaces. Our calculations show that the small adsorption energies, far equilibrium distances and electronic structures with little charge transfer all indicate the physisorptive character of Ag(211), Ag(533), Ag(322), Ag(755) and Ag(544) surfaces upon the adsorption of benzene. The MBD effects play a prominent role for all studied systems, reducing the binding energies by at most 0.16 eV for both Ag(533)and Ag(322) compared to the data from the pairwise DFT+vdWsurf method. We also find that the adsorption of benzene changes the WF by generating an interface dipole. Among these stepped surfaces, the WF of Ag(211) decrease the most by 0.71 eV. Interestingly, the higher the step density, the larger the reduction of the WF. On the other hand, the self-consistent vdWsurf effects can lead to a larger WF compared to DFT+vdWsurf, as same as the reduction of WF, due to a larger modification of the interface dipole. Our results provide important insight into the benchmark adsorption systems with stepped surfaces, which could help in designing more appropriate interfaces with low work functions for electron transfer.

Resume : Chemoresistive gas sensors based on two-dimensional (2D) materials such as graphene-based materials have attracted significant research interests due to its potential use in the next-generation technologies including the Internet of Things (IoT). However, required performances for the IoT like high selectivity, sensitivity, and reversible gas sensing behaviors have to be satisfied. Functionalization of 2D materials is considered as a key strategy to achieve the superior gas sensing properties because it can modulate chemical and electrical properties of 2D materials. Here, we present a facile synthesis and room temperature gas sensing properties of chemically fluorinated graphene oxide (CFGO) prepared by a solution process. The CFGO sensor exhibited ultrahigh response, selective and reversible NH3 sensing with detection limit of ~20 ppb. Influence of fluorine doping on sensing mechanism is investigated by first-principles calculations based on density functional theory. The calculations reveal that the doped fluorine changes charge distribution on functional groups in graphene oxide, resulting in preferred selective adsorption and desorption of NH3 molecules. We believe that the remarkable NH3 sensing properties of CFGO and the investigation by the calculations enlarge the possibility of functionalized 2D materials for practical gas sensing applications such as IoT.

Resume : Silica nanoparticles have been widely used in various fields such as medical, bio, chemical and display industry in our daily lives due to their broad applications. So many efforts have been devoted to preparing silica particles in various ways including ‘Stöber method’ devised in 1968. Stöber and co-workers reported that silica nanoparticles had synthesized through hydrolysis and condensation of silane precursor in alcohol and water with ammonia as catalyst. It is still considered as the most simple and convenient way for preparing silica nanoparticles because the reaction environment can be controlled easily by changing reaction parameters like pH, concentration and reagent type. So, tons of studies have been researched to synthesize monodispersed silica nanoparticles with controlled size via Stöber method. However, it is still challenging to obtain uniform silica particles over 500nm by single-step Stöber process in the presence of ammonium hydroxide or sodium hydroxide base catalyst. Here, we synthesized silica nanoparticles using organic amine base catalyst via single-step in order to prepare particles with over 500nm in size.

Resume : The aim of this project is to design new catalytic hybrid materials by grafting polyoxometalates (POMs) catalysts onto chiral inorganic silica nanoribbons and nanohelices (NANOPOMs), and to exploit their sustainable properties in asymmetric heterogeneous catalysis. The developments of such chiral nanomaterials are expected to have an important impact on nanoscience and technology, in particular in the field of polyoxometalates and asymmetric catalysis. Furthermore, these chiral nanocatalysts will be exploited as recoverable heterogeneous catalyst in the enantioselective oxidation of organic substrates. The preparation of chiral POM-based silica NANOPOM hybrids is performed in four steps based on: (1) the synthesis of organic nanoribbons and nanohelices with finely controlled diameters, pitches, lengths, and periodicity, by self-assembly of cationic surfactants bearing chiral organic anions [1], (2) the replication of organic nanoribbons and nanohelices to their inorganic silica counterparts [2], (3) the surface functionalization of silica nanostructures, and finally (4) the electrostatic and covalent grafting of POM units onto silica nanostructures. The characterization of these NANOPOM hybrids was monitored using complementary techniques such as UV, infrared (diffuse reflectance), and Raman spectroscopies, as well as transmission electron microscopy and high resolution transmission electron microscopy. The data obtained are consistent with the proposed NANOPOM structure in which POM units are grafted on chiral silica nanostructures. These NANOPOM hybrids were evaluated as recoverable catalyst in the oxidation of sulfides [3], with a good activity. References [1] A. Brizard et al. J. Am. Chem. Soc., 2007,129, 3754-3762. [2] T. Delclos et al. Nano Lett., 2008,8, 1929-1935. [3] C. Jahier et al. Chem. Eur.J., 2009,15, 8703-8708.

Resume : The exploration of efficient photocatalysts for sustainable energy conversion systems is of great importance and it is our undeniable obligation to come up with advanced energy solution in modern society. The simultaneous nitrogen doping and photosensitization of graphene quantum dots (GQDs) in conjunction with intimate interfacial integration with the photoanode components afforded by the layer-by-layer (LbL) assembly strategy were found to collaboratively contribute to enhanced performance in photoelectrochemical (PEC) water splitting. Our work introduced a facile and general strategy for the rational design of a large variety of N-GQDs/1D semiconductor nanoarchitectures for advanced environmental and energy applications. On the other hand, covalent bonding of graphene oxide quantum dots (GOQDs) onto amino modified polyvinylidene fluoride (PVDF) membrane has generated a new type of nano-carbon functionalized membrane with significantly enhanced antibacterial and antibiofouling properties. Our study opens up a new synthetic avenue in the fabrication of effective surface-functionalized polymer membranes for environmental applications, including waste water treatment and biomolecules separation.

Resume : Reduction chemistry can been used to both disperse, functionalise and hierarchically assemble single walled carbon nanotubes (SWCNTs) in a mild and effective manner. Here, a simple route to large scale reduced carbon nanotubes solutions has been identified which is suitable for even ultra-long SWCNTs and the conditions required to maximise surface functionalisation have been elucidated. The nanotubes solutions can be assembled into organogels through crosslinking with organo-dihalides and dried to form cryo/aerogels of controllable dimensions down to micron-scale thickness aerogel-films. Alternatively, high concentration solutions of SWCNTs can be subjected to a new reactive-coagulation spinning process to form fibres of isolated, individual, insulated SWCNTs at high loading (~30 wt%) with high dielectric properties. The mechanical behaviour of the fibres is dependent on SWCNT length with longer SWCNTs altering the failure mechanism to dramatically increase the toughness versus short nanotube composites.

Resume : Solution based thermochromic W doped VO2 particles were developed by a sinle step hydrothermal synthesis, which is a rapid way to obtain undoped and/or doped VO2 in monoclinic phase under economical and environmentally friendly conditions. W doped VO2 particles were successfully synthesized by hydrothermal process using V2O5, Magnesium salts, and oxalic acid as precursors. The structure of W doped VO2 was examined by X-Ray powder diffraction, while the thermochromic behavior was confirmed by DSC. Finally, we also demonstrate that the thermochromic VO2 in the form of a colloidal dispersion can be easily incorporated into thin thermochromic films deposited on plastic substrates which can be used as coatings for smart windows for energy efficiency.

Resume : Over the past decades, electronic skin has been extensively investigated for the development of advanced human interactive devices. Here, a stretchable, transparent, and skin-attachable strain sensor integrated with a flexible electrochromic device (ECD) is demonstrated for human skin inspired interactive color changing system. The strain sensor consists of spin-coated conductive nanocomposite film of PVA / MWCNT / PEDOT:PSS on PDMS substate. The sensor exhibits excellent performance of good gauge factor of 5.2 up to 50% strain, high durability over 10,000 cycles of stretch/release, and fast response time of 20 ms with high transparency of 77%. The skin-attached strain sensor shows successful detection of bio-signals such as finger and wrist bending, swallowing, and wrist pulse. The flexible ECD made of elecrochemically synthesized polyaniline nanofibers and V2O5 on ITO/PET film experiences the change in color from yellow to dark blue with change of applied voltage. The strain sensor and ECD are integrated via Arduino circuit for interactive color change with the variation of applied strain, which enables the real-time visual display of body-motion. This integrated system demonstrates high potential in interactive wearable devices, military applications, and smart robots.

Resume : A nanofilm of few-layer graphene (FLG) flakes on oxidized Si substrate was prepared from the FLG solution in 1-methyl-2-pyrrolidone (NMP) by a modified Langmuir-Schaefer technique. Subsequently, NiFe2O4 nanoparticles (d = 10 nm) were spin-coated on this FLG nanofilm at different rpm speeds to form coverages with different densities. The average FLG flakes thickness and lateral dimension were 5 nm and 100 nm, respectively. The samples were characterized by AFM, XRD, SEM and Raman spectroscopy. The NO2 gas sensing was tested in the mixtures of dry air with 1 - 200 ppm of NO2 at room temperature. The response of a reference FLG nanofilm (without nanoparticles) to 10 ppm of NO2 gas was 13%. Decoration by NiFe2O4 nanoparticles increased the sensitivity up to 27% for denser coverage. The resistance decreased on the decoration, the sensor response being of p-type. Such a behavior could be explained by chemisorption of NO2 gas molecules on the nanoparticle surface and the following charge transfer between the nanoparticles and FLG nanofilm. A contribution of the spill-over effect can also be considered as the nanoparticles are not closely packed. Hence, the approach developed allows to increase the FLG nanofilm sensitivity at room temperature. The fabrication method is simple, low cost, controllable and scalable.

Resume : A highly sensitive and environment friendly multimodal nanosensor encompassing magnetic and fluorescent functionality is designed for the simultaneous detection and removal of mercury ion in water. A significant fluorescence quenching is observed with the increasing concentration of Hg2+ with surprisingly low limit of detection. The detected analyte is successfully removed with the help of a bar magnet leaving no residual secondary pollution. The details mechanism of sensing is also investigated. The simple and elegant nanochemistry reported here provides a facile route towards field based mercury sensor development in future.

Resume : Herein, we demonstrate a skin-attachable and stretchable array of multi-functional sensors consisting of polyurethane foam (PU foam) and multi-walled carbon nanotube (MWCNT)-polyaniline (PANI) nanocomposite for detecting bio-environmental signals. With a single functional material of PU foam/MWNT/PANI based sensors, body temperature, wrist pulse, and toxic ammonia gas can be simultaneously detected after attaching onto wrist: The fabricated pressure sensor exhibits high performance such as a large pressure range up-to 30 kPa, a fast response time of 20 ms, and a high durability over 10000 loading/unloading cycles. Owing to the use of thermoelectric material of MWCNT-PANI, temperature is detected as output voltage under temperature gradient with a high temperature sensitivity of 28.7 μV/℃. Also, the gas sensor detects toxic ammonia gas with a sensitivity of 46.9 %, response and recovery time of 7.8 and 34 s, respectively at 25 ppm. In order to obtain skin-attachable mechanical stability of the multi-sensor array under deformation, the stretchable substrate is designed to use sticky and soft Silbione/PDMS film with locally implanted stiff PET films and embedded liquid metal Galinstan interconnections. 5 × 5 array of sensors are fabricated facile via use of cut and paste method. Such fabricated stretchable array of multi-functional sensors shows mechanical stability under biaxial stretching up-to 50% with no noticeable degradation of electrical signals from pressure, temperature and gas.

Resume : By tailoring size, shape and composition, the magnetic properties of iron oxide based nanoparticles can be controlled.[1-3] On the nanoscale, new magnetic effects occur. For instance, the particles can be engineered to behave superparamagnetically. They are strong magnets in an external magnetic field, but lose their magnetisation completely, once the field is removed. Thus, switchable magnets can be obtained. Considered as building-blocks, magnetic (iron oxide) nanoparticles can be used as basis to create more complex, nanostructured / nanocomposite particles thereof, so called supraparticles, which yield completely new properties and empower innovative applications. For instance, micron sized composite particles that are synthesised from these switchable magnetic nano-building-blocks may act as ?carrier particles? in fluids. With these, unwanted or valuable substances can be concentrated in fluids, collected, removed and recovered.[4-8] Moreover, such particles may act as detectors.[9] A more complex particle architecture from magnetic iron oxide nanoparticle building-blocks is for instance an ultra-lightweight hollow microballoon nano entity.[10] A further example of a complex particle architecture is anisotropic particle entities yielding highly fascinating optical effects, triggerable via magnetic manipulation.[11] [1] K. Mandel, F. Dillon, A. A. Koos, Z. Aslam, F. Cullen, H. Bishop, A. Crossley, N. Grobert, ?Customised transition metal oxide nanoparticles for the controlled production of carbon nanostructures?, RSC Advances, Vol. 2, pp. 3748 ? 3752, 2012. [2] K. Mandel, C. Kolb, M. Straßer, S. Dembski, G. Sextl, ?Size controlled iron oxide nano octahedra obtained via sonochemistry and natural ageing?, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 457, pp. 27-32, 2014. [3] W. Szczerba, J. ?ukrowski, M. Przybylski, M. Sikora, O. Safonova, A. Shmeliov, V. Nicolosi, M. Schneider, T. Granath, M. Oppmann, M. Straßer, K. Mandel, ?Pushing up the magnetisation values for iron oxide nanoparticles via zinc doping: X-ray studies on the particle`s sub-nano structure of different synthesis routes?, Physical Chemistry Chemical Physics, Vol. 18, pp. 25221-25229, 2016. [4] K. Mandel, F. Hutter, C. Gellermann, G. Sextl, ?Modified Superparamagnetic Nanocom-posite Microparticles for Highly Selective Hg(II) or Cu(II) Separation and Recovery from Aqueous Solutions?, ACS Applied Materials and Interfaces, Vol. 4, pp. 5633?5642, 2012. [5] K. Mandel, A. Drenkova-Tuhtan, F. Hutter , C. Gellermann, H. Steinmetz, G. Sextl, ?Layered double hydroxide ion exchangers on superparamagnetic microparticles for re-covery of phosphate from waste water?, Journal of Materials Chemistry A, Vol. 1, pp. 1840-1848, 2013. [6] A. Drenkova-Tuhtan, K. Mandel, A. Paulus, C. Meyer, F. Hutter, C. Gellermann, G. Sextl, M. Franzreb, H. Steinmetz, ?Phosphate recovery from wastewater using engineered superparamagnetic particles modified with layered double hydroxide ion exchangers?, Water Research, Vol. 47, pp. 5670-5677, 2013. [7] K. Mandel, F. Hutter, C. Gellermann, G. Sextl, ?Reusable superparamagnetic nanocom-posite particles for magnetic separation of iron hydroxide precipitates to remove and re-cover heavy metal ions from aqueous solutions?, Separation and Purification Technology, Vol. 109, pp. 144-147, 2013. [8] A. Drenkova-Tuhtan, M. Schneider, M. Franzreb, C. Meyer, C. Gellermann, G. Sextl, K. Mandel, H. Steinmetz, ?Pilot-scale removal and recovery of dissolved phosphate from secondary wastewater effluents with reusable ZnFeZr adsorbent @ Fe3O4/SiO2 particles with magnetic harvesting?, Water Research, Vol. 109, pp. 77-87, 2017. [9] T. Wehner, K. Mandel, M. Schneider, G. Sextl, K. Müller-Buschbaum, ?Superparamag-netic luminescent MOF@Fe3O4/SiO2 composite particles for signal augmentation by magnetic harvesting as potential water detectors?, ACS Applied Materials and Interfaces, Vol. 8, pp. 5445-5452, 2016. [10] T. Granath, A. Sanchez-Sanchez, A. Shemliov, V. Nicolosi, V. Fierro, A. Celzard, K. Mandel, ?Hollow Superparamagnetic Microballoons from Life-Like, Self-Directed Pick-ering Emulsions Based on Patchy Nanoparticles?, ACS Nano, Vol. 10, pp. 10347?10356, 2016. [11] K. Mandel, T. Granath, T. Wehner, M. Rey, W. Stracke, N. Vogel, G. Sextl, K. Müller-Buschbaum, ?Smart Optical Composite Materials: Dispersions of Metal-Organic Frame-work@Superparamagnetic Microrods for Switchable Isotropic-Anisotropic Optical Prop-erties?, ACS Nano, DOI: 10.1021/acsnano.6b07189.

Resume : We investigated the chemical sensing ability of three representative 2D materials (black phosphorus (BP), MoS2, and graphene) and firstly demonstrated superior chemical sensing performance of BP. In order to understand and to compare the sensing performance of each materials without any other control factors, identical fabrication process of the two-probe resistor type sensor was prepared with similar flake size distribution, film morphology, and molecular number. The dynamic sensing results onto various target gases showed that BP possessed about ten to twenty times higher molar response factor (~1870 %?mmole-1) than that of MoS2 (~150 %?mmole-1) and graphene (~100 %?mmole-1) sensors. Moreover, the response time of BP was about 40 times faster than the other 2D materials having percent per billion (ppb) level sensing ability of target analytes, which marks one of the most sensitive sensing performances compared to previously reported 2D materials based gas sensors. In addition, only BP showed highly selective response to NO2 molecules and unresponsive to oxygen functionalized molecules, while MoS2 and graphene have similar response to all the chemical compounds non-selectively. Theoretical calculations based on density functional theory (DFT) indicate that the superior sensing performance of the BP can be attributed to the higher molecular adsorption energy compared to the other 2D materials. In addition, ambient stability of our exfoliated BP sensor showed strong potential for practical sensing applications. With these superior properties in hand, it is anticipated that BP can lead the nano-sensing devices in the nearby future.

Resume : Graphene oxide (GO) is very promising material to develop a new class of high-performance sensing devices, due to the large surface area and the possibility to suitably functionalize it. GO contains different oxygen functionalities at the surface and edges of graphene flakes. Chemicals and thermal treatments can affect the presence of such oxygen groups modifying the conduction properties of GO. We studied the chemical, structural and morphological properties of GO and ethanol-treated GO (GOET) by SEM, electron energy loss spectroscopy, XPS and IR spectroscopy, before and after thermal treatment in the 60°C-300°C temperature range. The different GO materials were deposited between two electrodes by dielectrophoresis, in order to investigate the electrical conductivity in different environment conditions (air or N2) and temperatures (around room temperature). Proton conductivity is observed in GO due to the presence of epoxides only when the device is kept in air environment, indicating that a key-role is played by humidity. If GO is chemically or thermally treated, epoxides are removed and the dependence of the conductivity on the humidity is strongly suppressed. In this case, the temperature dependence observed can be a useful property to be exploited for temperature sensing applications such as in the case of freight of refrigerated materials (food, chemicals, drugs), where it is important to control temperature changes in a limited range around room temperature.

Resume : Synthesis and characterization of Single-Walled Carbon Nanotubes@silica nanocomposites applied to electrochemical sensing. Single-Walled Carbon Nanotubes (SWCNT) are remarkable materials by their outstanding properties that provide a wide range of applications, including electrochemical purposes as sensory devices or energy storage systems. However, the performance of SWCNT-modified electrodes is limited by the strong tendency of these system to form aggregates, that induces the loss of properties of these nanosystems. The present work shows how these SWCNT can be incorporated into silica matrices (SWCNT@SiO2) by electrochemical methods that avoids aggregate formation. In addition the silica layer allows the permeation of the redox active species to the electrode surface and improves the electrochemical reversibility indicating an electrocatalytic effect to several standard redox probes. As silica presents dielectric character the present study is also focused in the functionalization of the inert matrix with a conducting polymer (PEDOT-PSS) that improves the electron transfer between the electrode and the redox species in solution. In that manner, we performed the synthesis of new electrode hybrid materials prepared from an inorganic silica sol-gel matrix and an organic conducting polymer. The hybrid material presents an improved performance towards electrochemical reactions and allows the development of highly sensitive electrochemical sensors.

Resume : Transition metal oxides have attracted much interest not only due to their fundamental scientific issues but also their various technological applications such as environment-, energy- and bio- materials. WO3 among those oxides have wide-ranging applications such as, gas sensors, electrochromic for smart window, and photo-catalyst etc.. In this presentation, WO3 nanorods have been synthesized by microwave-assisted hydrothermal methods at various temperatures (150 ~ 210 oC) using sodium tungstate (Na2WO4·2H2O) as a precursor material. In order to fabricate one-dimensional nanorods, we have added a directional capping agent of citric acid during the preparation of solution. The morphology and structure of synthesized WO3 samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction technique, and BET methods for surface area measurements. Finally, dye-adsorption properties were investigated by simple UV-vis absorption methods depending on process-duration times by using methylene-blue (MB) organic dyes. To understand correlation between the surface area and the adsorption capacity of WO3 nanorods, Langmuir modeling was applied, resulting in good agreements between them.

Resume : One of the major challenges in nanomedicine is to develop nanoparticulate systems able to serve as efficient diagnostic and/or therapeutic tools against sever diseases, such as infectious or neurodegenerative disorder. The most powerful diagnosis toll in medical science is MRI (magnetic resonance imaging). To enhance MRI images interpretation, contrast agents were developed to clarify images. Among them Superparamagnetic iron oxide (SPIO) nanoparticles have received a great attention since their development as a liver contrasting agent 20 years ago1. Furthermore, their nanoparticulate properties represented by the nanosized dimension and shape allow different biodistribution and opportunities beyond the conventional imaging of chemical agents. The opportunity to coat those biocompatible NPs by a polymer shell that can ensure a better stability of the new materials in the body, enhance their biodistribution and gives them new functionalities appear as very challenging for medicinal applications2.We have thus in this work developed new responsive SIONPs that are able carry the anticancer drug doxorubicin (DOX)and release it in physiological media at physiological temperature. Two family of nanoparticles were synthesized, the first one consist in superparamagnetic Fe3O4 nanoparticules were functionalized by a biocompatible responsive copolymer based on2-(2-méthoxy) éthylméthacrylate (MEO2MA), oligo (éthylène glycol) méthacrylate (OEGMA), which lead to Fe3O4@P(MEO2MAx-OEGMAy). The second family consists in the same nanoparticles as previously mentioned, but we have covalently grafted biological cancer targeting molecule at the chain end, i.e the folic acid. For the first time, P(MEO2MAx-OEGMAy)was grown by activator regenerated by electron transfer–atom transferring radical polymerization (ARGET-ATRP) from Fe3O4 by surface-initiated polymerization. The core/shell nanostructures were fully characterized by the combination of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and by the physical properties of the nanostructures studied. We demonstrate the efficiency of the Atom Transfer Radical Polymerization with activators Regenerated by electron Transfer (ARGET-ATRP) process to graft polymers and copolymers at the surface of Fe3O4 nanoparticles. The influence of the polymer chain configuration (which lead to the aggregation of the NPs above the collapse temperature of the copolymer (LCST)) We could show that the magnetic properties of the core/shell Fe3O4 based nanostructures, only the amount of the grafted polymer plays a role on the saturation magnetization of the NPs, and no influence of the aggregation was evidenced. This simple and fast process developed in this work is efficient for the grafting of various co-polymer from any surfaces and the derived nanostructured display the combination of the physical properties of the core and the macromolecular behavior of the shell. The drug release experiments confirmed that only the DOX largely released above the co-polymer LCST. From the results obtained, it can be concluded that our new nanomaterials can be considered for further use as multi-modal cancer therapy tools.

Resume : Surface enhanced Raman spectroscopy (SERS) is a label-free and non-destructive vibrational spectroscopy technique that allows for ultrasensitive and fast structural detection of trace-level molecules through the enhanced electromagnetic (EM) fields amplified by the excitation of localized surface plasmon Resonances (LSPR). Compared to conventional rigid SERS substrates, e.g. glass and silicon, flexible substrates provide flexibilities of configurable assembly which is critical to the applications such as on-line trace level detection. In addition, large-scale production is another concern for reducing cost. Surface enhanced Raman spectroscopy (SERS) is a label-free and non-destructive vibrational spectroscopy technique that allows for ultrasensitive and fast structural detection of trace-level molecules through the enhanced electromagnetic (EM) fields amplified by the excitation of localized surface plasmon Resonances (LSPR). Compared to conventional rigid SERS substrates, e.g. glass and silicon, flexible substrates provide flexibilities of configurable assembly which is critical to the applications such as on-line trace level detection. In addition, large-scale production is another concern for reducing cost. In this work, we demonstrate a new type of double-sided, large-scale, and flexible metasurfaces for ultrasensitive, highly uniform, polarization-independent SERS detection. The SERS substrates are fabricated by simply sputtering densely packed gold nanoparticles on porous polycarbonate membranes which composed of conical pores created by asymmetric etching of ion tracks. Morphological characterizations reveal that the conical pores are uniformly distributed on both sides of membranes and uniform in shape and size. The porous polycarbonate membranes are covered with granular gold films which typically have sub-5 nm gaps among adjacent particles. Such metasurfaces show ultrasensitive SERS detection limit down to 10 pM which is comparable to the reported highest value (1 pM) for flexible substrates. The high uniformity is reflected by a low relative standard deviation (RSD) ~10% over the entire wavenumber range (300-1800 cm-1). Numerical simulations disclose that the enhanced EM fields of granular gold films are further amplified by conical pores. Such hierarchical metasurfaces represent a step forward to low-cost, high performance, and reliable flexible platforms for ultrasensitive SERS detection.

Resume : In this study, two kinds of piezoelectric polymer materials, poly(vinylidene fluoride) (PVDF) and Nylon-11 are introduced to harvest the mechanical energy when they contact with each other. The scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transfer infrared spectroscopy (FTIR) techniques were used to explore their morphologies and influences of electrospinning on their structure changes. It was confirmed that the β phase of PVDF and the γ phase of Nylon-11 were favorable for the improvement of their piezoelectric performances. And the strong negative triboelectric polarity from PVDF and the positive triboelectric polarity from Nylon-11 could help them produce the larger output voltage when they contacted with each other. These results imply promising applications for practical energy harvesting devices and wearable self-powered sensors.

Resume : We have synthesized molecular precursors for a decade for the application to chemical vapor deposition including MOCVD and ALD. The synthetic strategy of molecular precursors can also be applied for the synthesis of nanao-materials such as metals, metal oxide, and semiconductors. In this presentation, we will discuss the synthesis and characterization of designed molecular precursors of Cu, Zn and Sn including aminothiolate ligand. Thermolysis of each molecular precursor has been studied. Finally, thermolysis of three precursors together resulted in the formation of nanocrystalline CZTS (Cu2ZnSnS4).

Resume : Nanodiamonds embedding nitrogen vacancy (NV) centers have been emerging as nanoscale quantum probes for bio-sensing and imaging due to the stable fluorescence and biocompatibility. To fully exploit the capability of the NV electron spins for diverse applications potentially in bioscience, individual manipulation of their positions and orientations in fluids are essentially needed. However, current methods such as scanning probe techniques [1], optical tweezers [2], and Anti-Brownian Electrokinetic trap [3] are still limited to ?passive approaches?. Here, we developed a novel strategy to fabricate active nanodiamond (ND) swimmers, composed of a ND crystal and a light-driven self-thermophoretic motor. Three-dimensional shaping of the swimmers, enabling to manipulate their locomotion by geometry-dependent hydrodynamic interactions in fluids, is successfully achieved by glancing angle deposition (GLAD) method [4]. Here, we present our results and discuss the prospects of our work for potential applications in various vector metrologies in highly viscous fluids, potentially for biological systems. [1] Degen, C. L. Appl. Phys. Lett. 92, 243111 (2008). [2] Geiselmann, M. et al. Nat. Nano. 8, 175 (2013). [3] Kayci, M. et al. Nano Lett. 14, 5335 (2014). [4] Mark, A. G. et al. Nat. Mater. 12, 802 (2013).

Resume : Enhancing the large-scale use of electrochemical energy storage and conversion technologies through water splitting requires low-cost, efficient, and robust electrode materials for the oxygen evolution reaction (OER). The development of non-precious metal-based materials is a promising way to synthesize new catalysts for the OER. One main challenge is to increase the kinetics of this reaction that is slow due to high overpotentials. Cobalt-based nanoscale perovskite structures are promising catalysts and have recently demonstrated high catalytic activity towards OER [1]. Spray-flame synthesis allows tuning materials characteristics such as composition, particle size, and morphology over a wide range. So far, spray-flame synthesized LaCoO3 nanoparticles and the influence of partial substitution of Co by other transition metals on the OER has not been studied in detail. The motivation of this study is to synthesize and optimize the tailored formation of LaCoO3 and LaCo1 xFexO3-based nanoparticles by spray-flame synthesis. Using this technology, we are able to vary the particle size as well as the elemental composition. Particles with a size down to 10 nm in diameter could be obtained. Fe is homogeneously incorporated into the LaCoO3 phase during the synthesis with variable concentration. We identified that residuals of the combustion products partly cover the nanoparticles? surface, which can be removed by heat treatment at 250°C. This post-treatment improves the phase purity and the catalytic activity of the nanoparticles for the OER. The materials are processed by spin coating on an electrode support and characterized by TEM, XPS and a variety of electrochemical techniques. Key words: Oxygen Evolution Catalysts, Perovskites, Spray-flame Synthesis [1] Suntivich, J., A Perovskite Oxide Optimized for Oxygen Evolution Catalysis from Molecular Orbital Principles, Science 334:1383-1385 (2014).

Resume : The concept of all-polymeric yolk-shell nanocapsules as a tunable platform for designing hierarchically nanostructured catalysts is demonstrated. Such nanocapsules are investigated for catalytic CO oxidation. Polyaniline yolk-shell nanocapsules are synthesized in one-pot, without template and characterized by UV-Visible, IR, XRD, DLS, BET, TEM and EDS analysis. Yolk and shell parts of nanocapsules can be selectively doped: yolk-trapping of copper ions allows the in-situ synthesis of yolk-confined copper NPs. Hierarchical co-loading with gold (shell) and copper (yolk) can also be performed. By investigating the catalytic activities of all possible architectures with Cu and Au, the benefits of controlling the catalyst nanostructure and its hierarchical loading are demonstrated. Both confinement and cooperative effects are measured with a respective increase of catalysis performances of 2 and 7 times. Nickel can be loaded in the yolk part instead of copper, and platinum (shell) instead of gold, demonstrating that this catalyst design strategy is adaptable. A similar trend for catalysis performances is obtained with nickel based catalysts. Due to its polymeric nature, this yolk-shell platform is anticipated to be able to trap a large variety of catalytic centers, allowing on-demand design of catalysts. Applications for gas catalysis, electrocatalysis, fuel cells, and water splitting are anticipated. Ref: 1- Sanchez, Rydzek* et al.Nanostructured Polymeric Yolk-shell Capsules: a Versatile Tool For Hierarchical Nanocatalyst Design, JMCA, 4, 9850-9857

Resume : The mechanisms of dynamic adsorption and desorption of oxygen of nanocluster-assembled ZnSe film were studied through measuring and modeling the change of photocurrent, Iph, observed in oxygen-containing atmosphere under UV exposure. The film sample was prepared by selenizing a nanocluster-assembled supersonic-cluster-beam-deposited metal Zn film in Se vapor at 200 mTorr and 500°C for 1 hr. The film was composed of nanoclusters with sizes below 90 nm. Formation of the ZnSe phase was identified by Raman peaks at 248.1 and 493.7 cm-1 (LO modes), and 204.4 cm-1 (TO mode) of crystalline ZnSe. For measuring the dynamic Iph of the film to O2, the film was first placed in 0.01 - 21% of O2 concentration balanced in argon. UV light was then turned on to shine on the film surface. The recorded time dependent Iph exhibited different rising rates and asymptotic limits depending on the O2 concentration. In particular, the sensor response S  (asymptotic Iph - dark current Id)/Id dropped from 194 to 0.285 with increasing O2 concentration in the specified range. A time-dependent model, incorporating photo generation and recombination of electron-hole pairs, adsorption and desorption of oxygen species, was proposed to interpret the results. Calculated results reproduce the observed time variation of Iph detected at different O2 concentrations. Characteristic parameters like adsorption rate constant and recombination rate constant of the system used in the model were also determined.

Resume : In recent years, there has been a great interest in the development of layered double hydroxides (LDHs) oriented for applications in catalysis, in pharmaceutical and environmental technology. LDHs combine a number of advantages including their layered structure, large surface area, high anion exchange capacity, good chemical stability and low preparation cost. Especially, their ability to host anions in the interlayer spacing initiates their potential to provide high surface charge density and ion-exchangeability for the removal of heavy metals from water. In this work, we study Fe/Zn and Fe/Sn LDHs as candidate adsorbents in water purification for the uptake of arsenic, antimony and hexavalent chromium. The tested materials were synthesized by the co-precipitation of divalent/trivalent metal salts at alkaline conditions. The role of metals ratio, synthesis pH and various intercalated anions (CO3-, NO3-, SO42-) in the obtained chemical composition and crystal structure was investigated by means of X-ray diffraction (XRD), chemical analysis and electron microscopy techniques. Batch adsorption experiments were performed to evaluate their potential to operate as efficient heavy metal adsorbents able to reduce residual concentration below drinking water regulation limits. Adsorption mechanisms were examined by X-ray photoelectron spectroscopy (XPS). This work has been supported by EU in the framework of the NetFISiC project (Grant No. PITN-GA-2010-264613).

Resume : Smart capsules, like polyelectrolyte capsules, have shown great potentials for various biomedical applications1,2, such as the delivery of enzyme. However, activity of enzyme encapsulated in capsules fabricated by conventional methods can be deteriorated due to the unfavorable conditions involved. Previously, we have reported the fabrication of polyelectrolyte capsules based on aqueous two-phase system3. Control over the assembly of polyelectrolytes at water-water interfaces creates a biocompatible environment for fabricating polyelectrolyte capsules. The resultant capsules are smart that they show stimuli-responsiveness towards various external stimuli. In this work, we demonstrate the use of our fabricated polyelectrolyte capsules for encapsulating enzymes. β-amylase is used as the model enzyme for illustrating the ability of our approach in preserving the enzymatic activity following encapsulation. Our results suggest that the assembly of polyelectrolytes at water-water interfaces results in a biocompatible and mild environment for preserving the activity of the encapsulated enzymes. REFERENCES: 1. “Nanoengineering of inorganic and hybrid hollow spheres by colloidal Templating” F. Caruso, R.A. Caruso, H. Möhwald, Science 1998, 282, 1111-4. 2. “Layer-by-layer assembly of microcapsules and their biomedical applications” W. Tong, X. Song, C. Gao, Chem. Soc. Rev. 2012, 41, 6103. 3. “Affinity Partitioning-Induced Self-Assembly in Aqueous Two-Phase Systems: Templating for Polyelectrolyte Microcapsules” Q. Ma, Y. Song, J. W. Kim, H. S. Choi, H. C. Shum, et al. ACS Macro Lett., 2016, 5, 666-670.

Resume : Metal ?loaded ceria-zirconia oxides are promising catalysts for transformation of biogas/biofuels into syngas if spatial uniformity of Ce and Zr cations distribution in oxide domains is ensured. In this work procedures for synthesis of mixed Ce1-xZrxO2-? oxides (x=0.3÷ 0.7) in supercritical alcohols (butanol, isopropanol) in flow conditions with addition of acetylacetone as complexing agent were successfully developed. NiO was loaded by impregnation. The real structure and surface properties of samples were studied by XRD on SR, TEM with EDX, neutronography, EXAFS, WAXS, UV-Vis, XPS, FTIRS of adsorbed CO, oxygen mobility ?by oxygen isotope heteroexchange with C18O2. Catalytic activity in CH4 dry reforming was estimated in feeds with CH4 and CO2 content up to 20%, details of mechanism were studied by pulse microcalorimetry. Single-phase nanocrystalline mixed oxides with uniform spatial distribution of Ce and Zr cations prepared by optimized procedures and loaded with up to 10wt.% Ni demonstrate a high activity and coking stability. This is provided by a strong Ni-support interaction and a high oxygen mobility in CeZrO nanodomains ensuring operation of effective redox mechanism with independent stages of CH4 activation on Ni, CO2-on the surface vacancies of CeZrO producing CO and strongly bound bridging oxygen forms (Qads 650 kJ/mol O2), which rapidly migrate to Ni ?support interface and oxidize CHx species into CO+H2. Support by NiCe project is gratefully acknowledged.

Resume : Interfacial effects play a key role in magnetic properties of magnetic nanostructures. Symmetry breaking at interfaces, charge and spin transport through interfaces are strongly affected by the properties of the interfaces. In this study, we correlate the growth and the interface quality of Fe/Pt bilayers with its magnetic properties. Ultrathin films with a constant Fe thickness of 12 nm were grown on MgO substrates by means of electron-beam evaporation technique at different growth temperatures. We examine the role of Pt thickness (1-18 nm) in the microstructural details of the crystal lattices as a way to manipulate magnetic anisotropy and spin transport at the interface. Local structure and interface diffusion study was achieved by analyzing results obtained from X-Ray Diffraction, X-Ray Photoelectron Spectroscopy and High-Resolution Transmission Electron Microscopy. We show that the degree of the epitaxy of the interface influences the magnetic hysteresis loops and the magnetization dynamics of the bilayers. This work has been supported by EU in the framework of the NetFISiC project (Grant No. PITN-GA-2010-264613). IKYDA 2015 program is gratefully acknowledged for the financial support to conduct the research.

Resume : The discovery of giant magnetoresistance provided the opportunity for using electron spin as means of information transport, processing and storage (spin valves, MRAMs). Nowadays, the field of magnonics that refers to use of spin currents carried by spin waves, promises further development in information transport and processing technologies. In this work, we study the structural properties and transport of spin currents through an MgO spacer in Fe/MgO/Pt trilayers. Samples were epitaxially grown on MgO substrates by electron-beam evaporation technique, keeping a constant thickness of Fe (12nm) and Pt (6nm) layers. The effect of MgO-interlayer thickness (0.5-2 nm) on the structural features was analyzed by means of X-Ray Diffraction (XRD) measurements in comparison with images by High-Resolution Transmission Electron Microscopy (HRTEM). Moreover, the impact of the dielectric spacer on the magnetic properties was investigated by SQUID magnetometry measurements while the magnetization dynamics behavior was studied with ferromagnetic resonance technique (FMR) and inverse spin Hall effect (ISHE). We show that a very thin MgO layer up to 2 nm thickness only partially blocks the spin current transport. Support by EU in the framework of the NetFISiC project (Grant No. PITN-GA-2010-264613) and IKYDA 2015 program is gratefully acknowledged for the interdepartmental research.

Resume : Vanadium carbide (VC) is one of the promising precious-metal-free catalysts for the hydrogen evolution reaction (HER) which produces clean and renewable hydrogen as an alternative to fossil fuels. Hybridization between the V atoms and p-orbitals of the C atoms produces metallic properties and similar electronic and catalytic properties with the Pt-group metals. In this presentation, we report the design and fabrication of a hierarchical nanosheet structure comprising isolated vanadium carbide nanoparticles encapsulated in a highly conductive mesoporous graphitic carbon network (VC-NS). The unique structure has a large specific surface area and highly efficient HER activity. The VC-NS hierarchical nanosheet structure is synthesized by a hydrothermal reaction and subsequent low-temperature and environmently-friendly magnesium thermic reaction. The electrochemical performance of the VC-NS hierarchical nanosheets is evaluated electrochemically based on a three-electrode system. The results demonstrate that many nanoparticles with diameters of 10-30 nm are encapsulated in the graphitic carbon network forming a 2D hierarchical nanosheet structure with a large number of exposed active sites thereby providing fast electron transport paths and good electrical contact with the acitve sites to facilitate HER. The hierarchical VC-NS electrocatalyst shows an overpotential of only 98 mV at a current density of 10 mA cm-2 with a small Tafel slope of 56 mV dec-1. On account of the excellent durability, the overpotential shifts by only 10 mV after 10000 CV scans at a current density of 80 mA cm-2. The precious-metal-free electrocatalyst, which can be mass produced economically with less environmental impact than common precious-metal based electrocatalysts, delivers outstanding HER performance and has large potential in HER and related energy generation schemes.

Resume : Temperature-sensitive materials (TSMs) attract a lot of attention in recent years. The physical properties of TSMs can be tuned by temperature. Among TSMs, room-temperature switchable materials (RTSMs), which responses automatically around room temperature, is more interesting for researchers. Because they have great potentials in smart switches, smart building, high sensitive sensors, automatic filters, energy storage and can be used in daily life. In this paper, we prepared the room-temperature switchable materials by dispersing chemical functionalized CNTs into hexadecane. The DC conductivity, thermal conductivity and dielectric constant of RTSMs can be regulated simultaneously in a narrow temperature range around phase change point (18?C). By changing the volume fraction of octadecylamine-grafted MWCNTs in hexadecane, the switching ratio of DC conductivity, thermal conductivity and dielectric constant reaches 5 orders of magnitude, 3 times and 106.4, respectively. To our best knowledge, it is the highest switching ratio at room temperature in existing materials. The multifunctional switch is caused by the rearrangement of the fillers in hexadecane matrix during phase transition. During the freezing course, the fillers are squeezed into the grain boundaries of solid matrix to form percolating conducting networks. The conducting networks enhance the electrode injection, improve the interior electron migration and decrease the interface resistance at the same time. The interface between filler and solid matrix give rise to strong Maxwell-Wagner relaxation. These reasons make the DC conductivity, thermal conductivity and dielectric constant of frozen sample increase a lot. When the composite is remelting, the re-dispersion of fillers results in the DC conductivity, thermal conductivity and dielectric constant of sample decreasing again. The switch shows good stability during temperature cycles. The switching ratio can be easily regulated by the volume fraction of filler and temperature ramping rate. By using different long chain alkane as matrix, other multifunctional switchable composites with various trigger temperature can be easily achieved.

Resume : Multi-metallic nanoparticle-contained magnetic iron oxide nanoneedles (mIO-M, M=Au and/or Ag, and/or Pt) were successfully synthesized by a successive coating of polydopamine, noble metal nanoparticles (NP), and iron oxide nanoneedles on magnetic core. The structure of the mIO-M was characterized using field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). By controlling composition of the noble metal ion precursors, mono-metallic, di-metallic and tri-metallic mIOs could be prepared. The mIO-Ms exhibited an excellent performance of catalytic activity for the reduction of 4-nitrophenol showing that the reduction was completed within 3 ~ 15 min depending on the composition of the NPs and the thickness of the polydopamine layer. Tri-metallic mIOs (mIO-Au/Ag/Pt) showed the best catalytic activity due to the synergetic effects between multi-metals, and the catalytic efficiency increased as the thickness of the polydopamine layer increased. Moreover, the excellent magnetic property of mIO-M made it simple to recover from the solution by an external magnetic field and to be effectively reused. It observed that the mIO-M was reusable up to 5 times without loss of the catalytic efficiency. The catalytic effects on the different composition and content of the metal NPs and the pHs will be further presented.

Resume : Nanoparticles (NPs) are a powerful platform for the development of novel imaging probes with unique features that can be tuned by control of their components and design. Organic-inorganic hybrid NPs, in particular, offer the possibility of combining the properties of their constituents into one material, e.g. the stability of silica with the hydrophobicity of organic domains, ideal for incorporation of organic dyes. Here, we report a new class of organic-inorganic hybrid NPs comprised of a polyetheramine core bound to a siloxane shell via urea bridges, using a novel synthetic approach which combines nanoprecipitation4 and the Stöber method. Our approach initially yields NPs with a relatively low colloidal stability in water, which can be greatly improved by addition of tetraethylorthosilicate, which generates a core-shell nanoarchitecture with ~150 nm diameter and polydispersity index of ~0.15. The NPs are intrinsically weakly photoluminescent, which can be further enhanced through doping with an extrinsic fluorophore for imaging applications, either through (1) the non-covalent encapsulation of organic dyes (pyrene and coumarin C153) via hydrophobic interactions or (2) covalent grafting of fluorescein isothiocyanate (FITC) to the siliceous domains of the NP. While physical incorporation led to leaching of the dye with time, FITC-grafting resulted in a good doping level, which was retained even upon dialysis, showing the potential of these NPs for imaging applications.

Resume : The water splitting process with electrocatalytic and photocatalytic, as one of the next generation energy conversion technology for producing hydrogen and oxygen molecules have been widely considered candidates to solve energy and environmental problems. Up to date, precious metal based oxide materials (RuO2 and IrO2) as the efficient active catalyst for the half reaction of the oxygen evolution reaction (OER) have been used, however, the high cost, poor stability, and scarcity of these metals hinder their widespread practical and technical use. Hence, extensive research activities have focused on the inexpensive earth-abundant metal based materials such as multi-composite transition metal (Ni, Fe, Mn Co, Mn, etc.) compounds (nitride, oxide and hydroxide) as candidate catalysts for efficient OER electrocatalyst. For the most Co based materials (semiconductors and insulators), the poor intrinsic conductivity lead to limit efficient OER performance. Surprisingly, metal nitrides (Co-Mo-N, Ni2Fe2N, Ni3N and CoxN) with metallic properties show high electrocatalytic abilities towards the HER and OER due to the superior intrinsic conductivity. Despite their promising OER performance, one of the challenging issues to improve electrolytic property is thus control of the morphology and shape including highly exposed reaction sites, surface permeability and enhanced cycling performance. In this study, we focused on the monodispersed and mesoporous CoxN nanocubes based on simple nitridation via Prussian blue analogue (PBA) of Co3[Co(CN)6]2 nanocube precursors for efficient OER application.

Resume : Synthesis of pure carbyne crystal or long isolated carbon chains presents a major technological challenge due to instability of sp1 carbon. Therefore the production of macroscopic carbyne-based material is not demonstrated yet. One of possible ways is the ion-assisted condensation of carbyne-like linear sp1 carbon chains (LCC), ordered in a hexagonal structure with 0.5 nm interchain distance. LCC has been obtained and studied by a plenty of techniques [2]. The main problem is the lack of rapid characterization technique confirming structure of new material. AFM, TEM, XPS and electron diffraction are not suitable for macroscopic volumes. Conversely, the Raman scattering is capable to detect carbon chains [3] and describe C-C bond type distribution. This work is aimed to combine the experimental and calculated Raman spectra for the straight and helical carbyne crystal structural model. The influence of (100) and (111) copper substrates is taken into account. DFT calculations establish the dependence between chain structure, phonon frequencies and Raman susceptibilities, giving interpretation to experimental Raman bands. As a sample system, we used the 20 ? 400 nm films of chains on copper substrate synthesized by ion-assisted condensation in a high vacuum where the flows of carbon and Ar gas ions impinge on the substrate. 1. C.H. Wong et al. Carbon, 114, pp. 106-110 (2017). 2. F. Innocenti et al. J. Raman Spectrosc. 41, 226-236 (2010).

Resume : The versatile properties of the LaCoO3 perovskite nanomaterial have led to the utilization of this material in multiple applications such as gas sensing, reforming of methane using CO2, and catalytic oxidation of hydrocarbons and CO. The synthesis of these materials is usually done in batch processes using wet chemical routes with post-treatment. Aiming to prepare a functional LaCoO3 nanomaterial in a single step and in a cost-effective way, spray-flame synthesis is investigated as a synthesis route. This continuous gas-phase technology allows to synthesize mixed oxides in large quantities with improved structural and catalytic properties. In this work, the spray-flame synthesis of perovskites based on low-cost metal precursors (nitrates) is addressed. The challenges concerning a functional material with specific properties include the avoidance of secondary phases and the formation of a homogeneous material. We demonstrate that the use of polymeric solvents effectively avoids the formation of secondary phases. We attribute this to the creation of metal complexes by combining chelating agents and a polyol. We suppose that this combination undergoes an intermediate esterification reaction in the liquid phase when heated. For improving the particle size homogeneity, micro-explosions inducing solvents such as 2-ethylhexanoic acid were successfully used. It is shown that the obtained crystallite sizes range from 12 to 40 nm with morphologies depending on the selected solvents.

Resume : As commercial interest in flexible power-conversion devices increases, the demand for high-performance alternatives to brittle inorganic thermoelectric materials is ever growing. As one possible candidate, carbon nanotube yarn (CNTY) shows great potential for use in flexible thermoelectric materials because of its high electrical conductivity and controllable Seebeck coefficient. In this study, we demonstrate a flexible and ultralight thermoelectric generator based on CNTY with excellent thermoelectric performance. A flexible thermoelectric generator based on 60 pairs of n- and p-doped CNTY shows the maximum power density of 10.85 and 697 μW/g at temperature differences of 5 and 40 K, respectively. Our results provide a new direction for the preparation of flexible/or wearable power conversion devices.

Resume : The CO2 removal from flue gases using unconventional techniques based on membranes, known a significant interest in industry. Mixed matrix membranes combine the advantages of organic (easily processable and low cost) and inorganic phases (high selectivity, mechanical resistance, chemical and thermal stability). In this study, polysulfone incorporated with mesoporous inorganic materials MCM-41 were proposed. MCM-41 with 1160.878 m2g-1 specific surface area and 3.8 nm pore size were obtained and used as inorganic filler. The mixed matrix membranes were prepared by casting method. The effects of MCM-41 loading (5-20 wt.%) on the membrane characteristics were studied using SEM, XRD, TGA, while the gas transport properties were investigated using pure gas permeability tests of CO2 and CH4 and also gas mixtures permeation tests of 10vol%CO2/90vol%N2. The TGA analysis confirmed that the membranes are appropriate for operating at high-temperature condition, the complete degradation of polymeric chain being achieved after 650 °C. Well dispersion of MCM-41 particles in the polymer matrix was observed for 10 wt.% of MCM-41 into PSF membrane, in comparison with 20 wt.% of MCM-41 in PSF membrane where particles agglomerations were visible in SEM images. Even if the inorganic particles adhered each other the obtained membranes PSF/20 wt.% presented an ideal selectivity up to 41.52 and a real selectivity up to 45.06 for CO2/N2.

Resume : ZnO nanowalls (NWLs) represent a nontoxic, abundant, and porous material, with promising applications in low-cost, environmental friendly sensing devices. By using chemical bath deposition (at 70?95 °C), ZnO NWs grow vertically on Al (covered) substrates or contacts, with an intertwined, honeycomb-like pattern and c-axes parallel to the substrates, producing a huge surface-to-volume ratio and extremely thin wall thicknesses [1]. This work focuses on the synthesis and gas sensing properties of ZnO NWs grown ?in situ? on conductometric platforms consisting of an alumina substrate provided with Pt interdigitated electrodes. Post-deposition annealing enabled tailoring the film morphology and crystallinity of ZnO nanowalls. An extensive characterization was made to investigate the composition, morphology and microstructure of the nanowalls layer formed. The gas sensing properties of the films were investigated by measuring the changes of electrical resistance upon exposure to different gases. The sensor response to CO or NO2 was found to be deeply dependent on the post-annealing and operating temperature, providing a means to tailor the sensitivity and selectivity toward the target gases. The origin of these effects, the gas sensing mechanisms and the surface and bulk processes underlying the variations of the carrier type and affecting the sensing properties are highlighted. [1] K. Iwu, V. Strano, S. Mirabella et al. Crystal Growth and Design (2015)

Resume : Since the synthesis and characterization of lithium cation endohedral metallofullerene (Li+@C60) [1], several investigations have been performed on the application of Li+ @C60 to the functional materials [2]. The essential structural features of Li+@C60 would be as having lithium cation inside the spherical empty space of C60 fullerene. However, due to the low electron density related to the positional and dynamic disorder of the Li+, previous researches faced the limitations of the detailed information of the Li+. In the present work, we investigated the structure of Li+@C60 using powder neutron diffraction measurement at low temperature (3.7 K) with the IBARAKI Materials Design Diffractometer (iMATERIA) in J-PARC. Moreover, we studied the energy storage characteristics of Li+@C60 capacitor. The use of the neutron diffraction allowed us to determine the precise position of the nuclei of Li+ in the fullerene cage. The distance from the center of the benzene rings of the fullerene to the Li+ was 1.279 ?. In addition, the Li+ showed disorder over two positions with a refined occupancies of g = 0.5 and (1-g) = 0.5. And the energy stored by an ortho-dichlorobenzene solution of Li+@C60 (Li+@C60/o-DCB) capacitor was greater by several times than that stored by an ortho-dichlorobenzene solution of tetrabutyl ammonium (TBA+/o-DCB) capacitor under the same conditions. Furthermore, the charging speed of Li+@C60/o-DCB capacitor was faster than that of TBA+/o-DCB capacitor. This would originate from the weak solvation of Li+@C60 by the solvents. [1] Aoyagi, S. et al.; Nature Chemistry 2012, 2, 678, [2] For recent reports, see: K. Ohkubo et al.; Chem. Commun., 2013, 49, 7376, K. Kokubo et al.; Nanoscale, 2013, 5, 2317. [3] Ishigaki, T. et al.; Phys. B 2006, 1022, 385, Ishigaki, T. et al.; Nucl. Instrum. Methods Phys. Res., Sect. 2009, A 600, 189.

Resume : Amorphous chalcogenide materials provide numerous applications in the electronics, photonics and sensor fields. The last one, i.e. sensor field, is the focus of our research activity. In this framework, the development of new and more efficient sensors requires a rigorous methodology to determine all the relations between the composition, the structure, and the ionic/electronic transport properties in the solid material as the improved response of the sensors is ultimately directly correlated to all these characteristics and properties. Among the materials suitable for (i) the investigation of the composition-transport-structure correlations and (ii) the development of chemical sensors, are the silver-halide doped chalcogenide materials with high Ag ionic conductivity at room temperature. To this end, we have synthesized and characterized the (AgBr)x(As2S3)1-x (0.0 ≤ x ≤ 0.6) alloys that are amorphous up to x = 0.5. The density increases monotonically with x, while Tg decreases from 193 to 115 °C. The ionic conductivity increases by 13 orders of magnitude with increasing Ag ion concentration (max. Ag at. % = 14.3) while the activation energy decreases from ~ 1 to 0.3 eV. Two distinctly ion transport regimes, above the percolation threshold at xc, are distinguished and the origin of the conductivity changes is mostly structure-related. Preliminary results of high-energy X-ray diffraction and neutron diffraction will be presented for various samples.

Resume : A PH sensor based on Single Wall Carbon Nanotubes (SWCNTs)-polycarbazole(PCz) was fabricated by dropcasting the active layer between two gold electrodes printed on a transparent support. Functionalized SWCNTs were mixed with chemically polymerized Carbazole and then characterized by Atomic Forced Microscopy (AFM), Scanning Electron Microscopy (SEM) and Fourier Transformed Infrared spectroscopy (FT-IR). The obtained structure was tested in different solutions, having PH ranging from 1 to 13, determining its PH response by measuring the open circuit potential. The PH solution was calibrated with a high resolution PH-meter. The results showed a linear and reversible response, a good sensitivity and stability. This study shows that SWCNTs-polycarbazole based PH sensor can be a potential candidate for a PH bio-chemical sensor

Resume : Anthropogenic emission of carbon dioxide lead to greenhouse effect, global warming and ocean acidification. Therefore, how to reduce the emission of CO2 and convert CO2 into more reduced chemical species have been holding special attractions for researchers. MnO2 possesses advantages of low cost, environmental friendliness and high catalytic activity toward electrochemical reduction so as to be widely used as electrocatalysts in the process. The objectives of this study were to synthesize effective electrodes baes on alpha-MnO2 catalysts and then be used to electrochemically reduce CO2 into useful products. Firstly, MnO2 was prepared via hydrothermal method. Then, the conductive glass of ITO (indium tin oxide) and CNTs (carbon nanotubes) grown carbon fiber (CNTs/CF) were used to load alpha-MnO2 via spinning coating so as to synthesize the electrodes of alpha-MnO2/ITO and alpha-MnO2/CNTs/CF, respectively, in which the growth of CNTs on carbon fiber was via catalytic chemical vapor deposition. The final electrode products were obtained via calcination under 603K for 30 mins after spinning coating of MnO2. The physicochemical properties of obtained materials in this study were determined by TEM, SEM, XRD, CV and LSV. The electrochemical activity of obtained electrodes was conducted in saturated CO2 solution with the electrolyte of 0.5 M KHCO3. The main reduced compounds generated during the electrochemical reduction of CO2 were methane and carbon monoxide in this study.

Resume : In this paper we report the preparation of an assembly of iron nanoparticles inserted into vertically-oriented carbon nanotubes. They are prepared by the injection CCVD method with ferrocene as Fe precursor. By this process iron particles are continuously incorporated into the growing CNT films. We report the preparation, the structural and the chemical characterizations of the Fe@CNTs array by TGA, XPS, TEM, SEM, XRD, Raman spectroscopy, as well as the magnetic properties investigated by SQUIDD. Iron nanoparticles are mainly made up of cementite Fe3C. The magnetic properties osf such assembly were investigated either with the magnetic parallel or perpendicular to the direction of the carbon nanotubes [1]. Main results may be explained by the preferential anisotropy of the nanoparticles along the direction of the carbon nanotubes. [1] “Manifestation of the coherent magnetic anisotropy in carbon nanotubes matrix with low content of ferromagnetic nanoparticles” Danilyuk A.L., Komissarov I.V., Labunov V.A., Prischepa S.L., Le Normand F., Derory A., Hernandez J.M. and Tejada J., New Journal of Physics, 17, (2015) 023073/1-12.

Resume : Graphene is a semimetal or a zero-gap semiconductor. Few-layer graphenes show a semiconducting nature, with the resistivity showing little change in the 100–300 K range. Resistance of few-layer graphene decreases markedly if it is heated to high temperatures and also with increase in number of layers. However, electrical properties of graphene changes due to variables such as number of layers, interaction between graphene and substrate, defects etc. Dielectric or metal deposition induces defects in monolayer (1L) graphene and the carrier mobility is very sensitive to the graphene lattice defects and interface quality. In this study, graphene synthesized on Cu substrates using CH4 process gas by CVD were successfully transferred on the soda lime glass (SLG). Au/Pd contact was taken from the edge of the graphene via sputtering system. We prepared aqueous Al+3 and (SO4)-2 solution and using an electrochemical system, Al+3 ions transferred on to graphene layer. Graphenes were annealed at 500 oC for 1 hour under Ar atmosphere. Graphene samples were investigated by Raman Spectrometer, PL, sheet resistivity via 4-four probe and I-V characteristic. Results showed that the Raman intensities of Al increased with the amount of transferred charge. It was observed that the graphene layer was not change. However, annealing process caused the Al atoms to come together to form nano-sized particles. Electrical resistivity of graphenes increased with increase of amount of transferred Al+3 ions. This electrical property is very useful for transparent electrode applications for new generation solar cells.

Resume : Chronic exposition to hydrocarbon (HC) pollutants, including aromatic and non-aromatic molecules, negatively impacts on the environment and human health; therefore, their rapid detection is desired to limit the exposure associated health hazards. To date the used techniques have some limitations such as high costs, time-consuming procedures, complexity and non-selectivity. In this context, MWCNTs-based chemiresitors with fast response time, high sensitivity, selectivity, portability and low-power consumption are promising for the development of a new generation of sensors. In this contribution, an electrophoretic deposition process has been used to directly functionalize MWCNTs-based chemiresistors by electrochemically-preformed Au or Pd NPs [1,2], to improve the detection and selectivity towards HCs pollutants. The sensing properties of pristine and decorated MWCNTs were evaluated at 40°C towards various concentrations of alkane and aromatic compounds (e.g butane and m-Xylene), and related to the deposited metal. Metal-doped MWCNTs sensors exhibited a very high gas sensitivity, fast response, reversibility, good repeatability, and detection limit, with the sensing properties controlled by the type of deposited metal catalyst. Au-doped MWCNTs sensors exhibited a very high gas sensitivity to m-Xylene, detecting up to a very low concentration (80 ppb); instead, Pd-doped MWCNTs sensors exhibited a very high sensitivity towards alkanes. Finally, based on the gas sensing performance, sensing mechanisms have been proposed, evaluating the effect of their chemical composition. [1]E. Dilonardo et al., Sens. Act. B 2016, 223, 417?428. [2]K- Buchholt et al., Smart Sensors and Sensing Technology, Springer 2008.

Resume : Functional inorganic materials of rare earth (RE) tungstates have attracted extensive attention because of their potential technological applications as high performance phosphors and catalysts, particularly for methane oxidation. In this case, a new double rare earth tungstates NaCe(WO4)2 (NCWO) synthesized by our group [1], were used for the first time as catalyst for methane conversion. In this work, we report the influence of the morphology of NCWO structures on their catalytic activity and their conductivities. To the best of our knowledge, no study on this material as catalyst for methane oxidation has been reported in the literature. In addition, no literature result seems to be available on their electrical properties in the temperature range (300?1000°C) where mixed conduction and oxidation of methane are rather favorable. All samples were characterized by X-ray diffraction and electron microscopy to identify the structure and the morphology of each compound. The catalytic reactivity of the samples was analyzed using a homemade reactor coupled to a combined system of Fourier transform infrared spectrometer (FTIR) and mass spectrometer apparatus. The measurements were performed under methane gas ?ows with air gas carrier, in the temperature range of 500?1000 °C. The catalytic activity was determined as a function of time and temperature. In speci?c circumstances, FTIR experiments show that methane conversion occurred both by total and partial oxidation. The reactivity could be linked to oxygen species delivered by hierarchical solids and their morphology. Electrical impedance spectroscopy analyses have been carried out on compacted polycrystalline samples and Nyquist representations have been interpreted. The NCWO structures presented similar semiconducting behaviors, with different activation energy. [1] N. Dirany, M. Arab, A. Moreau, J. Ch. Valmalette, J. R. Gavarri, CrystEngComm, 2016, 18,6579?6593

Resume : Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors HEMTs. HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas 2DEG mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes.The electrical response of hydrogen sensors based on Al0.30Ga0.70N/GaN high-electron-mobility transistors (HEMTs) with Pt catalytic gate electrodes was measured in a flowing gaseous stream consisting of hydrogen in a pure nitrogen diluent at ambient and elevated temperatures. The sensor response was found to monotonically increase for a wide range of hydrogen concentrations (500 ppb to 5 vol%). Various models based upon Langmuir adsorption were investigated to describe the sensor response in this regime. The relevance of other modified Langmuir models to adequately describe the sensor response as a function of hydrogen concentration is also discussed.

Resume : A deeper understanding of the processes that govern heterogeneous catalytic reactions enables the development of new materials and innovative reactor designs, which reshape the efficiency and sustainability of chemical reactions in all major global industries. Carbon nanotubes with their excellent mechanical and electronic properties have been successfully applied as catalyst supports in numerous reactions. Recent developments in single walled carbon nanotube aerogel synthesis have enabled the formation of high surface area and conductive hierarchical networks on which nanoparticle, metal catalyst can be deposited. Such a catalyst-support structure is combined with a novel electrochemical reactor set-up, in which the application of a voltage allows the control of the catalyst's work function. The effect of a change in work function on catalytic activity and selectivity in an organic, hydrogenation reaction is observed. The study explores the possibility to in situ tune a metal?s work function and hence the catalyst?s performance using an external stimulus - a voltage source. The study bridges electrochemistry, heterogeneous catalysis and latest developments in carbon nanotube aerogel synthesis to design a novel reactor system and study the effect of electric fields on activity and selectivity of a liquid phase organic reaction.

Resume : Electrolytic water splitting is a promising technology for global scale storage of renewable energy in the form of hydrogen fuel. However, the sluggish kinetics of oxygen evolution reaction (OER) often requires rare metal-based catalysts characterized by high costs and a not sustainable supply. [1] Recently, a significant leap forward has been made by the discovery of highly efficient OER catalysts based on earth abundant multi-metal oxides [2] that have though intrinsically low conductivity and must be deposited on glassy carbon electrode thus precluding the development of free-standing monolithic electrode. The anchoring of transition metal hydroxides on carbon nanotubes (CNTs) have shown to overcome this limitation [3] and offer numerous advantages over traditional design such as high conductivity, large amounts of available catalytic sites and efficient charge transport thus overall enhancing the catalytic activity toward OER. [4] Here, we report the electrocatalytic activity of a carbon nanotubes forest (CNT-F) transferred on flexible polymer/CNTs nanocomposite (NC). To activate the CNT-F surface, we carried out different treatments such as reactive ion etching and chemical wet etching (FNC-WE). In alkaline media (NaOH 1M), the FNC-WE electrode is the most performing one and generates a stable current density of 10?mA cm?2 with an overpotential (?) lower than 0.36?V, a value comparable to those reported for benchmark catalysts such as Ir and Co oxide. Once we electrodeposited Ni, NiFe, NiAl hydroxides on the FNC-WE electrode, we observed a dramatic improvement in the electrode efficiency. In particular, the deposition of Al-doped Ni(OH)2 allows to reach about 20 mA/cm2 at ? = 0.35 V and to sustain 10 mA/cm2 at only ?=280 mA/cm2, a performance similar to the recently reported NiCeOx/Au. [5] Moreover, we report the chemical stability and OER performance of CNTs-based electrodes close to industrial operating conditions for alkaline electrolysers, namely in KOH 6M for 24 h at room temperature (and ambient pressure). The FNC-WE/NiAl produces a stable current density of 45 mA/cm2 at ? = 0.35 V, while at 1.7 V FNC-WE shows the impressive current density of 180 mA/cm2. Finally, we assemble both an alkaline and acidic electrolysers by using two FNC-WE/NiAl electrodes as both anode and cathode and discuss their performance in view of future development and implementation of CNTs-based electrode for electrocatalytic water splitting. Reference [1] C. C. L. McCrory et al., J. Am. Chem. Soc. 2013, 135, 16977-16987. [2] B. Zhang et al., Science 2016, doi:10.1126/science.aaf1525. [3] L. Wang et al., Adv. Energy Mater. 2016, 6, 15. [4] M. Gong et al., J. Am. Chem. Soc., 2013, 135, 23, 8452?8455. [5] J. W. D. Ng et al., Nat. Energy 2016, 1, 139, 16053-16061.

Resume : The synthesis of graphene domains on electroplated Copper nanoparticles using a low-pressure chemical vapor deposition technique is presented. Circular domains of graphene are grown on electroplated copper under acetylene gas flow. Characterization of the graphene domains under Scanning electron microscopy and Raman spectroscopy indicates that good quality graphene is grown on electrodeposited copper on Si substrates. Successful growth of bi-layer and few layer graphene is firmly confirmed by Raman spectroscopy. The durability of the graphene/Cu(NP) nanostructures to UV radiation and nitrogen plasma is investigated, and the functionalization of the graphene surfaces by adsorption of hydroxyl and other functional groups is studied by x-ray photoelectron spectroscopy. Finally, the graphene/Cu(NP) nanostructures are tested for their surface-enhanced Raman scattering (SERS) activity and the effect of the number of graphene layers to the near-field effects is investigated.

Resume : Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are rate limiting steps in fuel cells and metal-oxygen batteries which determine the applicability of these devices in large scale. In this regard, many researches have been devoted to design wise bifunctional structures facilitating both reactions in aqueous and non-aqueous media. Among all the catalysts proposed, Mn based oxides have shown superior ORR activity in both media, however, due to their low electronic conductivity and poor OER catalytic activity, they cannot be solely considered as the catalyst for device application. On the other hand, it has been shown that RuO2 is an efficient electrocatalyst for OER in acidic and alkaline media. Herein, we design a three dimensional nanostructure of RuO2 supported Mn2O3 nanorods grown on carbon nanofiber (CNF) by a simple two step microwave assisted hydrothermal synthesis. Transmission electron microscopy, x-ray diffraction and Raman spectroscopy confirm the ternary composite preparation and electrochemical results show the bifunctional catalytic activity of hierarchical RuO2/Mn2O3/CNF composite for ORR and OER.

Resume : Metal?organic frameworks (MOFs) offer an array of exotic properties such as an exceptionally large surface area, high thermal stability, and low density. Most remarkably, MOFs are inherently modular with property-correlated building blocks (nodes and linkers) yielding adjustable properties (e.g. chemical, electric, magnetic, thermal, kinematic). Motivated by (1) the promise of property guided MOF discovery and (2) to extend the kinematic properties of MOFs, we have developed a novel design approach for the high-throughput invention of shape-shifting, photo-actuated metal-organic responsive frameworks (MORFs). Its implementation is multistage and challenging. As one of the stages in our general design approach, we propose a stochastic computational dynamics method not yet attempted in the literature to advance the scientific understanding of one such ? crucial ? challenge: the effect of constraint (e.g. as is applied by the framework) on photoisomerizing moieties. Static models do not capture the complexity of photo-actuated molecules. We use the suggested methodology to explore the regions of interest in the ground- and excited-state energy landscapes of a perturbed molecular system (azobenzene) as a proof-of-concept investigation. This method will help lay the foundations for the development of a tool to classically model constrained isomerization for the rapid screening of MORFs to be incorporated in our general design approach. We expect the stochastic methodology suggested will be of use in the design of other smart materials requiring similar molecular actuators or switches.

Resume : In recent years, the investigation of the ZnO-based solar cells has attracted more attentions due to the low fabrication process and appropriate electrical efficiency provided by this technology. Unfortunately, ZnO as an absorber layer is quite restricted in visible and IR ranges due to its wide band gap value and the requirement of new approaches to improve the absorbance behavior for infrared and visible lights. Thus, in order to deal with the growing high conversion efficiency requirement, it is very important to develop new approaches and designs to achieve better trade-off between the electrical efficiency and manufacturing cost. In this paper, a new approach based on metallic nanoparticles engineering aspect is proposed to achieve superior absorption for ZnO-based solar cell. The overall device performance comparison with three different metallic layers (Au, Ti, and Ag) is performed numerically. We find that the power conversion efficiency is considerably enhanced as compared to the conventional design. Moreover, the proposed design is optimized design using particle swarm optimization (PSO) approach in order to achieve higher optical and electrical performance of the device. The obtained results make the proposed design methodology as a potential alternative for developing low cost and high performance solar cells.

Resume : Solution processing of graphene oxide with subsequent reduction is an easy and cost effective way of realizing graphene based large area applications. Being derivative of graphene, reduced graphene oxide (rGO) inherits superlative mechanical properties such as high Young?s modulus (E) and low mass density (?), which can be exploited towards realization of low-cost nanoelectromechanical systems (NEMS) for sensing applications. However, there has been a limited effort of fabricating rGO based NEMS due to the lack of adaptability of microelectronic processing, which affects the reproducibility to a large extent. We develop a solution based technology for large area processing of rGO film to be compatible with microelectronic technology. Successful patterning of rGO using photolithography process and deterministic transfer of the patterned rGO to any other substrates are the key innovations for implementation of this technology to a wide variety of applications including NEMS. We further demonstrate all electrical actuation and transduction of these resonators which enables the realization of practical applications such as sensors. Fundamental frequencies of fabricated resonators are found to be in the range of 20-35 MHz with a quality factor of around 110. The electrostatic tunability of resonant frequency is successfully demonstrated that can open up the possibility of voltage-controlled oscillators, increasing the bandwidth of applications.

Resume : One of the most explored application domains for graphene is nano electronics because of its high carrier mobility and atomic thickness. However, dielectric or metal deposition induces defects in monolayer (1L) graphene and the carrier mobility is very sensitive to the graphene lattice defects and interface quality. In this study, graphene synthesized on Cu substrates using CH4 process ganos by CVD were successfully transferred on the soda lime glass (SLG). Au/Pd contact was taken from the edge of the graphene via sputtering system. We prepared aqueous Al 3 and (SO4)-2 solution using AlCl3, NaOH and H2SO4. Using an electrochemical system, Al 3 ions (0.05 mC, 0.25 mC, 0.5 mC, 1 mC and 2 mC) transferred on to graphene layer. Graphenes were annealed ant 500 oC for 1 hour under Ar atmosphere. As-grown graphene samples and annealed graphene samples were investigated by Raman Spectrometer and SEM. Results showed that the Raman intensities of Al increased with the amount of transferred charge. It was observed that the graphene layer was not damaged. However, annealing process caused the Al atoms to come together to form nano-sized particles.

Resume : In the present study, we have synthesized nanoparticles of MnFe2O4 by coprecipitation method with ferric and manganese chloride as precursor and NaOH as precipitating agent. Also a new type of alkaline agent: the alkanolamine isopropanolamine is used for precipitation to improve chemical composition, enhance magnetic properties and get USPIO. Above a temperature of 100°C, MnFe2O4 was obtained directly without further calcination. XRD pattern shows the presence of an intense peak corresponding to the known (311) crystallographic orientation of the MnFe2O4 ferrite spinel phase. A mean size of about 10 nm of the nanoparticles was directly measured by TEM experiments, which is consistent with the value estimated from XRD analysis. Magnetic properties of the synthesized nanoparticles, measured using a SQUID magnetometer, showed a superparamagnetic behavior. Also a study of fonctionnalization with different molecules like dextran and polyethylen glycol (PEG) was done to get biocompatible nanoparticles. All these features make the synthesized nanoparticles good candidates in nanomedicine such as hyperthermia and RMN relaxation properties.

Resume : A polytetrafluoroethylene (PTFE)-reinforced Nafion composite material is a cost effective alternative to a pure Nafion membrane, which is often applied as membrane in proton exchange membrane fuel cell (PEMFC), simply by lowering the amount of expensive Nafion applied for the membrane production. The reduction in cost is an attractive factor, but it is still a challenge to produce the composite membranes as efficient as commercial membranes. Recent research and application activities with the reinforced composite membrane for PEMFC applications include fabrication processing of microporous PTFE, impregnation of the Nafion ionomer into the PTFE support, improving proton conductivity, and reducing gas permeability. In this talk, our recent results from these activities will be presented.

Resume : Two-dimensional (2D) Quantum Spin Hall insulator (QSH) , also known as topological insulators (TIs), are new and promising materials for the applications such as dissipationless transport, spintronics, optoelectronics due to their unique surface states that are topologically protected and thus robust against nonmagnetic impurities and disorders. The existence of these remarkable electronic states in TIs can be attributed to the large spin-orbit coupling (SOC) of their heavy elements such as Bismuth (Bi). Because of this, the researchers have paid attention to Bi based two-dimensional materials. Among them, GaBi3 and InBi3 are good candidates for 2D Tls materials. Although there are a lot of studies in 2D Tls, a detailed understanding of functionalization of Tls with atoms is lacking. Chemical functionalization with atoms is important, because functionalized 2D materials can be used in sensing and storage applications. Also the surface functionalization can change the electronic properties, which may enable to discover the unexpected properties of the materials. So, in this work, we have performed theoretical study of GaBi3 and InBi3 to investigate the effect of functionalization with atoms and molecules such as H2, O2, H2O, H, Li, B, C, O, Ti for exploring the adsorption geometries, adsorption energies, electronic band structures.

Resume : Two dimensional (2D) materials have gained much attention in science. One of the important properties of these types of materials is high surface to volume ratio which is important for sensing applications. Silicene, Germanene, boron nitride etc. have been used as a monolayer for sensing applications. On the other hand, phosphorene, has been also considered for the same purpose. Black and blue monolayer phosphorus are among the most stable allotropes of phosphorus. Also GaBi3, which is (2D) topological insulators (TIs), are new and promising material for the applications such as spintronics, optoelectronics and, can be used for sensing applications. Its unique surface state is topologically protected and thus it is robust against nonmagnetic impurities and disorders. Despite the importance of biomolecules–2D materials, a detailed understanding of the adsorption mechanism and features of biomolecules onto the surfaces of phosphorene and GaBi3 is lacking. It is required the immobilization of biomolecules on the surface of these materials for design and production of bioelectronics devices. Better understanding of interaction between Adenine, Histidine and these 2D surfaces will provide better understanding of same interaction mechanisms for DNA, peptides and proteins. In this work, we have performed density functional theory (DFT) with vdW-DF method calculations for exploring the adsorption geometries and adsorption energies of Adenine and Histidine / the two dimensional composite systems. It is also shown that how modify structural properties of the biomolecules on the monolayers by applied charging.

Resume : ZnO nanostructured thin films can be used as electron transport layers in ordered heterojunction quantum dot solar cells. An increased interface between electron and hole transporting layers will allow for a fast separation of the electron-hole pairs preventing their recombination. Consequently an improvement of the overall solar cell efficiency is expected. ZnO hierarchical nanorod thin films can provide the desired increase in interface area. In this work, we study their properties and compare them with simple ZnO nanorod films. The ZnO nanorod films were synthesized hydrothermally by placing the quartz/ITO substrates in a solution of zinc nitrate hexahydrate and sodium hydroxide at 90ºC. Hierarchical structures were obtained through a second deposition step. SEM was used to characterize the size and shape of the nanorods. Simple ZnO films displayed hexagonal nanorods with a diameter of around 125 nm while hierarchical films showed additional 30 nm diameter nanorods growing on the side surfaces of the primary 125 nm nanorods. Optical transmittance spectroscopy revealed a band gap of 3.36 eV for both structures. Current-voltage measurements in the high field regime of 104 V/cm were used to determine the density off trap states Nt through the application of the space charge limited current theory (SCLC).

Resume : A challenging matter of modern and sustainable catalysis is to re-think key-processes at the heart of renewable energy and environmental technology in light of metal-free catalytic architectures designed and fabricated from cheap and easily accessible building blocks. An innovative synthetic protocol based on cheap foodstuff components, allows for the effective “dressing” of an assorted range of macroscopic scaffolds with a coating of a highly N-doped, mesoporous carbon phase. Ammonium carbonate [(NH4)2CO3], citric acid (C6H8O7) and D-glucose are the non-toxic foodstuff constituents of a homogeneous aqueous pre-catalytic phase to be used as an impregnating solution where the catalysts scaffolds are soaked . Successive thermal treatments of the impregnated β-SiC (or α-Al2O3) supports generate highly N-doped, carbonaceous surface coatings featured by Specific Surface Areas (SSA) and basicity higher than those of the pristine host matrices. The as-obtained composites can be exploited as metal-free catalysts in industrial key-processes, offering high (and to some extent better) catalytic performance and long-term stability compared with those of the classical metal-based systems of the state-of-the-art. The versatility of the described technology allows for an easy scaffold selection (in the form of powder, grains, beads, extrudates or foams) depending on its ultimate downstream application (gas or liquid-phase catalytic reactors). The remarkable achievements in the partial H2S oxidation from refinery tail gas are promising1, and they set the way to the exploitation of the outlined catalyst technology to other industrial contexts. ---------------------------------------------------------------------- 1. H.Ba et al. , Chem.Commun. 51, 14393 (2015)

Resume : Nitrogen-doped carbon-based 1D and 2D nanomaterials have received a great deal in the last few years particularly in the light of their application as metal-free systems capable to promote efficiently several catalytic transformations, including many of those at the heart of renewable energy technology. At odds with their remarkable catalytic performance a metal-free catalysts, the severe synthetic conditions required for their production, a relatively low N-content effectively available as active phase as well as all limitations dealing with both the material process ability and handling, have largely restricted their widespread application. Herein, we describe an original and straightforward approach to the synthesis of unique macroscopic and highly porous nitrogen-doped carbon-based foams featured by a high nitrogen content, up to 10 wt %, starting from easily accessible and food processing raw materials, i.e. ammonium carbonate, dextrose and citric acid (1). The reported procedure allows for a full exploitation of the nitrogen species at the material surface, where the catalytic process is expected to takes place. The as-synthesized nitrogen-doped carbon foams have been successfully scrutinized as metal-free catalysts in the industrially relevant dehydrogenation of ethylbenzene to styrene processes, and the catalyst admit a higher performance compared to the promoted iron-oxide based systems of the state-of-the-art (2). References (a) Y.li, ngyuen-Dinh, H. Ba et al., European pat. No. EP 15-152038 (2015). (b) H.ba et al., Appl. Cat. B : Environ. 200, 343 (2017)

Resume : The variety applications of metal phthalocyanines (MPc) is a strong motivation to characterize their structure. Phthalocyanines (Pc) can accommodate a metal atom (M) in their tetrapyrrole cage. They are able to assemble in 2D order structures when deposited on substrates, stable enough to provide optimal candidates for model single atom catalysis. The present work aims to investigate the electronic and geometrical structure of Iron phthalocyanine on ultrathin alumina using ab-initio calculations and experiments.

Resume : The control of morphology, elemental composition and phase composition of Cu2ZnSnS4 (CZTS) nano-crystals depends on the control of complex formation and surface stabilization of nano-particles in solution based synthesis in oleylamine. At temperatures ? 280oC, the control of nano-crystal?s morphology and homogenous growth is difficult because of fast poly-nuclear growth occurring at higher temperatures. In the present work the effect of complex formation of oleylamine with different alkali ions (Na, K and Cs) on nano-crystals growth at synthesis temperature of 280oC was studied. It was found that nano-powders synthesized in the presence of Na+ and K+ ions show the formation of crystals of different sizes - small nano-particles, large aggregated crystals and large single crystals. The presence of Cs+ ions in the nano-powder synthesis solution promoted growth of nano-crystals of homogenous size. It was proposed that the formed oleylamine-Cs ion complexes a) enhance the formation of oleylamine?metal (Cu, Zn and Sn) complexes before the injection of sulphur precursor into the oleylamine?metal precursor solution and b) after addition of sulphur stabilize the fast nucleated nano-particles and promotes diffusion limited growth.

Resume : Power consumption and cost of present day gas sensors are both high and hinder their application in handheld devices, e.g., integration with wearables, mobile phones, and tablets. There has been considerable effort in recent years to reduce the power consumption of resistive gas sensors that typically operate at 200-400?C. One approach is to use a MEMS platform for sensor device development. Our CMOS MEMS gas sensor device consists of a tungsten micro-heater and gold interdigitated electrode within a membrane. The membrane, (thickness 5 µm), is formed using a deep reactive ion etching technique. The low thermal mass of the membrane helps to reduce the power consumption with the off-membrane temperature remaining close to room temperature; hence associated circuitry is not affected. The heated area is 250 µm diameter. The electro thermal efficiency of these devices is high with an 8.2ºC increase per mwatt of power. The effective sensing area is small. Hence the integration of sensing material is a challenging task. Here we have used an Au-SnO2 nano-composite as the sensing layer. The deposition was performed using a dip pen nanolithography system. The sensor devices were then exposed to acetone vapour varied from 250 to 1000 ppm. The optimum operating temperature was found to be 350?C. The sensitivity was found to be 0.04/ppm at 100 ppm concentration. Thus integration of nano sensing material with CMOS MEMS platform will be beneficial for future low power hand held gas sensor development work.

Resume : Telomerase has attracted much attention as a universal cancer biomarker because telomerase activity is overexpressed in more than 85% of human cancer cells while suppressed in normal somatic cells. Since a strong association exists between telomerase activity and human cancers, the development of effective telomerase activity assay is critically important. Here, we report a nanogap-rich Au nanowire (NW) surface-enhanced Raman scattering (SERS) sensor for ultrasensitive detection of telomerase activity in various cancer cells and tissues. The nanogap-rich Au NWs were constructed by simple deposition of nanoparticles on single-crystalline Au NWs. The prepared nanogap-rich Au NWs provided highly reproducible SERS spectra. The telomeric substrate (TS) primer-attached nanogap-rich Au NWs can detect telomerase activity through the SERS measurement after the elongation of TS primers, folding into G-quadruplex structures, and intercalation of methylene blue. This sensor enables us to detect telomerase activity from various cancer cell lines with a detection limit of 0.2 cancer cells/mL. More importantly, the nanogap-rich Au NW SERS sensor can diagnose gastric and breast cancer tissues accurately. The nanogap-rich Au NW sensors showed strong SERS signals only in the presence of tumor tissues excised from 16 tumor-bearing mice, while negligible signals in the presence of heated tumor tissues or normal tissues. We anticipate that the present nanogap-rich Au NW SERS sensors can be used for a universal cancer diagnosis and further biomedical applications including a diverse biomarker sensing.

Resume : Recently FIB techniques have attracted researchers towards its capability of forming ordered nano and sub-nanostructures via self-organization of the surface. Surface erosion and strain induced by ion beam sputtering creates an imbalance of surface energy. This leads to disturbance of the surface energy equilibrium and the surface atoms get re-organized in the form of ripples in order to minimize the surface energy. The FIB interactions with Ge has been studied earlier for their reorganization behavior and it mainly focused on the ripple formation, however, the resulting topography prediction and its control is still a challenge. In the present work we report evolution of nanostructures on Ge (100) with the variation of Ga ion beam overlapping and ion dose. We varied beam overlap from positive beam overlap (PBO) of +50% to negative beam overlap (NBO) of -200% in order to investigate the evolution of ripple morphology. We note that, for NBO the nanoripples (NRs) are aligned parallel to the FIB scanning direction, while for PBO the NRs are perpendicular to the scanning direction. Fast Fourier transform of the structures further reveals that extreme NBO yields broken and periodic NRs, however, small NBO yields continuous and randomly spaced NRs. This study gives an insight in controlling the formation of self-organized NRs and underlying mechanisms. Such NRs have potential to serve as functional nanostructures and are suitable for enhanced light trapping in Ge based devices.

Resume : The oxygen reduction reaction is largely considered an important although complex reaction that will play a key role in the energy converting technologies of tomorrow. Understanding and efficiently catalysing this reaction is of main importance. Up until today the number one option for catalysing the oxygen reduction has been platinum nanoparticles supported on high surface area carbon. However, the low abundance of platinum along with its inherent limitations urges the development of new engineered nanoarchitectures, exploring the potential of materials beyond the their classical properties. Changing the behaviour of materials by moving into the nanoregime is since long widely exploited but tailoring the catalytic behaviour of a material through lattice strain is much less explored. Here, we demonstrate how hybrid core-shell type catalyst particles can be efficiently tailor-made using a simple room temperature synthesis. Not only is the noble metal content kept to a minimum but we will also show how the lattice strain in the platinum shell, induced by fitting it onto a cheap metal, affects the catalytic activity of the particle. PtNi, PtCu and PtFe core-shell particles made though our microemulsion synthesis all show high activity and selectivity towards the oxygen reduction reaction.

Resume : Dynamic assembly and self-organization is a common phenomenon in living active matter systems, and the fabrication of artificial active systems that mimic this behavior is currently a research area of intense activity. The goals are to find model systems that can mimic the complex self-organization found in natural systems and to utilize the organization for non-equilibrium assembly. Here we show that artificial self-propelled colloidal particles can form dynamically assembled patterns of passive silica colloids. We have fabricated TiO2-SiO2 Janus colloids that self-propel when illuminated with UV light. The active colloids act as nucleation centers and draw in and assemble passive SiO2 particles through diffusiophoretic interactions. The enhanced diffusion of the active particles permits self-assembly at low particle densities. The particles swimming speed and interaction strength can be tuned by controlling the light intensity. We demonstrate that by controlling the interaction strength as well as the size-ratio of active/passive particles, we can systematically drive the system to assemble into clusters, crystals and glasses in a range of sizes and symmetries. This non-equilibrium system of controllable multi-component colloids can be used to fabricate new soft matter assemblies.

Resume : Magnetic nanoparticles (NPs) are a well-known and very attractive class of materials, due to the ever-growing number of novel, advanced magnetic nanostructures showcasing different shapes, compositions and properties, thanks to the constant push for a more precise control over compositions and morphologies by enhanced chemo-structural tuning [1]. In this context, the multi-layered core-shell systems represent an interesting route to develop novel materials by combining the properties of an internal layer acting as a seed (core) and one or more external layers (shell) with different properties. The seeded growth method, which revolves around the addition of one or more external layers (shells) to pre-existing seeds, represents the most efficient strategy to obtain such materials, but is usually hindered by a limited control over the desired shape and/or size of the final product. On the other hand, post-synthetic cation exchange (CE) reactions offer a possible solution, by partially or completely replacing the cations of parent NPs while concomitantly preserving the anionic sublattice, thus preserving the seeds shape, while giving rise to new compounds (total CE reactions) [2] or composite, structured systems (localized and/or partial CE reactions) [3]. In our study, we moved from a recent work on bi-magnetic Fe, Mn oxide-based core-shell NPs, synthesized by a seeded-growth approach on pre-synthesized magnetite NPs [4] to develop a bi-magnetic core-shell system based on a mixed CE/seeded growth approach and subsequently push the CE reaction to observe the structural and magnetic evolution of the multilayered system. In particular, we started from single crystalline, monodispersed colloidal iron oxide NPs and substituted the Fe2+ with Mn2+ ions by a post-synthetic CE protocol to obtain a mixed Fe/Mn shell, without affecting their crystal structure, shape and size. Further pushing the CE reaction resulted in the growth of a second Mn3O4 shell over the initial cation-exchanged composite core-shell. The evolution from seed to core-shell and finally to a multi-shell system was analized by combining chemo-structural characterization by TEM and DC magnetometry studies by SQUID. In fact, the variations in the structure of the Fe/Mn system also implied a drastic change in the resulting magnetic properties, with the initial ferrimagnetic response of the pure seeds leaving place to different interaction-based effects. While the formation of the first, CE-based shell determined a magnetic softening with respect to the starting material, accompanied by a ferrimagnetic coupling between the iron oxide seed and the CE-mixed shell, this was gradually overcome by an antiferromagnetic coupling between the core/CE-shell and the growing external Mn3O4 shell, which gradually resulted in a magnetic hardening of the whole composite system. Then, the structural evolution of this multilayered Mn-Fe system and the subsequent modification of its magnetic features open the possibility to increase or decrease the magnetic hardness of the final product by just varying the reaction conditions. [1] N.A. Frey et al., Chem. Soc. Rev. 2009, 38, 2532. [2] B.J. Beberwyck et al., J. Phys. Chem. C 2013, 117, 19759 [3] Z. Luo et al., ACS Appl. Mater. Interfaces 2016, 8,17435 [4] M. Estrader et al., Nat. Commun. 2013, 4:2960

Resume : In view of the demanding forthcoming applications in nanotechnology, it is of prime interest to create functions out-off the plane and fully exploit the room above the substrate. With this aim, it is necessary to go beyond the pre-programmed surface-confined supramolecular self-assembly. This why a general strategy for simultaneously generating surface-based supramolecular architectures on flat sp2-hybridized carbon supports and independently exposing on demand off-plane functionality with controlled lateral order is highly desirable in view of the noncovalent functionalization of graphene. Here, we report the first fluorescent molecular self-assembly on graphene. The quenching of the fluorescence of the adsorbed dye by the adjacent graphene is hindered at the molecular scale based on a spacer approach, through a specifically designed dual-functionalized self-assembling building block. This 3D tecton presents two faces, one forming a noncovalent graphene-binding pedestal and the other carrying a dye group linked by a spacer to the pedestal. The spontaneous ordering of the adsorbed layer is investigated by scanning tunneling microscopy, whereas the resulting optical properties of the whole graphene−dye hybrid system are characterized by absorption and fluorescence spectroscopies.

Resume : Asymmetric nanoparticle trimers composed of metal particles with increasing diameter have been the focal point of several theoretical studies, based on their ability to act as “plasmonic nanolenses”. These self-similar structures have been predicted to exhibit ultra-high confinement of electromagnetic radiation. The fabrication and experimental verification has proven challenging so far, as top-down fabrication techniques usually lack the precision to produce the required nanometer-sized gaps between individual particles. In this study we investigate the plasmonic properties and the lensing effect of hierarchical gold nanoparticle trimers. A simple electrostatic self-assembly method is used to produce the trimer structures from a choice of different particle sizes and material combinations. Electrostatic interactions of nanoparticle colloids functionalized with charge carrying molecules with a charged substrate are used to assemble the desired structures in a 3-step process with yields of over 60%. The ability of the self-assembled trimers to focus light is ascertained experimentally via UV-Vis, cathodoluminescence and electron energy loss spectroscopy and theoretically via an analysis of the optical properties of the nanoparticle trimers in terms of surface plasmon eigenmodes.

Resume : Various kinds of nanowires can be synthesized in a bottom-up manner in multiple ways, but the growth methods commonly produce irregular arrangements. Assembly-free strategies for single-nanowire device fabrication exist, but the transfer of nanowires from their growth substrate to a target substrate, e.g. by drop casting, is often the method of choice. Single nanowire positioning is here a major issue. The contact printing (CP) method offers a simple way to transfer and align nanowires on planar and rigid surfaces. The method involves shearing of the nanowire growth substrate over the target surface with nanowire transfer and alignment in the shearing direction by frictional interactions. Recently, surface-controlled CP was introduced by our group allowing for the first time large scale positioning of single-nanowires by means of so-called catchers altering locally the frictional force. Here we show how the CP concept can be significantly extended to decorate now also flexible and fragile substrates with aligned silicon nanowire assemblies supporting completely new nanowire device fabrication strategies. We successfully applied both, surface-controlled CP as well as conventional CP with and without lubricants to silicon nitride membranes with thicknesses smaller than 1μm while having an area about 200x200μm. We even used the CP methods on extended fragile silicon nitride cantilevers to assemble a new class of nanowire decorated atomic force microscopy probes.

Resume : A major challenge in the development of efficient semiconductor quantum dot (QD) optoelectronic devices is controlling the charge transport between adjacent nanocrystals over the macroscopic length scale of a device. As of now, our technology is limited by the lack of precise, large-scale control over nanoscopic objects, which is required for achieving strongly coupled, close packed superstructures [1]. We study the assembly of QDs in a binary solvent mixture which exhibits temperature dependent solvent fluctuations; remarkably, these fluctuations induce QD assembly even at the nanoscale [2]. This technique allows for the tuning of the inter-dot distance, QD superstructure size and fractal dimension by simply changing the temperature of the solution. By doing so, we are able to control the electrical transport in critical Casimir-assembled QD thin-films. [1] P. Guyot-Sionnest, “Electrical Transport in Colloidal Quantum Dot Films”, Journal of Physical Chemistry Letters, 2012. [2] E. Marino, T.E. Kodger, J.B. ten Hove, A.H. Velders, and P. Schall, “Assembling quantum dots via critical Casimir forces”, Solar Energy Materials & Solar Cells, 2016.

Resume : Recently, organic-inorganic hybrid nanowires (NWs) based on the assembly of conjugated polymers (CPs) and inorganic nanoparticles have been applied to the active layer in solar cells device to deliver efficient energy conversion with low-cost fabrication. In particular, pre-assembly of hybrid NWs at the solution-state has been recognized as a great alternative to the thermal and solvent annealings. However, since both molecular orientation and crystallinity within the hybrid NWs is of paramount importance in efficient photon-to-electron conversion, the precise control of CPs assembly and appropriate analyses have become necessary. In this talk, we will present that electron tomography (ET) can be used as a powerful tool for elucidating the complex organization of CPs and QDs, and their mutual interactions by direct visualization of as thin film based on NWs, in addition to X-ray analysis. The CPs/QDs hybrid NWs are fabricated using conventional solvent mixing method. Interestingly, the crystallization of conjugated polymers is interpreted by the nanoscale location of QDs within the hybrid NWs in which the QDs are arranged along to the longitudinal NW axis. The morphology of active layer and crystallinity of components could be demonstrated more easily using the location of QDs. The resulted well-segregated p-n interface provide an efficient pathway for exciton dissociation and charge transport. Therefore, precisely controlled hierarchical assembly from CPs to NWs and then to as thin film morphology and correlative visualization would have a great opportunity to optimize performance of thin film device in multi length scales.

Resume : The assembling of magnetic nanoparticles into arrays represents a very exciting and important challenge with regards to their high potential in the development of new nanodevices for spintronic, magnetic and magneto-electronic applications. Magnetic properties are strongly dependent on dipole-dipole interactions and can be finely tuned by controlling the spatial arrangement of nanoparticles in arrays. We will present different assembling strategies which consist in the chemical patterning of magnetic nanoparticles. 2D assembling is addressed by specific interactions between functional groups at both NPs and substrates functionalized by self-assembled monolayers (SAMs) of organic molecules. Two different kinds of interaction have been considered: (i) electrostatic and reversible interactions between polar terminal groups (carboxylic acid or hydroxide) and the nanoparticle surface [1] and (ii) covalent and irreversible triazol linkage resulting from the “click” chemistry reaction between azide terminated nanoparticles and alkyne terminated SAMs.[2] The fine control of the balance between reaction kinetics and dipolar interactions between nanoparticles led to the preparation of 1D assemblies.[3] The uniaxial shape anisotropy of nanoparticle chains enhanced significantly collective magnetic properties. Finally, the integration of nanoparticle assemblies will be also presented in order to explore their magneto resistive properties.[4] [1] B. P. Pichon et al, J. Phys. Chem. C, 114, 9041 (2010) [2] D. Toulemon et al, Chem. Commun., 47, 11954 (2011) [3] D. Toulemon et al. Adv. Funct. Mater., (2016), 26(15), 2454; Langmuir (2016), 32 (6), 1621 [4] M. Pauly et al. Small, 8, 108 (2012) ; D. Toulemon et al., Small, 11, 4638 (2015)

Resume : The ability to monitor the presence of pathogens originating in the hospital using a biosensing platform that is passive and requires no power can help prevent infection outbreaks. We have developed an enzyme-responsive platform that demonstrated an easily discernible 240 nm, red-to-blue, color shift for all targeted enzyme concentrations between 20 nM and 4 M. The color change was mediated by the rearrangement of particles in a hydrogel matrix, resulting in a compact colloidal array after protease-specific crosslink cleavage. To elucidate the mechanism responsible for the large color change, we investigated the role of particle size and charge in self-assembly. A library of particle hydrogel composites was fabricated by centrifugation. Both particle size and surface functionalization were systemically varied, resulting in composites with a range of observable structural colors. Small angle x-ray scattering (SAXS) and scanning electron microscopy (SEM) revealed that particle-to-particle spacing decreases after self-assembly compared to the initially fabricated composites. This spacing decrease can be observed by the naked eye and is corroborated by reflectance probe measurements that indicate the reflected light is of a shorter wavelength. While particle diameter did not affect the ability to self-assemble, particle surface charge is critical to the electrostatically-driven self-assembly mechanism. Only highly negatively charged particle surfaces facilitated the self-assembly of the particles to produce structurally colored composites. PEGylated particles did not self-assemble, and the corresponding composites degraded into solution in the presence of the protease. Composites with positively charged particle surfaces did not self-assemble into a colored material after crosslink cleavage, but also did not disperse into solution. These findings offer insight into the design parameters that will enable passive monitoring of cellular systems or of toxic enzymes with precise control of composite response.

Resume : Controlling surface properties and biological interfaces at the nanometer scale have become essential challenges in biotechnology for biosensing applications and biological studies. Self-assembled monolayers (SAMs) based on the chemistry of the organosilanes attracts a lot of attention for biomolecules immobilization on solid substrates.[1] Common approaches involve two-steps processes with first the formation of SAMs starting from silylated intermediates and then “post-chemical modifications” of SAMs. Our group has implemented recently a promising alternative strategy based on the elaboration of functionalized silanes which enable the preparation of functionalized SAMs in a single dip process, while controlling the density and the spatial distribution of exposed functional groups.[2] We demonstrated also that the functionalized SAMs are suitable platform for the covalent immobilization of biomolecules. Current challenges are now: 1) enhancing control of (bio)molecules spatial distribution and orientation during their tethering in order to best maintain their properties and 2) monitoring the ligation step in a straightforward manner. In this context, we will present our recent results towards the synthesis of bifunctional silanes incorporating a fluorogenic click-reactive extremity and the elaboration of the corresponding multifunctional nanofilms on silica surfaces. Depending on the choice of the immobilized object, this platform opens the way to wide applications in the fields of sensing and biomedical technologies. [1] a) Vashist, S. K.; Lam, E.; Hrapovic, S.; Male, K. B.; Luong, J. H. T., Chem. Rev. 2014, 114, 11083; b) Samanta, D.; Sarkar, A., Chem. Soc. Rev. 2011, 40, 2567; c) Haensch, C.; Hoeppener, S.; Schubert, U. S., Chem. Soc. Rev. 2010, 39, 2323. [2] a) Meillan, M.; Ramin, M. A.; Buffeteau, T.; Marsaudon, S.; Odorico, M.; Chen, S.-w. W.; Pellequer, J.-L.; Degueil, M.; Heuze, K.; Vellutini, L.; Bennetau, B., RSC Adv. 2014, 4, 11927; b) Rahma, H.; Buffeteau, T.; Belin, C.; Le Bourdon, G.; Degueil, M.; Bennetau, B.; Vellutini, L.; Heuze, K., ACS Appl. Mater. Interfaces 2013, 5, 6843; c) Ramin, M. A.; Le Bourdon, G.; Heuze, K.; Degueil, M.; Belin, C.; Buffeteau, T.; Bennetau, B.; Vellutini, L., Langmuir 2012, 28, 17672; d) Ramin, M. A.; Le Bourdon, G.; Daugey, N.; Bennetau, B.; Vellutini, L.; Buffeteau, T., Langmuir 2011, 27, 6076.

Resume : Solid-state nanopores with precise control of pore diameter and surface chemistry can enable highly selective, label-free biosensing at the single-molecule level. Aluminum oxide (Al2O3) coating by atomic layer deposition (ALD) appears to be most suitable for fine-tuning the pore diameter. Here, we present for the first time the successful functionalization of nanopores (diameter 20-30 nm) in 50 nm thick silicon nitride membranes that were coated with 4-5 nm Al2O3 and subsequently functionalized with self-assembled monolayers (SAMs) of organophosphonic acids (organophosphonates). SAM formation was studied for three different precursor molecules, namely 1,10-decyldiphosphonic acid (C10-bis-PA), 4-aminobutylphosphonic acid and 12-mercaptododecylphosphonic acid. The SAM-functionalized nanopores were characterized by means of ionic conductance measurements, showing the expected reduction in pore conductance after SAM deposition. In particular, coating some 16 nm diameter pores with C10-bis-PA effectively decreased the pore diameter down to ~12 nm, as extracted from the reduction of conductance from 45 nS to 25 nS. Also, we have found that the average translocation time of λ-DNA through nanopores coated with phosphonic acid-terminated SAMs is shorter, and that the DNA capturing rate typically decreases by about 40%, as compared with bare Al2O3-coated nanopores. These properties can be attributed to the influence of the SAM-coating on the interaction of the DNA with the pore walls.

Resume : The present study deals with the synthesis of zinc iron oxide ZnFe2O4 nanoparticles using the co-precipitation method. A particular attention was paid to control the pH of the reaction, which is one of the most important parameter during this type of synthesis. XRD patterns of the as-obtained samples shows the presence of a very intense peak corresponding to (311) crystallographic orientation of the spinel phase, which can be assigned to the ZnFe2O4 nanoparticles. The mean size of the nanoparticles estimated by using the Scherrer formula, it increases from 15 to 24 nm depending on the pH parameter, in agreement with the value measured by Transmission Electron Microscopy analysis which shows also a narrow size distribution for a given pH. A second type of particles was synthesized by inverse co-precipitation, in this case, the size of nanoparticles was smaller compared to the normal co-precipitation, corresponding to a mean value of 20 nm, but with a broad size distribution. Some typical analysis will be realized on these two types of nanoparticles in view of their potential use in hyperthermia applications.

Resume : Zero-dimensional semiconducting quantum dots (QDs) have unique optical properties, such as high quantum yield and emission spectra that are tunable by the quantum confinement effect. The dark-state currents of the QDs obtained using colloidal CdSe, self-assembled InAs, GeSi and Ge have been measured in the range of 10-9-10-12A using conducting atomic force microscopy, and their current–voltage characteristic curves revealed typical semiconducting behavior with a charge tunneling mechanism. Considerable effort directed at modifying the surface of QDs using capping agents have led to a simple solution-based process, the stabilization of QDs, and their uniform dispersion in solvent. Due to these unique properties, quantum dots are of increasing importance in the fundamental studies and in a wide range of technological applications such as optical power limiters, light emitting devices, photovoltaics, lasers or fluorescent labels [1-7]. Tacking the full potential of QDs in optoelectronic devices require efficient mechanisms for transfer of energy or electrons produced in the optically excited QDs. We propose semiconducting π-conjugated molecules as ligands to achieve energy or charge transfer. The hybridization of p-type π-conjugated molecules to the surface of n-type QDs can induce distinct luminescence and charge transport characteristics due to energy and/or charge transfer effects [5,6]. QDs and π-conjugated molecule hybrids with controlled luminescent properties can be used for new active materials for light-emitting diodes in flexible displays. In addition, such hybrid systems with enhanced charge transfer efficiency can be used for nanoscale photovoltaic devices [6]. Single molecule-based electronics using QDs and π-conjugated molecule hybrids with molecular-scale n–p or n-insulating (ins)–p heterojunction structures are new promising building blocks for nanoscale electronics and quantum device concepts. The charge transfer and energy transfer efficiencies between the n-type QD and p-type π-conjugated molecules depends on the degree of their spatial proximity and spectral overlap respectively. Along these lines, we designed and synthesized hybrid nanoparticles consisting of a CdSe/ZnS QD as a core and π-conjugated polythiophenes as well as carbazole as a shell. The nanoscale PL and molecular optoelectronic properties of hybrids consisting of QDs and π-conjugated molecules could be tuned by their relative distance and the degree of spectral overlap. The novel properties of hybrids consisting of QDs attached to π-conjugated organic molecules could find applications in molecular electronics and optoelectronics, including luminescent displays and energy harvesting cells. References [1] N. Cho, K. R. Choudhury, R. B. Thapa, Y. Sahoo, T. Ohulchanskyy, A. N. Cartwright, K.-S. Lee, P. N. Prasad, "Efficient photodetection at IR wavelengths by incorporation of PbSe-carbon nanotube conjugates in a polymeric nanocomposite", Adv. Mater., 19, 232-236, 2007. [2] W. J. Kim, S. J. Kim, K.-S. Lee, M. Samoc, A. N. Cartwright, P. N. Prasad, “Robust microstructures using UV photopatternable semiconductor nanocrystals, Nano Lett., 8, 3262-3265, 2008 [3] J.-J. Park, P. Prabhakaran, K. K. Jang, Y. G. Lee, J. Lee, K. Lee, J. Hur, J.-M. Kim, N. Cho, Y. Son, D.-Y. Yang, K.-S. Lee, “Photopatternable quantum dots forming quasi-ordered arrays”, Nano Lett.,10, 2310-2317, 2010. [4] S.-W. Baek, J.-H. Shim, H.-M. Seung, G.-S. Lee, J.-P. Hong, K.-S. Lee, J.-G. Park, “Effect of core quantum-dot size on power-conversion-efficiency for silicon solar-cells implementing energy-down-shift using CdSe/ZnS core/shell quantum dots”, Nanoscale, 6, 12524-12531, 2014. [5] Y. D. Han, Y.-B. Lee, S. Park, S. Jeon, A. J. Epstein, J.-H. Kim, J. Kim, K.-S. Lee, J. Joo,“Quantum dot and π-conjugated molecule hybrids: nanoscale luminescence and application to photoresponsive molecular electronics”, NPG Asia Mater., 6, e103, 2014. [6] Y.-D. Han, S.-M. Jeon, S.-D. Kim, J.-H. Kim, S.-Y. Kim, J.-Y. Kim, K.-S. Lee, J.-S. Joo,“Nanoscale photovoltaic characteristics of single quantum dot hybridized with poly(3-hexylthiophene)”, Org. Electron.,15, 2893-2902, 2014. [7] T. Basche, A. Bottin, C. Li, K. Muellen , J.-H. Kim, B.-H. Sohn, P. Prabhakaran, K.-S. Lee, “Energy and charge transfer in nanoscale hybrid materials, Macromol. Rapid Commun., 2015, 36, 1026−1046, 2015.

Resume : The construction of optoelectronic and electrochemical devices based on biological units such as enzymes or photosystems is a subject of intense research activity. An important aspect of this development is the optimization of current collector morphology enabling efficient integration of biological elements into electronic circuits [1-2]. We demonstrate that the use of nanostructured electrode architectures instead of conventional planar electrodes significantly improves the performance of such devices via a greatly increased loading as well as an optimized communication with the electrode. This presentation will give examples of various bioelectrochemical systems based on biological units integrated in nanostructured transparent conducting oxide layers acting as extended high surface area current collectors. We could show that the use of macroporous antimony-doped tin oxide (ATO) electrodes can accommodate high amounts of bulky photoactive photosystem I (PSI) protein complexes resulting in an 11-fold enhancement of their photocurrents compared to the PSI on flat electrodes [1]. Other successful examples are the entrapment of enzymes (pyrroloquinoline quinone-dependent glucose dehydrogenase and fructose dehydrogenase) into polymer films on macroporous indium tin oxide (ITO) electrodes for an efficient bioelectrocatalysis [3-4]. The catalytic current increased up to 200-fold compared to flat ITO electrodes. References [1] K. Peters et al. Adv. Funct. Mater. 2016, 26, 6682. [2] K. Peters et al. Chem. Mater. 2015, 27, 1090. [3] D. Sarauli et al. ACS Appl. Mater. Interfaces 2014, 6, 17887. [4] D. Sarauli et al. ACS Catal. 2015, 5, 2081.

Resume : Luminescent nanoparticles (NPs) have demonstrated potential as sensitive nanothermometers, especially in biological systems. Their small size offers the possibility of mapping temperatures with high spatial resolution. However, the temperature range is limited which prevents the use in high temperature applications such as microfluidics, nano-electronics and chemical reactors. In our work, we have prepared NaYF4:Er3+,Yb3+ NPs of ca. 25 nm overgrown with SiO2, creating core/shell NPs of ca. 50 nm. Using in situ TEM and XRD measurements up to 900 K, we show that the overgrowth with SiO2 is crucial for realizing thermally stable NPs. The thermally coupled energy levels in Er3+ results in a Boltzmann distribution of the excited states, giving rise to temperature dependent luminescence. The core/shell NPs are able to determine temperatures up to 900 K reproducibly and with an accuracy of ca. 5 K. This is the first work that allows NPs to be used for non-invasive temperature sensing at elevated temperatures with a (sub)micrometer resolution. The high thermal stability and the expanded temperature range allows for monitoring temperatures in catalytic reactions but also other applications e.g. microfluidics and, nano-electronics with high spatial resolution.

Resume : We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro-mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate (Na-4-VBS), hydroxyethylmethacrylate (HEMA), and acrylonitrile (AN). Different amounts (from 0.1% to 1.5% w/w) of biodegradable cellulose nanocrystals (CNCs), with sulfonate surface groups obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized and compared to that of the bare hydrogel. We observed that the embedding of the CNCs enhanced both the Young’s Modulus and the sensitivity to the applied electric field in the sub-volt regime (down to 5 mV/cm). A demonstrator integrating multiple actuators that cooperatively work as an on/off electro-valve is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.

Resume : Continuous monitoring and remediation of water quality is a necessity for protecting human health. The most common cationic water pollutants are As, Cd, Cr, Cu, Ni, Pb and Hg that need to be detected and removed to maintain drinkable standards. Commercial heavy metal sensors are either optical using bulky and expensive setup or electrochemical that use perishable electrodes. Here, we present a low temperature (~0oC), environment friendly ex-situ synthesis of RGO/Ni2O3 nanocomposite showing highly selective, ultra-low (LOD~125 ppb) and rapid room temperature detection (Response time ~3s) of Cr(VI) ions in aqueous medium over its pure oxide forms (LOD~50 ppm for Ni2O3 and ~100 ppm for NiO).The fabricated sensors are re-usable, stable and their performance is reproducible (tested continuously for a period of 30 days with 3 devices). The sensing mechanism uses the adsorption property and variation of surface charge of sensing material for sensing chemical analytes thereby removing the “perishability” of conventional electrochemical sensors. The composite is biocompatible (due to RGO encapsulation) and magnetic thereby easing its use as an adsorbent (adsorption efficiency ~83% in 3 minutes exposure time under optimal condition) in usable water remediation systems. The magnetic property aids complete removal of residual adsorbate particles thus reducing contamination of treated water. Thus, the material is multi-functional, aiding cheap and efficient maintenance of drinking water.

Resume : Nanostructures of noble metals can manipulate light at the nanoscale through excitation of collective electron oscillations known as plasmons. These light-induced excitations occur at certain resonance wavelengths. A significant fraction of the plasmonic excitations decay through phonon excitation and heat dissipation to the local environment. This makes plasmonic nanostructures suitable as light-driven nanoscale heat sources. In this work, we investigate the use of a particular type of plasmonic structures known as nanohole films. Our optical and heat transfer simulations show that plasmonic nanoholes can be very efficient light absorbers, when compared with their nanodisk counterparts or with gold reference films. Moreover, they offer very good light transmission, making them suitable for applications where semi-transparent materials are needed. Finally, as the holes are embedded in a gold film, they can be used both as absorbers and electrodes at the same time. This enabled thermistor-type plasmonic nanohole devices, which showed heating profiles in agreement with our theoretical simulations. As an application example, we used the thermistors as both top electrode and plasmonic heater for an organic thermoelectric device. Under simulated sunlight, we effectively obtain a difference of temperature and a corresponding thermoelectric voltage for our devices.

Resume : Metal quantum clusters are an important class of functional nanomaterials with growing applicative potential as size-tunable biocompatible luminescent probes for molecular theranostics and optoelectronic technologies. Here, we demonstrate for the first time that the optical properties of gold clusters (Au8), and in particular the energy separation between the emission and absorption spectra (Stokes shift), can be tuned by control of the inter-particle distance imposed by the capping ligands leading to the formation of inter-cluster excimers. Based on this newfound motif, we demonstrate a strategy for overcoming the intrinsic limitation to the use of molecular excimers in single-particle applications, that is, their nearly zero collisional formation probability in ultra-diluted solutions. To this aim, we use Au8 clusters as building blocks for fabricating permanent excimer-like colloidal superstructures (Au8-pX) held together by a network of hydrogen bonds between the capping ligands. In the ground state, unexcited clusters behave as individual photophysical entities, whilst optical excitation results in the formation of inter-cluster excimers featuring long-lived Stokes-shifted luminescence with no corresponding excitation transition. The obtained supramolecular architectures effectively represent a new aggregation state of matter conveying the photophysics of excimers into self standing individual particles that find their natural application as non-resonant emitters in cellular imaging and integrated photonic nanotechnologies. Importantly, in vitro confocal imaging experiments reveal the strong ability of Au8-pXs in scavenging cytotoxic reactive oxygen species responsible of premature cellular death, thereby further enhancing their potential for bio-medical applications. Reference Santiago-Gonzalez, B., Monguzzi, A., Azpiroz, J. M., Prato, M., Erratico, S., Campione, M., Lorenzi, R., Pedrini, J., Santambrogio, C., Torrente, Y., De Angelis, F., Meinardi, F. & Brovelli, S. Permanent excimer superstructures by supramolecular networking of metal quantum clusters. Science 353, 571-575 (2016).

Resume : Copper nanocrystals (Cu NC) are actively investigated as substitutes for costly silver nanocrystals in conductive inks. However, to be of any use for printed conductors, oxidation of Cu NCs to non-conductive copper oxides must be avoided. Here, we analyze the interplay between the Cu NC surface termination, oxidation suppression and bulk copper formation through thermal annealing using 3 nm Cu NCs synthesized via thermal decomposition of copper formate in oleylamine (OLA). By adapting the method introduced by Sun et al,1 we obtain stable Cu NC dispersions that do not oxidize when stored under inert atmosphere, while showing a rapid conversion into copper oxide when exposed to air or deposited to form a thin NC film. Using solution 1H NMR spectroscopy, we demonstrate that as-synthesized Cu NCs are capped by OLA. OLA is tightly bound at NMR time scales, yet slowly desorbes during storage of the Cu dispersions, a process that is accelerated by oxygen exposure. Addition of carboxylic acids leads to the displacement of OLA from the Cu NCs and the formation of a denser ligand shell, probably consisting of dissociated carboxylic acids. We demonstrate that carboxylic acid ligands make Cu NCs more oxidation proof and facilitate the conversion of films of oxidized Cu NCs into a dense copper film. This offers the prospects of using colloidal Cu NCs as main constituent in conductive, nano-copper inks for applications in printed electronics. (1) Sun, X. et al. Small 2005, 1 (11), 1081–1086.

Resume : Nanoscale welding of metal nanowires (NWs) is critical for the assembly and integration of NWs meshes in nanoelectronic and optoelectronic devices. In this work, MeV protons beam irradiation-induced nanowelding technique is employed to weld Ni-NWs in various shapes such as X-, Y-, V-, II-, T-shapes etc. These NWs are exposed to 2.75 MeV protons at a fluence of 1x1016 ions/cm2 at room temperature. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and x-ray diffraction (XRD) results disclose that perfect welds are obtained between Ni-NWs with stable crystal structure. Subsequently, a random two-dimensional large scale mesh of Ni-NWs is obtained by 3 MeV protons ion beam irradiation-induced welding of Ni-NWs at overlapping positions. Proton ion beam induced mesh fabrication on large scale is seen by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, these meshes are characterized optically and electrically using UV-VIS spectroscopy and four probe technique. It is observed that at a beam fluence of 1x1015 ions/cm2, perfect X-, II-, and V-shape interconnects between Ni-NWs are achieved and finally an optimum welded mesh is formed while morphology of nanowires is preserved. Structure of Ni-NWs remains stable under proton ions beam. These meshes are electrically conductive and optically transparent. The results exhibit that those Ni-NWs meshes are formed in three steps: (i) Ion beam induced heat spikes leads to local heating of Ni-NWs, (ii) formation of interconnect on small scale, (iii) formation of interconnects on large scale. These large scale NWs interconnects can be employed as transparent electrodes in optoelectronic devices. Protons beam induced nanoscale welding of Ni-NWs could improve electrical and optical properties by reducing contact resistance on intersecting points. This observation is important for application of optoelectronic devices based on Ni-NWs based transparent electrodes used in spacecrafts. It is found that Ni-NWs are stable materials in upper space.

Resume : Plasmonic nanoparticles provide excellent means for controlling electromagnetic near-fields at optical frequencies, which has led to a broad range of applications in various field such as surface enhanced spectroscopy, plasmonic light harvesting or optical metamaterials. Self -assembly of metallic nanoparticles offers an attractive route for fabricating well-defined plasmonic structures, since nanoparticles can be synthesized with well-defined crystallinity and assembly processes can be up-scaled to macroscopic dimensions. Thus, the step from nanoscopic particles to macroscopic functional ensembles becomes feasible. While much research is dedicated to understanding nanoparticle synthesis [1] and optimization for these tasks, understanding formation of supra-colloidal assemblies and unravelling their structure-property relations is still in its infancy. We discuss different assembly routes for the formation of hierarchical supra-colloidal structures like linear assemblies [2] and nanoparticle-clusters [3]. It turns out, that interfacial templating effects are a powerful tool for controlling particle order with nanoscale precision. We discuss the underlying physico-chemical effects and perspectives upscaling to macroscopic areas as well as perspectives for applications in Surface Enhanced Raman Spectroscopy and optical metamaterials. [1] Mayer, M.; et al. Controlled Living Nanowire Growth: Precise Control over the Morphology and Optical Properties of AgAuAg Bimetallic Nanowires. Nano Letters 2015, 15, 5427-5437. [2] Tebbe, M.; et al. Optically Anisotropic Substrates via Wrinkle-Assisted Convective Assembly of Gold Nanorods on Macroscopic Areas. Faraday Discussions 2015, 181, 243-260.Hanske, C.; et al. Strongly Coupled Plasmonic Modes on Macroscopic Areas via Template-Assisted Colloidal Self-Assembly. Nano Letters 2014, 14 (12), 6863 - 6871. Pazos-Perez, N.; et al. Highly uniform SERS substrates formed by wrinkle-confined drying of gold colloids. Chemical Science 2010, 1 (2), 174-178. [3] Höller, R. P. M.; et al. Protein-Assisted Assembly of Modular 3D Plasmonic Raspberry-like Core/Satellite Nanoclusters: Correlation of Structure and Optical Properties. ACS Nano 2016, 10 (6), 5740–5750.

Resume : A great effort has been devoted in designing and producing metal surfaces, which exhibit appropriate surface morphology that maximizes the occurrence of surface plasmons at specific spectral bands. Among the most promising applications of metal surfaces is surface enhanced Raman scattering (SERS), which is widely used in biosensing. In this work we take advantage of the ability to facilitate size-selective laser annealing and produce pre-determined patterns of metal nanostructures in an ultra-fast, high-throughput and low-cost manner. The nanopatterns vary in nanoparticles size, morphology and size distribution by changing crucial laser annealing parameters such as the applied laser beam wavelength, the number of pulses and the energy density (fluence). The laser-processed metallic nanostructures are used as SERS templates and studied by Raman Spectroscopy, X-ray Photoelectron Spectroscopy, water contact angle measurements, and Scanning Electron Microscopy in an effort to find the proper parameters that affect the efficiency of chemical sensing. The far-field optical performance and the plasmonic behavior of the templates are evaluated by optical reflection spectroscopy. The SERS performance of the produced patterns is evaluated by probing aqueous solutions of Rhodamine 6G. We provide solid evidence on the effects of nanoparticle morphology and size distribution to the hydrophilicity of the plasmonic templates, which is associated with the exposed Si surface among the nanoparticles and the SERS performance.

Resume : We will report on nanocomposite material which consist in Fe3O4 nanoparticles decorated ZnO nanorod arrays (Fe3-xO4/PBA/ZnO hybrid nanocomposite structure). Obtained thanks to a very simple preparation method based on self assembly mediated by specific interactions by using a bis phosphonic ligand (PBA), this strategy allows grafting irreversibly Fe3-xO4 nanoparticles onto ZnO nanorod arrays while preserving the original crystalline structure of both inorganic entities. Our strategy affords to consider nanomaterials supported onto a substrate which favour synergy between magnetic and optical properties of Fe3-xO4 nanoparticles and ZnO nanorods. Shape anisotropy induced by ZnO nanorods enhances significantly the collective magnetic properties of Fe3-xO4 nanoparticles by favouring the preferential orientation of coupling of magnetic moment through dipolar interactions along nanorod directions. The optical properties of ZnO nanorods have been also dramatically modulated as shown by the electronic transfer between Fe3-xO4 nanoparticles and ZnO nanorods which is activated by an unsaturated organic linker, namely PBA. Finally, our approach is versatile and can be used for the preparation of a nanocomposite which combines a wide range of inorganic and organic nanomaterials. This original synthetic strategy is believed to pave the way for future advanced applications requiring the integration of nanomaterials in devices.

Resume : An important economic improvement of white light emitting diode is based on the use of lanthanide-free phosphors that are supposed to convert UV light into visible one, thanks to down-conversion (DS) process. ZnO nanoparticles (NPs) have aroused an increasing interest since they possess a variety of intrinsic defects that provide light emission in the visible range without the introduction of any additional impurity. However, high photoluminescent quantum yield (PLQY), green/yellow emission, stable dispersion and easy scale–up process are expected for industrial applications. Li-doping and polymer surface modifications of ZnO nanoparticles are mainly used in order to reach high PLQY (>30%) but PLQY decay over few days, uses of sophisticated polymers or multi-step reactions are the main issues for industrial implementation. Herein, we present a quick and convenient chemical solution approach to get unique mesospheric self-assembly hybrid ZnO system with intense (PLQY = 40-75%) and stable visible emissions. We also demonstrate that the use of mixture of commercial polyacrylic acid-based polymers can provide scalable amounts of ZnO NPs clear water suspensions that can be dried and dispersed again in water without compromising the functional performance (e.g. transparency and PLQY) of the final DS layer. We will then address the effects of the ZnO NPs surface functionalization - such as nature, molecular weight, concentration, ratio of the PAA-based polymers and self-assembly process- on the enhancement of the efficiency of DS thin films in LED technology

Resume : Glasses are versatile materials which allow the dissolution and/or dispersion of other chemical elements in their composition, such as rare earth ions, metallic and magnetic nanoparticles.1 Phosphate glasses can be successfully obtained via coacervation process, in which a gel is obtained, making it possible to incorporate nanoparticles into the phosphate structure at room temperature, and later transform it into glass using a melting- quenching process.2 However, the preparation of magnetic glasses with controlled doping and appropriate parameters for their functionality, such as good homogeneity for example, is a great challenge.3 The synthesis of nanoparticles by thermal decomposition is convenient to produce particles with controllable size and morphology.4 The CoPt alloy is a candidate for high density magnetic recording media due to their high magnetic anisotropy and good chemical stability.5 This work aimed to prepare CoPt@SiO2 nanoparticles by thermal decomposition assisted by reductant, to coat them with a layer of silica and to perform thermal treatments at different temperatures between 500 and 1100 ° C, in order to obtain higher values of magnetization and consolidation of the silica layer, aiming the protection of the nanoparticles during glass melting. The best saturation magnetization was observed for particles treated at 900 ° C, which show average size around 15 nm and for this reason were selected to be incorporated into the coacervate matrix. Samples containing 0.5, 1.0, 2.0 and 4.0% mass of nanoparticles were prepared, the samples obtained were transparent and showed gray color. A sample containing 1.0 % of CoPt@SiO2, without previous thermal treatment, was prepared for comparison purpose. After melting, this glass presented blue coloration and an intense absorption band in the visible range, characteristic of Co2+ ions in phosphate matrix. When comparing the glasses containing nanoparticles with and without the heat treatment, we can imply that the heat treatment at 900°C is effective to protect the CoPt@SiO2 nanoparticles. Transmission electron microscopy (TEM) revealed the presence of nanoparticles dispersed through the glass. [1] Sugimoto. N. J. Journal of Non-Crystalline Solids, (2008) 354. [2] Widanarto, W.; Sahar, M. R.; Ghoshal, S. K.; et al. Journal of Magnetism and Magnetic Materials (2013) 326, 123-128. [3] Oh, Y. W.; Liu, J. P. Journal of Magnetics. (2006) 11,123-125. [4] Park. J. ; Cheon. J. Journal of the American Chemical Society. (2001) 123, 5743-5746. [5] [5] Palavit, G.; Montagne, L.; Delaval, R. Journal of Non-Crystalline Solids (1995) 189, 277-282

Resume : Functional hybrid silica-based materials are obtained by the hydrolysis-condensation (H-C) of organotrialkoxysilane precursors leading to silsesquioxanes or by grafting the latter onto suitably functional surfaces as for example silica or aluminosilica containing reactive surface-OH groups. In our efforts to synthesize functional silica materials, we have developed a new method to have access to organo-functional silanes, using the Click reaction.1 This involves the reaction of a terminal alkyne with an azide using a copper catalyst (Cu-catalysed variant of Huisgen cycloaddition reaction called CuAAC: Copper(I)-catalyzed Azide-Alkyne Cycloaddition), leading to a triazole. When either the alkyne group or the azido group bears a triethoxysilyl group, the resulting alkoxysilane molecule is a convenient precursor for obtaining silica based materials both by H-C or by grafting as mentioned above. In this work, the synthesis of functional precursors through the CuAAC reaction will be presented and the uses of these organosilanes as suitable precursors either to functionalise silica nanoparticles or to synthesize directly functional silsesquioxanes will be shown.2,3 Notably the preparation of mesoporous nanoparticles with capping molecules to close and to open the pores will be presented. These uncapping of the pores can be achieved by several stimuli: pH-stimuli and irradiation-triggering systems to deliver any cargo molecules (for example drugs) one can insert inside these pores.4-6 The efficiency of these nanoparticles have been investigated by in-vitro and ex-vivo studies for cancer treatment (Breast, Colon and Prostate). References: 1 - Cattoën, X.; Noureddine, A.; Croissant, J.; Moitra, N. ; Bürglová, K.; Hodačová, J.; de Los Cobos, O. ; Lejeune, M. ; Rossignol, F.; Toulemon, D.; Bégin-Colin, S.; Pichon, B.P.; Raehm, L.; Durand, J-O.; Wong Chi Man, M., Journal of Sol-Gel Science & Technology, 2014, 70, 245-253. 2 - Moitra, N.; Moreau, J.J.E.; Cattoën, X.; Wong Chi Man, M., Chemical Communications, 2010, 46, 8416-84 3 - Bürglová, K.; Moitra, N.; Hodačová, J.; Cattoën, X.; Wong Chi Man, M., Journal of Organic Chemistry, 2011, 76, 7326-7333 4 - Théron, C.; Gallud, A.; Carcel, C.; Gary-Bobo, M.; Maynadier, M.; Garcia, M.; Lu, J.; Tamanoi, F.; Zink, J. I. ; Wong Chi Man, M., Chemistry - A European Journal, 2014, 20 (30), 9372-9380 5 - Croissant, J.; Salles D.; Maynadier, M.; Mongin, O.; Hugues,V.; Blanchard-Desce, M.; Cattoën, X.; Wong Chi Man, M.; Gallud, A.; Garcia, M.; Gary-Bobo, M.; Raehm, L.; Durand, J-O., Chemistry of Materials 2014, 26, 7214-7220.

Resume : The association of iron oxide nanoparticles (IONPs) and carbon nanotubes (CNT) is promising in biomedical applications to develop theranostic nanoplateforms providing an image –guided therapy. IONPs are used as MRI contrast agents and display therapeutic properties through magnetic hyperthermia. CNTs have the property to act as contrast agents and as heat mediators for hyperthermia in the near infrared (NIR) range. We developped a method to synthesize IONPs inside CNTs which acted as a nanoreactor. Such nanocomposites can absorb and efficiently convert NIR light into heat to generate cell lysis and can be used as T2 agents for MR image-guided photothermal therapy. These promising properties could be enhanced by ensuring a higher loading of NPs inside CNTs and solving one main problem which is the lost of NPs due to the sliding of NPs outside CNTs during manipulation. We will present here a new strategy which consists in reducing the length of CNTs, optimising the iron precursor to ensure a higher loading in NPs and in coating filled CNTs by a silica coating to avoid the ejection of NPs out of the CNTs.

Resume : During last decade the method generally named Pulsed Laser Ablation in Liquid (PLAL or simply LAL) has been widely developed for producing nanostructured materials of different kinds. In this work it is going to be presented an overview of the processes involved during PLAL as well as some features of the generated nanostructures obtained using either metal or carbon based substrates. In order to evidence the main phenomena that are involved during PLAL and the time-scales at which they occur, different techniques, such as Optical Emission Spectroscopy (OES) and shadowgraph imaging data will be shown. In this manner, different stages of the process such as the laser induced plasma, shock wave and cavitation bubble dynamics, which occur until the generated nanoparticles are released into the solution, can be followed and surveyed. Varying some properties of the liquid or of the substrate, e.g. the liquid pressure or the typology such as bulk or wire, respectively, or the laser pulse duration, the dynamics of the PLAL features change without affecting greatly, at first glance, the produced nanoparticles. In order to characterize these, ex-situ techniques such as Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Raman spectroscopy and, for noble metal colloidal solutions, in-situ Surface Plasmon Resonance (SPR) spectroscopy, are used. In some circumstances, soon afterwards the production of nanoparticles, the formation of more complex nanostructures presenting properties of interest for applications such as titania microtubes, carbon nanotubes etc. can take place. It follows that the advantages and drawbacks of the method will be outlined so that prospectives for its further development can be envisaged.

Resume : Organo-metallic hybrid perovskite materials are unique materials that feature extremely high power conversion efficiency, therefore holding great promise for low-cost and up-scalable device applications in opto-electronics. Devices based on methylammonium lead iodide (MAPbI3) were successfully exploited as resistive sensor of ammonia or optical sensors for humidity[1,2]. It is also reported that MAPbI3 can strongly interact with oxygen gas, leading to a peculiar increase of its photoluminescence, and that Pb-O bond formation could be responsible for such an enhancement[3].Here we explore the electrical response of MAPbI3 in two-terminal devices under a controlled atmosphere with a variable amount of oxygen. The electrical resistance of the perovskite was found to be strongly correlated with gas percentage in the environment. The observed effect can be ascribed to a fully reversible passivation of the vacancies contained within the perovskite. When oxygen molecules fill an increasing number of trapping sites, the device current increases. The two-terminal device exhibit strong oxygen sensitivity with high detection range from few hundred of ppm to 100 %. Finally, MAPbI3 oxygen sensitivity was found to be highly related to the morphology adopted in the thin film, through the deposition process used to prepare devices. [1] C. Bao, J. Yang, W. Zhu, X. Zhou, H. Gao, F. Li, G. Fu, T. Yu, Z. Zou, Chem Commun 2015, 51, 15426. [2] L. Hu, G. Shao, T. Jiang, D. Li, X. Lv, H. Wang, X. Liu, H. Song, J. Tang, H. Liu, ACS Appl. Mater. Interfaces 2015, 7, 25113. [3] W. Kong, A. Rahimi-Iman, G. Bi, X. Dai, H. Wu, J. Phys. Chem. C 2016, 120, 7606

Resume : In the past few years, organic materials for use in photo-thermal therapy (PTT) has gained considerable interest and seen exciting progress. Several different types of organic materials have shown to be effective in killing tumor cells; they typically involve nanoparticle stabilization by small molecule or polymer surfactants to increase water-solubility, and are often synthesized through an emulsion process. Despite this, few studies have directly examined the effects of stabilizing surfactants on other properties of PTT nanoparticles. In this study, PTT nanoparticle stabilizing surfactant properties and compositions are tailored to investigate their effect on nanoparticles and by extension their resultant efficacy in PTT. Specifically, the effect of surfactant tailoring on near-infrared (NIR) absorption spectra, and by extension photo-thermal conversion efficiencies of emulsion-templated nanoparticles for PTT will be reported.

Resume : Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying physical principles of this optimized hierarchical design are embodied in Murray’s law. However, we are yet to realize the benefit of mimicking nature’s Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray’s law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter-ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid-solid, gas-solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes 1-4. References 1. X. F. Zheng, G. F. Shen, C. Wang, D. Darren, Y. Li, J. Brinker, B. L. Su, Nat. Commun. 8, 14921 doi: 10.1038/ncomms14921 (2017) 2. M. H. Sun, S. Z. Huang, L. H. Chen, Y. Li, X. Y. Yang, Z. Y. Yuan and B. L. Su, Chem. Soc. Rev. 45, 3794 (2016) 3. X. Y. Yang, L. H. Chen, Y. Li, J. C. Rooke, C. Sanchez and B. L. Su, Chem. Soc. Rev. 46, 481 (2017) 4. J. Liu, H. Zhao, M. Wu, B. Van Der Schueren, Y. Li, J. H. Ye, O. Deparis, G. Ozin, and B. L. Su, Adv. Mater. DOI: 10.1002/adma.201605349

Resume : Wearable pressure sensors that can detect pressure changes induced by human body have been attracting drastically increasing interest in various applications such as wearable health condition monitoring systems, human-machine interactions, and artificial intelligence . In particular, for the health monitoring applications, the wide pressure range produced by human body needs to be considered. For example, the pressure range of arterial pulse is ~ 10 kPa and the range by body weight and accordingly by walking can exceed ~ 90 kPa . A variety of pressure sensors employing different materials systems have been proposed to show ultrasensitive response and/or tunable operation ranges. However, an approach to tune the operation range of flexible pressures covering from sub kPa to hundreds of kPa by tuning materials properties has been elusive. Here we report that a biologically assembled conductive nanomesh of single-walled carbon nanotubes can be successfully employed for the fabrication of wearable pressure sensors with high sensitivity and wide operation range. We show that the tunable electrical properties and the nanostructures of the conductive nanomesh synergistically change the operation range of the pressure sensors. In addition, a very large sensitivity of 6.2 kPa-1 at lower pressure range, ~ 5 kPa, and a wide detection range, up to 100 kPa, with relatively high sensitivity could be successfully obtained using our scheme. Furthermore, the device shows excellent cycle stability at 100 kPa and consumes a relatively low power, < 25 μW. We envision that out approach would not only enable the development of high-performance wearable health-monitoring devices but also benefit other fields involving human-machine interface.

Resume : This work assesses the potential of colloidal nanoparticles for phase-change memory technology. Because solution-phase synthesis of phase-change materials (PCMs) is little developed, there are open questions regarding the ability to produce material of sufficient quality and amount to satisfy the needs of memory technology. We choose binary GeTe PCM nanoparticles as a case study. First, we will present a colloidal synthesis of amorphous GeTe nanoparticles that allows for accurate size control between 4 nm and 10 nm and narrow size distributions < 10%. About 2 g of monodisperse GeTe nanoparticles can be obtained from a single synthesis. Precise size tunability and high chemical yield of GeTe nanoparticles allow systematic study of their size-dependent crystallization and melting phase transitions using high-temperature X-ray diffraction, in-situ TEM heating, and differential scanning calorimetry. Finally, we will show a ligand exchange that enables the removal of insulating organic monolayer from the surface of GeTe nanoparticles. Our results suggest great prospects for PCM colloids in phase-change memory technology. Monodisperse PCM nanoparticles represent convenient template-free system to study size dependent phase transitions. Furthermore, the PCM colloids can sufficiently reduce the cost of PCM cells and give an access to easy solution-processing of PCM films on flat, flexible, and prepatterned substrates.

Resume : Surgical sealants reduce the risk of anastomotic leaks that may cause expensive, high mortality rate complications such as sepsis. Using a polymer nanofiber deposition method called solution blow spinning (SBS), we have developed sprayable fibrous coatings that soften due to a body temperature-mediated thermal transition. Poly(lactic-co-glycolic acid) (PLGA) was blended with poly(ethylene glycol) (PEG) in varying ratios in solution to increase tissue adhesion. We used this solution to fabricate fiber mats using SBS, and showed that PEG increases fiber diameter and affects fiber morphology. Increasing PEG content decreases the glass transition temperature of the material and creates a melting event at 31°C, which occurs after the material is applied to the body. Temperature controlled pull-off testing demonstrated increased tissue adhesive forces at body temperature. The degradation of this material was monitored for 28 days and compared to PLGA. Adhesive forces and burst pressures measured on ex vivo intestinal tissue at body temperature increased relative to PLGA fibers. In vivo testing of an optimized PLGA-PEG blend as a supplement to sutures in a leaky anastomosis mouse model showed increased burst pressure and improved survival rate compared to clinically-relevant controls. This blend could be deposited in situ directly to the site of surgery using an airbrush and changed from white to translucent after application, augmenting usability. We also evaluated PLGA-PEG as a coating for a no-suture anastomosis, where it performed similarly to cyanoacrylate glue (“superglue”) with reduced inflammation.

Resume : Transparent and conductive thin films are a key component of opto-electronic devices such as touch panels, e-papers, liquid-crystal displays and solar cells. Silver nanowire (AgNWs) thin films are investigated as a replacement material for the widely used Indium Tin Oxide and allow the elaboration of flexible transparent conductive thin films. Most of the studies published in the literature focus on random networks of AgNWs in which the highest possible transparency with highest possible conductivity is desired. In this talk, I will introduce the use of Grazing Incidence Spraying of AgNWs to build oriented multilayer thin films and investigate the influence of ordering on their opto-electronic properties. As an alternative to existing oriented assembly techniques, we have recently introduced Grazing Incidence Spraying, which consists in the low-angle spraying of an AgNW suspension leading to an oriented monolayer.[1-2] Furthermore, the Layer-by-Layer technique is used to build multilayer thin films in which each layer’s orientation can be controlled independently, as for instance 2 layers oriented at 90° from each other. The sheet resistance and optical properties of these structures will be compared to non-oriented AgNW films to highlight the influence of ordering of the nanowire network on the electrode performances. [1] S. Sekar et al. Faraday Discuss. 2016, 191, 373-389. [2] H. Hu et al. Nanoscale 2017, DOI: 10.1039/C6NR08045F

Resume : Within the vast field of metal nanoparticles research, increasing interest has been focused on anisotropic nanoparticles, because the presence of asymmetric axes originates additional physicochemical properties in comparison with the common spherical colloids. This includes peculiar optical responses as well as unique self-assembly behaviours forming liquid-crystalline architectures. Among the known nanoparticles without spherical symmetry, the most commonly studied type is represented by gold nanorods. Here we present our attempt of surface functionalisation of high aspect ratio gold nanorods with photochromic spiropyran derivatives. Spiropyran was chosen because of its unique variation of molecular dipole moment upon photoisomerisation from the closed neutral spiropyran form to the open, metastable zwitterionic isomer merocyanine. The merocyanine isomer has also other interesting properties with respect to the closed form, being it conjugated, therefore planar, intensely coloured and fluorescent. Moreover, interconversion between the two forms has shown to be possible also by chemical stimuli (pH, complexation of metal cations). The emerging properties of the gold nanorod-spiropyran system arising from the spatial confinement of the photochromic moiety on surfaces with different curvature radius (apex and sides) of the colloid were studied spectroscopically. We envision that the realisation of such photoresponsive nanoparticles could lead us to bi-stable dynamic systems in which the formation of aggregates of aligned nanocrystals on the mesoscale could be driven photochemically.

Resume : Zinc oxide is known as a good sensing material for hydrogen detection through its physical adsorption of this element. On the other hand, gas and liquid sensors development involve more and more nanotechnologies in enhancing their active surfaces performances. Nanostructures with controlled morphologies and structural properties are more and more used for building such sensor devices, and their properties control are critical issues in the fabrication processes. We have used Vapor-Liquid-Solid (VLS) technique in a Pulsed Laser Deposition (PLD) system for growing ZnO nanowires with controlled morphology and surface patterning. Nanowires morphological parameters was performed through catalyst and plume parameters control. Some physical processes limitations in VLS elementary processes were investigated together with their influence on the resulting morphology. Fabricated surface-acoustic-wave (SAW) sensors using such structures have proven to have (enhanced) performances depending directly on the nanowire morphology. Furthermore, using laser techniques, nanostructure surface patterning was proved as another key parameter in enhancing sensor performances. A summary of physical control (experimental) capabilities on ZnO nanowires in VLS/PLD systems and their direct influence on the SAW sensors performance is presented. Comparisons between different nanostructure patterns and structure morphologies with thin film surfaces are presented and exemplified on the hydrogen and deuterium detection.

Resume : Structural modulation of noble metal nanostructures at the atomic scale can greatly alter their catalytic properties.[1-2] For instance, decorating the surface of single-crystal metal substrates with other single- or few-layer metal atoms may induce the lattice strain, which plays a decisive role in determining the surface reactivity. The exposure of different metal atoms in bimetallic core?shell nanostructures is an effective strategy to enhance their catalytic activities as well. In this talk, a facile, versatile, and robust method to prepare ultrathin bimetallic core?shell nanosheets (NSs) will be introduced, in which the ultrathin 2D metallic NSs are incompletely covered by another atomically layered metal.[3] Submonolayered Ru decorated-ultrathin Pd NSs was synthesized using this seed-mediated growth method for the first time, which is referred to as Pd@Ru NSs. The underpotential deposition process is responsible for the formation of Pd@Ru NSs. Impressively, the as-synthesized novel bimetallic Pd@Ru NSs exhibit superior catalytic performance toward the reduction of 4-nitrophenol and the semihydrogenation of 1-octyne as compared to the pure ultrathin Pd NSs and Ru NSs. We believe that our synthetic strategy could be universally applicable to various similar metallic nanostructures, which might have promising catalytic applications. References [1] X. Huang, Z. Zeng, H. Zhang*, Chem. Soc. Rev. 2013, 42, 1934. [2] X. Huang, S. Li, Y. Huang, S. Wu, X. Zhou, S. Li, C. L. Gan, F. Boey, C. A. Mirkin, H. Zhang*, Nat. Commun. 2011, 2, 292. [3] Z. Zhang, Y. Liu, B. Chen, Y. Gong, L. Gu, Z. Fan, N. Yang, Z. Lai, Y. Chen, J. Wang, Y. Huang, M. Sindoro, W. Niu, B. Li, Y. Zong, Y. Yang, X. Huang, F. Huo, W. Huang, H. Zhang*, Adv. Mater. 2016, 28, 10282.

Resume : Recently, there has been a growing interest towards nanocomposites applied in thermally conductive polymeric materials such as thermal interface materials. Graphene nanoplatelets (GNPs) have been proposed as the next generation multifunctional nanofiller in order to improve the thermal properties of polymers because of their high intrinsic thermal conductivity. The main objective of our study is to synthesize via melt mixing and investigate the structural and thermal properties of GNPs, with different diameter size, into HDPE. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to determine the interlayer spacing of the filler and the spatial distribution of GNPs on structural homogeneities in the nanocomposites. Τhermogravimetric analysis (TGA) and thermal conductivity measurements were used to analyze the effect of GNPs on the thermal properties of HDPE. GNPs with the higher diameter size significantly enhance both the thermal stability and the effective thermal conductivity of the composites. The greater contact area increases the path for phonon diffusion within nanofillers, and decreases thermal interfacial resistance increasing the thermal conductivity. This indicates that graphene nanocomposites are able to withstand harsh environments and can be used for high-tech applications. This work has been supported by EU in the framework of the NetFISiC project (Grant No. PITN-GA-2010-264613).

Resume : Energy storage devices (ESDs) based on Na ions are considered promising next-generation power sources due to the ubiquity and abundance of Na-ions and their similar chemistry to that of popular Li-ion batteries. One of the key factors determining the electrochemical performance of ESDs is the active electrode material used for the anode or cathode. In the anodic potential range, Na-ions can be stored by insertion between pseudographitic layers as well as pseudocapacitive storage by chemisorption on topological defect sites. In the cathodic potential range, on the other hand, heteroatoms can act as redox centers for surface-driven Na-ion storage. Therefore, desirable electrochemical performance can be achieved through sophisticated material design. Herein, we applied a simple heating process to fabricate two kinds of nanostructured carbon materials from renewable bioresources as an electrode pair for surface-driven Na-ion storage. As an anode material, hierarchically porous carbon with highly defective pseudographitic layers was fabricated using bacterial cellulose composed of entangled nanofibers. For the cathode, microporous carbon nanosheets with enriched heteroatoms were prepared from waste coffee grounds. Asymmetric ESDs based on these anode and cathode materials showed a high specific energy of ~130.6 W h/kg and a specific power of ~15,260 W/kg as well as excellent cycling performance over 3,000 cycles.

Resume : Graphene has attracted considerable research interest due to its unique electronic structure and great application potential. Currently, there are several ways available to produce graphene, and epitaxial growth via chemical vapor deposition is considered to be the most promising way. Therefore, a better understanding of the growth mechanisms to control the epitaxy processes of graphene is needed to achieve high-quality large-grain size of the monolayer. In this manuscript, the long-time system growth evolution of graphene through a kinetic Monte Carlo approach for different temperatures (400?, 600?, and 900?) and coverage (10%, 20%, and 40%) is investigated. The simulation model is 2 dimensions with 100×100 point grids. The results show that graphene growth on copper turns out to be a catalytic, thermally-activated process that nucleates from carbon monomers, proceeds by adsorption of carbon atoms, and is not self-limiting. Furthermore, graphene growth seems to be more effective at carbon supersaturation of the surface. The temperature effect is not obvious in lower coverage. However, in higher coverage, the graphene edge is smoother when the temperature is higher. Our growth model and computational results are in good agreement with recent X-ray photoelectron spectroscopy experimental measurements. The methods introduced are totally general and can be used to shed light on many growth processes on different metallic substrates other than graphene on copper.

Resume : Small metal nanoparticles are prospective systems for future catalyst materials, as their high surface-to-volume ratio ensures an efficient utilization of the metal content. However, a drawback of these materials is their stability, as they tend to form larger aggregates. One strategies to overcome this issue is the protection by an organic ligand shell. Furthermore, the ligands offer the possibility to introduce new functionalities to the material or to passivate the particle in order to tune their reactivity. In this work the influence of the stabilizing ligands and their effects on the particles’ reactivity and stability is examined. Small Pt-nanoparticles, which can subsequently be functionalized with different ligands by the preservation of the particle size, are yielded by the decomposition of a platinum salt in ethylene glycol. In this way, studies of the influence of the ligands only become possible. In this work the particles were functionalized by different ligand molecules and characterized prior to being tested in the selective hydrogenation reaction of 3-hexyne. It is found that amine- and phoshine-protected particles exhibit a considerable high activity, but tend to coalesce during the course of the reaction. Conversely, thiol-protected particles are highly stable, but only show limited reactivity. However, a decrease in the thiol coverage results in an increase in the particles’ activity and, at same time, in a preservation of their stability.

Resume : For the implementation of graphene into microelectronic applications large area growth of graphene is required. Chemical Vapor Deposition (CVD) on transition metals like Nickel (Ni) is one of the mostly used method to grow graphene. Indeed, highest quality, monolayer graphene is grown on single crystal Ni (111), but its high cost and limited size are main drawbacks to use it. Several attempts were done in order to grow monocrystalline Ni (111) on MgO (111) or ?-Al2O3 (0001) substrates. However these substrates are not CMOS compatible, therefore the purpose of the present work is to employ and optimize the polycrystalline Ni, grown on 100 nm SiO2/Si substrates. 200 nm Ni layers were deposited at room temperature by DC magnetron sputtering. The as grown samples were polycrystalline as measured by X-ray diffraction (XRD). Two main orientations (111) and (200) were detected. In the next step a series of annealing steps were performed in the temperature range of 925-1025 ?C in either hydrogen or vacuum, keeping other parameters constant in order to investigate the effect of annealing on surfaces roughness, grain sizes and crystallinity of the layers. Annealing in vacuum was found to give superior quality of Ni compared to the ones annealed in hydrogen. Firstly, Ni partially de-wetted from the surface at 1025 ?C if the samples were annealed in hydrogen atmosphere, whereas no de-wetting was observed for the ones annealed in vacuum, even up to temperatures of 1050 ?C. Moreover, the surface roughness was lower (rms value 10.3 nm) for vacuum annealed samples compared to hydrogen (rms = 48.5 nm) as measured by Atomic Force Microscopy. The poly-crystallinity of the annealed samples was confirmed by XRD measurements (two main orientations (111) and (200)) as well as by Electron Back Scattering Diffraction technique. XRD omega scans over Ni (111) reflection were performed in order to see the effect of annealing on the mosaicity of Ni (111) orientation. Full width at half maxima (FWHM) was 4.57° (at 1050 ?C) in hydrogen annealing, and 6.69° after annealing on vacuum. Finally, the CVD growth of graphene was conducted on these annealed Ni samples (at 1x10-2 mbar pressure and at 925 ?C) by using ethylene (C2H4) and hydrogen (H2) as reactant and carrier gases respectively. The deposition time was 5 min. Full characterization by in-situ X-ray Photoelectron Spectroscopy and Raman techniques have been performed for the grown graphene samples and will be presented in this paper.

Resume : We　propose a development of ‘thread transistors’ based on carbon-nanotube(CNT)-composite threads(CNTCTs). It is known that the CNTs have many useful properties,　e.g., metallic and semiconducting properties, so that many researchers have focused on them. We have also focused on them to develop useful applications, and already succeeded to fabricate the CNTCTs. In this study, we have developed metallic-CNTCTs and semiconducting-CNTCTs using each CNT that shows the above property. Moreover, by using these two types of CNTCTs and insulating material, we have succeeded to construct ‘thread transistors’ by using our CNTCTs. We are now aiming to construct an electrical circuit using them, i.e., ‘thread circuit.’ We here use chemicals (polycaprolactone) as insulating film to obtain a thin film and find a suit material of the composite thread. In addition, we also try to obtain two types of transistors, i.e., p- and n-type ones, by using doping material. As results of some experiments, the drain-to-source current was clearly controlled by the gate voltage and showed micro-ampere-order value, and we confirmed the non-doped sample showed the p-type operation. For obtaining n-type thread transistors, we are now testing the use of doping materials. Some samples are showing a tendency to show the n-type property in our recent study. In near future, we will obtain the two types of thread transistors and be able to construct the unique circuits, i.e., thread circuits.

Resume : Even though magnetic nanomaterials have already been used in clinics for contrast enhancement in magnetic resonance imaging (MRI) [1], their broad employment has stopped due to their low reproducibility stemming from high batch-to-batch variation in their physicochemical properties. For small enough crystal sizes, iron oxides exhibit the so-called superparamagnetic behavior, a feature combining high magnetization with very low coercive forces. Such superparamagnetic nanoparticles show great potential in therapeutic applications due to their ability to transform the energy of an alternating magnetic field (AMF) to thermal energy in what is often called magnetic fluid hyperthermia [2]. Therefore, aqueous suspensions at relatively higher nanoparticle concentrations (g/L), the so-called ferrofluids, also increase their temperature in the presence of an alternating magnetic field [3]. In this work, we synthesize uniformly SiO2-coated Fe2O3 nanoparticles [4] using a highly reproducible and scalable nanomanufacture process, namely flame spray pyrolysis, and further fabricate a composite multi-scale structure consisting of biopolymer alginate, the functional nanoparticles and a model drug. We examine the potential of flame-made SiO2-coated Fe2O3 nanoparticles as the stimuli-responsive material in the multi-scale composite architecture. We perform detailed physicochemical and magnetic characterization on the hybrid alginate hydrogel beads and evaluate their potential in magnetic fluid hyperthermia and enhanced biomolecule release in the presence of an external AMF. The possibility to externally stimulate drug release will facilitate new possibilities in intelligent, on-demand drug administration [5]. References [1] A. Singh, S. K. Sahoo, Drug Discov. Today, 19, 474-481 (2014). [2] A. Jordan, R. Scholz, P. Wust, H. Fahling, R. Felix, J. Magn. Magn. Mater., 201, 413-419 (1999). [3] G. A. Sotiriou, M. A. Visbal-Onufrak, A. Teleki, E. J. Juan, A. M. Hirt, S. E. Pratsinis, C. Rinaldi, Chem. Mater., 25, 4603-4612 (2013). [4] A. Teleki, M. Suter, P. R. Kidambi, O. Ergeneman, F. Krumeich, B. J. Nelson, S. E. Pratsinis, Chem. Mater., 21, 2094-2100 (2009). [5] A. Teleki, F. L. Haufe, A. M. Hirt, S. E. Pratsinis, G. A. Sotiriou, RSC Adv. 6, 21503-21510 (2016).

Resume : Since its first practical evidence in 2004 graphene has shown a lot of astonishing properties. As a consequence of being a two-dimensional material, it has the highest surface-to-volume ratio making it an interesting candidate for sensing applications [1]. Despite that applications using graphene are still rare. By means of catalytic chemical vapor deposition (CCVD) of in-situ graphene [2], we show an easy method for the direct fabrication of field effect transistors (FETs) from structured, electrically disconnected metal catalyst sites. These metal catalyst sites are finally connected by lateral growth of nanocrystalline graphene during the CCVD process yielding the final device structures. Here we report on the utilization of different thin film metal catalyst systems, encapsulating a thin PMMA layer, for the growth of large area FETs. Output characteristics for the devices were recorded by electrical testing in atmospheric environment, showing different growth ranges and electrical characteristics for the various catalyst systems. Finally, the largest fabricated devices have been tested for humidity sensitivity in a resistive configuration. [1] A. C. Ferrari et al., Nanoscale, 7, 4598 (2015) [2] P. J. Ginsel, et al., Design & Technology of Integrated Systems in Nanoscale Era, (2011)

Resume : In this study, we developed a technique to fabricate Two-dimensional crystalline composite colloidal monolayers using the suspension composed of Poly(methyl methacrylate) (PMMA) microspheres and Titanium oxide (TiO2) nanoparticles at air/water interface. The compactly floated composite arrays of PMMA/TiO2 on water surface were successfully transferred to the solid substrate. Our method can provide the highly reflective 2D photonic crystal by incorporation of nano-particles beneath photonic crystal array. Moreover, we can obtain TiO2 inverse opal layer which has 'egg plate' structure upon calcination of template particles. We also reinforced the TiO2 inverse opal structure by additional spin coating of TiO2 nanoparticles. This intriguing conformation is expected to be utilized for various photonic applications.

Resume : Hybrid halide perovskites are being intensively studied as active layers in photovoltaic cells. They combine cost efficiency due to solution processability and high power conversion efficiency due to electrical transport properties and proper band gap. The chemical stability, which is often affected by quality of surfaces and interfaces, still remains a concern. Meanwhile, lead sulfide (PbS) is rocksalt-structured semiconductor with low band gap, which can be easily made as large single crystals. PbS is also well known for quantum dot material with high radiative efficiency. Epitaxial growth of CH3NH3PbBr3 on PbS with low lattice strain is possible, which may positively affect to stability of the perovskite. Recently, quantum-dot-in-perovskite crystals reported as promising optoelectronic material as well. Therefore, understanding the interface between lead sulfide and halide perovskite is mighty important. In this study, we perform first-principles density-functional theory (DFT) calculations to investigate atomic contact properties (e.g. interface geometry) and electronic contact properties (e.g. charge redistribution and band offset). As a preliminary step, we focus on interface between PbS and CsPbBr3. Our results predict spontaneous growth of CsPbBr3 on PbS is feasible, and consequentially form type I band alignment.

Resume : The novel and efficient magneto-optical bifunctional Fe3O4/ZnS@LaF3:xCe3 ,xGd3 ,yTb3 (x = 5; y = 5, 10 and 15 mol%) nanocomposites have been reported. A hydrothermal synthesis for inverse spinal Fe3O4 and chitosan assisted co-precipitation method to coat LaF3:RE3 materials over the ZnS semiconductor functionalized iron oxide particles were used. The trigonal structure of synthesized bifunctional nanostructure was confirmed by XRD and HRTEM. The M-H and ZFC/FC manifested superparamagnetic behavior of the materials at 300 K along with magnetic contributions of doped rare earth ions at low temperature. A broad emission band was observed in range 400-550 nm due to the sulphur vacancy on the surface of Fe3O4/ZnS nanocomposite. The excitation spectra of bifunctional NPs revealed broad absorption bands centered at 270 nm attributed to the 4f(7F7/2)5d interconfigurational transition of the Ce3 ion with narrow absorption lines due to 4f–4f intraconfigurational transitions of the Tb3 ion. The emission spectra under excitation at 258 nm corresponding to the from 4f(2F5/2 to 5d interconfigurational transition of the Ce3 ion showed dominant narrow emission lines assigned from 5D4 to 7FJ transitions (J = 6-0) of the Tb3 ion accompanied by Ce3 (4f(2F5/2) to 5d) and Gd3 (6P7/2 to 8S7/2) transitions. The luminescence decays suggested cross relaxation for the 5D4to 7F5 transition of Tb3 ion. Further, the investigated characteristics suggested efficient candidature for the magnetic light-converting molecular devices and high energy radiation detection, the reason being Ce3 as radiation sensitizer, Gd3 as neutron captor and Tb3 as wavelength shifter.

Resume : Recent studies revealed that low-temperature fuel cells (FCs) equipped with catalyst support show improved electrochemical properties of the FC catalyst, as the support provides a high dispersion of catalyst nanoparticles, facilitates electron transfer, and enhances the water/gas management. Corrosion of the support, resulting in low durability, provides obstacles in scaling low-temperature FCs. We design high-durability catalyst supports using carbon xerogels (CX), synthesized by the catalytic polycondensation of resorcinol and formaldehyde in the presence of a basic catalyst within centrifugal fields of various magnitudes, followed by thermal treatment at high temperature. After chemical functionalization, the carbon xerogels are decorated with metallic nanoparticles (Ni, Co, and Fe). We characterize and discuss the electrochemical performance of the functionalized CX as alkaline FC catalyst support.

Resume : In this paper, the study and the development of integrated Pd–PANI/CNT based sensors for H2, D2, and NH3 gas mixtures measurement at different concentration are reported. The sensors were elaborated by direct deposition of an active doped layer, previously obtained from a Pd–PANI/CNT conducting mixture, on gold interdigitated planar electrodes on sensors surfaces using dropcast method. For the experimental campaign two sensors with the same active layer were fabricated and tested at room temperature. The sensors sensing mechanism is characterized by the variations of the electrical resistance. Adsorption of H-atoms in interstitial sites in the palladium lattice provides an increase in lattice parameter which induces an external volume expansion of the active sensing surface. This physical behavior confirms the existence of a resistive path formed by the Pd lattices in the structured layer provided by the PANI/CNT that will act as a flexible conducting network. Sensing characteristics and variation of resistance ratio of the sensors based on Pd–PANI/CNT conducting mixture are presented for pure H2, D2 and respectively NH3 gas batches and also for different mixing ratio of those gases. The obtained sensors show remarkable sensing, stability and recovery capabilities and could be incorporated in an efficient and accurate low-powered sensor-system for gas detection applications.

Resume : Monolithic porous carbon was prepared from resorcinol(R) and formaldehyde via hydrothermal reaction, but no additives such as catalyst and surfactant. Pore size was controlled by varying R/W ratio as well as R/F ratio. The samples were prepared in 50 ml vials and cured at 90°C for 6 h, followed by complete drying. Then, the samples were pyrolyzed at 900°C for 2 h under N2 flow and then activated at 900°C for 2 h under CO2 flow. The morphology of the samples were analyzed by SEM, while surface area was measured by BET method.

Resume : Carbon nanotube is an expected candidate of field emission cathode due to its excellent field emission characteristics, high electrical conductivity and structural stability. The previous reports pointed out that field emission current density of perfect individual carbon nanotube can reach to ~1000 A/cm2, and 100 A/cm2 for ideal carbon nanotube arrays with ~10% filling factor. Until to now, only several A/cm2 in carbon nanotube array was achieved in previous reports. Lower adhesive strength between the carbon nanotubes and the substrate limited further increase of field emission current density and their applications in field emission. In this work, the tip of tungsten needle was coated by a uniform layer of conductive carbon glue. A bundle of carbon nanotube array was transferred from the array without hardly any breaking of array structure. By the curing of the glue in air, the adhesive strength between the carbon nanotube bundle and needle was over 200 N/cm2, and distinctly larger than that between the as-grown array and substrate (about 10 N/cm2). Field emission measurement demonstrated that the current density can reach to 10 A/cm2 and the maximum was about 30 A/cm2. This carbon nanotube-tungsten needle structure is easily used as the cathode of field emission devices for a wide range of applications such as displays, X-ray tubes and lamps.

Resume : Bur-like iron oxide nanocapsules (IO-NCs) with or without organic polymer core were synthesized by a temperature-controlled heat treatment of iron oxide nanoneedles grown on spherical polymer template. The structure of the IO-NCs was characterized by scanning electron microscopy, X-ray diffractometer, FT-IR, and thermal gravimetric analyses. Due to a synergistic effect of IO nanoneedles and organic core, the IO-NCs with organic polymer core (IO-oNCs) showed a good removal efficiency for heavy metal ions, Pb(II) and Cu(II) showing adsorption capacities of 123.4 mg/g and 32.7 mg/g, respectively. In addition, the IO-oNCs exhibited an excellent photocatalytic activity in the degradation of methylene blue (MB) and methyl orange (MO) visible light irradiation, which showed the degradation efficiency of 99.7% and 99.5% for the MB and MO degradation within 20 minutes. The further systematic studies on the inorganic and organic pollutant removal by the IO-NCs, such as effects on the pH of the solvent, concentration of pollutants, and dosage of the IO-NCs will be presented in detail.

Resume : In the past decades, nanocarbons (NCs) including carbon nanotube (CNTs), graphene, graphene nanoribbon (GNR), and graphene quantum dot (GQD) have spurred intensive interests due to their exceptional physical and chemical properties. Recent theoretical and experimental works demonstrated that NCs are promising materials for many applications such as energy generation and storage, chemical and biosensors, catalysis, nanocomposites, and nanoelectronics. To further boost the advantages of NCs, metal nanoparticles (NPs) were selected to form various types of NC-NP heterostructures for applications including, energy storage, photocatalyst, electrochemical sensors, and especially catalysis. The unique nature of NC-NP composite materials with high surface area and exceptional materials properties can assist the chemical reaction to lower the activation energies and increase reaction rates of reactions. Here we report a rational design of NC-NP composites for catalysis. We used the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a testing platform to exam the catalysis properties of NC-NP heterostructures. 4-NP has been a persistent wastewater constituent from various industries. Consequently, a catalytic method is sought-after in reducing 4-NP to less toxic and commercially important4-AP. In our work, we comprehensively prepared various NC-NP heterosctrutures. The NCs were including multi-walled CNT, singled-walled CNT, graphene, graphene oxide, GNR, GQD, and the NPs were including different metal NPs including Pt, Ag, and Au. Detailed materials characterizations and systematic catalysis study indicates that GNR-PtNP heterostructures showed exceptional catalytic performance with a normalized reaction rate constant (kn) of 120 x 10-3 mmol.s-1g-1 for 4-NP reduction. Our work suggests that nanoengineering of NC-NP composites can open a new venue to develop an effective and stable catalyst for environmental protection.

Resume : Recently graphene quantum dot (GQD), a unique type of graphene derivatives, has stimulated a lot of attentions due to their exceptional properties including low toxicity, photo-stability, biocompatibility and excellent solubility, making them promising for biosensing. Moreover, bio-compatible gold (Au) and silver (Ag) nanostrutures can provide great electromagnetic fields generated upon excitation of their localized surface plasmon resonance, allowing surface-enhanced Raman scattering (SERS) occurred for an ultra-sensitive molecular-level detection [1] and catalysis [2]. However, the conventional approaches to prepare such nanoheterostructures are usually complicated, time consuming, inefficiency, and high temperature required. Here we demonstrate a facile synthesis of GQD/AuNP and GQD/AgNP heterostructures by using atmospheric-pressure microplasmas. Microplasmas [3] are defined as gaseous discharges formed in electrode geometries where at least one dimension is less than 1μm. Due to surface volume change, microplasmas can be operated stably with an aqueous solution as an electrode at atmospheric pressure. Energetic species formed in the microplasma are capable to initiating electrochemical reactions and nucleating particles in solution without chemical reducing agents. Detailed microscopic and spectroscopic characterizations indicate that the morphology and size distribution of as-produced GQD/AuNP and GQD/AgNP nanoheterostructures can be controlled by the reaction conditions. The SERS and photoluminescence (PL) spectroscopic studies [4] further explore the optical properties of as-produced GQD/AuNP and GQD/AgNP nanoheterostructures and suggest that GQDs/AuNPs nanoheterostructures can performed as an effective material for SERS-based and PL-based biomolecular sensing and chemical catalysis of 4-nitrophenol.

Resume : Facile yet rational design of efficient reversible oxygen electrocatalyst is critical for many renewable energy conversion and storage technologies. Here we report a simple and general synthetic protocol for fabricating hierarchically porous and heteroatom doped carbon catalyst, which exhibited outstanding oxygen reduction/evolution activities (with a metric potential difference of 0.72 V in 1 M KOH, the best value for metal-free catalysts reported to date) with good stability in different electrolytes. The excellent performances of the catalyst were primarily endowed by our synthetic protocol, which integrates good conductivity, abundant accessible dopant species and suitable porous architectures within an in-situ pyrolysis reaction. As a result, the performances of the rechargeable Zn-air battery based on the optimized catalyst substantially outperform those afforded by benchmark Pt/C catalyzer. Our work is expected to open up new avenues for developing other efficient catalysts in a facile and viable way.

Resume : Reduced graphene oxide (rGO) is one of graphene derivatives which shows similar electrical properties with graphene, and enough conductivity to act as a channel material for electronic devices. In addition, rGO can be synthesized in large quantities with low cost using inexpensive reagents and uncomplicated chemical process. Also degree of GO reduction can strongly affect the characteristics of rGO, such as conductivity and tensile strength, which means that they could be finely controlled by reduction condition. Rich density of defect sites allows rGO a very suitable material for humidity sensing. In this study, rGO@MoS2 (MS-GO) hybrid composites were used for the detection of humidity. Base resistance were controlled by changing the ratio of rGO and MoS2 with atomic percent. The change of atomic percent greatly influenced the humidity sensing performance of the resulting composites. Hybrid composites consisted with 3:2 atomic percent of rGO : MoS2 showed superior sensing properties compared to the pristine rGO and MoS2. The enhanced sensing properties are based on the increased change of potential barrier by p-rGO-n-MoS2 junction in the H2O ambient. This study suggests optimal atomic ratio of rGO and MoS2 to obtain the maximum humidity sensing properties in rGO-n-type MoS2 composites by controlling the ratio of atomic percent.

Resume : Finding reliable and low cost sensing solutions of air environmental pollutants remain a present and challenging issue. This work addresses to gas detection, namely NO, NO2 and NH3, and propose a novel sensor design having as substrate functionalized single walled carbon nanotubes (SWCNTs) doped with Cesium (Cs), deposited on an interdigitized Au electrode structure. To synthesize the doped SWCNT, the functionalized SWCNTs, mixed with Cs, were subjected to a simple (stright forward) thermal solid-state reaction. The sensible material was further characterized by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, to confirm its structure. Apart from highlighting the responde and recovery time of the proposed sensors structures, several important parameters controlling the fabrication of the sensible substrates were investigated and optimized. Overall it was concluded that the combination SWCNTs – Cs are emerging as an alternative solution and an important member of the SWNCTs based gas sensors large family.

Resume : Generation of hydrogen via electrochemical water splitting is one of promising technologies to overcome our dependency on fossil fuels, but the efficiency of this process is very low without catalysis of both half-reactions. Particularly, catalysis of oxygen evolution reaction (OER) is of great importance for improving the total efficiency of water electrolysis. Doped nickel oxide-based compounds attract enormous interest as very efficient and abundant catalysts. However, in spite of the large amount of publications, there is still no clear understanding on the role of dopants in the catalytic process. The discrepancy in the literature data is largely explained by a large amount of possible active phases in the nickel oxide system and a complex dynamic character of their transformations. We have developed a synthesis procedure enabling controllable formation of nanosized nickel hydroxide and nickel oxide polymorphs substituted with transition metal ions such as V, Cr, Mn, Fe, Co, Ru, Ir, Ce, and investigated their structure-activity correlation in electrochemical water oxidation. The difference in electrocatalytic activity could be mainly attributed to the inhibited crystallization of highly active ?-Ni(OH)2 to a less active, but more stable ?-polymorph by transition metal ions, which is important for understanding the mechanisms of electrocatalytic activity of nickel oxide-based compounds.

Resume : The one of the highly important areas of science and technology are closely connected with lightweight and mechanically strong materials with huge prospects in the fields of modern automotive and especially aerospace industry where even a small reduction of craft weight can give rise to a considerable drop in the operation costs. Nowadays the materials used in this area are mostly based on aluminum, which is a reasonable compromise between weight, cost and mechanical characteristics. Should be noted that reinforcing by carbon or boron nitride nanostructures, which have high mechanical characteristics, can potentially increase relatively modest mechanical characteristics of Al. Here we perform atomistic simulations at density functional theory (DFT) and analytical potential levels to carry out a fundamental study on the interfacial mechanical properties of the nanocomposites based on Al strengthened by BN/graphene nanoribbons and their dependence on the nanoribbon widths. It was found that of the non-passivated edges strongly improves nanocomposite mechanical characteristics. We found that contrary to carbon and BN nanotubes the active chemical edges of the ribbons create strong chemical bonding between filler and metal matrix and yield critical shear stress in GPa range. This result combined with the enhanced rigidity of narrow nanoribbons indicates that such nanoribbons can be considered as perspective fillers in the metal composite. We also investigate the interaction of carbyne with Al matrix and assess the mechanical characteristics of such material. Finally, keeping in mind the possible simultaneous use of the composites for reinforcement and electrical applications, we study the electronic transport in the composite material. The authors gratefully acknowledge the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (No. ?2-2015-033).

Resume : The properties of Carbon nanotube (CNT) is critically restricted by strong aggregation tendency and resultant local heterogeneity. Within selected solutions containing conjugated polymers, functional materials like CNT and fullerene derivatives were found to preferably disperse within liquid phases of conjugated polymers as being driven to establish favorable pi-pi interactions. Hence, the distribution pattern of liquid phase of conjugated polymer Poly (9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) and insulate polymer Poly(methyl methacylate) (PMMA) in the solution has been studied, as an attempt to create the templates for guiding the dispersion of CNT and achieve the percolation network of functional carbon allotropes. The preliminary research has systematically verified the selectively dispersion of CNT within polyfluorene liquid phases. During the regular stacking of crystalline lamellae of polyfluorenes, CNTs were found to associate in between lamellae, therefore resulting in parallel stacking patterns of CNTs. The polyfluorenes which is unable to crystallize is motivated by annealing process at selected temperature, and lead to the growth of rectangular board-like domains in order to reduce interface area with substrate. Within the flow field of liquid crystalline domains, originally dispersed CNTs were found to gradually adopt vertical orientation in a parallel manner in order to maintain favored interactions with the matrix of liquid crystalline conjugated polymers, viewed as the vertical association of CNT. To sum up, ordering alignment of polymeric matrix has been identified as feasible mechanisms able to organize the dispersion of CNTs into regular stacking patterns within polymeric thin films.

Resume : In this research, we report facile synthesis method of shape-controlled highly branched palladium (HBPd) nanocatalysts supported on graphene nanoplatelets (GNP) and their application as a cathode in a non-aqueous Li-O2 battery. The HBPd nanocatalysts on GNP (HBPd-GNP) were prepared through a simple wet-chemical synthesis by reducing Na2PdCl4 with ascorbic acid in cetylpyridinium chloride-functionalized GNP dispersion. The synthesized HBPd with average size of 14 nm grew via particle attachment mechanism and strongly anchored on GNP with well-distributed states. To investigate the electrochemical performance of HBPd-GNP in a non-aqueous Li-O2 battery, binder-free flexible HBPd-GNP/graphene oxide (GO) (HBPd-GNP/GO) films were fabricated through a vacuum-filtration and used as cathode. Thanks to the high catalytic activity of the highly branched structures in Pd nanocatalysts, the Li–O2 cell using the HBPd-GNP/GO electrode showed significantly lower overpotentials both on discharge and charge compared with catalysts-free GNP/GO electrode and even irregularly shaped Pd nanoparticles contained GNP/GO (PdNP-GNP/GO) electrode. In addition, we found that Li2O2 formed on the HBPd-GNP/GO electrode had an amorphous nanosheet-like morphology, which decomposed more efficiently than did the large toroidal product formed on the GNP/GO paper electrode. Consequently, the Li–O2 cell using the HBPd-GNP/GO electrode exhibited greatly enhanced energy efficiency and cyclability as compared with that of the GNP/GO and PdNP-GNP/GO electrode.

Resume : Tunability of Photovoltaic and photocatalytic properties of the layered perovskites have attracted lots of attention because of their potential for possible future applications in the field of optics, energy conversion and environmental treatment. Layered oxide materials are important because of their physical and chemical stabilities and layered materials can be modified with intercalation, Ion-exhange or doping to optimize their properties. Layered oxides can be exfoliated into their 2D nanosheets to produce nanostructures as building blocks for functional materials. Different classes of nanosheets doped with different lanthanide cations can be utilized to fabricate thin composite films emitting light at different wavelengths. For this purpose, we have successfully synthesized various Ti, Ta, and Nb Aurivillius phase layered perovskites co-doped with Yb and various lanthanides. Upconversion examples of these type of layered oxides doped with lanthanides will be presented. Upconversion experiments have been conducted at room temperature and 980nm IR laser was used as a source of excitation. Green, red, blue and IR emission bands have been observed and results have shown that playing with ratio of sensitizer/activator concentration (Yb/Ln3+) can change the relative intensities of the emission bands. We would like to acknowledge TUBITAK for funding through project 114Z452 (Synthesis of two dimensional luminescent perovskite nanosheets).

Resume : Antimony (Sb) based nanomaterials have attracted considerable interests due to their great potential in a broad range of applications, including batteries, electronics and catalysis devices. For instance, Sb chalcogenides (Sb2S3, Sb2Se3) are kinds of multifunctional semiconductor with their high theoretical sodium storage capacity, high thermoelectric power and high photosensitivity. Herein, we report various facile and universal methods (e.g. hydrothermal method, microwave irradiation) for the synthesis of novel Sb based nanostructures, including three-dimensional Sb@C networks, mesoporous Sb2S3@SiO2 nanorods and ultralong Sb2Se3 nanowires. The rational construction of advanced Sb based nanostructures with unique architectures has been confirmed to effectively improve their sodium storage performance. Besides, the fast, green and facile microwave synthesis (within 0.5 h) of Sb chalcogenides (Sb2S3, Sb2Se3) with optimized nanostructures (highly uniform, disperse nanowires) also demonstrate its importance towards next-generation promising energy applications. Acknowledgement: Our work was supported by the National Natural Science Fund for Distinguished Young Scholars (51425204) and the Programme of Introducing Talents of Discipline to Universities (B17034).

Resume : The modification of carbon materials via nitrogenation has been widely studied in recent years due to their performance as electrodes in applications including electroanalysis, electrocatalysis and energy storage. In this work we synthesized nitrogenated amorphous carbon thin film electrodes (a-C:N) with varying nitrogen content via DC magnetron sputtering and characterised them using a combination of spectroscopic and electrochemical methods. Results indicate that low levels of nitrogenation yield carbon materials with narrow optical gaps and semimetallic character. These materials also display fast electron-transfer kinetics to the outer-sphere hexammine ruthenium(II)/(III) redox couple, which suggests a correlation between bulk optoelectronic properties and electrochemical performance for outer-sphere redox probes. Increasing levels of nitrogenation decrease the metallic character of the electrodes and increase the impedance to charge transfer, ultimately yielding materials with optical and electrochemical properties consistent with disordered cluster aggregates. Interestingly, using ferrocyanide as a surface-sensitive redox probe resulted in a monotonic increase of the impedance to charge transfer vs. nitrogen content. This suggests that surface chemical effects may dominate the electrochemical response, even when nitrogenation results in enhanced metallic character in carbon electrodes.

Resume : The main objective of the project is the development of novel methods for the synthesis and functionalization of conductive nanocarbons for a new generation of field effect transistor sensors suitable for high sensitivity bio-sensing applications. Advanced carbons (carbon nanotubes, nanowalls and nanoporous carbon) have been synthesized by means of low temperature plasma-based techniques, PVD and wet chemical method. Prior to bio-molecule immobilizing, nanostructured carbon materials have been treated using plasma system (CO2 N2, N2/H2, NH3) to generate carboxylic and aminated groups. This plasma treatment not only functionalizes the advanced carbon film but also permits to avoid the collapse phenomena keeping then a high surface/volume ratio. The adhesion of protein biomolecules such as bovine serum albumin onto such surfaces has been tested positively. Dual gate transistors based on polysilicon have been developed and act as surface charge sensors. The main objective is to combine the advantages of dual gate structures for the increase of sensitivity of detection and the high surface / volume ratio of nanomaterials. The process has been optimized and is fully compatible with nanomaterials integration, such as the temperature deposition.

Resume : Search for new catalysts promoted during the last decades ferroelectric materials, where their polarization may be used for molecular attachment [1] and subsequent dissociation of these molecules [2]. A wealth of phenomena are concurring to the observed catalytic activity, and in order to discriminate between these phenomena, work on prototype systems, such as single-crystal ferroelectric thin films with minimal contamination and defined polarization state is needed. This work will present results obtained when CO or NO are adsorbed on such a prototype system, lead zirco-titanate PZT(001). Molecular adsorptions are shown to be intimately connected with the polarization state of the film, while dissociations are promoted by the electric field at the interface of the free ferroelectric. As a consequence, most carbon is found on the surface in the reduced form. The reduced C is desorbed from the surface when the polarization is lost in the form of CO2. The NO dissociation has as a consequence the attachment of oxygen to the surface and nitrogen elimination. These results may be further used or combined in order to propose new catalysts for Fischer-Tropsch synthesis, reduction of noxes or three-way catalysts. [1] L.E. ?toflea et al., J. Mater. Chem. A 2, 14386 (2014). [2] L.C. T?nase et al., Sci. Rep. 6, 35301 (2016).

Resume : Nanoscale solid-state systems are boosting the prospects of material science by providing unparalleled optical and electronic functionalities. Here, we combine quantum dots and dielectric resonators as building blocks of a hierarchical metamaterial, which not only inherits the intrinsic optical and electronic properties of its nanoscale constituents, but also features enhanced performance. This simple yet powerful scheme is of great impact for applications in sunlight energy conversion, as well as for increasing the sustainability of the available optoelectronic devices. Specifically, in this work we integrate confined luminescent silicon nanocrystals (Si-NCs) within SiO2 nanocylinders, arranged in a 2D array. We demonstrate that the resulting metamaterial preserves the radiative recombination properties of the Si-NCs, inherit the nanocylinders spectrally-selective absorption and features enhanced photoluminescence intensity. As a proof of concept, we tackle the spectral requirements of a light down-converter for solar cells. The principle demonstrated here is general and the Si-NCs can be replaced with other semiconductor quantum dots, rare-earth ions or organic molecules. Similarly, the dielectric medium can be adjusted on purpose. We envision a large use of this hierarchical design for efficient photovoltaic, photo-catalytic and artificial photosynthetic devices with spectrally selective absorption and enhanced efficiency.

Resume : We present a novel class of electroactive soft actuators based on ionic gel/metal nanocomposites produced by implanting supersonically accelerated neutral gold nanoparticles into an engineered ion conductive soft polymer. The ionic gel consists of chemically cross-linked poly acrylic acid and poly acrylonitrile networks, blended with halloysite nanoclays and imidazolium-based ionic liquid. The material exhibits mechanical properties similar to that of elastomers (Young's modulus ~ 0.35 MPa) together with high ionic conductivity. The fabrication of thin (~ 100 nm thick) nanostructured compliant electrodes by mean of Supersonic Cluster Beam Implantation (SCBI), does not significantly alter the mechanical properties of the soft polymer and provides controlled electrical properties and large surface area for ions storage. SCBI is cost-effective and suitable for the scale up manufacturing of electroactive soft actuators. We report high-strain electromechanical actuation performance in a low voltage regime (from 0.1 V to 5 V) and robust stability up to 76000 cycles, with no electrode delamination or deterioration. The observed behaviour is due both to the intrinsic features of the ionic gel (elasticity, ionic transport capability) and to the electrical and morphological features of the electrodes, providing low specific resistance (< 100 Ohm/cm2), high electrochemical capacitance (~ mF/g), and minimal mechanical stress at the polymer/metal composite interface upon deformation.

Resume : Sol-gel technology provides a valuable method for the preparation of porous film silica through the hydrolysis and condensation of silicon alkoxydes. The use of tetraorthosilane and organic modified silanes precursors in the sol-gel process introduces specific functionalities in the silica matrix which can improve the chemical specificity controlling the porosity and/or polarity of the pore. In order to modulate the properties of the silica layer, its chemical composition was modified with different organic groups to form organically-modified silicas (ORMOSIL). These ORMOSILs promote the presence of specific binding pores by interacting chemical functions. These hybrid materials with modulated hydrophobicity or ion conductivity have been synthetized by electrochemical method in the present work and were characterized using different techniques: TEM, FESEM, FTIR and TG. The ORMOSIL films have been applied to the development of selective electrochemical sensors for the detection of the major catecholamine neurotransmitters (dopamine, norepinephrine and epinephrine). Functionalized silanes (containing phenyl, propyl, octyl, isobutyl and methyl groups) have been chosen due to their ability to interact noncovalently with these molecules within the silica film and provide the chemical ambient for rebinding. The affinity of the film to these neurotransmitters was investigated by electrochemical methods. The selectivity and sensitivity of the films was further investigated for its ability to discriminate between the different neurotransmitters.

Resume : The covalent functionalization of carbon nanostructures was largely exploited and different techniques were employed to achieve fine control of their electronic properties. Carbon nanostructures were decorated with large variety of atoms and molecules, using wet chemistry, hydrothermal reactions and plasma process. Among the possible grafting species, fluorine has emerged because of the suitability of fluorine-based carbon systems for implementation in devices as gas sensors and batteries. Within this context, we present the tuning of electronic properties of vertically aligned carbon nanotubes (vCNTs) via plasma fluorination. The functionalization is performed in a µ-wave plasma chamber by using two different precursor gases (Ar:F2 and CF4). The fluorination mechanism and its effect on the electronic properties of vCNTs are investigated by advanced synchrotron-based techniques. The fluorinated carbon nanotubes are then integrated in a chemical gas sensor to address two main drawbacks that affect the sensing layers based on carbon nanomaterials: 1) insufficient sensitivity to low concentrations of target gases and 2) interference of humidity in the environment. The selective response to 100 ppm of NO2 and NH3 is presented. The gas sensing stability in humid condition is also shown thanks to the improved hydrophobicity of the carbon systems after fluorination.

Resume : The graphene oxide is a very promising material for its own properties and for its use in the production of graphene by reduction. In previous works we estimated the feasibility of a graphene monolayer grew over GaN(0001) surfaces1. In this work we will present Density Functional Theory (DFT) calculations of the surface structure resultant from introduction of oxygen on a monolayer of graphene to obtain a graphene oxide monolayer. The unit cell used was 3√3•x3√3graphene/4x4(0001)GaN. First of all we considered the adsorption of a single oxygen atom over the unequivalent carbon atoms in respect to the Ga and N atoms of the substrate. The sites considered are: over Ga or N atoms, between two Gallium atoms, and some other sites. The total energy calculations show that the position between two Ga atoms is the preferred adsorption site. Then we introduce more oxygen atoms up to four by unit cell, and finally we studied the adsorption of hydroxyl groups and different combinations of hydroxyl and oxygen. The results obtained seem to indicate that this could be a good method to fine tuning the gap. Acknowledgments: DGAPA project IN114817. The authors are grateful to A. Rodriguez for his technical assistance. Calculations were performed at the DGCTIC-UNAM under project SC16-1-IR-57. References 1 Espitia-Rico, Rodríguez-Martínez, Moreno-Armenta, Takeuchi; Applied Surface Science 326 (2015) 7–11

Resume : Metal fluorides present many applications in sensors, batteries, actuators or optical devices. Many methods have been developed for synthesis of metal fluorides nanoparticles and their self-assembly. Among them, microemulsion method is exploited for the preparations of metal fluoride nanostructures, like self-assembled YF3 uniform nanoparticles or BaF2 nanoparticles produced by reverse microemulsion. Here our attention is paid to the synthesis of NiF2 nanoparticles. NiF2 is attracting attention as conversion reaction material for Li ion batteries due to its comparatively high voltage (2.96 V) and specific capacity (554 mAh/g), and the electrochemical performance of NiF2 nanomaterials could be improved by engineering self-assemblies having open facets. Beside the electrochemical interests in NiF2, its magnetic properties are also interesting, and could be modified by nanostructuration. In this talk, we present the synthesis of hydrated NiF2 nanoparticles which self assembles into truncated bipyramidal structures by reverse microemulsion. The self-assemblies of nanoparticles into theses architectures are controlled by varying the reaction time and water to surfactant ratios. Few examples of nanostructuration of NiF2 are given in the literature, generally by ball-milling method. An important drawback is the formation of hydrated NiF2, and the dehydration of the resulting nanomaterials remains difficult. Here, we come up with a new strategy to synthesize NiF2 nanoparticles and their self-assemblies. Hydrated-NiF2 is transformed to dehydrated-NiF2 under F2 and the self-assemblies of nanoparticles are successfully retained. Electrochemical and magnetic properties of resulting nanomaterials have been studied.

Resume : Graphene is a two-dimensional carbon nanomaterials with superior electronic, thermal, and mechanical properties and currently explored in advanced electronics, transparent protective coating, energy storage devices and polymer composites. It is highly desirable to economically produce high-quality graphene in industrial quantities to commercially realize its applications; however, no scalable method exists. Mechanochemical approaches to graphene nanosheets synthesis offer the promise of improved yields, new reaction pathways, and greener and more efficient syntheses, making them potential approaches for low cost production of graphene nanosheets. Here we report the scalable production of single- and few-layer graphene nanosheets with low defect densities by an efficient water-assisted mechanochemical exfoliation of graphite in N-methylpyrrolidinone (NMP). The mechanochemical exfoliation could be further improved by applying high speed homogenization and ultrasonication as pretreatments. It is found that the former step homogenized the graphite-solvent solution while the latter provided sufficient energy to weaken the van der Waals interactions and promoted the intercalation of solvent molecules into the graphene sheets within bulk graphites. Significantly, when NMP with water was employed as the cosolvent in the mechanochemical exfoliation, it was found to be possible to produce graphene nanosheets with less defect. Detailed materials characterization including transmission electron microscopy, Raman spectroscopy, and UV-Vis absorbance spectroscopy suggest that single- and few-layer graphene nanosheets were successfully prepared with the concentration and yield up to 15.8 mg/mL and 31.5%, respectively. The yield may be further improved by optimizing the process conditions. Our work provides a guide of rational design of a solvent system to improve the yield and stability of the exfoliated materials.

Resume : This work emphasizes the study of efficiency for copper electroplating as a method to improve and enhance the soldering process of microelectronics using a cost-effective procedure. Printed circuits boards (PCB?s) with an electrode pattern, having a gap of 1 millimeter between electrodes, were used. A liquid electrolyte of CuSO4 and H2SO4 in water was located inside a cell in the PCB. The copper that was going to be coated, which is known as the cathode, was located inside the cell containing the electrolyte solution. A part of the copper that was going to be used as the plating material to bridge the gap between the two electrodes, known as the anode, was also placed inside the cell. Using this method the deposition of the copper took place in the part known as the cathode using a variation of constant voltages in each sample. Using low temperature soldering can help improve and develop better techniques to solder components to PCB at a low cost under simple conditions.

Resume : We reported a unique strategy to constrain the nucleation centers for multilayer graphene (MLG) and later single-crystal graphene domains through gettering the carbon source on backside of the flat Cu foil, during chemical vapor deposition (CVD). Hitherto, for a flat Cu foil, merely top-surface-based growth mechanism has been emphasized during CVD growth, while overlooking backside graphene. However, our systematic experimental findings indicated the strong correlation between backside graphene and MLG growth on the top surface, which governs by the carbon diffusion through the bulk Cu. This understanding steers us to devise a strategy of mitigating carbon diffusion to the top surface by using a ?getter? substrate such as nickel for carbon at backside of the Cu foil. Later, depth profiling of the nickel substrate, along with Density Functional Theory (DFT) calculation, verifies the gettering role of nickel support. Implementing, backside carbon gettering (BCG) approach to single-crystal graphene growth resulted in lowering of the nucleation density by two orders of magnitude, enabling growth of single-crystal domains of ? 6 mm lateral size on untreated Cu foil. Finally, we demonstrate the growth of large area polycrystalline SLG, free of unwanted MLG domains, with significantly improved field-effect mobility of ~ 6800 cm2V-1s-1 and 97.7% transmittance, offering potential for high-performance optoelectronic device applications. Our approach provides an unusual methodology for control in chemical vapor deposition of 2D materials.

Resume : Title: A novel method to reduce the population of various size of particles with less than 10 um (PM10) based on the electro-hydrodynamic spraying processes. Ambient air quality tends to be worse due to the particle pollution in the region where the rapid commercialization is going on. Particulate matter (PM) describes fine inhalable particles with the specific diameter and smaller, and air quality monitors measure concentrations of PM throughout certain area. Generally, breathing in PM can be harmful to human health and fine particles, called PM2.5, are more dangerous because they can get into the deep parts of human organ or even into the blood. Due to environmental concerns, various dust collection systems (cyclonic separators, filters, wet scrubbers, electrostatic precipitators) are applied for the degradation of fine particle concentration. These system have each pros and cons but they commonly need more energy or resource as the particles size become smaller. In this study, electro-hydrodynamic spraying process is applied in the flow chamber system in order to generate very small liquid droplet which is used for the enhancement of particulate material aggregation on the surface of droplets. The spraying process is based on the phenomena that conductive liquids pushed through a thin capillary may form conically shaped menisci as a result of electrostatic forces and surface tension when an electrical field is applied. PM2.5 dust removal abilities are quantified by the variation of droplet size and concentration with the measurement of particle concentration of inlet and outlet. We also evaluate the effect of electrolyte type in the liquid droplets and process conditions for particle removal abilities with different size.

Resume : Hybrid energy storage devices (HESDs) have been widely studied as next-generation power sources because of their advantages such as high energy and power densities and stable cycling performance, which originate from a mixed electrode configuration comprising a high-energy faradic electrode and a high-power non-faradic electrode. One of the key issues with HESDs is adjusting the energy and kinetic balances between the faradic and non-faradic electrodes, which can be solved by developing a high-power faradic electrode and/or a high-energy non-faradic electrode. In this study, nano-sized orthorhombic Nb2O5-based materials supported by three-dimensional porous carbon nanowebs (3D-CNWs) were fabricated for use as a faradic electrode in HESDs. The 3D-CNW/T-Nb2O5 nanohybrids showed a high reversible capacity of ~125 mA h g−1 and rapid Li-ion storage kinetics, as well as long-lasting cycling performance over 70,000 cycles. Moreover, HESDs consisting of 3D-CNW/T-Nb2O5 nanohybrid anodes and activated carbon nanosheet cathodes showed a high specific power of ~5300 W kg−1 at ~24.0 W h kg−1, a high specific energy of ~80.0 W h kg−1 at a specific power of 180 W kg−1, and superior capacitance retention of ~80% after 35,000 cycles.

Resume : Copper (I) oxide (Cu2O) is an important p-type semiconductor with a band gap of 2.17 eV and has been paid much attention to due to its remarkable properties and wide potential applications in fields such as gas sensing, catalysis, solar energy conversion, biosensing, and electrode materials. In this work, solution based Cu2O nanocubes have been developed by hydrothermal synthesis, which is a rapid way to obtain Cu2O nanocubes in different sizes under economical and environmental friendly conditions. In specific, Cu2O nanocubes were successfully synthesized by a rapid single step hydrothermal synthesis, at Room Temperature, using Copper acetate, ascorbic acid and sodium hydroxide. The obtained Cu2O nanocubes were characterized by X-Ray powder diffraction, SEM and TEM techniques. The dispersion ability of Cu2O in different solvents was also examined. Finally, the sensing properties of Cu2O nanocubes against O3 were studied.

Resume : Development of cheap and robust chemiresistive CO2 sensors is extremely important for various applications including breath and blood analysis, fire detection, gas monitoring and climate control. However, despite CO2 molecules can adsorb on some oxide surfaces, it does not provide significant sensing response. This behaviour is attributed to the outstanding chemical stability of CO2, which makes it difficult to ionize upon adsorption. Thus, further development of CO2 sensing technologies requires new non-ionizing sensing mechanisms utilizing selective CO2 chemisorption on material surfaces. In this work, we perform a first principle study of CO2 adsorption on the SrTiO3 perovskite surfaces. Owing to their stability and unique electronic properties, this class of materials received considerable attention in the field of gas sensing. Numerous theoretical and experimental reports show that CO2 adsorption on perovskite surfaces is remarkably strong. Our first principles calculations confirm this trend, showing strong CO2 chemisorption on both SrO- and TiO2-terminated (001) surfaces of SrTiO3, whereas CO and O2 adsorption is found to be much weaker. Besides that, we also found that unlike for CO2, adsorption of CO and O2 leads to ionisation of the adsorbed molecules, suggesting different adsorption chemistry. Furthermore, CO2 adsorption increases band gap energy of SrTiO3 surface, which is mainly attributed to passivation of surface dangling bonds. This effect can be used to design new chemiresistive non-ionizing CO2 sensor. This work is supported by a President Graduate Fellowship from the Ministry of Education of Singapore and Research Council of Norway (Projects 221469 and 250346). We also acknowledge access to high-performance computing resources via NOTUR.

Resume : Transition metal carbides (TMCs) have found growing application in materials science over the past decade, especially due to their desirable elastic properties. Their versatility is in part thanks to their unique bonding, which displays a mixture of ionic, metallic and covalent character. In addition to applications requiring superhard materials, TMCs have also been used more recently as catalysts in several industrially relevant reactions. While the bulk structure of zincblende (ZB) PtC has been investigated several times, a detailed understanding of the electronic and structural properties of its low-index surfaces is lacking. In this work, we present an ab-initio investigation of the properties of five crystallographic ZB PtC surfaces (Pt/C-terminated PtC(100), PtC(110) and Pt/C-terminated PtC(111)). Adsorption geometries have been identified for the atomic oxygen, and its interaction with surface atoms is characterized in terms of adsorption energies and the nature of the bond between the adsorbed and surface atoms. Calculated vacancy formation energies indicate facile C removal on the (111) surface while Pt-vacancy formation is endothermic.

Resume : Electrochemistry has been defined as green chemistry due to the usage of clean reagents such as hydroxyl radicals and electrons generated on the electrodes, etc. Because of the unique properties and simple operation, the electrochemical process can deal with organic and inorganic harmful pollutants in the solids, liquid, and gaseous media so as to be also defined as a vital and high potential technology. The top priority in the aspects of electrolytic performance of electrochemical system was the improvement of electrode materials. Therefore, the objectives of this study were to prepare the PtNPs-based electrode with high electrocatalytic ability so as to be sequentially applied on the electrochemical oxidation of phenol in the aqueous solution. The physicochemical characteristics of the obtained materials were determined by TEM, XRD, Raman spectroscopy and CV. The results showed that the size of PtNPs synthesized via polyol process were between 8.5 nm and 20.5 nm and at an average size of 14.5 nm. The CNTs/CF was used to load PtNPs to prepare the final electrode. The Raman spectra indicated the structure of CNTs grown on CF was slightly affected by the generated hydroxyl radicals near electrode. Furthermore, the obtained electrode was very effective for phenol degradation and the degradation efficiency even reached 99% under the electrolyte of 0.01 M H2SO4. This study has successfully prepared the cheap and useful electrode for phenol degradation.

Resume : Hydrogen peroxide and biothiol are involved in diverse biological events pertaining to metabolism and diseases. In this study, we found that the interface of nanocrystals and capping thiolate ligands can be utilized as a platform for sensing hydrogen peroxide and thiol molecules. Our approach is based on the close relationship between surface passivation degree and photoluminescence of CuInS2-ZnS nanocrystals. Upon the addition of hydrogen peroxide, photoluminescence (PL) of thiolate-passivated nanocrystals was quenched while pristine ligands were oxidized and detached from the crystal surface on which dangling bonds were generated. It was shown that the PL of these nanocrystals could be fully recovered by feeding thiol into the system, which re-coordinated surface atoms. This presentation will offer detailed discussions on the optical and chemical analyses of the PL switching phenomena and applications for assay of biothiols.

Resume : Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte.Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors HEMTs . HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas 2DEG mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. The electrical response of hydrogen sensors based on Al0.30Ga0.70N/GaN high-electron-mobility transistors (HEMTs) with Pt catalytic gate electrodes was measured in a flowing gaseous stream consisting of hydrogen in a pure nitrogen diluent at ambient and elevated temperatures. The sensor response was found to monotonically increase for a wide range of hydrogen concentrations (500 ppb to 5 vol%). Various models based upon Langmuir adsorption were investigated to describe the sensor response in this regime. The relevance of other modified Langmuir models to adequately describe the sensor response as a function of hydrogen concentration is also discussed.

Resume : We investigate the magnetic properties of iron-based nanoparticles (NPs) inserted into carbon nanotube (CNT) aligned arrays, with magnetic fields oriented either along or perpendicular to the CNT axes. Samples have been synthesized by the floating catalyst chemical vapor deposition. They are characterized by HRTEM and XRD. A low continuous iron concentration in the gas mixture allows to insert selectively the iron particles inside the nanotubes. The NPs are mainly made up of iron carbide Fe3C displaying different crystallographic orientations but oriented preferentially in a uniaxial direction along the CNT direction. Their number density is directly related to the iron concentration. Results show that the magnetic properties near saturation are strongly dependent on the density of Fe3C particles, both inside the same nanoparticles but also inserted on near nanotubes. [1] “Manifestation of the coherent magnetic anisotropy in carbon nanotubes matrix with low content of ferromagnetic nanoparticles”, Danilyuk A.L., Komissarov I.V., Labunov V.A., Prischepa S.L., Le Normand F., Derory A., Hernandez J.M. and Tejada J., New Journal of Physics, 17, (2015) 023073/1-12. [2] “Impact of CNT Medium on the Interaction Between Ferromagnetic Nanoparticles” A.L Danilyuk, I.V. Komissarov, A.V. Kukharev, G. Melinte, F. Le Normand, J.M. Hernandez, J. Tejada and S.L. Prischepa, in preparation

Resume : Josephson junctions (JJs) can be used as the elements of quantum computers. By varying the dissipation parameter, which can be done easily by temperature variation, we can assure an efficient control of the Josephson nanostructure. In our work we effectuate a theoretical research of the Josephson systems with different dissipation and coupling parameters, and different number of junctions in the stack. We observed manifestation of a second hysteresis zone on Current-Voltage-Characteristic, nearby the McCumber hysteresis zone, which can be viewed as a new state of the system of JJs. The appearance of the second hysteresis occurs due to presence of longitudinal plasma wave in the system. The detailed study of its behavior, along with Fast Fourier transoms for temporal charge oscillations are presented. This work was partially supported by the Romanian Ministry of National Education by the contract PN 16 47 0101 with UEFISCDI and project 2016 / 25.of JINR-Romania collaboration.

Resume : Supercapacitor is the most promising electrical energy storage for applying scientific fields such as hybrid vehicle and portable electric device. The advantages of supercapacitors, which produce electric energy by the principle of electric double-layer capacitor (EDLC), are high charge/discharge efficiency, high electron conductivity and high electrode stability in charge/discharge process. However, EDLC has limitation of application due to low energy density of EDLC materials. Active carbon, which is EDLC materials, exhibits high electrical conductivity as well as stability in charge/discharge process. In particular, Mesoporous or hollow carbon shows high specific efficiency and provide broad solid-liquid interface for fast electron movement through short ion diffusion path between electrolyte and electrode. Moreover, heteroatoms doped carbon such as nitrogen (N) and sulfur (S) improves wettability of carbon surface and electronic conductivity. Especially, N-doped carbon groups provide enhanced surface wettability, superb electronic conductivity and ability of pseudo-capacitance from redox reaction of N doped carbon groups while charge/discharge process. In this study, we successfully synthesized hollow N-doped carbon structure via SiO2@dopamine core shell by annealing and etching process. FE-SEM and TEM analysis suggest perfect hollow structure of N-doped carbon. The crystallinity, chemical bond and composition of hollow N-doped carbon were confirmed by XRD and XPS.

Resume : Removing of heavy metals from industrial wastewater is an urgent technological need. One of the most promising methods of such kind of water purification is grounded on adsorption of heavy metals on artificial adsorbents. Undoped and doped carbon nano-structured materials in particular carbon nanotubes (CNTs) are considered as very perspective adsorbents for such application. Theoretical modeling of molecular adsorption on the surface of CNTs can provide a quantitative description of adsorption capacities of CNT-based materials. In this work we consider adsorption of XO42- (X = Cr, Mo, W) molecular oxyanions on the surfaces of pure and N/B-doped SWCNTs, MWCNTs and graphene sheets. DFT-based geometry-optimized calculations of the electronic structures of carbon nanostructures with adsorbed oxyanions are carried out by Gaussian 09 program package [1]. Relaxed geometries, binding energies between oxyanions and adsorbents, electronic wavefunction contours were calculated and analyzed. Excited states of XO42- molecular oxyanions adsorbed on the surfaces of studied carbon nanostructures are calculated by TD-DFT method. Effects of water solvent on studied adsorption case are considered in a model of polarizable continuum. Calculation results are discussed in view of potential application of the carbon nanostructures materials as efficient adsorbents of heavy metals. The publication is based on the research provided by the grant support of the State Fund For Fundamental Research (project F64/42-2016). [1] M.J. Frisch, G.W. Trucks, H.B. Schlegel, et al. // Gaussian 03 (Gaussian, Inc.,Wallingford, CT, 2003).

Resume : Nowadays, there is a rising demand for new materials with large specific surface areas to be used in many research fields such as adsorption, chromatography, catalysis, sensor technology, energy storage device, and gas storage. Aerogels are examples of these materials that exhibit very high relative pore volume and surface area [1]. Polyoxometalates (POMs) are a colossal class of nano-sized oxygen bridged multi-transitional metal clusters characterized by a daunting structural variety, resulting in different dimensions, shapes, charge density, and surface reactivity. Known to be green and efficient catalysts, POMS were previously investigated in homogeneous and heterogeneous catalysis of many reactions where high activities were reported [2]. In the present work, we report the synthesis of titania and silica aerogels using low-temperature traditional sol-gel chemistry followed by supercritical drying [3]. The titania aerogels were prepared using methanol and the surface area obtained was higher than what was previously reported in literature. Furthermore, a method developed by Al-Oweini et al. [4] was used to immobilize POMs onto the pre-synthesized silica and titania aerogels. In addition, POMs were added to the synthesized alcogel and were incorporated into the aerogels after being supercritical dried. The structural, textural, and morphologic characterization of these materials was performed prior and after immobilization and incorporation of POMs. The obtained surface area of the aerogels that were incorporated with POMs was much higher than that of functionalized aerogels with POMs. Finally, the catalytic activity of these clusters in homogeneous and heterogeneous catalysis of methyl phenyl sulfide oxidation by hydrogen peroxide was compared for all catalysts prepared. The results showed an improvement in the catalytic activity for some of the functionalized and incorporated aerogels compared to activity of POMs under homogeneous conditions. Furthermore, the catalytic activity of incorporated aerogels was much higher than functionalized aerogels. References [1] C. Folgar, D. Folz, C. Suchicital, D. Clark. J. Non-Cryst. Solids, 2007, 353, 1483?1490. [2] M. Carraro, A. Sartorel, M. Ibrahim, N. Nsouli, C. Jahier, S. Nlate, U. Kortz, and M. Bonchio. Polyoxometalates as Homogeneous Oxidation Catalysts in Innovative Catalysis in Organic Synthesis: Oxidation, Hydrogenation, and CX Bond Forming Reactions. Wiley-VCH, 2012, 1-25. [3] A. C. Pierre and G. M. Pajonk. Chem. Rev., 2002, 102, 4243?4266. [4] R. Al-Oweini, S. Aghyarian, H. El-Rassy. J. Sol-Gel Sci. Technol., 2012, 61, 541-550.

Resume : The assembling of magnetic nanoparticles with polymers are highly useful in the development of novel stimuli-responsive materials ? the presence of magnetic materials gives advantages such as detectability by imaging techniques, controllability by an external magnetic field and thermal heating, here proposed for application in the environmental field. Particularly, the thermal heating effect caused by the interaction of nanoparticles? magnetic moments with an alternating magnetic field (AMF) ? magnetic hyperthermia ? is proposed here as proof of a concept to illustrate the remote controlled recycling of magnetic nanosorbents during the treatment of water containing toluene, a potentially toxic and volatile contaminant. Nanosorbents were synthesized by functionalization of ~15 nm coprecipitated cobalt/manganese mixed ferrite with polydimethylsiloxane. Structural, chemical, and magnetic characteristics of the nanosized adsorbent were investigated by ICP-OES, XRD, HRTEM, FTIR and vibrating sample magnetometry. Batch experiments indicated that nanoadsorbents, which can be magnetically recovered, exhibit high adsorption affinity for toluene in aqueous solution (~325 mg/g) and that adsorption follows the Langmuir model. Moreover, application of AMF resulted in uniform heating within the nanosorbents (after being magnetically separated from the contaminated water) and triggered toluene desorption/evaporation, leading to accelerated release of pollutants from the nanosorbent, improving its reusability; even after seven cycles the removal efficiency was quite high (83%).

Resume : It is well known that the localized surface plasmons during the relaxation process increase the temperature of the plasmonic metals and the local environment. Currently, plasmonic effects in spherical metal nanoparticles are explored most deeply, while electrooptical properties of more complex plasmonic structures like nanocubes or ordered systems of specific shape nanoparticles remain unknown. In this study, transient absorption spectroscopy (TAS) measurements were applied to analyze ultrafast plasmon dynamics of Ag nanocubes. The analyzed high monodispersity Ag nanocubes had sizes of edges from 40 to 105 nm. Measurements of colloidal solutions revealed mechanical oscillations of Ag nanocubes. We demonstrate that plasmons relaxation process is responsible for the intense heating of Ag nanocubes and appearance of such oscillations. It was found that such oscillations of Ag nanocubes are very sensitive to the environment and therefore this effect could be applied for chemical or biochemical detectors. Capillary force assisted particle assembly method was applied for creation of regularly arranged nanocube arrays from their colloidal solutions in ethanol. Such regular arrays were studied by TAS and finally were applied for Surface Enhanced Raman spectroscopy of microwave plasma synthesized graphene. Femtosecond laser irradiation of the regularly deposited particle was applied to tune the nanocube geometrical dimensions and to optimize surface enhancement effects.

Resume : Interaction between organic semiconducting single Crystals (OSSCs) and metallic electrodes have been widely studied during the last decades because of good electrical performance of OSSCs in devices like field effect transistor. Here we report on the use of different Self-Assembled Monolayers (SAMs), deposited via drop casting onto gold substrates, as a way to change the charge injection behavior of TIPS-Pentacene (a well know organic semiconductor) single crystals and their characteristics of electrical exchange with the electrodes. In particular, their electrical characteristics are reviewed against the different types of SAMs applied to the electrodes; AFM and KPM analysis have been involved for a more precise investigations. Considerations over the effect of the different SAMs of the developed crystals are made, and criteria for choosing SAMs able to influence the charge transport at the crystal/electrode interface are discussed.

Resume : Ratiometric pressure sensitive paints (r-PSPs) are all-optical probes for monitoring O2 flows in the vicinity of complex or miniaturized surfaces. They consist of a porous binder embedding mixtures of a reference and a sensor chromophore exhibiting O2-insensitive and O2-responsive luminescence, respectively. Here, we demonstrate the first example of an r-PSP based on a single two-color emitter that removes limitations of r PSPs based on chromophore mixtures such as different temperature dependencies of the two chromophores, cross-readout between the reference and sensor signals and phase segregation. In our approach, we utilize a novel ?double-sensor? r-PSP that features two spectrally separated emission bands with opposite responses to the O2 pressure, boosting the sensitivity with respect to traditional r-PSPs. Specifically, we use two-color-emitting dot-in-bulk CdSe/CdS nanocrystals, exhibiting red and green emission bands from their core and shell states, whose intensities are respectively enhanced and quenched in response to the increased O2 partial pressure that effectively tunes the nanocrystal?s Fermi energy. This leads to a strong and reversible ratiometric response at the single particle level and an over 100% enhancement in the pressure sensitivity. Our proof-of-concept r-PSPs further exhibit suppressed cross-readout thanks to zero spectral overlap between the core and shell luminescence bands and a temperature-independent ratiometric response between 0 and 70 °C.

Resume : Potential toxicity of dye molecules encourages the creation of effective materials for their sensing, concentration and removal. In the present work, functionalization of mesoporous silica with β-cyclodextrin (CD) groups was realized via co-condensation of tetraethyl orthosilicate with β-CD-silane prepared under mild conditions. Control under functional coverage of synthesized silica material was achieved by use of chemical and IR spectral analysis of surface layer whereas structural characteristics were estimated from the data of x-ray diffraction, low-temperature nitrogen adsorption-desorption, and transmission electron microscopy studies. Adsorption of indicator dye, alizarin yellow (AY), on the surface of MCM-41 and CD-MCM-41 silicas was carried out in phosphate buffer solutions with pH 7.0. Analysis of AY equilibrium adsorption data was realized using Langmuir, Freundlich, and Redlich-Peterson isotherm models. Comparison of the coefficients of determination and the reduced Chi-squares obtained from error analysis showed that the Redlich-Peterson isotherm model is the most appropriate for fitting the equilibrium adsorption of AY on MCM-41 as well as CD-MCM-41 surface. It was proved that oligosaccharide macromolecules localized in surface layer of CD-MCM-41 contribute into the removing of AY from neutral aqueous solutions. Synthesized polyfunctional mesoporous silica material with immobilized β-CD groups have promising potential in sensing, adsorption, separation and controlled delivery processes.

Resume : Ternary oxides, such as Zn2SnO4, CdIn2O4, NiSnO3, ZnSnO3 etc., have the potential to exhibit better electrical, optical and chemical properties than the commonly fabricated binary oxides. CdSnO3 is an n type ternary oxide semiconductor with wide optical band gap and has application as the anode material for Li ion batteries, dye sensitized solar cells [2-3], and as gas sensing material [4-6]. In this report, we successfully synthesized the rhombohedral CdSnO3 nanoparticles by calcination of the synthesized precipitate, obtained by coprecipitation method, at 800 0C for 1 hour. Tin (II) chloride, cadmium acetate were used as the initial component and the ammonia carbonate was used as precipitant. The phase and structure of the synthesized nanoparticles were characterized using x ray diffraction (XRD), the crystallite size were also calculated using Debye-scherrer formula corresponding to the maximum intensity peak (110). Morphological studies were carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and found that the synthesized nanoparticles have spherical shape with diameter lying in the range of 40-60 nm which is an accordance with the crystallite size as calculated using XRD. Energy dispersive spectroscopy (EDS) analysis also carried out of the synthesized nanoparticles to study the elemental composition and found that the synthesized nanoparticles contain Cd:Sn:O is in 1:1:3 (approximate) ratio without any impurities. Further the optical band gap of the synthesized nanoparticles were calculated using the UV-Visible spectroscopy. We also demonstrate the gas sensing properties of the synthesized rhombohedral CdSnO3 nanoparticles. To examine the gas sensing properties of the synthesized nanoparticles, we prepared a thick film of the synthesized nanoparticles on Si substrate using doctor blade method and two Ag contact were made on the film to measure the electric resistance of the film as our sensing mechanism based on the change in electric resistance of the sensing material in different gas environment. Sensitivity of a sensing material highly depends on the working temperature, size, and morphology of the sensing material particles. Here in this study we examine the gas sensing behavior of the synthesized nanoparticles for methanol, ethanol, propanol, ammonia and acetone gases at 150 0C and found that synthesized nanoparticles have good selectivity for propanol against the other gases. The gas sensing mechanism also discussed. References 1. R.D. Shannon, J.L. Gillson, R.J. Bouchard, J.Phys. Chem. Solids 38, 877-881, (1977) 2. Y. Sharma et al. Journal of Power Sources 192, 627?635 (2009) 3. Gayatri Natu , Yiying Wu J. Phys. Chem. C 114, 6802?6807, (2010) 4. Wu Xing-Hui et.al. Material Chemistry and Physics 77, 588-593, (2002) 5. Xiaohua Jia, Huiqing Fan, Xiangdong Lou, Jiaqiang Xu Appl Phys A 94, 837-841, (2009) 6. Chu Xiangfeng, Cheng Zhiming Sensors and Actuators B 98, 215-217, (2004) 7. Andr ey V. Sidorak, Viktor V. Ivanov, Alexander A. Shubin Material Science and Applications, 2, 1219-1224, (2011)

Resume : Nanosphere lithography is a low-cost technique, which deploys hexagonally close packed mono- or double layers of spheres as masks for patterning of large surface areas. For many applications of such patterned surfaces a narrow size distribution of the structures and therefore of the structure-defining mask openings is desirable. Recently it has been shown that in the case of polystyrene sphere monolayers the position variations of the spheres in the triples constitute the most important reason for the observed width of the opening size distribution [1]. In this contribution we address the question how the sphere material influences the opening size variation. By means of a self-developed automated SEM image analysis algorithm [1] the opening size variations of submicroscale polystyrene and silica sphere monolayers are evaluated. It is shown that silica spheres have a significantly lower tendency to form string-like bridges between neighbouring spheres as well as a lower deformability as compared to polystyrene spheres. Thus, the position variations of the spheres account for only ~50% of the observed variation of the silica sphere monolayer openings as compared to ~80% in the case of polystyrene sphere monolayers. This result demonstrates the benefit of using silica as sphere material for achieving narrow size distributions of the mask openings. [1] T. Riedl, J.K.N. Lindner: E-MRS Fall Meeting 2016, Warsaw, talk E.13.5

Resume : This work reports on the use of nickel sulfide decorated a silicon carbide foam as an active phase for the low-temperature selective oxidation of high concentration H2S (0.5 up to 1%) into sulfur with a total sulfur yield close to 99%. The reactions were carried out at temperature of 60°C in a discontinuous-mode with a complete H2S conversion and sulfur selectivity close to 99%. The catalyst also displays an extremely high resistance as a function of the cycling tests, i.e. reaction-regeneration, as well as a total insensitivity towards the presence of trace amount of hydrocarbon. Regeneration was carried out at 300°C in helium flow. Cycling tests indicate the extremely high stability of the NiS2/SiC foam catalyst as no deactivation was observed after more than several cycles.

Resume : We report on design, synthesis and application of nanostructured organosilicon luminophores (NOLs), which consist of two types of covalently bonded via Si atoms organic luminophores with efficient Förster energy transfer between them [1-4]. NOLs combine the best properties of organic luminophores and inorganic quantum dots: high absorption cross-section and photoluminescence quantum yield, fast luminescence decay time, good processability and low toxicity. A variety of organic luminophores allowed us to design and synthesize a library of NOLs, absorbing from VUV to visible region and emitting at the desired wavelengths with maxima varying from 390 to 650 nm. Using NOLs in plastic scintillators, widely utilized for elementary particles and radiation detection, led to their high light output and fast decay time [1,4]. Thin films of NOLs or their composites with optical plastics are transparent [3], which leads to efficient conversion of UV light useful for different types of photodetectors [5,6]. Properties of NOLs and their constituent organic luminophores will be compared and discussed. This work was supported by Russian Foundation for Basic Research (grant 16-03-01118). [1] S.A. Ponomarenko, et al., Sci. Rep. 2014, 4, 6549 [2] S.A. Ponomarenko, et al., Proc. SPIE, 2015, 9545, 954509 [3] M.S. Skorotetcky, et al., Silicon, 2015, 7, 191 [4] T.Yu. Starikova, et al., J. Mater. Chem. C, 2016, 4, 4699 [5] N. Surin, at al., NIM A, 2014, 766, 160 [6] Y. Jin, et al., NIM A, 2016, 824, 691

Resume : Thanks to their good thermal, electrical, mechanical and optical properties, graphene and its derivatives are involved in many new applications especially use in analytical and life sciences. One of the recent application is their use as inorganic matrix for surface assisted laser desorption/ionization mass spectrometry (SALDI-MS), as they are able to lower the background of interfering peaks in the < 500 Da mass range, comparing with organic matrices (1). However, the main drawbacks of using co-deposited graphene/analyte spots in the mass spectrometer, concern the ion source contamination and the electric discharge. Herein, we present boron doped hydrophobic carbon nanowalls (vertically aligned graphene nanosheets) as versatile SALDI-MS interfaces for detection of small compounds (fatty acids, lipids, metabolites, saccharides and peptides) by mass spectrometry in aqueous solutions and real samples. The low background, good sensitivity (36.58 mM-1) and LoD (0.32 pmol) for the detection of glucose, allowed us to quantify glucose in blood serum and soft drink (Coca-Cola) without the use of internal standard. The results were compared with conventional colorimetric method and the percentage error was 8.85%. Other compounds such as melamine (63 ng/µl) was also spiked and detected in urine, together with other natural compounds (e. g. creatinine). Paracetamol and 3-nitro-paracetamol (one of its metabolite) were also detected in urine, after oral ingestion. Our work proves that the CNWs interfaces can be applied over a huge variety of classes of molecules, replacing the classical MALDI-MS. Moreover, they can provide a good opportunity of developing new methods for detection of metabolites, even when MALDI-MS is useless or ineffective (such as urine, blood or other biological real samples). (1) Y. Coffinier, R. Boukherroub and S. Szunerits, in Carbon Nanoparticles and Nanostructures, Springer, 2016, pp. 331-356.

Resume : In this study we investigate and compare the structural parameters of β-cyclodextrin(CD)-containing MCM-41 silicas with various loadings of oligosaccharide groups and their sorption properties. It was realized hydrothermal sol-gel synthesis of three β-CD-MCM-41-type silicas with different concentration of functional groups. β-CD-containing silane and tetraethyl orthosilicate as silica sources were applied for co-condensation in the presence of ionic template. Several types of β-CD-silanes were prepared by modification of (3-aminopropyl)triethoxysilane with oligosaccharide activated by N,N'-carbonyldiimidazole at various molar ratio of reaction mixture. Obtained functional materials were characterized by FT-IR spectroscopy, chemical, XRD and TEM analyses as well as low-temperature adsorption-desorption of nitrogen. It was shown that increased β-CD groups’ attendance in synthesized materials bring out the considerable structural perturbation of the silica framework accompanied by decrease of hexagonal pore ordering, surface area and pore volume. However, the presence of more immobilized oligosaccharide groups on the surface increases the adsorption ability of synthesized silicas in the region of small equilibrium concentrations. This is evidence that immobilized β-CDs’ functional groups have a higher affinity for benzene adsorption as compared with other surface centers. The proposed synthesis route may be useful for obtaining of β-CD-containing MCM-41 silicas with high affinity to aromatic compounds of suitable geometry for potential applications in catalysis, adsorption, drug delivery, and sensing.

Resume : Semiconducting organic polymer X-ray detectors are emerging as flexible, low cost technology complementary to current inorganic and gas-filled X-ray detectors. However, such organic diodes suffer from low responsivity to X-rays due to the low Z number of active organic materials. In this work, novel ?inorganics-in-organics? hybrid semiconductor detectors using a conjugated polymer blend with the inclusion of high atomic number (Z) metal oxide nanoparticles have been optimized. The introduction of the high Z nanoparticles improves X-ray attenuation compared to the polymer blend alone. The semiconductor diodes exhibit a satisfactorily low dark leakage current of 4 × 10-6 A cm-2 proving its suitability as a solid-state X-ray detector. Furthermore, the optimized diodes exhibits a high sensitivity of 280 µC mGy-1 cm-3 under a 50 kV Tungsten X-ray source and also perform a sensitivity of 30 and 58 µC mGy-1 cm-3 for 6 MV and 15 MV X-rays respectively which are obtained from medical linear accelerator. This exceptional performance under the wide broad-band energy range confirms the suitability of the detector to be used in a wide range of applications such as mammography scanning, securing screening and cancer treatment among others. More importantly, the hybrid detectors lead to real time radiation monitoring with the added advantage of being processed at room temperature and potentially over large areas overcoming some of the limitations of current inorganic X-ray detectors.

Resume : In recent years researchers have devoted much attention to study of intervalley double electron-phonon processes in single- and bilayer graphenes, which determined main strips of Raman spectra. We experimentally investigated dispersion (dependence phonon energy prom quantum energies of exiting radiation) of 2D` band in micro-Raman spectra of light scattering in single- and bilayer graphenes. D` band, as a D band are defect-activated. Its frequencies depend on wavelengthes of exiting radiation. But unlike the D band, for which intervalley electron scattering mechanism is implemented, D` band associated with intravalley electron scattering on defects. The 2D` strip is it’s overtone. Established non-monotonic, but the same of both structures dispersion nature of 2D` bands. which allowed by selection rules, and defined their half-widths are equal 10 cm-1. It’s shown that “sharpness” of the intravalley double electron-phonon resonance processes in graphenes can by used to experimental determination of localization state density maxima (or phonon energy maxima) on i-LO phonon branches in single- and bilayer graphenes.

Resume : A variety of synthetic dyestuffs released by the textile industry pose a threat to environmental safety. Azo dyes account for the majority of all dyestuffs, produced because they are extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries[1]. Bacillus subtilis, gram positive bacteria, has proved its ability to decolorize and degrade azo dyes and has been introduced in an eco-friendly treatment method of dye effluents. In order to develop this method, we studied the effect of magnetic nanoparticles on the bacterial cells. Iron Oxide nanoparticles with a strong magnetic moment have an attractive and novel potential, they are: detectable, remotely manipulated, responsive by a magnetic field, biocompatible and chemically inert. In the present study, the immobilization of Bacillus subtilis was carried out onto magnetic iron oxide nanoparticles by adsorption to decolorize and degrade several azo dyes. This method offers the possibility of reusing bacteria by magnetic recovery as a novel and economic separation solution [2]. Moreover, high decolorization rate was noticed for Congo Red and immobilized cells have the similar decolorization activity to that of free cells. The system could be reused for seven batch cycles. The results of this work can be applied in the development of bacterial bioreactor for several applications: biological treatment of leather, degradation of a textile dyes and toxic aromatic molecules present in the effluent of textile industries. Keywords: Iron oxide nanoparticles; cells immobilization; azo dyes decolorization; bacterial bioreactor, Textile industry. References: 1. Saratale, R.G., et al., Bacterial decolorization and degradation of azo dyes: A review. Journal of the Taiwan Institute of Chemical Engineers, 2011. 42(1): p. 138-157. 2. Ebrahiminezhad, A., et al., Magnetic immobilization of Bacillus subtilis natto cells for menaquinone-7 fermentation. Appl Microbiol Biotechnol, 2016. 100(1): p. 173-80.

Resume : High surface area columnar Si substrates have been functionalized with two different selective cavitand receptors, a simple quinoxaline bridged cavitand (QxCav) and a cavitand (QxBox) in which the quinoxaline moieties are bonded both to the cavity upper rim and each other through ethylendioxy bridges. Both receptors have been covalently anchored to columnar porous silicon (PSi) through hydrosilylation of the undecylenic feet of the receptors. Compared to flat substrates, the high surface area of PSi improved system sensibility and allowed to study the recognition properties of anchored receptors through FTIR, Thermal Desorption and XPS. Both receptors were proved to retain their recognition properties after anchoring and were able to recognize aromatic VOCs without interference with not- aromatic compounds such as linear and cyclic alkanes. The complexation process of both receptors towards benzene, toluene and p-nitrotoluene has been studied by DFT computational approaches adopting the M06 hybrid meta-GGA functional. Results indicates that QxCax, whose cavity undergoes reversible changes between open and close conformation, has a better affinity towards benzene, but QxBox that possesses a rigid ?vase? cavity is much more efficient for p-nitrotoluene. Finally, computational results have been validated with competitive experimental tests. The high affinity of QxBox decorated columnar PSi for p-nitrotoluene makes these systems of interest for explosive detection.

Resume : Nanocrystals (NCs) embedded in glasses are able to enhance their physical properties or to implement new active properties. In this context copper-halide (CuCl, CuBr) semiconductor NCs embedded in dielectrics have recently attracted much attention and have shown promising applications for light emission, non-linear optics, optical information storage and optical switching [1-3].< br> In this work we report the optical response of CuCl semiconductor NCs embedded in borosilicate glasses at room temperature (RT) and when heated up to 500 ºC. The measured transmission spectra of the CuCl NCs-doped glasses at RT show an absorption band with a maximum at 367 nm. Upon excitation at 355 nm the glasses show a clear and intense photoluminescence centered at 382 nm attributed to CuCl excitonic emission. Besides the CuCl nanoparticles show a low melting point (450ºC) compared to that of the embedding glass matrix (820ºC). Taking advantage of these properties it is possible to induce reversible thermal changes related to the phase change of the CuCl NCs in the glass and detect them optically. The thermo-optical response of the composite glasses is characterized by detailed measurements of the transmission at the excitonic wavelength. It is found that upon melting there is an increase in the transmission, and there is a large hysteresis cycle (150ºC) upon melting and solidification of the NCs. Furthermore heating-cooling can be interrupted during the CuCl NCs phase change giving rise to different optical switching possibilities. The potential of developing optical switching devices in the UV region based on Cu-halide NCs systems will be discussed. < br> [1] F.E. Kalff, M.P. Rebergen, E. Fahrenfort, J. Girovsky, R. Toskovic, J.L. Lado, J. Fernández-Rossier, and A.F. Otte, Nat. Nanotechnol. 18, 1 (2016). < br> [2] D. Ahn and S.-H. Park, Sci. Rep. 6, 20718 (2016). < br> [3] I. Kriegel, C. Jiang, J. Rodríguez-Fernández, R.D. Schaller, D. V. Talapin, E. Da Como, and J. Feldmann, J. Am. Chem. Soc. 134, 1583 (2012).

Resume : Nanosphere lithography is a cost-effective method for periodic nanoscale patterning of solid surfaces on large areas by means of local material deposition, etching or other chemical modifications. Typically, the mask openings of hexagonally close packed mono- or doublelayers of spherical particles are used to define the size and shape of the structures. In this way, ordered arrays of semiconductor quantum dots for optoelectronics, or of metal nanoparticles for plasmonic devices and catalytic nanowire growth have been realized. In order to reduce the structure size, shrinking of the mask openings by thermal annealing of polymer sphere monolayers has proven beneficial. In the present contribution we analyze the morphologic changes of polystyrene sphere monolayers in dependence of the annealing temperature and time by means of scanning electron microscopy (SEM) imaging. Thermal annealing of monolayers with sphere diameters between 220 nm and 618 nm on Si substrates was conducted in ambient air at temperatures around or slightly above the bulk glass transition (95-115°C) for different durations. The resulting size and shape of the openings as well as of the spheres were statistically evaluated by means of a self-developed automated SEM image analysis algorithm. We find that the temperature required for the shrinkage and closure of the openings slightly decreases with decreasing sphere diameter.

Resume : Hybrid Cerium dioxide (CeO2)-Cobalt oxide (Co3O4) nanotubes were synthesized by a combination of electrospinning and thermal annealing using precursors of CeO2 and Co3O4. Structural characterizations of prepared nanotubes were imaged by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the electrospun CeO2-Co3O4 hybrid nanotubes, porous surface texture with small dimensions containing the outer diameter of 100 nm and 80 nm for its inner diameter was identified. Additionally, well-defined CeO2-Co3O4 composite nanostructure showed that the nanoparticle like crystalline structures of CeO2 and Co3O4 are homogenously distributed and continuously connected to form the shape of nanotube in the length of a few micrometers. It is expected that the structure of CeO2/Co3O4 hybrid nanotubes is attributed to the different evaporation behaviors of solvents and matrix polymer between core and shell in as-spun nanofibers in the course of thermal annealing. Catalytic activities of electrospun CeO2/Co3O4 hybrid nanotubes toward the oxidation of Carbon monoxide (CO) were carefully measured by a continuous flow system. CO Oxidation over CeO2/Co3O4 hybrid nanotubes exhibited the favorable catalytic activity and also showed eminently remarkable catalytic stability between 150oC and 200oC without the deactivation of the catalyst from the accumulation of reaction intermediates such as carbonate species.