12th International Symposium on Electrochemical/ Chemical Reactivity of New Materials – „Surface Science – key to understand advanced materials”

Resume : Understanding the electrode processes occurring at the electrode/electrolyte interface and in the bulk electrode material is necessary for developing the electrochemical performances of lithium-ion (LIB), sodium-ion, sulfur or metal-air batteries. The main electrode processes are insertion/extraction reactions that induce changes in the host electrode materials; they are accompanied by decomposition of electrolyte that leads to formation of a solid electrolyte interphase (SEI) layer on the electrode surface. Two principal surface-sensitive techniques, particularly suitable for analyzing these processes are: X?ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Our approach is to use model, nanometer-thick electrodes with a good surface finishing with a minimum roughness. New types of high capacity negative-electrode materials having a potential application in LIB will be presented: a conversion-type electrode consisting of iron oxide and an alloying-type electrode consisting of silicon. Apart the chemical composition of the SEI layer formed on the surfaces of these electrodes, the evidence of a dynamic increase/decrease of SEI upon lithiation/delithiation, and surface modifications upon cycling will be discussed. The irreversible chemical bulk modifications and volume changes of the electrode materials will be also evidenced by ToF-SIMS ion depth profiles. These modifications are detrimental to performance of battery cycle life.

Resume : The analytical studies are presented on the chemical composition and bonding in the near-surface region of the nanophase tungsten carbides, particularly in connection with their promising uses in catalysis and hardmetal industry. The materials are produced through a DC thermal plasma technology that has reached a significant level of development and upscaling. The analytical information has been primarily gathered using X-ray photoelectron spectroscopy (XPS). The XPS analysis was combined with Raman spectroscopic, HRTEM, and thermal evolution studies. The analytical work resulted in a distinction between the major surface conditions for the nano-WC, including that equilibrated with the bulk. The analytical determinations concerned the nature/thickness of the surface segregations of carbon, the coverage/bonding of adsorbed oxygen, the effect of the average bulk stoichiometry on the surface composition, etc.

Resume : The recent progress in Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) using functionalized tips provided unprecedented atomic resolution of single organic molecules [1,2]. Here we will provide insight into the origin of the high-resolution AFM/STM images [3]. We will show that the mechanism could also stand for atomic resolution observed in electrochemical STM [4] or high-resolution STM images taken in contact mode [5]. We will also briefly discuss what other information can be gained from the high-resolution AFM/STM images going beyond the simple imaging of chemical structure. [1] L. Gross et al., Science 325,1110 (2009). [2] C. Weiss et al., Phys.Rev.Lett. 105, 086103 (2010). [3] P. Hapala et al., Phys. Rev. B 90, 085421 (2014); P. Hapala et al., Phys. Rev. Lett. 113, 226101 (2014). [4] P. Broekmann, M. Wilims, K. Wandelt, Surf. Rev. Lett. 06, 907 (1999) [5] J.A. Stroscio, R.J. Celotta, Science 306, 242 (2004).

Resume : Self-assemblies of nanoparticles of gold and the anionic clay matrices of layered double hydroxides (LDHs) were fabricated using the manifestation of the structural memory effect of the LDHs in AuCl3 aqueous solutions, at room temperature [1]. We used specific compositions of ZnCeAlLDHs containing Zn2+, Ce3+ and Al3+ + as cations in the LDHs layers. Controlled thermal treatment of Au/LDHs assemblies gave rise to the complex systems of nanosized mixed oxides. Powder X-ray diffraction (PXRD), high resolution transmission electron microscopy (TEM, see Figure 1), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy (UV-Vis) were used to investigate the structural, composition and size-morphology characteristics of the Au/ZnCeLDHs. Results point out that Au/LDHs nanoarchitectonics consists of small nanoparticles of Au that are highly dispersed on much larger nanoparticles of the LDHs while the composition of the evolved mixtures of mixed oxides is a function of the composition of the LDHs precursor. UV-Vis analysis indicates specific plasmonic responses of Au nanoparticles under Vis and UV light revealing the photo-cooperativity of the components in the nanostructured gold-clay system. X-ray photoelectron spectroscopy (XPS) was used to investigate the state of gold on the surface of the specific LDH matrices. Acknowledgment: The authors are grateful for the financial supports from the Romanian National Authority for Scientific Research, CNCS-UEFISCDI (PN-II-ID-PCE-75/2013), the Kazuchika Okura Memorial Foundation, “Planting Seeds for Research” program from Tokyo Institute of Technology, “Grant-in-Aid for Young Scientists (A; 25708037)” from Japan Society for the Promotion of Science (JSPS), and by the project “Development Base of Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic” of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan. 1. S. Kawamura , M. C Puscasu, Y. Yoshida, Y. Izumi, G. Carja, App. Cat. A, in press DOI: 10.1016/j.apcata.2014.12.042.

Resume : The expected widespread diffusion of several energy related technologies relies upon the development of innovative materials, which could allow overcoming some current limitations. New chemical compositions as well as structural and thermodynamic conditions are then explored in order to develop and improve the properties different devices for energy storage and conversion including secondary batteries, supercapacitors, hydrogen production and storage systems, fuel cells, piezoelectric devices. To this regard is recent the attention to nanosized materials confined within mesoporous matrices which combine thermodynamic metastability with several advantageous morphological features as high surface area, pore diameter between 2-50 nm, good corrosion resistance etc. We focus here on the synthesis and the applicative properties of new materials related to the above cited technologies. A series of mesoporous materials were synthesized by sol-gel methods, using EISA (Evaporation Induced Self-Assembly) and Hard Templating approaches. Composite systems were also prepared by melting infiltration or wet impregnation of nanosized phases within the porous matrixes. A detailed characterization of the prepared material and the investigation of their reactivity and applicative properties is fulfilled through a number of instrumental techniques.

Resume : This work relates to a large scale synthesis of gold-titania core shell nanoparticles and their application to photo-activated reactions. Nanoparticles have been synthesized using an innovative process involving titanyl solutions, allowing large scale synthesis of crystalline gold-titanium dioxide nanoparticles, up to 0.7 g.L-1. The absence of alkoxyde allowed us to work in aqueous media, with low cost chemicals and a controlled reactivity, which is a key parameter for industrial up-scaling. These nanoparticles have been successfully assembled into compact electrodes and probed using electrochemical methods to describe electrochemical exchange between metallic core, semi-conductor shell and various electrolytes. Reaction between gold nanoparticles and triiodide has been scrutinized to explain limitation of plasmon enhancement in standard DSSC involving iodine based electrolytes.

Resume : Addition of some other metals to platinum causes significant increase of its catalytic activity towards ethanol electrochemical oxidation. In this work various M@Pt core-shell nanoparticles and hollow Pt nanoparticles were synthesized and their catalytic activity towards ethanol electro-oxidation was determined and compared with the catalytic activity of one element Pt nanoparticles. We found that higher catalytic activity towards ethanol oxidation of some core-shell nanoparticles than solid Pt nanoparticles is rather not caused by different adsorption of CO molecules on solid Pt and core-shell nanostructures. We suppose that better performance of core-shell M@Pt nanoparticles than one elements Pt nanoparticles towards ethanol electrochemical oxidation can be explained as follows: core-shell nanoparticles are probably much more defected than one-element nanoparticles, hence the M@Pt nanoparticles posses greater number of active sites (kinks, adatoms, and so on) for ethanol electrochemical oxidation.

Resume : Silver nanoparticles have a number of interesting optical, catalytic and antibacterial properties. Many silver nanostructures may be synthesized using various photochemical reactions. In this work we describe the influence of stabilizing agent on the photochemical transformation of small, spherical silver seeds into bigger anisotropic nanostructures. In the first stage of the photochemical transformation, silver clusters (silver seeds nanoparticles) are partially dissolved. Then, Ag+ cations from the solution are photocatalyticaly reduced to Ag0. The photocatalytic reduction of Ag+, and hence deposition of metallic silver, occurs preferentially at such places of the silver nanoclusters, at which strong surface plasmons are excited (usually sharp etches or slits between nanoparticles). In this work we used sodium salts of many various poli-carboxylic acids as stabilizing agents. We found that used stabilizing agent significantly influences the photo-transformation process (finally obtained nanostructures have different shape and size). Many synthesised silver nanostructures have very interesting plasmonic properties. For example, we found that light-induced transformation of silver sols may be used to significantly increase their activity in surface-enhanced Raman scattering (SERS) measurements.

Resume : Fabrication of protective coatings with various functional purposes is one of the main task of industry, material science and solid state physics. This work is focused on study and characterization nanocomposite protective coatings based on metal nitrides MoN. Samples were obtained on high-speed steel X18H9T substrate using Arc-PVD deposition in vacuum-arc unit “Bulat-6”. Negative substrate voltage Us=-(100÷200) V and pressure of nitrogen atmosphere in chamber p=(0,2÷0,5) Pa were used. The thickness of coating was ranged from 7 µm up to 22 µm. Element composition analysis of coatings were performed using energy-dispersive spectroscopy (EDS), morphology of coatings and surface topography were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) respectively. Structure-phase composition of coatings was investigated by X-ray diffraction analysis (XRD). The hardness and elasticity values of coatings are also shown. Relations between deposition conditions and features of the structure, composition and physical-mechanical properties of obtained coatings. The interaction at the interface between the steel substrate and MoN coatings under stress was found.

Resume : The anti-reflective coating using SiO2 nanoparticles (NPs) is used to improve the energy conversion efficiency of the Si solar cells [1]. In addition, TiO2 NPs are known as well decomposing the organic contaminants by photo-catalytic effect [2]. In this study, we synthesized SiO2 and TiO2 NPs with various size and surface morphology. The spherical SiO2 NPs with smooth surface are synthesized using tetraethyl orthosilicate (TEOS), ethanol, ammonia hydroxide, and water. The particle size of the silica NPs is controlled by ammonia hydroxide and stirring intensity. The wrinkled silica NPs are synthesized using TEOS, cetylpyridinium bromide, urea, iso-propanol and water. The density of wrinkles is controlled by isopropanol and n-butanol. The TiO2 NPs are synthesized using titanium (IV) butoxide, acetyl acetone, 1-butano, nitric acid and water. The anti-reflective and self-cleaning SiO2/TiO2 nano-composite films are prepared by dip or spin coating using the synthesized SiO2 and TiO2 NPs. The optical properties and surface morphology of the nano-composite films are characterized by UV-visible spectrometer, SEM, AFM, and TEM, respectively. Keywords: anti-reflective, self-cleaning, nano-composite film, surface structures [1] G. San Vicente et al., Thin Solid Films, Vol. 517, p. 3157 (2009). [2] A. L. Linsebigler et al., Chem. Rev., Vol. 95, p. 735 (1995).

Resume : In recent years Cu-doped Y-stabilized ZrO2 composites are intensively investigated due to their excellent properties (such as environmental degradation, catalytic activity, tribologocal behaviour). These latter were found to be depended on Cu localisation. Therefore, the effect of calcination temperature (Tc=500-1100C) on Cu localisation in such composite was investigated byXRD, EPR and photoluminescnece (PL) methods. The samples calcinated at Tc=500-800C show the tetragonal ZrO2 phase mainly. EPR spectra demonstrate the signal caused by Cu-related surface complexes in this Tc range. At the same time, the Tc increase from 500 to 800C results in the lattice constant decrease along with the decrease of EPR signal intensity. This testifies to Cu incorporation into nanocrystals from the surface entities that is accompanied by the PL quenching due to increase of intrinsic defect density. Besides, the additional green PL band, which can be ascribed to Cu atoms at Zr sites, appears. The futher Tc increase (up to 1000C) causes the transformation of tetragonal phase to monoclinic one, the higher Cu content, the higher the temperature of this transformation. Simultaneously, the tetragonal lattice constant and total PL intensity increase. This can be explained by the outward Cu diffusion from nanocrystals that is confirmed by the decrease of green PL band intensity and the appearance of surface EPR signal for samples calcinated at Tc=1100C.

Resume : Extreme conditions of the ultrasonic cavitation such as local temperature and the pressure are widely used in chemistry, as for example to synthesize nano-materials, to enhance the electrochemical reactions and to modify the surface properties of electrodes, as well as to generate the novel materials in a liquid medium. The ultrasonic irradiation is a powerful tool in promoting of the chemical reactivity in the liquids at solid surfaces also. In our experiments described here, an attempt to drive the chemical and structural transformations on a semiconductor surface by the ultrasonic cavitation effect was made. The properties of the silicon samples subjected to cavitation impacts have been studied. Optical, atomic force and scanning electron microscopy techniques, Raman spectroscopy as well as energy dispersive X-ray spectroscopy and X-ray diffraction measurements were used. It was found the dendrite-like micron-scale array formation as well as a change of the chemical composition up to the new phase occurrence inside the ultrasonically structured region. In particular, the sonochemical synthesis of CaSiO3 compound on the silicon surface was fixed. Calcium inosilicate have been studied as materials for hard tissue repair, artificial bones and dental roots. Biomaterials containing CaO–SiO2 appeared to excellent bioactivity and were found to bond have to living bone and soft tissue.

Resume : In recent years, a greater demand for dental and orthopedic implants can be noticed. The clinical success of these implants is related to their early osseointegration and this is related to their surface properties. Surface modification of titanium implants for bone contacting applications is a very active field of research. Presently, the approaches to the surface modification of titanium implant devices involve surface topography modification or the application of inorganic/organic coatings. In this research, the hydroxyapatite-collagen-silver coatings have been deposited onto titanium implants by a combined method involving hydroxyapatite/collagen electrochemical deposition, combined with silver ions reduction and in-situ crystallization processes on titanium surface. The electrolytic processes implies the nucleation and growth of hydroxyapatite crystals on the surface of the titanium implant in a simulated body fluid under physiological conditions of pH and temperature, applying a constant current for different periods of time. The collagen has been used to modify titanium surfaces in order to enhance their bioactivity. The silver incorporation into hydroxyapatite coatings is an alternative that can provide good antibacterial properties of these coatings. The morphology, composition and phase structure of the hydroxyapatite-collagen-silver coatings were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD). The implants were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials.

Resume : Currently, roughened metal nanostructures are widely studied as highly sensitive enhanced Raman scattering (SERS) substrates that show application potential in biochemistry, food safety or medical diagnostic. In this work, we report on optical and structural properties of thin gold films deposited on highly ordered nano-patterned titanium templates for SERS applications. The templates are formed in following processes: a) formation of TiO2 nanotubes via a two-step anodization, b) etching of TiO2 nanotubes via overnight immersion in oxalic acid after the first and second anodization step. SEM images reveal the formation of honeycomb nanostructures with the cavity diameter of 80 nm. The thin (5-20 nm) quasi-continuous Au films are produced by pulsed laser deposition (PLD) using the UV (355 nm) laser operated at fluence up to 1.5 mJ/cm2 in vacuum conditions at room temperature. Due to strongly inhomogeneous distribution of the electromagnetic field in the vicinity of the Au film irregularities/discontinuities the measured average SERS signal is markedly higher than observed for bare Ti templates. It is shown that the enhancement factor can be optimized by adjusting the thickness of the deposited Au layer. Results confirm that the bimetal structures consisting of PL-deposited Au films on Ti templates can be used in surface enhanced sensing. KG and KS acknowledge the National Science Centre of Poland for financial support via grants 2012/07/N/ST5/02139 and 2012/07/D/ST5/02269.

Resume : Nanoscale factor significantly affects diffusion controlled processes such as structural and phase transformations. Nowadays those factors have not been thoroughly studied, and available results are quite unusual and controversial. Interdiffusion in nanofilm systems in comparison with bulk materials is characterized by more extensive mass transfer at low temperatures. This phenomenon is caused not only by high defects concentration and small diffusion distances, but also by significant surface influence. In thin films sequence of phase formation may vary from phase formation for bulk materials, and nanoscale factor plays an important role in causing these differences. Grazing-incidence x-ray technique and secondary neutral mass spectrometry have been applied to study layer-by-layer concentration, phase composition and phase transformation in Pd(30nm)/Ho(20nm)/SiO2 thin films. According to the phase equilibrium diagram for bulk materials next phases must be formed: Ho5Pd2, Ho3Pd2, HoPd, Ho3Pd4, Ho2Pd3, HoPd2, HoPd3. However, results show that after annealing in vacuum and in hydrogen formation of HoPd3 intermetallic phase only was registered. Also reflexes from Ho2O3 and HoH2 were registered on the surface using GIXRD. An interplay of phase formation at the outer surface and in the bulk has been investigated and it was discovered that the domination of processes on the external surface inhibits phase formation in the bulk and the other way around.

Resume : Silicon based electronics is often limited by phenomena occurring at the new structure-silicon interface. Most of the thin films used in micro-technology exhibit stress, which might affect both further processing during a fabrication cycle and final performance of fabricated micro-devices. Stress reducing is the key for improving of such opto- and/or electronic devices. Amorphization of silicon surface is one way of obtaining the goal. The silicon thin films were deposited using ASM LPCVD furnace on 100 mm oxidised silicon wafers at wide range of process conditions. The films of different structural (amorphous and polycrystalline) and mechanical (different stress level) properties were obtained. Raman studies for various wavelength excitation were performed. Confinement of phonons in a finite dimension of nano grains results in a change in the line-shape and position of the peaks in first order Raman spectrum. The average size of silicon nano grains in the thin silicon films have been obtained on the base of the spectroscopic studies. The maps of the grain size distribution to analyze the nonuniformity of the silicon film surface will be presented. Additionally appearance of specific surface and interface vibrational contribution for surface state evaluation will be discussed.

Resume : The aim of the presentation is to show evidences how important are scaffolds and their surface properties in regenerative medicine. There are several tissues that show limited self-healing abilities. It was proven that the critical defects of peripheral nerves and bones usually do not heal themselves. One of the most promising methods in treatment of such defects is tissue engineering and using of bioactive scaffolds that could mimic the extracellular matrix (ECM) and assist in tissue regeneration. For instance, bio-composite nanofibrous scaffolds made from synthetic and natural polymeric blends provide suitable substrate for tissue engineering and it can be used as nerve guides eliminating the need of autologous nerve grafts. Nanotopography or orientation of the fibers within the scaffolds greatly influences the nerve cell morphology and outgrowth, and the alignment of the fibers ensures better contact guidance of the cells. In bone tissue engineering the composition of the scaffolds, their mechanical properties, degradation kinetics, and surface properties (wettability, surface energy, and roughness) strongly influence response of human bone marrow mesenchymal stromal cells (HBMC) and whole regeneration process. By optimising these parameters using smart materials and advance biofabrication methods we will be able to control cells reaction and enhance process of new tissue formation.

Resume : An efficient separation of the air-borne moisture using silica sorbents is one of key operations in a range of industries, including electrotechnics, machinery, food preservation, chemistry to either preserve the product quality and to prevent degradation (due to aging, corrosion, decaying), or to remove quantitatively moisture from the air, whenever a low moisture air must be used (wood, paper industries). The specific surface of a sorbent material is very important parameter for high sorption capacity and should be as high as possible. This is possible using nanostructured sorbent, typically in the form of particles. However, they cannot be used repetitively as their desorption is tedious and costly. Large-scale production technologies for these materials are also often not available. Nanofiberous silicagels offer great moisture-capture capabilities and kinetics that can overcome conventional silicagels at comparable price. Moreover, they are capable of recovery at lower temperatures. Larger number of desorption cycles prolonging lifetime of these sorbent is realistic, thus making an additional positive cost figure. The presentation will show recent results in the synthesis of new efficient sorbent based on silica nanofibers using advanced production technology – force spinning – that has recently attracted large scientific as well as industrial attention. In particular, we will present results on surface and sorption characteristics of this material.

Resume : We have plenty of renewable energy available but sun and wind are unevenly distributed over time and geographically, therefore energy storage is increasingly important. Metal hydrides have extremely diverse chemistry, structures and reactivity and often high energy density [1]. We have recently developed new synthesis strategies combining mechano-chemical and solvent based methods, which are also useful for coordination chemistry. A series of 30 new complex borohydride perovskite-type materials are presented with interesting photophysical, electronic and hydrogen storage properties. Furthermore, anion-mixing provides a link to the known ABX3 halides [2]. New metal hydrides, which are fast lithium, sodium and magnesium ion-conductors are also discovered and are now tested in batteries [3]. A fascinating structural chemistry is discovered within metal borohydrides, e.g. up to 30% ‘empty’ space in the porous structures and physisorption of small molecules. Recently, we stabilized NH4BH4 with extreme hydrogen density, 24.5 wt% H2 [2]. Tailoring materials properties by nanoconfinement is also promising [4]. We conclude that the chemistry of hydrides is very divers, towards rational design of multi-functional materials, including ion-conductors for batteries, hydrogen storage etc. Ref: [1] Ley, et al, Mater. Today, 2014, 17(3), 122. [2] Schouwink, et al, Nature Comm., 2014, 5, 5706. [3] Ley, et al, Chem. Mater. 2012, 24, 1654. [4] Nielsen, et al, Nanoscale, 2011, 3, 2086.

Resume : Many functional materials are traditionally synthesized by slow reaction processes that are energy and time consuming. In the present world there is strong demand on development of modern materials and materials processing methods that could offer rapid reaction rates, energy efficiency and be environmentally safe. Here we report application of newly developed Electric Discharge Assisted Mechanical Milling (EDAMM) [1] technique for generation of rapid chemical reactions in plasma environment. Electro-mechano-chemical processing of solids is a new and exciting materials processing technique which combines the attributes of conventional mechanical milling with all effects generated by electric discharges. It is demonstrated that Electro-mechano-chemical method can be used to process wide range of materials and synthesize a range of functional materials in a matter of minutes, rather than days. In this study we show application of this method in reduction of oxides, generation of replacement reactions, solubility of nitrogen and hydrogen in metals and non-metals, reactions between carbon and metals, and synthesis of complex oxides from simple oxides or metals. Also the effect of AC and DC plasma on reaction rates will be presented and discussed. Obtained results will be compared and contrast with conventional processing methods such as sol-gel reactions, solid state reactions, mechanical alloying and mechano-chemical approaches that have been used to create reactions between species. [1] Nature, 419,(2002)147-151

Resume : Nanostructured materials are characterized by grains ranging in size from 1 – 100 nm and as a result high surface area of grain boundaries. Grain refinement down to nanometre scale offers a great increase in mechanical strength such as yield strength or hardness according to Hall-Petch relationship. However, the effect of reduced grain size on the corrosion resistance is not yet well understood. Due to high volume fraction of intercrystalline regions, they possess a great concentration of defects which increases reactivity and diffusivity. In addition, nanostructure is chemically more homogenous comparing to conventional microstructure, which can decrease the role of corrosion microcells in the electrochemical processes. In this study, the corrosion resistance of aluminium alloys with various grain size and precipitation state was investigated. The measurements were performed in 0.1M NaCl. The potentiodynamic polarization measurements showed that nanocrystalline sample has lower corrosion potential and lower corrosion current compared to microcrystalline one. The observations of surface morphology after immersion in 0.1M NaCl revealed the galvanic corrosion related to the presence of intermetallic particles. For microcrystalline sample, the intergranular corrosion attack was observed. The special attention has been paid on the role of grain boundary misorientation angle and second phase particles.

Resume : Graphene is a material with outstanding physical, chemical and electronic properties which are relevant to several technological applications, including catalysis. In fact, although perfect graphene is chemical inert, morphological defects may strongly enhance its chemical activity. In the present work we focus on structural defects in graphene epitaxially grown on Ni(111), mainly carbon vacancies partially filled by nickel adatoms. By combining high resolution scanning tunnelling microscopy images and ab-initio calculations, we identify and characterise the structural and electronic properties of the most common defects and, as a preliminary study, we investigate their interaction with small molecules of environmental interest.

Resume : A radical scavenger based on Ce-oxide supported on sulfonated silica was synthesized by a simple method and physico-chemically characterized to investigate the structure and morphology. The material was introduced in ePTFE reinforced membranes prepared starting from suitable Aquivion® PFSA dispersions. The aim is to mitigate the peroxy radicals attack to the polymeric membrane under fuel cell operating conditions. The influence of this hydrogen peroxide decomposition catalyst on the membrane durability was investigated ex-situ by using a Fenton’s test and under OCV accelerated stress test in a real fuel cell. These membranes show much longer lifetime in Accelerated Stress Tests (AST) and reduced fluoride release in Fenton’s tests than the radical scavenger-free membrane without any loss in electrochemical performance. These results confirm the stability of the modified membranes and the excellent activity of the composite scavenger in mitigating the polymer electrolyte degradation. Furthermore, the silica supported scavenger is more stable in terms of leaching behaviour than a membrane containing unanchored Ce(III) ions.

Resume : Al alloys are electrodeposited from chloroaluminate molten salt or ionic liquid containing AlCl3. In this presentation, I report electrodeposition of Al-Pt alloys, Al-Sn alloys, and Al-Ta alloys. To form Al-Pt alloys, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl molten salt containing PtCl2 at 448 K. The voltammogram showed cathodic reduction of Pt ions to start at a potential of 1.4 V vs. Al/Al(III) in the molten salt. Deposition of pure Pt was possible at 1.2 V and there was co-deposition of Al and Pt at potentials more negative than 1.0 V. The co-deposit was a mixture of intermetallic compounds of AlPt2 or AlPt3. Electrodeposition of Al-Sn alloys was performed in the AlCl3-NaCl-KCl molten salt containing SnCl2 at 423 K or 1-ethyl-3-methyl imidazolium chloride (EMIC)- AlCl3 ionic liquid containing SnCl2 at 303 K. Co-deposition of Al and Sn occurred at potentials more negative than 0.1 V. In comparison of morphology of electrodeposits, Al-Sn electrodeposit formed in ionic liquid became more fine particles than that formed in molten salt. In the structural observations of Al-Sn alloys, an alternate stacked structure of Al and Sn is obtained in the molten salt. Al-Ta alloys was electrodeposited in the AlCl3-NaCl-KCl molten salt containing TaCl5 at 423 K. In the voltammogram, 2 step cathodic reduction of Ta ions occurred at potential of 0.7 and 0.45 V in the molten salt. When Ta concentration in the electrodeposit increased, size of Al-Ta electrodeposit d

Resume : New synthesized anthracene-based and carbazole-based polymers as well as commercially available polymers such as polyfluorenes and polyphenylene vinylenes were applied as emitting materials in organic light-emitting diode (OLED) devices. Initially, spin coating and subsequently printing processes were used for the fabrication of the polymer thin films and the final devices either in rigid or flexible form. The photoluminescence (PL) of the polymeric films were evaluated by Fluorescence Spectroscopy revealing the characteristic emission of each material. The optical properties of the polymers were investigated by NIR-Vis-far UV Spectroscopic Ellipsometry. The accurate determination of the thickness and the optical constants (refractive index, dielectric function and absorption coefficient as a function of wavelength) were derived. Furthermore, quantum yield measurements, brightness, chromaticity and current density–voltage characteristics of the devices were obtained. A strong correlation between the optical properties, the thickness and the devices’ performance was established since external quantum efficiency of electroluminescence also depends on the optical interference of the beams of emitted light multiply reflected from the layer interfaces. This provides substantial insights into the final design of the optimum final multi-layer structure of the OLEDs whereas the potentiality for the development of flexible OLEDs with bigger active area devices is demonstrated.

Resume : Nanostructures including nanoparticles, nanowires and nanosheets are the ideal building blocks for the bottom-up fabrication of functional materials. They offer an immense variety of interesting properties, which not only depend on the composition, but also on the crystal structure, the particle size and shape and on the surface chemistry. Accordingly, potential synthesis routes have to provide full control over all these parameters. In addition, for most applications the nanoparticles have to be assembled and processed into useful geometries, architectures and bodies, and for this purpose, the surface properties of the nanoparticles have to be tailored carefully. The talk will cover the synthesis of metal oxide nanoparticles with different morphologies by nonaqueous sol-gel chemistry and their use as building blocks for the fabrication of 2- and 3-dimensional architectures. Fine-tuning of the surface chemistry of the nanoparticles makes it possible to self-assemble them over several length scales from the nanometer to the centimeter range [1]. For specific applications the nanoparticles can also be processed into thin films. Finally, we will show how such a bottom-up approach using preformed building blocks can be extended to the fabrication of macroscopic metal sponge monoliths [2]. [1] Metal Oxide Particles in Materials Science: Addressing All Length Scales, D. Koziej, A. Lauria, M. Niederberger, Adv. Mater. 2014, 26, 235-257. [2] Wet-Chemical Preparation of Copper Foam

Resume : Magnetic hollow fibers containing ZnFe2O4 nano-crystallites were fabricated by bio-templating. In sample preparation, kapok fibers were submerged in a mixture of Zn(NO3)2 and Fe(NO3)2. The infiltrated kapok fibers were dried and heat-treated at high temperature in ambient. Characterization showed that the appearance of the as-prepared sample resembled to those of the original kapok fibers. However, they were fully covered with ZnFe2O4 nano-crystallites (size of 30 to 50 nm), and with pores ranging from 2 to 10 nm. The adsorption kinetics and thermodynamics of the organic dye (acid fuchsin) molecules attached onto the ZnFe2O4 fibers were investigated. The adsorption was spontaneous and exothermic and the process could be well-described by the Langmuir model, and the pseudo second order kinetics model as well. The maximum adsorption capacity of these hollow fibers for acid fuchsin was determined to be 150.4 mg/g. Electrostatics and specific interactions between the dye molecules and the organic groups on the fiber surface were considered to be the drive of adsorption. The hollow fibers also exhibited strong ferrimagnetic behavior. This favored their high-efficient magnetic separation from waste water under applied magnetic field after dye adsorption. The fabrication route of the magnetic ZnFe2O4 hollow fibers by using kapok as bio-template is facile. In adsorbing organic dyes during water treatment, they appear effective and user-friendly.

Resume : The interactions between organic molecules and surfaces of steels were studied. Various organic acids were used with different chain lengths and different chemical bonding. Two materials were used as substrates, stainless steel 316L and carbon steel N80. These two materials were chosen regarding their opposite corrosion resistance: stainless steel 316L has a high resistance and a wide range of applications, whereas carbon steel N80, which is used for instance in petroleum industries, shows a low corrosion resistance. Surface binding was created and the surface energy was decreased, which induced a decrease in the wettability. In order to analyze the homogeneity of the coatings as a function of the immersion time, concentration, chain length and the chemical bond between the molecules and the surface, sum frequency generation spectroscopy was used. In a previous study for this kind of organic coating, the interaction between surface roughness and surface energy according to the Cassie-Baxter model led to superhydrophobic surfaces with a contact angle above 150°. We also examined the correlation between the immersion time, concentration, chain length and chemical binding of the molecules and the corrosion resistance and wettability. Electrochemical investigations revealed a shift of the corrosion potential values into the positive direction, a decrease of the corrosion current density, this correlating with an improvement in the hydrophobicity of the samples.

Resume : Scanning droplet cell microscopy (SDCM) recently found applications in fields with implications beyond pure electrochemistry. Due to a new special tip design allowing for stationary or flowing electrolyte conditions, a high reproducibility of the wetted area is achieved which makes the SDCM a preferred tool for local corrosion testing on metallic surfaces as well as for performing electrochemical screening of thin film combinatorial libraries. The electrochemical behavior of Hf-Ta thin film alloys deposited by co-sputtering in a wide compositional range (21 to 91 at.% Ta) was investigated. The transition from hexagonal Hf to tetragonal Ta along the compositional spread occurs through an amorphisation region where Hf-Ta metallic glasses were evidenced. The properties of anodic oxides grown on Hf-Ta alloys were mapped along the compositional gradient. Remarkable dielectric properties of the mixed Hf-Ta oxides were identified with direct applications in electronics as high-k materials. The use of highly sensitive downstream analytics (inductively-coupled plasma mass spectrometer) coupled to a flow-type SDCM allowed a careful quantitative study of the corrosion behavior of the Hf-Ta alloys. The corrosion rates dependence on the Hf-Ta composition are presented for the entire compositional spread analyzed. This is highly relevant for challenging applications such as nuclear fuel element cladding, liquid alkali metal containment or bio-medical applications (e.g. orthopedic implants).