Recent advances and challenges in chemical synthesis and solution processing of advanced inorganic nanomaterials

Resume : Metal oxide nanoparticles have widespread applications and represent an important field in research as well. The synthesis is usually based on bottom-up approaches taking advantage of the principles of sol-gel chemistry. Among the different requirements for metal oxide nanoparticles, a high degree of crystallinity, control of the particle size and the dispersibility in common solvents are major targets. The synthesis of nanoscopic inorganic materials in ionic liquids (ILs) represents a promising approach, taking advantage of special properties of ILs. In particular, ILs enable unusually low temperatures – compared to classical syntheses - being required for the nucleation of crystalline solids. Aside from the reduction of crystallization temperatures and grain sizes, ILs can even direct the crystallization to unusual and metastable structures such as the Bronze-type TiO2(B). Meanwhile, the materials/substanzes being synthesized in ILs span a wide variety of unusual reactions/reactivity (e.g. of elemental phosphorus) and complex inorganic compounds, including alloys and ternary oxides such transparent conducting oxides such as indium-tin-oxide (ITO) which are difficult to synthesize with high crystallinity by other methods. The talk is intended to give an overview on reports about the synthesis of unusual compounds and nanoparticles in ILs, giving special focus on metal oxides and on the special role of the IL in directing the synthesis.

Resume : Sonochemistry relies on the use of ultrasound to induce the nucleation, growth and implosive collapse of gas and vapor filled bubbles within a liquid medium. Each cavitation bubble can be considered as a microreactor in which non-equilibrium plasma conditions are formed. Since sonochemistry can generate very specific chemical and physical effects, this technique has attracted much attention during the last decades for the synthesis of nanomaterials. Carried out within aqueous media, sonolysis of water will lead to the formation of H and OH radicals. In situ formed species can therefore initiate chemical reactions, especially the reduction of noble metal without addition of further reagents. High frequency ultrasonic irradiation at room temperature was considered for the deposition of Pt, Pd or Pt-Pd nanoparticles on the surface of thermosensitive polystyrene beads and their transfer into a sol-gel derived porous silica matrix leading to the formation of tunable catalysts with hierarchical porosity. On the other hand, ultrasonic cavitation can be applied in a wide range of experimental conditions and even during hydrothermal treatment. The coupling of ultrasound with high temperature and autogenic pressure can offer an opportunity to obtain new catalysts or materials with enhanced properties. This how for the first time a simple, easily scalable and environmentally friendly synthesis of stable Ti@TiO2 core-shell nanoparticles was developed for energy and environment purposes.

Resume : Ni-based nanostructures are attractive catalytic materials for many applications among which electrochemical (bio)sensing, gas sensing and energy storage. In this work, we clarify the synthesis kinetics of Ni-based nanowalls grown by low-cost chemical bath deposition at various growth times and temperatures. At room temperature a quick random growth of disordered NiOOH sheets was first observed, followed by a slower growth of well-aligned Ni(OH)2 sheets (20 nm thick). The higher growth temperature of 50°C, leading only to well-aligned sheets, enabled superior electrochemical and catalytic properties. Based on these findings, we produced a Ni nanofoam (composed of 20 nm metallic Ni clusters) and applied it for non-enzymatic glucose detection, demonstrating an unprecedentedly high sensitivity (31 mA/cm2 mM) even at glucose concentrations as low as those in human saliva [1]. Then, a partial oxidation of Ni nanofoam led to a room temperature outstanding NO2 sensor in the sub-ppm range with high sensitivity, selectivity and stability [2]. Finally, Ni(OH)2@Ni core-shell nanochains were obtained upon electrochemical oxidation in alkaline solution, showing almost ideal energy storage performances for hybrid supercapacitors in terms of high specific capacity (237 mAh/g at 1 A/g) and rate capability [3]. [1] M. Urso et al. Nanotechnology 29, 165601 (2019) [2] M. Urso et al. Sensors and Actuators B: Chemical 305, 127481 (2020) [3] M. Urso et al. Scientific Reports 9, 7736 (2019)

Resume : Photochemistry has emerged in the last years as a powerful tool for the low-temperature solution processing of functional metal oxide thin films. It has demonstrated a great potential in the integration of oxide films with the low melting point substrates (e.g., polymers) used in flexible electronics. Electronic excitation is dominant when the precursor solution or the solution deposited layer is irradiated with continuous UV light. This mainly produces photolysis and/or photoinduced charge transfer, giving rise reactive chemical species (e.g., free radicals, oxidizing compounds) that accelerates the decomposition of the metal precursor, the condensation and densification of the metal-oxygen network, and the nucleation and growth of the crystalline oxide.1,2 These processes advance the formation and crystallization of the metal oxide film to an earlier stage. The possible photochemical reactions that can be driven by UV-light at the different stages of the chemical solution deposition of thin films will be described here, showing the potential of photochemistry in the low temperature processing of metal oxide thin films through relevant examples reported in the literature. 1. Bretos et al., Chem.Eur.J., in press; Chem.Soc.Rev., 2018, 47, 291. 2. Bretos et al., Chem.Soc.Rev., 2018, 47, 291. Financial support from MAT2016-76851-R and MAT2017-91772-EXP. I. B. acknowledges the Spanish "Ramón y Cajal" Programme (R&C-2016-20047)

Resume : The formation of ZnO nanowires (NWs) by the low-cost and low-temperature chemical bath deposition (CBD) technique on a polycrystalline ZnO seed layer is of high interest for their integration into a large number of nanoscale devices [1]. Their morphology is basically governed by the effects of the structural properties of the ZnO seed layer and by the physicochemical processes at work in aqueous solution, which are still not completely understood. In this context, we investigate the formation mechanisms of ZnO NWs grown by CBD under standard conditions using zinc nitrate and hexamethylenetetramine on ZnO single crystals with non-polar [2], semi-polar [3], and polar [4] orientations. This allows us to elucidate the formation mechanisms on the more complex polycrystalline ZnO seed layer. The elongation process is further modeled by solving Fick’s diffusion equations to obtain a general expression for the axial growth rate of ZnO NWs and study the crystallization process on their top face [5]. These findings results in a general overview of the mechanisms to form ZnO NWs by CBD with controllable structural properties. [1] L. Vayssières et al. The Journal of Physical Chemistry B 105, 3350 (2001) [2] S. Guillemin et al. The Journal of Physical Chemistry C 117, 20738 (2013) [3] T. Cossuet et al. Nanotechnology 29, 475601 (2018) [4] T. Cossuet et al. Langmuir 33, 6269 (2017) [5] C. Lausecker et al. The Journal of Physical Chemistry C 123, 29476 (2019)

Resume : Electrospinning of polymer nanofibers has been studied extensively and has shown to be possible via stable, reproducible and controllable processes. Studies on ceramic nanofibers are less comprehensive. Ceramic materials are hard and inert and are therefore known for their excellent properties such as high temperature resistance and chemical inertness. These promising characteristics allow ceramic nanofibers to be investigated for various applications such as biological applications, filtration, composites, catalysis, advanced sensors. Recently, our group successfully produced ceramic silica nanofibers without the need of a sacrificing polymer. In contrast to other work, in which a well-spinnable organic polymer is mixed with a metal oxide precursors to facilitate the electrospinning process, direct electrospinning of a sol–gel solution of a tetraethyl orthosilicate (TEOS) precursor eliminates the need for a postproduction removal of the organic polymer component. This results in dense silica nanofibers with superior mechanical properties, without a rough and uneven surface of the fibers. In addition and even more important, it offers the benefits of a simple, more tunable material design. In the present work we show the use of these materials towards both sensing applications and advanced purification.

Resume : Zinc Oxide (ZnO) nanostructures, thanks to biocompatibility, non-toxicity, low cost, earth abundance, and chemical and thermal stability, have attracted a large industrial and academic interest for applications in a lot of fields going from sensing to the realization of blends of sustainable plastics. Still, a cheap production of massive amount of nanostructures with optimized properties is challenging and the usage of low-cost approaches is highly demanded. In this work we investigated the production of different ZnO nanostructures (3D nanoflowers, 2D nanowalls or nanobelts, 1D nanorods) by using chemical bath deposition (CBD) with Zn nitrate and HMTA, at the operating temperature of 70–95°C. Physical-chemical properties have been investigated by Scanning Electron Microscopy, X-Ray Diffraction, Photoluminescence, sensitive mass weighting. By varying the operating temperature, the chemicals or the substrate, we got several nanostructures like urchin-like ensamble of nanorods, microspheres (diameters in the range 0.2–2.5 µm) composed of intertwined, honeycomb-like nanowalls, nanobelts (as large as 20-100 nm and as long as 1-4 µm), etc. Proper strategies to obtain massive production in aqueous solution have been tried to maximize the yield and to allow a clever manipulation of the micro-scale arrangement of the polymer phases in blends based on eco-friendly plastics .

Resume : Based on the synthesis from Bawendi et al., we developed a synthesis for CdSe/CdS giant-shelled nanocrystals with adjustable diameter from 8-20 nm. By analytical in situ characterization and systematic parameter variation, we got the key knowledge of the growth mechanism. Further, we managed to upscale the synthesis to the gram-scale with a focus on reproducibility. To achieve this it was necessary to control the precursor flow rates precisely over time with an automatic set up. The resulting particles show a very high crystallinity, quantum yields >90%, red emission at 625 nm and an adjustable size (8-20 nm). Furthermore, by changing only one parameter the shell geometry can be easily tuned from a sphere to a flat hexagon (plate), see figure. This exact control over the growth mechanism from thermodynamic to kinetic is achieved by changing the precursor concentration. Those plates have the property to align with the crystallographic c-axis perpendicular to the substrate. Aligned 2D materials show interesting properties, like a circular polarized light emission. Like the spherical giant-shelled nanocrystals this plate synthesis is highly reproducible, too. Both materials show very high absorption below 480 nm, high quantum yields and high photo stability. This makes them ideal for display applications.

Resume : Nanomaterials present outstanding properties that are giving rise to a variety of exciting applications. However, these properties strongly depend on their physical characteristics including shape, dimensions and chemical composition (bulk and surface). Frequently, additional features such as prolonged hydrodynamic stability and avoidance of aggregation are also demanded. These strict requirements represent a serious challenge to their mass production. In fact many of the most sophisticated nanomaterials are prepared in complex batch laboratory procedures that never reach production rates beyond a few tens of milligrams per day and present serious reproducibility issues. As a consequence, the availability of engineered nanomaterials with the required characteristics in sufficient amounts is one of the key hurdles to be overcome in the development of nanotechnology-based products. An intense effort to develop continuous and scalable processes for their manufacture is strongly needed. In this lecture we will consider the key challenges regarding the continuous production of nanomaterials, with emphasis in a precise control of their physical characteristics dimensions and state of aggregation. Special focus will be on the potential of microfluidic systems and laser pyrolysisreactors for a continuous production of nanoparticles with a high control on their nanoscale characteristics.

Resume : Bulk liquid metals have prospective applications as soft and fluid electrical and thermal conductors in electronic and optical devices, composites, microfluidics, robotics, and metallurgy with unique opportunities to tune their chemistry for specific functionality. “liquid metals” defines as metals and alloys with melting points (mp) up to 330 °C. Yet liquid metals’ great potential in nanotechnology remains in its infancy. Their high surface tension prevents them from exploring further in fabrication and processing and they cannot be synthesised as 2D materials with high yields and concentrations through conventional methods. Our studies show that liquid metals surface can be delaminated into 2D nanosheets of metal oxides if undergone shear stress forces with mechanical agitation. This process leads to a versatile, high yields production of nanoscale sheets of metals and metal oxides in a very cheap, fast and reliable technique that can be beneficial for further fabrication processing. Room temperature Gallium-based liquid metal has been alloyed with different metals such as Ce and Fe. The alloys were added to water before being shacked vigorously under mechanical agitation. After a few seconds, the liquid metal transformed into many nanosheets made of atomically thin metals oxide, which can be exfoliated from the liquid metal droplets over a few second centrifugations. This scalable new technique will accelerate the processing and fabrication of liquid metals devices and advances their use in wide varieties of applications.

Resume : Reproducible large-scale production of inorganic nanomaterials is essential for their application as building blocks in various devices. Applying wet chemical methods allows for an excellent control over parameters, such as morphology, crystallinity, and functionalization. Here we report about a microreactor approach, which can be used for the production of different nanoparticles, such as metal oxides, silsesquioxanes, or phosphates. Under optimized conditions, a production rate of up to 25 g/min was achieved with a laboratory scale set-up. In many cases, highly crystalline particles are obtained. Due to the high mixing rates and the resulting excellent control over nucleation and growth, the method is ideally suited for particles, which usually show a poor control in their formation due to low solubility products and thus fast precipitation. Recently we also succeeded in the production of particles based on slow formation rates. The obtained particle suspensions with high solid-state content can be directly used for further processing, such as spin casting or dip-coating. In collaboration with other groups, we investigated the obtained particles as building blocks for nanocomposites, energy, or sensing devices. Many of them show excellent properties in these applications without further treatment.

Resume : Zinc/vanadium oxide bronze batteries could potentially achieve an energy density breakthrough with their high capacity (> 300 mAhg-1) if a high discharge voltage can be maintained. Currently, two unsolved problems inhibit these batteries from high-quality electricity output. The first problem is that the discharge is always accompanied with a rapid drop of the voltage output, resulting in the capacity at a voltage above 1.0 V being usually less than ～19 % of the total capacity. The second problem is their unsatisfactory cycling stability, as most currently reported systems can only be cycled 2000 times or less. In this work, we develop a high-voltage output and long-lifespan zinc/vanadium oxide bronze battery using a designed vanadium oxide bronze cathode pillared by interlayer cobalt ions & water molecules (Co0.247V2O50.944H2O nanobelts). The high crystal architecture could enable the fast and reversible Zn2 intercalation/deintercalation at highly operational voltages. The developed battery exhibits a high voltage of 1.7 V and delivers a high capacity of 432 mAhg-1 at a current density of 0.1 Ag-1. The capacity at voltages greater than 1.0 V reaches 227 mAhg-1, which is 52.54 % of the total capacity and higher than the values of all previously reported Zn/vanadium oxide batteries. The simultaneous high voltage and high capacity contributes to a record high energy density of 458.7 Whkg-1 in terms of the cathode material, which is higher than those of all reported zinc batteries and comparable to the well-established Li-ion batteries. Further study reveals that, compared with the pristine vanadium oxide bronze, the absorption energy for Zn2 is increased from 1.85 to 2.24 eV by cobalt ion intercalation. Furthermore, it also shows a high rate capability (163 mAhg-1 even at a high current density of 10 Ag-1) and extraordinary lifespan over 7500 cycles, with a capacity retention of 90.26 %. These performances far exceed all reported zinc/vanadium oxide bronze batteries. Subsequently, a nondrying and anti-freezing tough flexible battery with a high energy density of 432 Whkg-1 at 0.1 Ag-1 is constructed, and it reveals excellent drying and freezing tolerance as well as high flexibility. Our research represents a substantial advance in vanadium materials for various battery applications, achieving both a high discharge voltage and high capacity, thus remarkably boosting their energy density.

Resume : Zn-air batteries (ZABs) offer promising commercialization perspectives for stretchable and wearable electronic devices because they are environmental friendly and have high theoretical energy density. However, current devices suffer from limited energy efficiency and durability because of the sluggish oxygen reduction and evolution reactions kinetics involved in the air cathode of the battery during charge/ discharge processes as well as degenerative stretchability of solid-state electrolyte in high alkaline condition. Herein, we show that excellent bifunctional catalytic activity and cycling stability can be achieved using newly developed Co-N-C nanomaterials with uniform virus-like structure, prepared via a facile carbonization of a prussian blue analog (PBA) precursor. Enhanced performance is attributed to the favorable virus-like structure with rough surface, high conductivity, and relative high surface area as well as synergetic Co and N co-doping effects. We further synthesize a solid-state dual - network sodium polyacrylate and cellulose (PANa-cellulose) based hydrogel electrolyte with good alkaline-tolerant stretchability enabled by the cellulose and N, N"-methylenebis-acrylamide (MBAA)-assisted toughening, hydrogen bond cross-linking and the carboxyl groups neutralized by hydroxyl and cellulose as alkaline stabilizer. A solid-state fiber-shaped Zn-air battery fabricated using this hydrogel electrolyte, the virus-like Co-N-Cs air cathode, as well as zinc spring anode displays excellent stretchability of up to 500% strain without damage, and outstanding electrochemical performance with 128 mW cm-2 peak power density and good cycling stability for > 600 cycles at 2 mA. The facile synthesis strategy demonstrated here opens up a new avenue for developing highly active PBA-derived catalyst and show, for the first time, that virus-like structure can be favorable for electrochemical performance. The enhanced reactions kinetics of the fabricated cathode and the high stability in alkaline conditions of the stretchable solid electrolyte provide important insights towards the commercialization of stretchable and wearable ZABs.

Resume : Azo dyes are easily involved in stacking interactions due to the planar aromatic structure of molecules. They are able to form homo- and heteroaggregates in solution even at micromolar analytical concentrations. In the present work, aggregation phenomenon was used in design of organosilica material for effective sorptive removal of azo dyes from aqueous solutions. It was expected that chemical immobilization of methyl red in surface layer of MCM-41 by templated sol-gel synthesis will enhance its sorption affinity to adsorbate due to stacking interactions arising between aromatic rings of dye molecules immobilized on silica surface and supplied from solution. Along with attraction of dye molecules to the chemically immobilized dye containing sorption centers, the adsorbate-adsorbate interactions, cooperative sorption mechanism can be realized due to the interaction of adsorbate with secondary sorption centers formed on silica surface. The hexagonally arranged mesoporous structure of synthesized material was confirmed by low-temperature nitrogen adsorption-desorption, x-ray diffraction, and TEM studies. Chemical composition of MCM 41 type organosilica was established by FT-IR spectroscopy and chemical analysis of surface layer. It was found that synthesized mesoporous organosilica demonstrates improved sorption properties in relation to azo dyes. Obtained results could be useful in design of sorbents for azo dyes removal from effluents.

Resume : In recent years, research for surface hierarchical structures for chemical sensor and bio-sensor devices applications has been highlighted owing to their relatively large ratio of surface-area compared to the volume. Especially, the hierarchical micro-nanostructures (organization of the nanostructure within the microstructure) including nanoscale passages have been intensively studied, because nanoscale passages are necessary for single-molecule DNA sequencing. In order to realize a hierarchical micro-nanostructure, the fabrication process for micro- and nano-scale structures should be applied together, controlling each pattern size precisely. Therefore, the properties of lateral Ni film etching by TFB etchant at room temperature were investigated by using samples with patterned lamellae layers consist of Ni, Al2O3, and SiO2 for fabricating hierarchical structures for the fabrication of hierarchical structure including nanoscale passages. Moreover, the influence of Ni film thickness on lateral etching characteristics was also investigated. In this presentation, the fabrication process based on lateral Ni film etching in lamellae layers by liquid etchant at room temperature will be presented systematically for bio-sensor applications.

Resume : Nanostructured hybrids of metal oxides can provide high performance in electrochemical applications such as supercapacitors and batteries. However, their complex synthesis methods hinder scalable fabrication, thereby increasing the time and cost. Herein, a novel combustion-driven synthesis method for tunable TiO2/RuO2 hybrids is developed as high-performance electrode materials of supercapacitors. The combustion waves propagate along a precursor comprising TiO2 nanoparticles and nitrocellulose, and it concomitantly produced sacrificial carbon template around metal oxides, while the residual structure of amorphous carbon can be controlled by the initial mass loading of nitrocellulose. Subsequently, a tunable TiO2/RuO2 hybrid of core-shell TiO2@RuO2 nanostructures or RuO2 clusters with embedded TiO2 NPs was obtained by replacing the carbon template with RuO2. The types of the hybrid could be selectively obtained by the initial formation of the carbon templates. The electrodes fabricated with the hybrids presented outstanding specific capacitance (1,200 F/g per unit mass of RuO2 and 532 F/g per total mass at 0.5 A/g) and cyclic capacitance retention (95.2% after 10,000 cycles) than commercial RuO2-based electrodes. The optimal thickness of the RuO2 can promote diffusion of proton to provide high specific capacitance, while stability of inner TiO2 and the amorphous nature of the external RuO2 can provide robustness against stresses during the charge-discharge cycles. This work proposes new strategies for the scalable fabrication of the hybrids, which can contribute to develop electrochemical devices, catalysts, and electromagnetic shielding.

Resume : Vanadium dioxide is one of the most promising thermochromic solid-state materials. It has potential application in the field of thermal regulation of buildings, as a “smart” coating on glazing systems, due to its unique optical switching property in the infrared spectrum, related to its inherent and reversible structural transition near room temperature. Moreover, a potential application of this material could be in the textile industry, with the use of autonomous heat regulation on ‘smart textiles’. In this work, the effect of additives on the low-temperature hydrothermal synthesis route of thermochromic VO2 composites is presented. Additionally, the use of polymer matrices is investigated in order to turn hydrothermal synthesized VO2 powders into films that can be used as thermochromic coatings for deposition on rigid and/or flexible substrates. Thus, we report on an optimized hydrothermal route to synthesize thermochromic VO2 composite powders, with enhanced thermochromic behavior, of reduced transition temperature, along with results on heat regulation of thermochromic coatings on glass substrates as well as in textiles.

Resume : Magnesia (MgO) is currently employed as a coating material for forming insulation layers on semiconductors, metals, etc., due to its superior electrical insulation property and thermal stability compared to silicate or alumina. However, the insulating quality of MgO is degraded owing to high hygroscopicity, surface staining, and surface defects. In order to improve these problems, powders of a new binary system were synthesized by substituting various transition metal ions (Mn, Co, and Ni) for some Mg ions in MgO, based on co-precipitation method using chloride precursors as starting materials. The characteristics of powders, such as size, shape, crystal phase, microstructure, and reactivity, were evaluated according to the type and content of substitutional element, slurry pH, and the amount and type of catalyst. In addition, the phase transformation behavior, ion diffusion, and general properties (magnetic, electrical, and mechanical properties) of the synthesized powders were theoretically studied through atomic simulation, and the results were compared with experimental results. As a result, the optimum powder composition in the binary system could be derived for forming the MgO-based insulation coating layer with the more improved characteristics, compared to that of the insulation layer using only MgO, and its processing parameters were determined.

Resume : Solution processed metal oxides come out as an enabling technology for the low-temperature preparation of high-performance layers that can be integrated with flexible substrates to build electronic devices. Major efforts have been focused on metal oxide semiconductors, where solution methods are able to reduce the temperature of formation of the functional amorphous oxide (<350 ºC). But, for other oxides like ferroelectrics, crystal structure, which is obtained at high temperatures (>600˚C), is the origin of the physical properties. However, the use of ferroelectrics in flexible devices would make real applications not possible before (i.e., smart skin with multisensing capacities), associated to their intrinsic multifunctionality. This work shows the low temperature solution preparation and functional characterization of ferroelectric thin films of the (1-x)BiFeO3-xPbTiO3 solid solution with compositions close to the Morphotropic Phase Boundary (MPB), where high ferroelectric/multiferroic, piezoelectric and pyroelectric responses are reported for bulk-ceramics.1 The potential of these films prepared on flexible polymer substrates for applications in electronic skin is evaluated based on their functional properties. 1. Amorín et al., J.Appl.Phys., 2014, 114, 104104. Financial support from MAT2016-76851-R and MAT2017-91772-EXP. I. B. acknowledges the Spanish "Ramón y Cajal" Programme (RYC-2016-20047). L.Z. acknowledges the financial support of the HEC of Pakistan.

Resume : Heat load management in a building infrastructure is predicted to reduce around 30% of greenhouse gas emissions at UNEP report at 2016. One of the management approaches is the development of a thermochromic coating (VO2) for smart windows that is switched by temperature and controls the transmission of infrared radiation (IR) through glass windows on a building. Vanadium (IV) oxide (VO2) has been the focus of much research because its electrical conductance varies by several orders of magnitude at 68 °C: from that of a semiconductor with a large IR transmittance to exhibiting metal-like conductivity with a high IR reflectance. To achieve the smart window, fabricating a large area of VO2 thin film on a glass substrate using a cheap and simple method is necessary for cost-effective optical applications. Although there are various techniques such as pulsed laser deposition and radio frequency sputtering, these methods require expensive equipment because they use a vacuum, and this is a limitation for deposition on a large glass. Vanadium is a transitional metal that has abundant oxide forms and is very sensitive to changes in deposition conditions such as pH and temperature. In this study, we present the synthesis and characterization of thermochromic VO2 using chemical bath deposition (CBD), which is the simplest method for applying a glass substrate for a smart window. Notably, we discuss the process in which a metal dopant such as Sn is used to control the phase transition temperature of VO2 during CBD.

Resume : Vanadium dioxide is one of the most promising thermochromic solid-state materials. It has potential application in the field of thermal regulation of buildings, as a “smart” coating on glazing systems, due to its unique optical switching property in the infrared spectrum, related to its inherent and reversible structural transition near room temperature. Moreover, a potential application of this material could be in the textile industry, with the use of autonomous heat regulation on ‘smart textiles’. In this work, the effect of additives on the low-temperature hydrothermal synthesis route of thermochromic VO2 composites is presented. Additionally, the use of polymer matrices is investigated in order to turn hydrothermal synthesized VO2 powders into films that can be used as thermochromic coatings for deposition on rigid and/or flexible substrates. Thus, we report on an optimized hydrothermal route to synthesize thermochromic VO2 composite powders, with enhanced thermochromic behavior, of reduced transition temperature, along with results on heat regulation of thermochromic coatings on glass substrates as well as in textiles.

Resume : Template synthesis of 1D nanowires(NWs) through anodic aluminum oxide(AAO) nanochannels is cost-effective, with better structural uniformity and tunable morphological parameters compared to other bottom-up approaches[1]. In this work, a two-step anodization was used to create a highly ordered porous oxide film. The dielectric barrier beneath the template was electrochemically thinned down, exposing the base aluminum, to enable easy electrodeposition and handling[2]. Various metallic/alloy NWs were grown in the AAO template, such as Ag, Ni, Pt, Sn-Co and Ni-Zn, via electrodeposition. Galvanostatic or potentiostatic mode was used to deposit these NWs. Using a Cu/Ni seed layer promoted uniform deposition of Sn-Co NWs in AAO. Sn-Co NW electrodes of high contact area accommodate volumetric expansion leading to better cycling stability in Li-ion batteries. Cyclic Voltammetry data showed broad oxidation and reduction peaks of Sn, indicating its participation. NiO-ZnO NWs based p-n heterojunction photodetectors are superior for their high surface area/volume ratios. These NWs enhance hydrogen selectivity in gas sensors, further sensitized via porous NiO NWs. Pt NWs are potent catalysts for fuel cells and Zn-air batteries. Synthesis of porous Ni NWs by dealloying Ni-Zn NWs was also attempted. Performance of some 1D structures in devices would be highlighted. References: [1] David J. Hill et al., Material Matters, 12, 10-13(2017) [2] G. ArulKumar et al., Appl. Nano Mater., 2, 5981-5988(2019)

Resume : Tin oxide/reduced graphene oxide (SnO2/RGO) nanomaterials were synthesized by hydrothermal method using stannic chloride pentahydrate and graphite oxide as raw materials and ammonia as precipitant. The structure and morphology of the obtained samples were characterized by XRD, SEM, TEM, HRTEM and BET. We discussed the effects of temperature, ethanol concentration and other factors on sensitivity. The results indicate that SnO2/RGO has a 3D structure and high specific surface area of 175.83 m2/g. The sensor based on SnO2/RGO exhibits good gas-sensing properties, and the sensitivity to 100ppm ethanol is 20.6 at the optimum operating temperature (280℃), which almost doubles that of the SnO2 sensor (8.5).

Resume : Nickle foams (NFs) have been widely used as a substrate to support various electrocatalysts due to their framework structures, low-cost and high-conductivity. As a kind of relatively active metal, nickel is prone to corrode or to be etched during the hydro-/solvothermal process, however, as far as we knew, when using NFs as the scaffold to support Ni-free electrocatalysts, most of the published papers overlook or ignore the effect of the nickel corrosion on the activities of such electrocatalysts. By using a simple comparison method, we systematically studied such effects from the aspects of temperature and precursors. Our results show that the nickel will corrode and diffuse into the electrocatalysts, in turn affect their electrocatalytic performance. Moreover, in-situ Ni, Fe co-doping cobalt carbonate hydroxides were prepared on the NiFe foam substrate via a facial hydrothermal method. Importantly, the concentration of the dopants and morphologies on the catalyst can be easily tuned via changing the proceed hydrothermal temperature. The excellent electrolytic performance indicates the potential practical application of Ni, Fe co-doping cobalt carbonate/NiFe electrode in overall water splitting. More importantly, our work experimentally proves the important role of the substrate on the targeted catalyst during the hydrothermal reaction, which provides a new strategy for the modification of catalyst performance.

Resume : Controlled synthesis of high-quality lead halide perovskite (LHP) nanostructures not only benefits fundamental research but also offers great promise for practical applications [1,2]. Although catalytic vapor-liquid-solid (VLS) growth is widely recognized as an effective route to achieve single-crystalline low-dimensional nanostructures with precise control over morphology and chemical composition, etc [3,4], there is still not yet any detailed report on VLS grown LHP nanomaterials due to the emerging challenges in perovskite synthesis. Here, we successfully develop an unique VLS growth process for defect-free single-crystalline all-inorganic lead halide perovskite (i.e. CsPbX3; X = Cl, Br, or I) nanowires (NWs) for the first time. When configured into photodetectors, these NWs exhibit high-performance photodetection with the responsivity exceeding 4489 A/W and detectivity over 7.9×1012 Jones towards the visible light regime. Meanwhile, this is also the first demonstration of field-effect transistors based on individual CsPbX3 NWs, where they show the superior hole field-effect mobility of up to 3.05 cm2/Vs. All these device parameters are comparable or even better than other newly developed LHP devices. Evidently, this work provides promising opportunities for assessing the fundamental properties and potential utilizations of these one-dimensional perovskite nanostructures. [1] Ek, M. et al. Acc Chem Res 2018, 51 (1), 118-126. [2] Feng, J. et al. Nature Electronics 2018, 1 (7), 404-410. [3] Fu, Y. et al. Nature Reviews Materials 2019, 4, 169-188. [4] Quintero-Bermudez, R. et al. Nat Mater 2018, 17 (10), 900-907. [5] Meng, Y. et al. ACS Nano 2019, 13 (5), 6060-6070.

Resume : As the use of fossil fuels increases, a global warming becomes a more serious problem, owing to the huge emission of CO2 into the atmosphere. Therefore, various investigations have been conducted to reduce the CO2 concentration. Among them, the electrochemical reduction of CO2 to useful products has been received a spotlight. As one of the useful products, the CO is known to have the economic benefit because the market price of CO is higher than other products. Au-based and Ag-based catalysts are commonly used to convert CO2 to CO. In order to achieve highly active and selective conversion, the various efforts are being conducted to control their composition, oxidation states, facets, size and morphology, which could influence the intermediate adsorption, grain size, and electrochemical surface area. In this study, AuCu nanoparticles were directly fabricated on carbon paper substrate by using electrodeposition method. The deposition parameters such as deposition time and precursor concentration were changed to control the morphology and composition of AuCu catalysts. At a certain condition, the CO Faradaic efficiency of ~80 % was achieved at a potential of -0.7 VRHE. Further modification on catalytic performance was conducted with post-treatments such as anodizing or dealloying methods.

Resume : To solve the global warming problem caused by indiscriminate use of fossil fuel, hydrogen production technology via water electrolysis is drawing attention. It is known that the Pt catalyst has been reported to be excellent for hydrogen evolution reaction, which inhibits commercialization of water electrolysis due to its high price. For this reason, non-noble metal-based catalysts have been investigated to achieve cost-effectiveness with acceptable catalytic performance. In this study, M-Se catalysts (M = Ni, Cu, Co, and etc.) were prepared on the carbon paper substrate using electrodeposition method. Deposition parameters such as deposition potential/time and bath configuration were changed to control their morphology and composition. Their catalytic activity for hydrogen evolution reaction was tested in half-cell measurement with the alkaline electrolyte. Then the activity orders based on geometric current, specific activity, and mass activity were connected with the results from analysis on material properties. Furthermore, employing the optimized catalyst in cathode, the performance of anion exchange membrane water electrolyzer was tested.

Resume : Hydrogels have gained prominence as wound dressing scaffolds for the treatment of burns and other skin lesions due to their hydrophilic nature and soft tissue- like properties1. Hydrogels with inherent antibacterial ability helps reduce the risk of infection in partial- and full-thickness wounds, over percutaneous line sites and surgical incisions. In this work, we have formulated a PEG-PVA based hydrogel incorporated with magnesium oxide nanoparticles, which are found to be blood compatible and highly antibacterial in nature2. PVA and PEG 4000 have been used to formulate the hydrogel due to their biocompatibility, water solubility and ability to resist protein fouling and magnesium is known to help in wound healing. These hydrogels demonstrated high water content, significant water vapour transmission capability, optimum swelling ratio and gel fraction, which are necessary for an ideal wound dressing. These nanocomposites are quite stable in terms of PVA release and retention of moisture up to 30 days. TGA and DSC results give an idea about their thermal properties and EDX spectra indicate the presence of magnesium embedded within the layers of the hydrogel films. Their antibacterial assay of these films also showed about 99% (5 log reduction) of colony counts of both gram-positive (Bacillus subtilis) and negative (Pseudomonas aeruginosa) strains. These hydrogel films prove its potential as antibacterial wound dressings, which can be further demonstrated by in-vivo studies. 1 A. S. Hoffman, Adv. Drug Deliv. Rev., 2012, 64, 18–23. 2 P. Bhattacharya, et. al., J. Mater. Chem. B, 2019, 7, 4141–4152.

Resume : Cancer targeted drug delivery is a technique, that delivers a drug into the site of interest, thus increasing the bioavailability of the drug and sparing the normal cells. We have developed doxorubicin-loaded gold nanoparticles coated with folate conjugated silk fibroin for slow, sustained and targeted drug delivery. The nanoparticles with uniform shapes and a size of about 5-10 nm were formulated by a green synthetic route using chitosan.The loading of dox on the nanoparticles was confirmed by FTIR spectroscopy and zeta potential measurement, which shows an increase in the value in loaded ones indicating the presence of positively charged dox. The silk coating was confirmed by UV-Visible and FTIR spectroscopy. Here, the silk coating was not only used for slow release but also as a platform for conjugating the targeting moiety. We have also developed dox encapsulated microparticles from the same material. Microparticles fabricated from chitosan-gold nanoparticles can act as a potent encapsulating material for various types of anticancer drugs for their oral and depot drug delivery. They were synthesized using TPP as the crosslinking material which is a non-toxic agent. 900-1000 µm particles was formed which was evident from optical microscope and FESEM. The coating of beads was confirmed by fluorescence microscopy. The coated materials in both the cases showed superior property compared to the uncoated ones in terms of shape, surface uniformity and drug release profile.

Resume : As a cost-effective and highly transparent electrode for high-performance thin film heaters (TFHs), the tin-doped indium oxide (ITO) nanoparticles (NPs) films were fabricated by using a solution spin-coating process on glass substrates. The electrical and optical properties of ITO NPs films depended on the number of spin coatings and post-annealing with various conditions (temperature, time, ambient gas). The optimized 3 layer-ITO NPs films at 600-degree post-annealing under nitrogen-rich ambient showed a low sheet resistance of 14 ohm/sq and high optical transmittance of 88% in the visible wavelength region (400 ~ 800 nm). Due to thermal stability and uniformity of ITO NPs film, the time-temperature profiles and IR images showed the high-performance TFHs with ITO NPs film. This results that the solution-coated, ITO NPs films can be applied as a transparent electrode in a cost-effective and smart window for buildings and automobiles.

Resume : Thermocol generates a lot of waste in the environment causing pollution. So reduction of it can be focused by developing it into functional polystyrene nanocomposites. Polystyrene polymer nanocomposites provides a better alternative against the conventional polymers as polystyrene has excellent processing properties due to its thermoplastic nature. Addition of silver nanoparticles enchances its mechanical properties as well as gas barrier properties and thermal stability etc. In this study silver nanoparticles (AgNPs) were synthesized using peels of Musa balbisiana (Bhimkol; an indigenous variety of banana of Assam, India) which is a green process. AgNPs were characterized by UV-Visible spectroscopy, Field Emission Scanning Electron Microscope (FESEM) and Field Emission Transmission Electron Microscope (FETEM) and impregnated into polystyrene (PS) matrix. The PS/AgNPs nanocomposites were developed in different concentrations and their morphology were characterized using FESEM and FETEM. Fourier transform infrared spectroscopy (FTIR) were used to evaluate the surface chemical bonding and surface composition of the prepared nanocomposites. UV-Visible spectroscopy determines the optical features of the polystyrene nanocomposites Also, its enhanced mechanical properties were estimated using Universal Testing Machine(UTM). These nanocomposites revealed antibacterial effect against E.coli which is a gram-negative bacteria commonly found in water. These nanocomposites can be used for water disinfection purpose and further can be utilized for water storage purposes in rural areas. Keywords: Thermocol waste; green synthesis; AgNPs ; Polystyrene/Ag nanocomposites; water disinfection

Resume : ZnO nanowires (NWs) have recently been widely used as abundant wide-bandgap semiconductor nanostructures in gas sensors, piezoelectric nanogenerators, solar cells, and UV LEDs. For those applications, intrinsically n-type ZnO nanostructures have intentionally been n-doped by incorporating metal (III) elements, mainly by vapour phase deposition techniques. However, controlling the doping during the growth of ZnO NWs by solution deposition techniques is still a major issue. Here we show that the doping of ZnO NWs, mainly with gallium, can be achieved by the low-cost, low-temperature, and easily implemented chemical bath deposition technique [1]. Gallium nitrate and ammonia are added in various concentrations to the standard precursors, tuning not only the crystal structure and the morphology of ZnO NWs, but also the gallium incorporation [2]. The formation mechanisms are thoroughly investigated and supported by thermodynamic simulations: the doping only occurs if the pH of the solution favours the formation of charged gallium hydroxide complexes. This further emphasizes the electrostatic origin of doping mechanisms in aqueous media [3]. Temperature-dependent Raman spectroscopy and XRD reveal the n-type doping of as-grown ZnO NWs and the formation of compensating acceptors after annealing under oxygen, strongly affecting their electrical and optical properties. N-type ZnO NW heterostructures on p-type GaN layers deposited by MOCVD on sapphire are eventually presented for UV LED applications. These findings show a simple, thorough way to control the doping of ZnO NWs grown in aqueous solution, which opens the way for their more efficient integration into nanoscale devices. [1] R. Parize et al., The Journal of Physical Chemistry C 120, 5242 (2016) [2] P. Gaffuri et al., Inorganic Chemistry 58, 10269 (2019) [3] C. Verrier et al., Inorganic Chemistry 56, 3573 (2017)

Resume : Metal oxides nanomaterials have a versatile usage as catalysts, ceramics, electronic and etc. In order to achieve further development of such applications, it is required to establish simple and universal method for the region-selective formation of the layer. Unlikely to the complex vapor phase deposition, solution-based deposition techniques are preferred for easy handling and simplifying the reaction chemistries. Two representative strategies are proposed in this manner, a region-selective thin film formation with solution-based atomic layer deposition (sALD) technique and preferential deposition of nanoparticles (NPs) by tuning the functionalities of the surface of NPs. By creating the contrasts of surface functionalities, both methods are expected to create a region-selective metal oxide layer. To proof of the concepts, these layers will eventually be used as a functional layer of the electronic devices to analyze their properties. In terms of the second strategy is intended to be realized the region - selective deposition of core-shell nanoparticles (NP) for 3D hierarchical assemblies. At this moment is pretended to agglomerate the aluminum oxide (AlOx) NPs functionalized by 6-Phosphonohexanoic acid (6-PA) where is presented the carboxylic acid terminated group to control the over layer thickness. The AlOx thin film on Si substrate behaves as substrate for deposition reaction of self - assembled monolayer (SAM) of amine phosphonic acid (PA) over which occurs deposition reaction of AlOx NPs functionalized by 6-PA. During research project the nanoassemblies can be rearranged permuting core-shell NPs. The NP functionalization is analyzed by IR – spectroscopy, TGA, DLS and deposition stack are characterized by SEM, AFM, Surface Contact Angle technique with definition of region selectivity. As final part of this research project, the nanostructure is pretended to be tested and analyzed as electronic device for different objectives.

Resume : Metal organic frameworks (MOFs) are hybrid materials that consist of organic ligands and metal ions or clusters. Recently, MOFs have been found to show great potential in CO2 capture due to their high surface area. In this work, we synthesized HKUST-1 in the lumen of Halloysite clay nanotubes (HNTs). HNTs were worked as nanocarriers and the inner surface of HNTs was modified with acid to extend the space volume. HKUST-1 consisted of copper nodes and organic ligands is one of the most widely studied MOFs owing to its high porosity. By confining space inside the nanotubes, we could make specific boundary for growing MOFs with longitudinal aixs of HNTs and enhance water stabililty of MOFs. Experimentally, even loading of a MOF precursor among HNTs in a solution phase, and following solvothermal reaction while the precursor is suspended selectively inside of the HNTs. XRD for structural analysis of this hybrid was done showing characteristic reflections. TEM and EDS illustrated the formation and the elemental compositions of this materials. Gas adsorption capacity was analyzed by Brunauer-Emmett-Teller (BET) using N2 and CO2 gases. N2 gas adsorption capacity increased around 4 times, from 95.449 cm3(STP)g-1 to 386.06 cm3(STP)g-1 by acid etching and this hybrid synthesis. This work can be a significant point to synthesize a variety of hybrid nanotube materials to yield synergistic effects and can be applied to competitive adsorbents for gas capturing.

Resume : In this work, we investigated about the bias stability improvement of sol-gel processed titanium (Ti) -doped tin dioxide thin-film transistors (TFTs). The sol-gel processed tin dioxide TFTs have many strengths in terms of electrical performance and fabrication process, however, they still have electrical instability by originating from oxygen vacancies and other defects. To overcome this issue, we analyzed the change of electrical properties by doping the titanium as an oxygen suppressor. In this experiment, Ti-doped (0 to 0.3 wt%) tin dioxide TFTs are fabricated by means of a sol-gel method. The conventional devices were fabricated in 0.25M tin precursor solution synthesized with tin (II) chloride dehydrate and ethanol. This devices have a mobility of 6.65 cm2/Vs and -6.36 V threshold voltage shift under negative bias stress (NBS) condition. However, in case of 0.3 wt% Ti-doped tin dioxide TFTs, they indicate a mobility of 2.63 cm2/Vs and -0.64 V threshold voltage shift under NBS condition. These results show remarkable betterment in terms of bias stability under NBS condition. We expected that Ti-doped tin dioxide TFTs have great promise for high stability applications in transparent electronics.

Resume : Novel, low-voltage, high-detectivity, solution processed, flexible near-infrared (NIR) photodetectors for opto-electronic applications were realized and their opto-electronic properties were investigated for the first time. This was achieved by synthesizing Ag₂Te nanoparticles (NPs) in aqueous solutions, and depositing highly crystalline Ag₂Te thin films at 150 °C with re-distributed Ag₂Te NPs in aqueous inks. The high conductivity and low trap concentration of the 150 °C annealed Ag₂Te films result from the Ag formed inside the films and the improved film quality, respectively. These factors are both critical for the realization of high-performance flexible photodetectors. The fabricated device exhibited a high detectivity of 1.43×10^9 Jones (above 1×10^9) at room temperature, delivering low power consumption. This detectivity is superior to those of reported low bandgap semiconductor systems, although the device had undergone 0.38% compressive and tensile strains. Moreover, the performance of the device is better than that of MoS₂-based phototransistors, black arsenic phosphorus field-effect transistors (FETs) or commercial thermistor bolometers at room temperature (D* ~10^8 Jones) and exposed to mid-infrared (MIR) light.

Resume : The objective of this study was to investigate the characteristics of brush-painted Ag nanowires (NW) network electrode on a SiO2 coated invar substrate for high performance curved thin film heaters (TFHs). To prevent the effect of a conductive invar metal foil substrate, a thin SiO2 film was deposited on an invar substrate as an insulating layer. We measured electrical, optical, and surface morphological properties of Ag NWs/SiO2/invar as a function of the number of brush painting from one to four times. Optimized brush-painted Ag NWs network on a SiO2/invar substrate had a low sheet resistance 38.52 Ω/square, which was suitable for the fabrication of curved TFHs. Based on a bending and fatigue tester, the critical radius of the optimized Ag NWs/SiO2/invar electrode was revealed to be 6 mm. It proved superior repeated flexibility of an Ag NW/SiO2/invar substrate. Furthermore, we demonstrated the applicability of using a brush-painted Ag NW/SiO2/invar substrate as an electrode for curved TFHs. These curved TFHs fabricated on an Ag NW/SiO2/invar substrate represented rapid heating properties and high saturation temperature even at low applied voltage due to low resistivity of Ag NW network. This shows that a brush-painted Ag NW/SiO2/invar substrate is a promising flexible electrode and substrate for high performance curved TFHs.

Resume : Novel, low-voltage, solution processed, and low temperature processed based resistive random-access memory (RRAM) devices were realized and their memory properties were investigated for the first time. This was achieved by synthesizing Ag2Te nanoparticles (NPs) in aqueous solutions, and depositing highly crystalline Ag2Te thin films at 150 °C with re-distributed Ag2Te NPs in aqueous inks. The high conductivity and low trap concentration of the 150 °C annealed Ag2Te films result from the Ag formed inside the films. The fabricated Ag2Te RRAM consists of Al bottom electrode, Ag2Te NPs and Ag top electrodes. The fabrication process was conducted under low temperature (<200℃) which is crucial process in order to have the flexibility of the device. The fabricated devices showed the conventional bipolar switching characteristics, and low voltage operation. The ratio of high-resistance state (HRS)/low-resistance state (LRS) was approximately over 10¬2, deciding RRAM cell number of arrays.

Resume : Biphasic calcium phosphate (BCP) bioceramics, composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP), have been attracted wide attention as ideal bone substitutes for reconstructive surgery because of their similar chemical composition to bone mineral. The inorganic minerals in human bone exhibit complicated chemical elements including minute quantities of trace elements such as magnesium (Mg), cerium (Ce), and silicon (Si). Among these elements, Si is the important trace element found in bone with specific metabolic activities concerned to the mineralization of natural bone for facilitating bone growth. In addition, Ce is accumulated in a natural bone at the lower level of concentrations, which exhibits excellent antibacterial efficacy. In this study, we have attempted to fabricate microporous Si- or Ce-doped BCP scaffold by combining wet chemical precipitation and gelcasting methods to mimic the nature of bone as well as to improve the anti-inflammatory activity of BCP scaffolds. The BCP nanoparticles were first synthesized in the presence of alginate as a template and used them to fabricate microporous BCP scaffolds. The morphologies, chemical structures, and crystalline phases of the resulting BCP nanoparticles and scaffolds were systematically examined. Resulting BCP scaffolds exhibited three-dimensionally interconnected microporous structures. The results of cytocompatibility tests demonstrated that Ce-BCP promoted more rapid MC3T3-E1 proliferation compared with other scaffolds. Moreover, Ce-BCP effectively upregulated osteoblastic differentiation and suppressed cytokine expression. These results suggest that the synthesized microporous BCP scaffolds are potential bone graft substitutes for bone regeneration.

Resume : We demonstrate sol-gel processed Y-doped SnO₂ thin film transistors showing high performance and enhancement mode (normally off) device for the first time. Most of metal oxide semiconductors induce to disturbances of stability, and controllability of Vth. These are due to internal oxygen vacancies, and it is important to control these. In this experiment, we choose yttrium to use a dopant to suppress the carriers in the SnO₂ semiconductor system, due to its lower electronegativity, SEP and higher bonding strength. The Y-doped (0 to 1 wt%) tin oxide prepared from a synthesized solution of tin (II) chloride dehydrate precursor and ethanol has a mobility of 12.7 cm²/Vs and -8.8 V threshold voltage. Meanwhile, the SnO₂ TFTs doped with 0.5 wt % Y shows a mobility of 1.1 cm²/Vs and a noticeable 3.5 V threshold voltage. Our results suggest that sol-gel processed Y-doped SnO₂ TFTs are a promising candidate for use in normally off and high-performance applications in transparent devices

Resume : Bacterial infections are a major threat to human health. Metal oxides have exhibited significant antibacterial activity which has resulted in death of bacterial strains. CuO-NiO mixed metal oxide (MMO) nanoparticles were synthesized by co-precipitation method. FESEM and TEM showed the surface morphology and the average particle size of MMO nanoparticle is 8 ± 2nm respectively. The antibacterial tests showed the MMO nanoparticle had a promising antibacterial activity against Escherichia coli and Staphylococcus aureus. In the present study, we have tried to establish the changes in cell surface permeability of bacteria S. aureus and E. coli by studying the permeability of bacterial membrane by electric conductivity study. The effect of nanoparticles on outer membrane permeability was evidenced by the uptake of the dye crystal violet. The mechanism of action of nanoparticles against E. coli and S. aureus cells may be described as: nanoparticles making firstly a break through cell membrane which led to the leakage of electrolytes as well as losses of proteins and nucleic acid. A significant enhancement in the uptake of crystal violet was observed in both the bacterial cells treated with the MMO nanoparticles when compared to control sample. This supported the above hypothesis of cell membrane damage. These changes resulted in cell decomposition and cell apoptosis. This was validated by the reduction in the number of bacterial count from the colony forming unit (CFU) reduction study. Moreover, the FESEM study showed bacterial cell rupture. Keywords: Nanoparticle, Antibacterial activity, Cell permeability, Escherichia coli and Staphylococcus aureus

Resume : Hybrid composites of CdS nanoparticles and Ti-based metal-organic frameworks as visible-light-driven photocatalyst for solar hydrogen production have been developed. First, the positively surface-charged CdS with narrow size distribution in 2-4 nm was synthesized. For hybrid composites, crystal growth of Ti-based MOF (NH2-MIL-125) was solvothermally induced in the mixed solution (MeOH:DMF) containing the synthesized CdS nanoparticles. In particular, the ratio of CdS/MOF was adjusted to find optimal photocatalytic properties. A combinatorial analysis of powder X-ray diffraction, transmission electron microscopy, and selected area electron diffraction clearly demonstrates the formation of CdS/Ti-MOF hybrid composites; the typical XRD patterns indicating the existance of CdSs and Ti-MOFs in the composites, and TEM images showing CdS nanoparticles decorated on the surface of Ti-MOFs. According to the UV-vis spectroscopy, the hybridization between two materials causes a change of bandgap energy in comparison to unhybridized materials. Also, photoluminescence spectroscopy shows an efficient electron transfer from CdSs to Ti-MOFs. On the basis of the obtained results, the photocatalystic test of the hybrid composites was carried out for photocatalytic H2 production under visible light irradiation (λ≥420 nm). We found that the hybrid composites have better photocatalytic performance than individuals. Particularly, the photostability of CdS nanoparticles significantly improved in comparison to not only bare CdS but also CdS-attached Ti-MOFs (synthesized Ti-MOFs first and then attached CdSs). This suggests that CdS nanoparticles are strongly coupled to MOFs. From the obtained results, the present synthetic process guarantees the stability of CdS nanoparticles against photo-dissociation. In this work, we will discuss in detail about synthesis procedure, photocatalytic ability, photostability, and photocatalytic mechanism for the present hybrid composites.

Resume : 2D materials are promising candidates for energy storage and solar energy harvesting, and exhibit intriguing phenomenon such as quantum spin hall effect. However, due to their high surface energy wet synthesis of 2D materials result in the formation of large aggregates, which limits their performance and also results in poor stability in aqueous phase. For obtaining thin layers, techniques like ultrasonication/ chemical exfoliation are employed but, these techniques are known to induce undesirable changes in the exfoliated sheets. For inhibiting aggregation, a plausible solution is to cap the faces of 2D materials with other material. Herein we present the colloidal growth of MoS2 and plasmonic MoO3-x within the interlayer space of a synthetic clay comprised of particles having a diameter of 25 nm and a thickness of 1 nm which forms stable dispersions in aqueous media. This approach leads to the formation of well separated stack of thin layers which terminate in Laponite® particles. These hybrid particles show outstanding performance in catalysis, photocatalysis and H2O2 sensing. The enhanced functionality of these hybrid particles is attributed to their small size which yields more number of active sites as compared to their pristine counterparts and improved stability in aqueous phase. In addition, high adsorption capacity of Laponite® further improves the catalytic and photocatalytic performance of these hybrid particles.

Resume : Metal nanoparticles (NPs), when spaced by a distance close to their localized surface plasmon resonance (LSPR), can produce a surface lattice resonance (SLR) featuring strong extinction peaks. This hybrid resonance is a consequence of coupling between LSPR and in-plane diffracted light. SLR-supporting structures require precise control of NP placement and size; therefore, they are usually produced using lithography processes, which are slow and expensive. A high-throughput alternative is the combination of wet-synthesis or laser ablation with self-assembly, but these come with a challenge of monodispersity and single-particle positional control. Here, we demonstrate our wet-synthesis and laser ablation results of producing Ag, Au, Al, and Cu nanocrystals. Subsequently, we deposited these NPs into predefined patterns on PDMS templates: 600 nm pitch hexagonal lattice and 500 nm pitch square lattice. We used the capillary force assisted nanoparticle assembly method for this, which allows for a seamless and high-yield particle placement. We characterized these arrays using free-space UV-Vis spectrometry and showed that these arrays feature strong SLRs with a Q-factor in the range of 100. The observation of SLRs in a self-assembled system of wet-synthesized NPs is proof that we have achieved long-range positional control and exceptional monodispersity of NPs.

Resume : Mesoporous silica nanoparticles (MSN) have been widely used in recent decades due to their unique properties, such as controllable size, shape and porosity, ordered pore structure, very high specific surface area and good chemical stability, making them attractive for a variety of applications like catalysis, separation processes or sensing. In addition, MSN also present important biocompatibility, high loading capacity and ease of functionalization making them gain a tremendous attention as drug delivery systems. As novel platforms for biomedical application, the control of their physicochemical properties is extremely important as they play a key role in the biodistribution and tissue accumulation of these nanoparticles. In the present work, MSN with different characteristics have been prepared by fine control of the synthesis parameters; namely, the precursors and their ratios, the reaction time, temperature and type of agitation. The obtained nanoparticles have been characterized by complementary techniques, including electronic microscopy, spectroscopy, thermal analyses and adsorption studies. Particles with different size, morphology and pore size and structure have been obtained thus shedding light on how the selected synthetic approach and employed conditions modify the MSN properties, highly relevant for the targeted biomedical application.

Resume : Metal oxide nanoparticles (e.g. perovskites) have been thoroughly reported due to its wide range of applications such as electronics, medicine or catalysis. Nowadays, one of the main targets is to control a robust methodology to obtain a well-defined shape, crystallinity, size and homogeneity on the oxide NPs. Herein, we report a tunable-size synthesis of well-defined BaMO₃ (M= Ti, Zr, and Hf) perovskites by using a modified polyol route by hybrid solvothermal methodology consisting of a combination an aqueous sol-gel process with a solvothermal treatment. Via this approximation, purely cubic-shape crystalline nanoparticles were obtained. Not only we can synthesize BaMO₃ series but also this novel pathway gives us the opportunity to produce a different range of metal oxide nanoparticles changing the divalent cation to strontium SrMO₃ (M= Ti, Zr, and Hf). We stated that an increase in the temperature (from 150 to 210ºC) or the time from minutes to various days, is not affecting the final size, shape or crystalline structure of the formed nanoparticles. Using this approach, we were able to easily tune the final size of NPs by controlling the hydrolysis step. In addition, the long-time stability (months) of the colloidal solution in polar media has been stated in a deep range of concentrations. Concerning their applicability, the synthesized perovskite nanoparticles had been tested it in the Chemical Solution approach to superconducting ceramic (YBCO) demonstrating a novel and successful process where the nanocomposites enhance the superconducting properties compared with the pristine layers.

Resume : Over the past decade, eco-friendly I−III−VI based semiconductor quantum dots have been intensively investigated in an effort to replace commonly available II−VI based QDs, which are environmentally harmful, which, in turn, limits their suitability for numerous applications. We report a new synthesis of highly luminescent Ag-In-Ga-Zn-S (AIGZS) quaternary QDs and the Mn-doping of these NCs via an organometallic precursor thermal decomposition process. Manganese stearate was reacted with Ag, In and Ga nitrates and Zn diethyldithiocarbamate in a water-methanol mixture to prepare the precursors of AIGZS QDs. The Ag/In/Ga/Zn ratio was varied to tune the PL emission wavelength of AIGZS QDs. These complexes were decomposed in the presence of oleylamine used as a solvent and capping ligand. Transmission electron microscopy and X-ray powder diffraction show that QDs are in the range of 1-3 nm and that they exhibit the cubic zinc blende structure. AIGZS QDs show PL quantum yield up to 30% and the emission wavelength can be controlled by varying the Ag/In/Ga/Zn ratio. Upon Mn-doping, the dopant related emission at ca. 610 nm is observed for all the dots. Mn-doped AIGZS QDs also show magnetic properties. AIGZS QDs can be transferred to aqueous phase by using poly(maleic-alt-1-octadecene) or glutathione. The tunability of the PL emission wavelength, the magnetic properties and the facile transfer to the aqueous phase should make AIGZS QDs of high interest for various biological applications.

Resume : Ternary I–III–VI2 quantum dots (QDs) have stimulated great attention due to their potential applications such as light-emitting diodes, biomedical labeling, solar cells and photocatalysis. Theses QDs exhibit high photoluminescence (PL) quantum yields (QY), long PL lifetimes and low toxicity compared to the more toxic Cd-based QDs. In this study, ternary AgInS2 (AIS) and quaternary (AgInS2)x(ZnS)1-x (AIZS) QDs were successfully prepared in aqueous medium using AgNO3, In(NO3)3.5H2O, Na2S.9H2O and Zn(OAc)2.2H2O as precursors and 3-mercaptopropionic acid (3-MPA) as the ligand. AIS cores crystallize in the tetragonal chalcopyrite phase. After the alloying and shelling with ZnS, AIZS QDs exhibit the cubic zinc blende structure.Transmission electron microscopy shows that AIZS QDs have a small size of ca.2.1nm. AIZS exhibit high PL QY,up to 65%, which is the highest value reported to date for these nanocrystals prepared in aqueous phase. An atypical blue-shift of the PL emission maximum was observed with the increase of the Ag/In ratio.Our results demonstrate that this blue-shift originates from Ag-3-MPA and In-3-MPA complexes present in the reaction medium. Moreover,AIZS QDs exhibit high colloidal and photostabilities. Finally, size-selective precipitation using 2-propanol as a non-solvent allows the separation of up to 13 fractions of AIZS QDs emitting from the orange for the largest ones to the blue-green for the smallest ones.The highest PL QY (78%) was measured for medium-sized QDs.

Resume : Currently, ferrites nanoparticles are widely used in the fields of biomedicine, chemistry, and electronics due to their attractive fundamental electronic and magnetic properties. These properties depend on the preparation conditions of the nanoparticles. A new approach for preparation of ferrite nanoparticles is suggested. The method is based on using ultrasonic spray pyrolysis technique with subsequent calcination. The novelty of this method is the choice of substrate for spray pyrolysis stage along with addition of a matrix-forming substance at this stage. According to the idea cobalt ferrite nanoparticles CoFe2O4 were prepared using ultrasonic spray pyrolysis technique. First suspension of ferrite was prepared by coprecipitation from aqueous solutions of iron and cobalt nitrates, then sodium chloride NaCl was added to the derived suspension. Only then spray pyrolysis was carried out. The powders obtained were annealed at 300-900 °С in order to increase specific magnetization of nanoferrites. Sodium chloride particles form matrix for ferrite nanoparticles and prevent their agglomeration. Therefore, the particles retain a small size in an inert matrix. After annealing, sodium chloride was separated from ferrite nanoparticles by washing with deionized water. The average size of the obtained particles does not exceed 50 nm, and they exhibit a low coercive force. This indicates the feasibility of using this method to obtain small-size ferrite nanoparticles with high magnetization and crystallinity.

Resume : Fluorescent and water soluble alloyed ternary Mn-doped ZnSeS and ZnSeS:Mn/ZnS core/shell QDs with pure dopant emission have been synthesized through a simple aqueous synthetic route using thiolactic acid (2-MPA) as a capping ligand. The influence of various experimental variables, including the pH-value of the reaction medium and the Mn-dopant concentration, have been systematically investigated in order to optimize the Mn-related dopant emission at ca. 590 nm. Through the growth of a ZnS shell on Mn:ZnSeS cores, a significant increase of the PL QY of Mn:ZnSeS/ZnS d-dots was observed (up to 30%). PL excitation and time-resolved PL measurements suggest that Mn2+-dependent trap states are involved in the PL emission. The crystal structure, shape and size distribution of the Mn:ZnSeS and Mn:ZnSeS/ZnS core/shell were studied using XRD, TEM and HRTEM. XRD reveal that both Mn:ZnSeS core and Mn:ZnSeS/ZnS core/shell QDs exhibit the ZB crystal structure. With the overcoating of the ZnS shell, the XRD peaks shift from those corresponding to ZnSeS to those of ZnS. TEM and HR-TEM results show that upon the growth of ZnS shell on Mn:ZnSeS cores, the particle size increases from 2.4nm to 3.7nm, which confirms the epitaxial growth of the shell on the cores. The composition of this QDs was also confirmed by XPS measurements. Mn:ZnSeS and Mn:ZnSeS/ZnS QDs exhibit also magnetic properties. In addition, Mn:ZnSeS/ZnS QDs can easily be transferred to the organic phase using the DDT hydrophobic ligand without alteration of their optical properties.

Resume : Slippery lubricant-infused porous surfaces (SLIPS) provide a powerful approach to prepare anti-wetting surfaces due to their excellent repellency against various liquids. However, there are critical limitations that prevent SLIPS from being used widely in practical applications, which include complicated preparation processes and the stability of the lubricant layer. It is thus essential to develop a new approach that can enhance the stability of the lubricant layer while maintaining scalable manufacturability. Herein, we describe a robust method for the fabrication of highly stable SLIPS via capillary rise infiltration of silicon oil into ZnO nanowire (NW) arrays. The ZnO NW surface, which is formed via a chemical bath method, provides a porous template with interstitial nanogaps that can be infused with silicon oil through capillary forces. We study the effect of nanowires orientation on the infiltration rate of silicon oil as well as the wetting properties and the stability of the lubricant-infused ZnO NW arrays. The as-prepared SLIPS exhibits self-cleaning and self-healing properties against surface damages due to the self-recovery property of the oil. We also study the resistance of the as-prepared SLIPS to high temperature, UV light exposure, and acid/base solutions, which would expand their applicability in harsh conditions.

Resume : Ce3+-doped Y3Al5O12 nanocrystals (YAG:Ce NCs) are efficient light converters upon blue excitation and are widely developed to be used as nanophosphors for white LED fabrication (Kasuya et al. 2005, Aboulaich et al. 2012). Their photoluminescence (PL) intensity depends on two key parameters: (1) well-crystallized YAG:Ce NCs should be synthesized as the presence of volume defects strongly affects the PL internal quantum yield, iQY. (2) one should prevent Ce3+ → Ce4+ oxidation during the NC formation as only Ce3+ emits light (Ce4+ may even have a role as luminescent quenchers) We addressed the first point by developing an original solvothermal method (Dantelle et al. 2018), we here tackle the second point. Different gases (Ar/H2, O2 and Ar) were bubbled inside precursor solutions prior to the solvothermal synthesis. As assessed by X-ray absorption spectroscopy, we show that gas bubbling modifies the Ce3+:Ce4+ ratio in YAG:Ce nanocrystals: evolving typically from 68:32 with no bubbling to 71:38 with Ar/H2 (95/5) gas bubbling. Additionally we show by X-ray diffraction and Transmission Electron Microscopy that the bubbling process influences the size and crystal quality of the formed YAG:Ce nanocrystals, as evidenced. The presence of bubbles in the precursor solution even at 60 bars induces heterogeneous nucleation, leading to larger YAG:Ce nanocrystals with high crystal quality and high optical efficiency (Cantarano et al. in prep.): 60nm sized nanocrystals with a iQY of 55 ± 5%

Resume : Woven ultra-high molecular weight polyethylene (UHMWPE) fibers have been shown to possess high strength-to-weight ratio, low density, high energy absorption and abrasion resistive properties, while maintaining high flexibility. For these reasons, UHMWPE fabric is a popular choice in ballistic protection equipment such as vests, helmets and military vehicle components. Despite its inferior ballistic protection performance, woven UHMWPE fabric presents a cheaper and considerably less complex fabrication process relative to unidirectional UHMWPE. For this reason, research has been recently moving to focus on improving the ballistic performance of UHMWPE fabric. However, the primary failure mode in woven UHMWPE fabric is yarn pullout, a result of the poor inter-yarn friction within the polymeric fabric. Drawbacks of certain approaches for improving the inter-yarn friction can be an increase in the weight of the fabric or a weakening of the mechanical properties of the fibers. To overcome these issues, this work investigates the use of hydrothermally grown Zinc Oxide Nanowires (ZnO NW) on UHMWPE fabric to improve its inter-yarn friction and ballistic properties. First, we study and optimize a plasma surface functionalization to increase the adhesion between the ZnO NWs and the surface of the UHMWPE fiber to further increase the inter-yarn friction and corresponding ballistic performance. The introduced nanostructured ZnO interphase does not result in an increase in fabric weight or a decrease in the mechanical properties of the UHMWPE fibers. Tow pullout was used to assess the inter-yarn friction within the UHMWPE fabric, a 223.89% increase was observed in ZnO NW coated UHMWPE, relative to untreated UHMWPE fabric. Moreover, an increase of 663.51% was observed for UHMWPE that was plasma treated for 30 seconds before the ZnO NW growth, relative to untreated UHMWPE fabric. The ballistic speed limit (V50) is also observed to increase by a maximum of 59.13% in 30 sec plasma treated and ZnO NW coated fabric, relative to untreated ones. This a result of the UHMWPE fabric’s ability to absorb approximately 100% greater impact energy post plasma functionalization and ZnO NW coating. Thus, the results discussed here can further advance the use of UHMWPE fabric as a cost-effective, simple and equally potent alternative to unidirectional UHMWPE for ballistic protection applications.

Resume : The present paper has proposed the clarification of some aspects regarding the methodology of obtaining the nanostructured Y2O3 for the development of biomaterials. In this direction, using a sol-gel process based on acetyl acetone (as a chelating agent), the influence of the process parameters (raw materials type and concentration, time and temperature, the influence of surfactants and of intermediate stages etc.) on the Y2O3 properties was studied and not in the least, the usefulness of oxide dopin. The quality and composition of the yttrium oxide was structurally confirmed by FTIR, XRD and EDX spectrometry. The type of crystalline structure, chemical bonds and atoms from the molecule, and material purity were determined. The morphological properties influence the applicative capacity of the oxide, not to raise toxicity problems in the liver or kidneys, we have proposed and managed to obtain particles with an average size of about 35 nm. The demonstration of the applicative capacity in the biomedical field has been studied both from the morphological point of view using SEM, as well in point of optical properties by photoluminescence spectrometry. The developed materials can find applicability both in the field of biotechnologies for the development of theranostic devices, as well as in optoelectronics and aerospace.

Resume : Confirmed near depletion of fossil fuels along with their serious climatic impact have become the biggest preoccupations attracting the common interest of researchers to find alternative power sources. In order to meet the demand of energy generation fuel cell is one of the most promising solution owing to their potential for high energy conversion efficiencies with environmental sustainability. Oxygen reduction reaction (ORR) at cathode incurs at the highest energy barrier (~0.3 to 0.4 volt) among all assembled components in fuel cells and therefore needs nanocatalysts (NCs) to enhance sluggish kinetics. The high fabrication cost and low electrochemical activity of Pt-based NCs are major technical bottlenecks for reliable and cost-effective fuel cell development. Herein, quaternary metallic nanocatalysts comprising Pt-decorated Co-Sn-Pd hierarchical structure (CSPP) are prepared for oxygen reduction reaction (ORR) in alkaline medium (0.1 M KOH). The CSPP NCs have been synthesized with different Pt loadings (1.0, 2.0 and 14.0 wt.%) by using wet chemical reduction method on carbon nanotube (CNT) support. Of most importance, the mass activity of CSPP-1 NCs is 2146.2 mAmg-1 , which is ~32 folds increased, as compared to that of commercial J.M.-Pt/C catalyst at 0.85 V vs RHE. By cross-referencing results of microscopic and spectroscopic analysis, we demonstrated that such enhanced ORR activity for the ultra-low dosage of Pt is mainly dominated by incorporation of Pt atoms into defect sites of SnPd2@SnO2 shell composite. These Pt-atoms lowering down the adsorption energy of oxygenated species, resulting in enhanced kinetics of ORR.

Resume : Wettability is a feature of a surface that characterized his ability of being wetted or not by different kinds of liquids. This feature is synergistically dependent of both the surface chemistry and morphology. Many studies have been devoted to understand this effect and it has been proven that the well-known lotus leaf can enhance both effects by their hierarchical roughness with nanometric and micrometric roughness. However, most of the man-made superhydrophobic materials lost their superhydrophobic behavior in few days to few weeks, exhibiting a Cassie-Baxter to Wenzel transition as well as a strong decrease of the water contact. Herein, we present a simple wet-chemistry based strategy to create superhydrophobic coatings. The superhydrophobic feature arise from the sol-gel based fabrication of a micro/nano dual-roughness coating composed of zinc oxide nanowires (ZnO NWs). The rough ZnO NWs coating was then functionalized with a monolayer of hexadecyl trimethoxysilane (C16) to yield a superhydrophobic surface without fluorine. We show that the micro/nano-roughness ZnO NW coating maintained its superhydrophobic feature of above 170° over more than a month even in the case of an underwater storage. In addition, antibacterial and anti-fouling properties were also investigated linked to the coating properties.

Resume : Two dimensional (2D) materials have attracted significant attention due to their unique electrical, chemical, optical and physical properties. These 2D materials can be utilized to design different electronic devices featuring low power consumption, increased integration density, and high performance. 2D titanium dioxide (TiO2) has been extensively studied since it features low toxicity, low cost, well-known dielectric and optical properties. Obtaining 2D TiO2 nanosheets utilizing the regular synthesis strategies lead to nano flakes with non-uniform sizes and shapes, which are difficult to be implemented into electronic devices. Herein, we report an alternative and novel approach to the synthesis of 2D TiO2 nanosheets using liquid metal as solvents and applying Cabrera-Mott oxidation processes. This process allows us to produce high quality rutile phase 2D TiO2 nanosheets, with lateral dimensions of 1.5 ± 0.2 μm and a thickness of 2 ± 0.5 nm. The dielectric constant of the produced nanosheets was measured using high resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) which disclosed the dielectric constant of the obtained 2D TiO2 nanosheets to be approximately 24. The developed method is simple and requires only ambient air and a liquid gallium-titanium alloy as precursors. The method is also facile, scalable and likely applicable for the production of other transition metal oxide nanosheets.

Resume : A flagship application of miniaturized chemical optical sensors is the real-time monitoring of cell cultures in the biomedical field. The principle of these sensors is based on variations of the fluorescence signal when a fluorophore, encapsulated in a matrix permeable to gaseous and excited to a suitable wavelength, is contacted with dissolved oxygen in an aqueous medium. Their integration in the form of miniaturized devices is based on the deposition of a thin-layer matrix doped with the fluorophore. While this configuration is perfectly suited to miniaturized devices, it suffers from limitations in terms of detection limit due to the small amount of fluorophores incorporated in the thin-film matrix and to the small fraction of light emitted redirected toward the photodetector. This work aims at proposing a new sensor configuration based on the sol-gel fabrication of fluorophore-doped channel waveguides equipped with diffracting couplers. This work particularly highlights the potential of a high refractive index titanium oxide based sol-gel photoresist that can be imprinted through a single photolithography step to form a given pattern. We will present the elaboration process of the micro-structured architecture composed of diffraction gratings imprinted on channel waveguides, as well as the optimization of this architecture based on modeling. The efficiency of light coupling in the channel waveguide using diffraction gratings will also be presented and discussed.

Resume : Clean air is considered to be an essential need for human health and wellness. However, air pollution is one of the significant threats to human health around the globe. Among many pollutants, nitrogen dioxide (NO2) is a more toxic and dangerous air pollutant. It can cause several serious health problems such as wheezing, colds, skin disease, lung cancer, respiratory diseases, genetic disorder, flu, bronchitis, and many more. Hence, the detection of NO2 gas in air ambient is essential in order to protect and cure human health. Co3O4 is one of the fascinating p-type semiconductor materials and have attracted considerable attention in the past decade due to their unique morphological structures resulting in improved physical/chemical properties for various applications. It can be noted from the literature that n-type metal oxide semiconductors (MOS) based sensors have been extensively explored but p-type MOS based sensors were less studied. In this work, Co3O4 samples have been synthesized using hydrothermal method. The XRD pattern and Raman spectra confirmed the cubic crystal structure of Co3O4. Herein, we have studied the effect of Co3 /Co2 cations and induced defects states on NO2 detection. The quantification of these surface defects has been studied using XPS, and we attempt to develop our understanding on how these defects associated with improved NO2 detection. The maximum sensor response of ~22% was observed towards 100 ppm of NO2 at an operating temperature of 200°C.

Resume : Nitrogen exists in our water storage reservoir and wastewater in the toxic form of ammonia and its removal requires time-consuming and costly chemical and biological water purification procedures. Electro-oxidation of wastewater containing ammonia could be considered as a promising alternative due to the generation of hydrogen gas fuel as a by-product with an overpotential less than that of pure water electrolysis. The main electrocatalyst for this purpose are mainly based on expensive noble metals such as platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), iridium (Ir), platinum (Pt), and gold (Au) which are rare and senseless to use in the industry level.[1] A bottleneck for this technique is to reduce the loading of noble metal in the catalyst electrodes, meanwhile reducing the risk of poisoning on the metal surface during the electro-oxidation should be suppressed. Herein, we show a co-electrodeposition of a copper-platinum (Cu-Pt) bimetallic superlattices containing ultralow noble metal Pt content (< 3 wt. %) onto high surface area carbon fibre-based electrodes.[2] This novel electrode shows better electrocatalytic performance than that of both bare Pt and pure Pt on carbon fibres, indicating that we are able to make cheaper and more efficient electrodes in near future based on ultralow noble-metal content. Compared to pure Pt, our Cu-Pt alloy coated filaments demonstrated less electrode poisoning over its lifetime and bonded more strongly and uniformly onto the carbon fibre due to better mechanical interlocking between the two phases of bimetallic alloy and carbon filaments. The results, therefore, provide a promising step towards large-scale wastewater treatment combined with clean energy generation. Key Words: Wastewater treatment, Electro-oxidation, Superlattice, Hydrogen Fuel References [1] C. Zhong, W. B. Hu, Y. F. Cheng, J. Mater. Chem. A 2013, 1, 3216. [2] A. M. Pourrahimi, R. L. Andersson, K. Tjus, V. Ström, A. Björk, R. T. Olsson, Sustainable Energy & Fuels 2019, 3, 2111.

Resume : We developed a low-cost, single-step procedure for the synthesis of gold nanocrystals from hydrogen chloroauric acid (HAuCl4) with atmospheric pressure plasma jet. Non-equilibrium chemistry in a plasma-vapour interface is used for the synthesis of gold nanocrystals devoid of any reducing agents. In this way, nanocrystals with hexagonal, triangular and polyhedral shapes were produced. The size of the nanoparticles could be tuned from 5 nm to several hundred nanometres by varying the carrier gas flow, thereby the concentration of Au ions, and the distance between plasma and the substrate. Optical emission spectroscopy was used to understand the plasma-vapour interface interactions, which converts Au3 ions to Au0 atoms, leading to nucleation and growth. An investigation of the growth process of Au nanocrystals was conducted using analysis of high-resolution SEM and TEM micrographs. The evolution and reconfiguration of Au atoms in the nanoclusters (layer by layer addition of atoms) may occur due to the interaction of atmospheric pressure plasma. The size and shape of the crystals depend on the surface energy of the initial crystal plane. The Au nanocrystals made by this method are highly pure and offer a wide range of applications.

Resume : The design of new nanoscale architectures composed of different inorganic materials constitutes a challenge that can lead to interesting emergent properties. In particular, the combination of ferromagnetic and antiferromagnetic phases can lead to an exchange bias (EB) effect. This phenomenon results in a shift of the hysteresis loop along the field axis and frequently an increase in coercivity [1,2]. This approach is promising to gain magnetic stability at room temperature [3,4], opening the way to many applications (magnetic recording, therapeutic mediators...). Nanoparticles (NPs) exhibiting EB have been mainly studied on core-shell systems [4]. In this work, we tailor the shape of the composite NPs as Janus and raspberry-like and use them to explore exchange-coupling and related EB effects. The two associated materials are maghemite (ferrimagnetic) and cobalt oxide (antiferromagnetic), as characterized by 57Fe Mössbauer spectrometry, high-resolution TEM (including EELS analysis) and SQUID. NPs were prepared via thermal decomposition and the relationship between shape and resultant magnetic properties was studied. Fine-tuning of morphological and magnetic properties in nano-assemblies allows for a precise adaptability according to final applications. [1] J. Nogués et al, Phys. Rep. 422, 65 (2005) [2] A. Bollero et al, Appl. Phys. Lett. 92, 022508 (2008) [3] G. Franceschin et al, Part. Part Syst. Charact. 35, 1800104 (2018) [4] M. Dolci et al, Adv. Func. Mater 18, 1706957 (2018)

Resume : The majority of the nanowire (NW) synthesis methods utilize catalyst particles to guide the nanowire geometry. In contrast, catalyst-free methods are attractive for facile fabrication of pure nanowires without the need for catalyst preparation1. Zinc oxide nanostructures have received broad attention due to their distinguished performance in electronics, optics, gas sensing and piezoelectronics. Zinc oxide tetrapod (ZnO-T) is one of these structures, consisting of 4 nanowires, is especially interesting for its simple synthesis, however growth mechanism is not thoroughly understood. Here, we propose a simple non-catalytic one-step process method for an efficient and rapid synthesis of ZnO tetrapods by Zn vapor oxidation under air environment and application for multifunctional coatings and UV sensors.

Resume : Spray pyrolysis (SP) is a very flexible and cost-efficient deposition method for functional thin films. The properties of these sprayed thin films can be easily adjusted through process parameter variation (substrate temperature, distance to target) as well as the chemistry of the precursor solution. At Fraunhofer ISE we use SP for photovoltaic applications such as passivation layers (Al2O3), photovoltaic absorber layers (Cu2SnS3) and ZnO based TCO’s. In this publication we will present transparent ZnO thin films showing smooth surfaces and low sheet resistances (around 10-3 Ωcm) while containing only 3-5 at% of indium as dopant (type 1). Lowering the concentration of the precursor solution leads to highly preferential growth of the thin film, resulting in a columnar (crystal) structure that was verified by XRD pole figures (type 2). By changing the dopant to sodium and nitrogen, the growth mechanism changes to dendritic growth, resulting in a needle like fiber structure suited for anti-reflective coatings (type 3). For application in Si based photovoltaics, the contact resistance of the sprayed ZnO:In to TOPCon (Tunnel Oxide Passivated Contact on Si) was analyzed and showed values of 250 mΩcm2, yielding solar cell efficiency of up to 21.6%. Currently, further applications of SP in the fields of Perovskite solar cells and optical layers are assessed in order to investigate SP’s potential to replace standard deposition techniques like sputtering or atomic layer deposition.

Resume : The surface plasmon resonance of noble metals can be tuned by morphology and composition, offering interesting opportunities for applications in biomedicine, optoelectronics, photocatalysis, photovoltaics, and sensing. Here, we present the results of the symmetrical and asymmetrical overgrowth of metals (Ag, Pd, and Pt) onto triangular Au nanoplatelets using AA and/or SA as reductants. By varying the reaction conditions, various of Au nanotriangles (Au NTs)-metal hetero-structures can be easily prepared. We show that the controlled growth of different metals on Au NTs allows manipulating the plasmonic properties of bimetallic Au NT-M (Ag, Pd, and Pt) structures. In the second part, we systematically investigated the structure evolution of Au NT-metal (Ag, Pd, and Pt) core-shell nanoparticles (NPs) by a combination of in-situ and/or ex-situ TEM techniques and spectroscopy methods. The Au NT-metal (Ag, Pd, and Pt) core-shell nanoparticles can be turned into alloyed Au-metal NPs and/or Au-metal (Pd or Pt) Janus nanostructures via precisely controlling the heating conditions. In the third part, we present the results of synthesizing Au NT based core and Ag-Pt alloyed shell ternary metallic NPs, the morphology of which can be easily adjusted from yolk-shell to core-shell structure by changing the concentration of AgNO3 or Au NT seeds, and the shell thickness can be precisely controlled by adjusting the concentration of K2PtCl4. Moreover, the Au NT-Ag-Pt yolk-shell NPs were found forming via a growth-Galvanic replacement synergistic route by monitoring the growth process with UV-VIS spectra and scanning transmission electron microscopy (STEM) technique. The plasmonic properties of as-synthesized nanoparticles were investigated by a combination of optical absorbance measurements and Finite-Difference Time-Domain (FDTD) simulations.

Resume : From Molecules to Materials: 2D Molecular Frameworks as Platforms for Energy Conversion and Storage Transitioning towards a sustainable energy economy is contingent on new materials solutions. Due to their earth-abundance and low cost, carbon-based materials have become the backbone of a variety of sustainable energy technologies ranging from photovoltaics to supercapacitors. The unique combination of resource efficient synthesis and molecularly defined structures of 2D frameworks such as carbon nitrides and covalent organic frameworks (COFs) have put a new spin on the development of metal-free semiconductors for “soft” photocatalysis. In this talk, I will present synthetic strategies including solid state, solvothermal, and ionothermal synthesis to access new types of molecular framework materials for the light-induced hydrogen evolution reaction. In particular, a new family of 2D carbon nitrides called poly(heptazine imide), PHI, will be discussed, which stands out due to its high crystallinity, chemical inertness, and the ability to store light-induced charges in a persistent photoreduced state. I will highlight the structural, optoionic and catalytic boundary conditions in this material family and demonstrate how they can be used to develop new “hybrid” energy concepts such as “dark photocatalysis” and solar batteries.

Resume : Materials presenting a nanostructured architecture have been at the forefront of research for many years in various field of research, because they can offer a very large range of properties. A promising synthetic approach for these materials is the use of nanometric building blocks, such as 2D nanosheets. In this respect, lamellar compounds, among which lamellar oxides, are particularly interesting. Nevertheless, the controlled synthesis of oxide nanosheets remains a challenge. We present here an original strategy for the synthesis of oxide nanosheets, which combines functionalization of the starting lamellar compounds and liquid phase exfoliation. The inorganic phases are lamellar oxides with perovskite structure. These compounds can be easily functionalized using microwave-assisted reactions. The inserted/grafted molecules then enable or ease the subsequent liquid phase exfoliation, using shear forces or ultrasounds, which were previously only used for Van der Waals compounds. Finally, functionalization of the nanosheets participates to the stability of the colloïdal suspensions. The nanosheets are characterized in suspension by Dynamic Light Scattering. They are also deposited on substrates (gold or Si) and studied in spectroscopy (XPS, Raman) and microscopy (AFM, SEM, TEM). We will more particularly underline the influence of the initial functionalization and of the various parameters (solvent, shear rate and duration) on the charateristics of the obtained nanosheets.

Resume : Supercapacitors show promise as power source units for modern electronics systems because of their high power density, relatively high energy density and long cycling life. Different techniques such as spray coating, vacuum filtration and laser scribing have been reported to fabricate supercapacitors. However, those techniques show several limitations, such as low-resolution, high-cost and bad control over the morphology of devices. Inkjet printing with simple, versatile and low-cost funtonal inks shows potential to fabricate supercapacitors on arbitrary substrates such as paper, silicon and flexible polymer substrate. Especially the inkjet printing of two-dimensional materials, which have a high surface area to volume ratio, are easily accessible for electrolyte ions and show flexibility attracted great attention recently. δ-MnO2 nanosheets with high specific capacitance have been demonstrated as ink for printed supercapacitors that show comparable performance with other state of the art systems. However, δ-MnO2 nanosheets exhibit low electrical conductivity. Here, we demonstrate that substitutional doping of 3d metal ions (Co, Fe and Ni) into MnO2 nanosheets can improve the device performance. Especially, the volumetric energy density of Fe-doped MnO2 supercapacitor was improve to 1.13 × 10−3 Wh cm−3 at a power density of 0.11 W cm−3. New electronic states near the Fermi level were introduced by substitutional doping which further enhance the electronic conductivity within the nanosheets and contribute to the formation of redox-active 3d surface states. Beyond MnO2 nanosheets, we also demonstrated that water-based additive-free MXene ink can be inkjet printed as electrodes for supercapacitors.

Resume : 2D layered nanomaterials are emerging rapidly due to their exceptional chemical and physical properties. But 2D nanomaterials synthesized by bottom-up methods often aggregate, which causes them to show poor catalytic performance. Many studies find that reducing the number of the layers is beneficial to improve the catalytic performance of 2D layered nanomaterials. Different strategies have been proposed to reduce the layers of 2D layered nanomaterials such as solvent/surfactant-assisted exfoliation, molecular intercalation/exfoliation, sonication-assisted exfoliation etc. However, it is difficult to control the size and composition by the exfoliation method. Self-assembly is a spontaneous process that coordinates the creation of organized structures or patterns from pre-existing disordered components through weak local interactions (such as van der Waals forces, hydrogen bonding, ?-? interactions). Here, Using In2S3 as an example, we present a facile and effective hydrothermal method to synthesize few-layers In2S3 in the interlayers of Laponite®. The synthesized In2S3 are found to have few layers in the interlayers of Laponite®, which facilitates efficient transport of electrons. When evaluated as photocatalytic materials for dye degradation and water splitting, the few-layer In2S3 shows outstanding performance and colloidal stability.

Resume : Two-dimensional materials have been widely investigated but mostly are the highly symmetric hexagonal structures exhibiting isotropies such as graphene and MoS2. Less is known about the low-symmetry 2D materials that possess novel anisotropic physics, in particular, the research on synthesis and characterization. In this study, we presented a feasible approach to synthesize the inherently asymmetric-structure PdSe2 on graphene. Drop-casting is performed to disperse the palladium complexes on the substrate followed by the low-temperature selenization. Through tuning the concentration of our precursor and the growth time, the continuous PdSe2 film is well covered on the graphene substrate. Aberration-corrected scanning transmission electron microscopy is used to image the grain boundaries and planar defects in the as-grown PdSe2. Additionally, the selenium-deficient phases were revealed by reducing the growth time. The results shown in this study controlled the synthesis of PdSe2 and indicated the mechanism for selenization, which can further be integrated into scalable device fabrication.

Resume : Two-dimensional (2D) materials research is one of the most active fields within materials science. While 2D materials can be exfoliated from bulk crystals to yield small nanosheets, the large-scale synthesis of 2D materials for the industrial production of electronics is both challenging and reliant on toxic chemicals that are applied in CVD reactions. Liquid metal-based approaches offer a new approach towards inducing two-dimensional growth. Most metals feature an atomically thin oxide layer at the metal air interface that growth due to the Cabrera-Mott process.[1] This also applies to low temperature liquid metals including molten tin, indium, gallium and their alloys. In many cases this oxide layer grows in a self-limiting reaction providing a pathway towards atomically thin, two-dimensional materials.[2] These ultrathin sheets can be exfoliated form the liquid metal interface and deposited as centimetre sized nanosheets on desired substrates, providing a platform for the development of 2D material-based integrated electronics. Since the reaction directly occurs between atmospheric oxygen and the desired metal, the technique does not require any toxic chemicals or gases. Furthermore, the method allows for the clean exfoliation of the 2D sheet, allowing the liquid melt to be re-used, minimizing the loss of precursor metal. Overall the method is energy efficient, simple, scalable and provides a sustainable pathway towards 2D material based electronics and oxide electronics. Once the 2D nanosheet is deposited, the 2D oxide may be converted into other desired compounds while preserving the two dimensional nature, offering access to a wide array of 2D materials including metal oxides, [2-4] chalcogenides,[5] and nitrides.[6] References: 1. Daeneke et al., Chemical Society Reviews, 2018 ,47, 4073-4111 2. Zavabeti et al., Science 2017, 358 (6361), 332-335. 3. Daeneke, et al. ACS Nano 2017, 11 (11), 10974-10983. 4. Datta et al. Nature Electronics 2020, accepted doi: 10.1038/s41928-019-0353-8 5. Carey et al. Nature Communications 2017, 8, 14482. 6. Syed et al. Journal of the American Chemical Society 2019, 141, 1, 104-108

Resume : With their low densities, large porosities and high surface areas, aerogels offer many of the properties required for successful use in catalysis or photocatalysis. At the same time, they suffer from several disadvantages, which are a direct consequence of the typically applied synthesis method involving aqueous sol-gel chemistry. In particular, the compositional variety is relatively narrow and the crystallinity of the as-synthesized materials is low. These limitations can be circumvented by replacing the molecular sol-gel approach by a particle-based assembly route [1]. But independent of the synthesis method the aerogel monoliths remain mechanically fragile and they immediately pulverize, when they come in contact with a liquid. These two issues can be overcome by supporting the aerogels with a 3-dimensional rigid scaffold and by exclusively performing reactions in the gas phase [2]. In this talk, we will propose strategies how preformed nanoparticles are assembled into 3-dimensional, porous networks that after supercritical drying result in aerogel monoliths with macroscopic sizes. The controlled gelation of the initial colloidal nanoparticle solutions into volume-filling gels is the decisive and challenging step. Careful selection of the nanoscale building blocks enables subtle tuning of the compositional, morphological, structural, and optoelectronic properties of the aerogels. Gelation inside a 3D-printed polymer scaffold not only improves the mechanical properties, but also offers a versatile tool to tailor the macroscopic aerogel architecture. As a proof-of-concept, we will show the use of metal-metal oxide composite aerogels in the photocatalytic reforming of methanol in the gas phase. [1] F. Rechberger, M. Niederberger, Synthesis of Aerogels: From Molecular Routes to 3-Dimensional Nanoparticle Assembly, Nanoscale Horiz. 2017, 2, 6 [2] M. Schreck, M. Niederberger, Photocatalytic Gas Phase Reactions, Chem. Mater. 2019, 31, 597

Resume : Vanadium dioxide (VO2) is a strongly correlated material showing promising properties for use in a wide spectrum of electronic devices ranging from ultrafast switchers and solar cells to solid state batteries and gas sensors. Having the same chemical formula, VO2 exhibits a number of stable and metastable polymorphs with completely different structural and electronic properties. Controlled deposition of these VO2 polymorphs, in the form of thin layers, is a challenging but decisive step towards the realization of efficient devices based on VO2 semiconductor system. In this context, we demonstrate the Aerosol Assisted Chemical Vapour Deposition of phase pure and highly oriented layers of vanadium dioxide in its VO2(B) and VO2(M) phases. Strong relation between growth conditions and/or different substrates (glass, Si, sapphire) and crystalline structure of VO2 films was observed, with the clear effects on its morphology and electrical properties. In particular, samples obtained on sapphire at low substrate temperature up to 400 °C have VO2(B) phase with the closely packed grains, whereas an elevated temperatures of 450 and 500 °C promote the formation of VO2(M) phase with the nano-porous morphology. Meanwhile, VO2 films deposited on glass substrates exhibit plate-like grain structure and VO2(B) phase. Thus, by variation of growth conditions and type of the substrate we may control phase composition and crystalline structure of VO2 thin films.

Resume : One important property of metal nanoparticles is plasmonic excitation under an electromagnetic field, dependent on a number of factors, such as composition, surrounding medium, spatial arrangement, and geometrical factors like size and shape. Here, we describe the synthesis of Ag nanoplates and their application in plasmonic sensing and Surface Enhanced Raman Scattering (SERS). Initially, spherical Ag nanoparticles are produced by pulsed laser ablation in water solution in presence of citrate. Spherical nanoparticles are transformed into flat nanoplates by irradiation under white or monochromatic light and hydrogen peroxide addition. Such process does not involve any harmful chemical. Nanoplates are triangular, 100-200 nm wide depending on the irradiation conditions and 15-20 nm thick, as characterized by TEM, SEM and AFM. Such materials exhibit a plasmon sensitivity of nearly 500 nm/RIU and a SERS enhancement factor of the order of 104

Resume : Cold plasma–based magnetron sputtering (MS) of atoms onto liquids allows obtaining high purity dispersions of small nanoparticles (NPs). Despite this process has been actively studied since 2006, the mechanism of NP formation is still not fully understood. To provide more insight on this topic, the systematic study of MS of silver and gold onto castor oil, rapeseed oil and its polymers has been done as these vegetable oils withstand vacuum and might be an alternative to ionic liquids and PEGs because they have low cost, low toxicity, and are stored in air. The effects of sputtering time, sputter power, Ar pressure, type of sputtering plasma (Direct Current Magnetron Sputtering vs High-Power Impulse Magnetron Sputtering), and viscosity of host liquid are studied. MS of silver and gold leads to the formation of a dense cloud of particles underneath the oil surface. Metal films form in case of polymerized oils with high viscosity. The morphology of the particles was characterized by STEM and stability of solutions was monitored by UV-vis spectroscopy. Au NPs have higher stability in castor oil than Ag NPs but secondary growth processes take place.

Resume : Since its discovery, the unique properties of graphene have attracted an unprecedented degree of interest in many different fields. In many of these applications the challenge is to incorporate graphene into three-dimensional assemblies (e.g. composites, foams or devices) while retaining the degree of structural control required to achieve improved performance. In this talk we will show how graphene oxide (GO) can be incorporated into wet processing technologies such as freeze casting or robotic assisted deposition to fabricate different composites and devices. Graphene oxide is a very effective additive that can be used to manipulate the rheology of suspensions and pastes in order to tailor them for specific shaping technologies. Subsequent treatments can be used to reduce graphene oxide and recover some of the properties of graphene. We will review how these technologies can be used to create graphene-containing structural materials whose architecture is designed to enhance mechanical response while adding functional capabilities such as sensing or self-healing. This can be achieved by using the unique 2D structure of graphene to form microscopic networks of conductive interfaces with well-designed architectures. We will use the results to discuss the role that graphene can play on the additive manufacturing of ceramics.

Resume : Ferroelectric (FE) materials possess wide-ranging applications in electronics, communication, health, and energy. While lead-based FEs have remained the predominant mainstay of memory industry for decades, lead-free alternatives are limited due to relatively low Curie temperatures (TC), low polarization and/or high cost and difficult processing in many cases. Reports are there to enhance TC and to enhance FE polarization by controlling orientation, and through strain engineering, but often involving energy-intensive and expensive fabrication of thin epitaxial films on lattice-mismatched substrates. We are exploring novel lead-free FE systems, of noncentrosymmetric (NCS) materials variety (ZnSnO3 and ZnTiO3) as well as traditional (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCT-BZT) and BiFeO3 materials.[1] Simple, Scalable chemical syntheses routes such as sol-gel and solvothermal, are adopted to fabricate nanocrystalline materials of the mentioned compositions and their FE, dielectric and optical properties are extensively explored. For BCT-BZT, more than three-fold enhancement of TC as compared to the bulk is observed.[3] For NCS type Zn based FE materials, an enhancement in polarization in both ZnSnO3 and ZnTiO3 are observed when properly oriented and/or poled. The results offer cost-effective solution-based approach for structure and strain-tuning in promising, novel lead-free FE systems, thus widening their current applicability in memory and sensing.[1] References. [1] Datta et al., Small 2014 (10) 4093, Advanced Functional Materials 2017 (27) 1701169, Chapter 19, Metal Oxide-based Thin Film Structures: Formation, Characterization and Application of Interface-based Phenomena, Elsevier, 2018, Pages 465–488.

Resume : ZnO is a worldwide employed activator of rubber sulphur vulcanization, as it influences the curing kinetics and promotes the shortening of sulphur cross-links between rubber chains. However, its low distribution into rubber matrix leads to a high-required zinc content, connected to non-negligible potential environmental risks due to zinc release from rubber products. In this context, aim of the work is the introduction of a novel activator, composed of more dispersed and active zinc species, to reduce the ZnO amount by keeping a high curing efficiency. Thus, zinc single sites were anchored onto the surface of silica nanoparticles, a common reinforcing filler, to obtain a novel double function filler, with both reinforcing and activating properties (ZnA-SiO2). The material was synthesized by using a two-steps procedure, in which silica was first functionalized with a silane-grafting agent and then reacted with a zinc precursor. A deep surface characterization showed the so-formed isolated zinc centers coordinated with two silane amine groups bonded to silica, where the zinc amount is tunable by varying the silica functionalization degree. ZnA-SiO2 exhibited high efficiency as activator in the vulcanization of silica/isoprene nanocomposites, leading to a considerable kinetic impact, high cross-linking degree and improved dynamic-mechanical properties. The results highlighted that ZnA-SiO2 is a promising candidate to substitute ZnO in the industrial rubber vulcanization.

Resume : The low-temperature, solution-based syntheses provide promising strategies for fabrication of electrode materials and interfacial engineering in dye-sensitized and perovskite solar cells. Examples are compact thin films from n-doped semiconductors (TiO2 or SnO2) which are applicable as the electron-selective layers at the negative electrode, and p-doped semiconductors (CuSCN or CuSCN/graphene) which are applicable as the hole-selective layers at the positive electrode. A general strategy to grow such rectifying interfaces is based on sol-gel deposition of thin film on various substrates, including optically transparent oxides, such as F:SnO2 (FTO). In certain cases (TiO2, CuSCN) electrochemical deposition provides promising alternative to grow thin films on conducting substrates under well-controlled conditions. Electrochemical techniques, including electrochemical impedance spectroscopy, are suitable for testing of the films’ quality. Salient data follow from photoelectrochemical and Raman spectroelectrochemical studies of these electrodes in aqueous or aprotic environments, which can be inter-related to UHV or NAP studies by photoelectron spectroscopy (XPS, UPS). One of the key inputs for the optimization of solar cells is the engineering of the electronic band-edge position through tuning of the films’ materials. Acknowledgement: This work was supported by the Czech Science Foundation grant No. 18-08959S.

Resume : Barium Strontium Titanate is intensively studied due to its high pyroelectric coefficient and can be used for sensing and energy harvesting. The advantages of chemical solution-based processing methods, like sol-gel, is a large-scale and possible flexible production leading to cost-effective processing technologies. Although the sol-gel method is widely used, the fundamental mechanisms governing the formation of inorganic thin films remain poorly understood. Ba0.7Sr0.3TiO3 thin films were studied by X-ray diffraction, electron microscopy and synchrotron Grazing Incidence Small Angle X-ray Scattering (GISAXS) which is a powerful tool for exploring morphology at the nanoscale. In situ GISAXS performed at low annealing temperatures allowed studying the inorganic-organic phase separation. Ex situ GISAXS performed at high annealing temperatures allowed studying pore formation. Moreover, a theoretical model based on solvent evaporation, convection and solution viscosity is presented leading to a fundamental understanding of the formation of inorganic sol-gel thin films in general. In addition, the relation between the material porosity and the dielectric constant is established by a general simple model. Hence, a thorough understanding of the relation between the sol-gel deposition process and the final solid-state dielectric properties has been achieved.

Resume : Structural engineering of inorganic materials at atomic level is a promising way to tune the physicochemical properties of materials and optimize their performance in various potential applications, especially electrocatalysis. Here, we report that the lithiation-induced amorphization of layered crystalline Pd3P2S8 activates this otherwise electrochemically inert material as a highly efficient hydrogen evolution catalyst. The lithiation process transforms Pd3P2S8 crystals to amorphous ultrasmall lithium-incorporated palladium phosphosulfide (Li-PPS) nanodots (NDs) with abundant vacancies. The structure change during the lithiation-induced amorphization process is investigated by X-ray absorption spectroscopy, nuclear reaction analysis (NRA) and other characterizations in detail. In the meantime, such electrochemically inert Pd3P2S8 materials are activated as a highly efficient hydrogen evolution catalyst. The amorphous Li-PPS NDs exhibit excellent electrocatalytic activity towards the hydrogen evolution reaction with an onset potential of −52 mV, a Tafel slope of 29 mV dec−1 and outstanding long-term stability. Experimental and theoretical investigations reveal that the activation of its intrinsically inert electrocatalytic property can be attributed to the morphology and structure change of Pd3P2S8 including dimension decrease, crystallinity loss, vacancy formation and lithium incorporation. This work provides a unique way for structure tuning of material to effectively manipulate its catalytic properties and functionalities.

Resume : The demand for transparent electrodes (TE) has been lately growing for many devices such as solar cells, LEDs or transparent heaters. Indium tin oxide (ITO) has so far dominated the field of TE, however, its critical associated drawbacks (indium scarcity or brittleness) have limited its industrial integration. Metal-based nanowire networks is a very promising alternative material [Sannicolo et al., Small, 12 (2016) 6052]. Silver nanowire (AgNW) networks exhibit outstanding properties with sheet resistance values below 10 Ω/sq, optical transparency of 90% and very high flexibility. Research so far has mainly focused on the optimization of each step, from the nanowires growth, the deposition techniques to the post-treatment processes and integration into devices. However, in order to build a robust and mature technology, there are still challenges to be tackled. Physical phenomena that take place at the scales of both the network (macroscale) and the nanowire-to-nanowire junctions (nanoscale) have still to be better understood and observed [Sannicolo et al., ACS Nano 12 (2018) 4648]. Electrical or thermal stability are also crucial issues. One way to efficiently enhance the AgNW based TE stability is to deposit over AgNW networks a conformal very thin ZnO layer by spatial atomic layer deposition [Nguyen et al., Nanoscale 11 (2019) 12097]. Such methods allow to design AgNW based functional nanoscale and integrate efficiently such nanomaterials in industrial devices.

Resume : Mitigation of an ever-growing thrust of global energy demand coupled with adverse climatic impacts relies on the implementation of a sustainable energy economy. To this end, fuel cells are hailed to be potential green alternatives for efficient interconversion of chemical to electrical energy without increasing the carbon footprints. Despite their great merits, a critical element in the pursuit of this quest is the development of efficient and economical cathodic nanocatalysts (NCs) to boost the sluggish kinetics of oxygen reduction reaction (ORR), which is a central limiting index preventing fuel cells from “seizing the market”. Carbon supported platinum nanoparticles (Pt/C) are by far the most prevalent nanocatalysts (NCs) for ORR. However, limited reserves in the earth crust and high primitive cost of Pt severely restricts them for widespread application. Additionally, an exceptional high overpotential (~0.3-0.4 V), imbalanced reaction kinetics and material durability at counterpart electrodes in harsh redox conditions are fundamental issues detaining Pt-based NCs at fuel cell cathode. In this event, rationally designed heterogeneous interfaces with tailored structural and functional properties are highly sought to realize fuel cell technology. Herein, tri-metallic heterogeneous NCs consisting of atomic-to-nano scaled Pt-clusters decorated Pd nano-islands on NiO2 base underneath (namely NPP) are fabricated on carbon nanotube (CNT) support with improved heteroatomic interactions for ORR in alkaline medium (0.1 M KOH). By cross-referencing results of structural characterizations, electrochemical analysis and device performance, we unveiled the ORR pathways with respect to dimension effects of Pt-clusters. In optimum case, the mass activity of NPP-1 (~1.0 wt. of % Pt) NC is 4705.3 mAmg-1, which is ~70.12-folds increased as compared to that of commercial J.M.-Pt/C catalyst (20 wt.% of Pt) at 0.85 V vs RHE. Moreover, NPP-1 NC exhibits outstanding power density (339.1 mW cm-2) and short circuit current density (910.8 mA mc-2) as compared to that of commercial J.M.-Pt/C catalyst (174.9 mWcm-2 and 720.4 mA cm-2) in an alkaline fuel cell stack test. Such an improved catalytic performance for the ultra-low dosage of Pt is mainly dominated by incorporation of Pt atoms into interfacial regions of Pd nano-islands and NiO2. These Pt-atoms lowering down the adsorption strength for oxygenated species via electron confinement from adjacent sites, resulting in enhanced splitting and relocation kinetics of subsequent oxygen molecules on NC surface and thus ORR performance. The result obtained in this study is very intriguing and is an important clue for the development of next-generation ORR catalysts.

Resume : Aluminum and their alloys are one of the most commonly used materials due to a range of benefits, for example, for both aircraft and space flight engineering. This work shows processes and mechanisms that lead to the improvement of the surface properties of aluminum alloys: low-secondary electron emission yield under electron bombardment (<1.3), corrosion and wear resistance. Microstructured coatings of Cu and Ni were grown on aluminum alloys substrates using electroless plating technique. An intermediary layer of compact anodic aluminum oxide was also used to avoid the substrate corrosion. The anodization voltage was performed at the rate 0,0122 μm/V. The thermal emissivity, ε, increased linearly as a function of the oxide thickness, d. from ε = 0.02 (substrate) to 0.8 (anodic oxide). The composition of the alloying element and the selected deposition temperature (50-80ºC) have a critical role to improve the adhesion and to increase the thickness of Cu and Ni coatings due to redox processes. Cu can produce the corrosion of Al, however, for example, for AA2024 the composition of the intermediary elements of this aluminium alloy is Cu (4.6%wt, Eo = +0,34 V), Mg (1.28%wt, -2.37 V) and Mn (0.37%wt, −1.18 V) and it was successfully coated with both Cu and Ni. The results obtained in these experiments contribute to a better understanding of the processes of surface coating deposition on aluminum alloys.

Resume : Magnetic micro/nanoparticles are widely exploited in many biotechnological or biomedical applications [1,2]. However, frequently the superparamagnetic particles are deposited onto the inorganic oxide matrix from colloidal suspensions yielding only limited adhesion of the particles to the matrix. Herein, we demonstrated new solvothermal oleic-acid based approach for the fabrication of TiO2 1D anodized nanotubes decorated with Fe3O4 nanoparticles. The resulted composite materials were decorated with 11.1-16.9 nm nanoparticles in inner and outer shell of the nanotubes. The as-prepared materials demonstrated superparamagnetic properties with the saturation of magnetization ranging from 0.66 to 8.8 emu g-1 and revealed enhanced photocatalytic activity in photodegradation of methylene blue under visible light irradiation. According to studies [3,4], double-walled nanotubes, containing secondary layer of electrolyte deposition, display lower degradation rate in comparison to single-walled samples. Therefore, single-walled TiO2 nanotube composites were shown to have higher rate constants, namely, 0.41ּּּ 10-2 and 0.48 10-2 min-1, compared to non-decorated TiO2 nanotubes. Based on these data, we can conclude, that as-prepared materials represent promising magnetically guidable photocatalysts in biomedicine for drug delivery [5]. [1] Gijs M. et al. Chem. Rev. 2010, 110, 1518 [2] Schladt T. D. et al. Dalton Trans. 2011, 40, 6315 [3] Mirabolghasemi H., Liu N., Lee K., Schmuki P. Chem. Commun. 2013, 49, 2067 [4] Motola M., Sopha H., Krbal M., Hromadko L., Olmrova Zmrhalova Z., Plesch G., Macak J.M. Electrochem. Commun. 2018, 97, 1 [5] Beketova D. et al., Ms submitted to ACS Appl. Nano Mater.

Resume : Selection of an appropriate heat transfer agent (HTA) and thermal energy storage (TES) material is important for minimizing the cost of the solar receiver, thermal storage and heat exchangers, and for achieving high receiver and cycle efficiencies. It has also been observed that the use of the molten salt eutectic composition as an HTA / TES fluid in many different areas is effective in increasing system efficiency. Current molten salt HTAs have high melting points (>200°C) and degrade above 600°C. The main problem with this application is that it can easily freeze in the evening or in the winter months and clog the pipeline to make working conditions difficult. For this reason, there is an urgent need for inexpensive salt melt compositions having a lower melting point and a higher thermal stability temperature. To do this, a new nanostructured eutectic molten salt was designed to achieve lower melting point (>200°C) and higher thermal conductivity. In this study, we prepared phase diagrams of molten salts and anodic alumina oxide (AAO) with different pore size (25 to 400nm). Maximum melting temperature depression was observed as T=~170°C for AAO/KNO3 composites for 35nm pore size. Furthermore, a drastic increase on thermal conductivity (73%) was recorded for the same composite.

Resume : In the past years, two-dimensional (2D) Transition metal dichalcogenide (TMD) materials have attracted numerous attention for next-generation nanoelectronics applications due to their unique electrical and physical properties. However, the technical solution regarding how to reliably obtain the p-type 2D field-effect transistor (FET) is still under investigation, thus limiting the applications of 2D FETs in CMOS circuits. In this report, we have developed a chemical method for the synthesis of the NbxW1-xS2 flake, and further demonstrated that the 2D NbxW1-xS2 flake serving as source/drain material is beneficial for the realization of p-type WS2 FET. The chemical vapor transport (CVT) method was used to synthesize large-scale NbxW1-xS2 flakes. The thickness of the as-grown NbxW1-xS2 flake was thinned down to be at the level of few nanometers using the mechanical exfoliation method, followed by the dry transfer method to place the 2D NbxW1-xS2 flake onto the Si/SiO2 substrate. The material characterizations of the large-scale 2D NbxW1-xS2 materials were conducted by using the SEM, Raman spectra, and AFM tools. The electrical properties of the 2D NbxW1-xS2 materials were explored through the two-terminal device architecture, revealing a low-resistive material feature. Finally, the p-type multilayer WS2 FETs were experimentally realized by adopting the NbxW1-xS2 flakes as the source/drain materials. This report paves a way from material synthesis points of view towards modulating the dominantly operational polarity in 2D WS2 FETs for future nanoelectronics applications.

Resume : In the scope of the global pursuit toward improved renewable energy technologies, there is a crucial need for development of materials with improved efficiency and reduced costs for applications in energy storage, solar water splitting, and pollutant degradation. In this poster, a recent body of work focused on the combination of 2D materials and an organic matrix for the bio-inspired colloidal self-assembly of functional nanomaterials is discussed. Layered silicates stabilized with functional organic polymers and small molecules were used to form bulk self-assembled nacre-like materials with tunable mechanical and functional properties. In addition to previously studied systems aimed at novel plasmonic sensors, recent advances in fabrication of such materials for robust supercapacitors are described herein.Overall, this work provides a facile approach for the rational design of hybrid self-assembled functional materials, and provides a testbed for future studies of heterostructured layered nanomaterials in such composites for applications in energy storage and generation.

Resume : Surface-enhanced Raman scattering (SERS) is a powerful vibrational spectroscopic technique that enables ultrasensitive molecule detection due to the enhancement of its characteristic Raman signals when it is attached or in close proximity to a plasmonic nanoparticle (NP)/nanostructure. The low Raman cross-section of many interesting analytes (i.e. heavy metals) requires the use of highly efficient, robust and reproducible SERS substrates.1 However, despite the inherently higher SERS activity of Ag compared to Au, its higher reactivity arising from oxidation limits its applicability. 2 Here, we report the fabrication of a SERS sensing platform based on the electrostatic layer-by-layer (LbL) assembly of Ag NPs.3 The optical properties and SERS efficiency were analyzed as a function of size and loading of Ag NPs. This study provides accurate information on the plasmonic platform, elucidating the relationship between optical properties and SERS efficiency in hot-spot containing systems. Finally, the most efficient SERS substrate was used for the ultradetection of toxic heavy metal cations in water. The design and optimization of this type of plasmonic platforms pave the way for the detection of other relevant (bio)molecules in a broad range of fields, such as environmental control, food safety or biomedicine. 1Gu, X. et al. Annu. Rev. Anal. Chem. 2018, 11 (1), 147 2Han, Y et al Anal. Chem. 2011, 83 (15), 5873 3Montes-García, V. et al. ACS Appl. Mater. Interfaces 2017, 9 (31), 26372

Resume : Photochromic molecular switches, whose (at least) two distinct photoisomers can be interconverted reversibly by light stimulus, have been applied in artificial molecular machines, data storage, imaging and sensing. However, to regulate the photoisomerization processes (at least in one direction) of molecular switches, such as azobenzes, spiropyrans and diarylethenes, UV light is generally required, which shows shorter penetration depth and can induce cellar apoptosis. Here we demonstrate that molecular switches can be driven upon visible light irradiation by using CdS semiconductor nanocrystals as triplet sensitizers. CdS semiconductor nanocrystals with various size were synthesized to match the triplet energy levels of different molecular switches. Photoisomerization upon visible light irradiation was observed in UV/vis absorption spectroscopy. Triplet energy transfer from CdS semiconductor nanocrystals to molecular switches was confirmed by transient absorption spectroscopy. The marriage of semiconductor nanocrystals and molecular switches will expand further application in many fields, from materials science to biological sciences.

Resume : Research involved in developing alternative energy sources has become a necessity to face global warming. However, a new technology affordable worldwide is seldom easy to obtain, as for superconductivity, an appealing solution to enhance importantly clean electrical energy, but still at the dawning due to high production costs. By implementing chemical solution deposition techniques, low cost nanostructured epitaxial cuprate superconductors are demonstrated. Here we present a versatile and tunable solution method suitable for the preparation of epitaxial cuprate superconducting films. Disregarding the renowned trifluoroacetate route, we center our focus on Fluorine-free solutions, thus meeting the requirement of greener chemical processes and achieving ultrafast growth rates beyond 100 nm/s using transient liquids during the epitaxial growth of the superconducting layer in the innovative framework of TLAG (transient liquid assisted growth), a high-throughput scalable process [1]. From Y, Ba, and Cu propionates we prepare solutions of different molar ratio with a facile and fast preparation method, of endured stability, and tunability of the final film thickness, directly related to solution concentration and viscosity. Employing in-situ XRD synchrotron radiation, the distinct compositions provide us with a wide overview of the TLAG growth process, yielding a strong correlation between high performance properties and solution chemistry. [1] L. Soler et al, Nat. Comm., in press

Resume : Zeolitic imidazolate framework-8 (ZIF-8) is widely investigated for molecular sorption, storage and separation, and heterogeneous catalysis due to its 1) exceptional stability; thermally and in aqueous/organic solvents, 2) tailorable crystals and surfaces, and 3) easy and rapid scalable synthesis at ambient pressure and temperature or solid-state routes. Recent years witness a rapid rise of ZIF (MOF)-derived carbonaceous electrocatalysts. In particular, ZIF-8 or its analogue ZIF-67 is one of the most extensively used precursors as a sacrificial template for this purpose. However, this route, via high temperature thermolysis, pose significant challenges for controlling the composition, functionality, heterogeneity, nanophase, and porosity, as well as for mass production. Therefore, it is highly viable to use ZIFs/MOFs directly but found very few successful attempts have been found. Here, for the first time, we unveil a surprisingly high and stable electrocatalytic activity of the ZIF-67 for both the oxygen evolution and reduction reactions (OER and ORR) in alkaline electrolyte. As-synthesized ZIF-67 has a controlled particle size and shows impressive OER activity, and is significantly enhanced, >50%, in the ZIF-67/CB (carbon black). It exhibits a low-overpotential of ≈320 mV at a current density of 10 mA cm−2 in 1 M KOH electrolyte. Next, the bifunctional activity is demonstrated directly from ZIF-67@Pt/C. These ZIF-based catalysts show high activity durability for both OER and ORR. Notably, ZIF-67@Pt/C exhibits enhanced ORR durability compared with Pt/C alone; ≈85% vs ≈52%. Rechargeable Zn-air battery based on ZIF-67@Pt/C delivers a high open circuit voltage of 1.42 V and a power density of >150 mW cm−2 with stable long-life cyclic performance for measured 50 h. Such activity merits are equivalent to the carbon-based catalysts. This work can provide useful guidelines in advancing the electrocatalysts from MOFs alone without resorting to the energy intensive post-processing methods.

Resume : Electrochemical reduction for conversion of CO2 to value-added chemicals is considered a promising method to relieve global warming. To develop a highly active and selective electrocatalyst for efficient CO2 conversion, it is essential to overcome the large overpotential and to suppress the competitive hydrogen evolution reaction (HER). Herein, we report a simple and controllable fabrication method for Ag electrocatalytic films using all-water-based solution processes via a seed-meditated metal growth technique. Varying the deposition conditions allows the N/S doping ratio in Ag films with high coverage and good adhesion to be easily controlled in the range of 1.14–8.23. The doping ratio has a significant effect on the CO Faradaic efficiency (FE), as the S content modulates the binding energy of reaction intermediates, whereas the N content is effective for suppressing the HER on the Ag film surface.

Resume : Carbon nanotubes (CNTs) have received substantial attention as alternatives to indium tin oxide for the production of transparent conductors. However, problems associated with the dewetting of liquid thin films have hindered the reliable fabrication of networked conducting CNT films via solution-based processes. In this study, the dewetting of liquid thin films containing single-walled carbon nanotubes (SWCNTs) on substrates is successfully retarded by simply adding ethylene glycol to the SWCNT dispersion, and highly uniform SWCNT thin films are obtained using the meniscus-dragging deposition (MDD) method. The dewetting-free coating conditions for the uniform SWCNT films are determined by calculating the dewetting and drying times of the liquid thin films formed by the MDD method. When the dewetting time was 2.5 times longer than the drying time of the liquid thin layers, uniform SWCNT films are formed over the entire substrates without breakage or rupture of the films. In addition, the transmittance and sheet resistance of the transparent SWCNT films are easily controlled over a wide range by varying the coating parameters.

Resume : Aluminum oxide (Al2O3) has received a great deal of attention as a heat dissipation material for electrical devices because it has a high thermal conductivity, electrical insulating properties and low cost. Herein, we report the simple technology of densely packed Al2O3-resin hybrid films by a inkjet printing (IJP) process for highly dissipation properties. It was found that packing density of Al2O3 film is much critical for the heat transfer among the particles of Al2O3 particles as well as the intrinsic thermal conductivity. For the first time, we fabricated Al2O3-resin hybrid film which can effectively transfer the heat of the device to the heat sink by inkjet printing. The thermal conductivity of Al2O3-resin hybrid films was more than 5 times higher than that of conventional thermal interface materials (TIMs). The Al2O3-resin hybrid film has excellent electrical insulation property that does not occur electrical short at high voltages above 1 kV. The Al2O3-resin hybrid film has a packing density of more than 50 vol.% with a thin thickness of 20-30 um and flexibility. This work suggests that Al2O3-resin hybrid films fabricated by IJP process are promising for highly effective heat dissipation substrate of various electronic devices.

Resume : Despite many efforts to exploit phenomena occurring in nanomaterials, their practical uses remain limited. Here, we propose an industrially applicable inorganic-polymer nanowire with a backbone exclusively composed of copper and chlorine atoms. Our synthetic approach facilitates the mass production of the nanowires because the simple mixing of inexpensive chemicals at room temperature completes the overall reaction. Due to the polymeric nature of the nanowires, these materials give rise to unusual phenomena that have never been observed. The nanowires absorb a considerable amount of various atoms and molecules at the atomic scale. Moreover, these nanowires are amorphous and can readily be crystallized into different crystalline structures depending on the external energy sources. In this manuscript, we use the scalable, harmless, and cost-effective nanowires as a single-atom catalyst supporter, thermoelectric material, and scavenger of toxic molecules.

Resume : Light emitting diodes (LEDs) with Er3+ ions implanted TiO2 thin films have attracted considerable interest due to the 4I13/2→4I15/2 transition of Er3+ ions at about 1.55 um corresponding to the minimum loss window of the silica optical waveguide has potential application in optoelectronic interconnection [1, 2]. Recently, Re3+(Er, Tm, Nd and Eu)-related visible and near infrared (NIR) EL from TiO2:Re3+ film LEDs fabricated by magnetron sputtering have been achieved [3, 4]. However, to our knowledge, there are few reports on LEDs with Re3+ doped TiO2 thin films prepared by sol-gel method, because it is difficult to obtain high-quality films due to the wet fabrication process. In the present work, we prepared Er3+ doped TiO2 thin films with various doping concentrations via a facile sol-gel method combining with the spinning-coating and optimized post-annealing treatments. Furthermore, we fabricated LEDs with the ITO/TiO2:Er3+/SiO2/n+-Si/Al structure. Both the Er3+-related visible and NIR EL emissions can be detected under the operation voltage as low as ~5 V. The influences of Er3+ doping concentration on the structure and EL performance of Er3+ doped TiO2 thin films were studied. Our results indicated that the as-prepared LEDs with low driving voltage shows a potential application in optoelectronic interconnection. This work was supported by National Key R&D Program of China (No.2018YFB2200101) and NSFC (No.61735008). References [1] M. Jiang, C. Zhu, J. Zhou, J. Chen, Y. Gao, X. Ma, D. Yang, Journal of Applied Physics, 120 (2016), p. 163104. [2] Y. Yang, L. Jin, X. Ma, D. Yang, Applied Physics Letters, 100 (2012), p. 031103. [3] C. Zhu, C. Lv, Z. Gao, C. Wang, D. Li, X. Ma, D. Yang, Applied Physics Letters, 107 (2015), p. 131103. [4] C. Zhu, C. Lv, C. Wang, Y. Sha, D. Li, X. Ma, D. Yang, Optics express, 23 (2015), pp. 2819-2826.

Resume : To recover the surface defects, annealing is one of the widespread techniques in material science. In recent years, a novel method of annealing is developed, that is, laser annealing which has been studied in the crystal growth and defects remove. Carbon nanotube (CNT) supported ternary metallic nanoparticles (NPs) are synthesized by wet chemical reduction method with the configuration of Cu and NiPd (namely CNP). In order to realize the effect of the energy per pulse containing to catalyst surface modification, the energy used are 1 and 10 mJ/pulse and keeping the total absorbed energy, 1 J. In this study, to investigate the physical characterizations of CNP NPs before laser annealing, the cyclic voltammetry (CV), high resolution transmission electron microscopy (HRTEM), and X-ray absorption spectroscopy (XAS) has been used. The CV result shows that the as-prepared CNP NPs are in the presence of two isolated phases, Ni oxide and Pd metal, respectively. However, the 10 mJ/pulse laser annealing manipulates the surface configuration from the isolated phase into a uniform phase as a NiPd alloy, which can be seen as the left-shift of the oxide reduction peak in CV curve compared with as-prepared one. The reason for phase mixing is the NPs accumulates enough activation energy for the phase mixing from the 10 mJ laser pulses. To find a practical use, the CNP NPs are in the process of CO2 reduction reaction to investigate the phase effect for the performance improvements.

Resume : Photocatalytic water splitting has attracted much attention as an efficient pathway for converting solar energy into chemical energy due to the increased importance of renewable energy. BiVO4 has been considered one of the most promising photocatalysts for visible light driven photocatalyst due to its small band gap, sufficient overpotential for water oxidation, superior chemical stability, and cost effective features. However, pristine BiVO¬4 has a low solar-to-chemical energy conversion efficiency due to its inherent sluggish hole transfer kinetics and significant charge recombination. In this paper, highly porous, one dimensionally elongated tungsten-doped BiVO4 nanofibers (W:BiVO4 NFs) have been successfully synthesized for the first time using a facile electrospinning process. To enhance cost-effective photocatalysis, crystalline nickel nanoparticles (Ni NPs) were introduced as co-catalysts on the surface of the W:BiVO4 NFs. The water oxidation performance was evaluated using a suspended photocatalyst system under visible light irradiation. The outstanding water oxidation properties were obtained through (i) the control of polymer/precursor to achieve porous W:BiVO4 NFs with increased surface area, (ii) the optimization of tungsten-doping concentration for fast charge transfer, and (iii) the optimization of the loading amounts of Ni NPs to provide efficient charge pathway suppression of charge recombination.

Resume : Lithium (Li) metal has been intensively studied as an ultimate anode due to the high capacity (3860 mAh g-1) and the lowest electrochemical redox potential (–3.04 V vs SHE) for rechargeable batteries. However, the practical implementation of the Li metal anode is still hindered by the obstacles such as the poor cyclability and the Li dendrite growth. Here, we report the modified Li anode with the copper nitride nanowires (Cu3N NWs) for the stable cycling and dendrite-free Li metal batteries. Cu3N NWs are easily prepared by a solution etching method and subsequently the Cu3N NWs are transferred to the Li metal surface by the one-step roll pressing. The transferred Cu3N NWs form the Li3N/Cu through the conversion reaction with Li, which is confirmed by XRD and XPS analyses. The Li3N/Cu NWs layer on Li could assist the dense and planar Li plating behaviors due to the high Li ion conductivity of Li3N and the channel guiding nanowires structure of Li3N/Cu. With those synergetic effects, the modified Li electrode shows the dendrite-free Li plating behaviors even deposited up to 20 mAh cm-2. The symmetric cells prepared with the modified Li exhibit stable cycling performances even at a high current density of 5.0 mA cm-2 with a capacity of 1.0 mAh cm-2 over 500 cycles, showing much lower overpotentials compared to the bare Li. Furthermore, the long-term cyclability with the dendrite-free morphology is realized in the full cells using LiCoO2, Li4Ti5O12, and LiNi0.8Co0.1Mn0.1O2 cathode materials with the practical current density above 2 mA cm-2. These findings offer a new avenue for building a stable protective layer on the Li metal anode for the dendrite-free and the stable cycling performance in Li metal batteries.

Resume : As a kind of ultra-high-temperature ceramics (UHTCs), ZrB2 has been received a lot of attention as a heat-resistant material for outer wall of space shuttles, power plants and so on. Especially, due to research and development of space shuttles, the field of a heat-resistant material was focused about ability such as reusability and durability. To coat the ZrB2 with SiC, SiO2, a base material for forming SiC, was coated on a single particle surface coating layer through surface treatment using selective acid. The consideration of heat treatment conditions for carbonization of the surface SiO2 was accompanied. Multifaceted consideration of the phenomenon of carbide surface coating process was included. In particular, the effect of the chemical reaction of the surface reaction of ZrB2 particles using acid was evaluated in terms of core-shell structure. In addition, consideration was given to the preferential reaction between the core ZrB2 and the added C with the nanoscale SiO2 layer. The core-shell structure of non-oxide ceramics powder has been included for future application to advanced technology, as well.

Resume : Piezoelectric strain sensor with high sensitivity and reliable flexibility have attracted extensive interest in wearable electronics. In this paper, a 3D printing technique was developed to fabricate flexible piezoelectric strain sensor based on surface modified Barium titanate (M-BaTiO3)/Poly(vinylidene fluoride) (PVDF) composite film. Specifically, the BaTiO3 nanoparticles were modified by 1H,1H,2H,2H-Perfluorodecyltriethoxysilane, resulting in enhanced dispersion stability over a month. The piezoelectric coefficient (d33) of the M-BaTiO3/PVDF composite based sensor was two times higher than that of the pristine BaTiO3/PVDF composite film and the linear relationship with the piezoelectric coefficient was observed as a function of the filling percentage of M-BaTiO3. At the content of 20% surface modified BaTiO3, the piezoelectric coefficient of the composite film achieved 34.5 pC/N. Simultaneously, the output voltage value of 20% surface modified BaTiO3 film was 50% higher than the 10% counterpart. After 1000 cycles of bending test, the output voltage of the piezoelectric strain sensor remained consistent, indicating that the sensor exhibited high mechanical endurance as well. This novel approach provides an innovative platform for wearable electronics.

Resume : Self-modified flower-like rutile phased TiO2 film is fabricated by using simple hydrothermal thermal with various precursor concentrations (0.05-0.15 M) on fluorine-doped tin oxide (FTO) substrate. The catalysts are characterised by using XRD, FESEM, TEM, FTIR, PL, XPS, contact angle, and UV-Vis spectroscopy. The photocatalytic activity is tested for degradation of methylene blue (MB) which resulted with the following order: 0.10 M (42%) > 0.15 M (37%) > 0.12 M (35%) > 0.07 M (28%) > 0.05 M (25%). The dye degradation increases when the photocatalytic activity is conducted under pH 12 and reaches 60%. The most important properties which are oxygen vacancy and Ti3+ surface defect hugely assist in dye degradation by narrowing the band gap and act as electron trapper. Furthermore, the stack effect between flower-like TiO2 and the flower-like structure itself provides a more active area for MB to absorb in dye degradation. The reusability of the film is still stable even after 5 runs without any severe deactivation of the catalyst. This study demonstrated the advantages of film that could avoid post-separation, the combination of flower-like rutile structure and self-modified defect that could extend the light response range in which will contribute to highly efficient wastewater treatment.

Resume : In this study, MgxZn1-xO thin films, which can be used in various fields such as solar cell, high mobility field effect transistors and power semiconductor devices, were fabricated using the sol-gel method. MgxZn1-xO solution synthesized by the sol-gel method and the thin film was grown by spin coating on Si (100) substrate and sapphire substrate The solutions was synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) were added to the mixed solution as sol stabilizer. Zinc acetate dihydrate [Zn(CH3COO)2·2H2O] was used as a ZnO precursor. Mg nitrate hexahydrate [Mg(NO3)2⋅6H2O] and Mg acetate dihydrate [Mg(CH3COO)2⋅2H2O] were used as a MgO precursor. The molar concentration of the Zn precursor in the solvent was varied from 0.1 M to 0.3 M. And the amount of the Mg precursor was 30% of Mg 2 / Zn 2 . The optical and structural characteristics of the fabricated thin films were compared. The optical characteristics were measured by UV-vis spectrophotometer and the transmittance of each wavelength was measured. Structural characteristics were x-ray diffraction (XRD), transmission electron microscope (TEM) and energy. Analysis was performed using an energy dispersive X-ray spectrometer (EDX). The MgxZn1-xO thin film was well formed.

Resume : Vulcanization is a consolidated process of the tire industry to improve the mechanical properties of rubber. In this process, microcrystalline ZnO is the most efficient activator worldwide employed to enhance and control its reaction rate. However, ZnO entails non-negligible potential environmental risks: according to the Environmental Protection Agency (EPA) “zinc ion can become available from zinc oxide through several mechanisms” and “zinc ion can reasonably be anticipated to be toxic to aquatic organisms”. As such, the reduction of ZnO level in rubber is becoming an urgent issue in rubber production and particularly tire manufacturing. In this context, the project aims at the industrial reduction of the ZnO amount and improvement of the vulcanization efficiency by introducing a novel activator (ZnO-NP@SiO2-NP), composed of ZnO nanoparticles anchored to silica, a common filler of rubber composites for tires. So far, this material has been synthesized by a sol-gel procedure and used for the successful lab-scale production of highly performant rubber composites employed in common tires. This work intends to promote the substitution of the conventional ZnO with ZnO-NP@SiO2-NP at the industrial scale. For this reason, a comprehensive study about the scale up of the ZnO-NP@SiO2-NP production has been performed, focusing on the optimization of the key synthetic parameters for the development of a sustainable synthetic process.

Resume : Scalable and green technologies for the production of pure water in world zones lacking large infrastructures is a huge unresolved humanity problem. Efforts devoted to studying new, efficient and low-cost methods of purifying water, eliminating the consumption of chemical compounds have to be made in the next few years. Titanium oxide is very interesting in this contest due to its good low cost, stability, harmless and hits photocatalytic activity. Indeed, taking advantage of this last property, it can be used in the decomposition of pollutants in water and in killing harmful bacteria. In this work, we exploited the higher exposed surface area of TiO2 nanowires (NWs) to improve hits photocatalytic action. We used an easy, one-step synthesis method for the growth of nanowires on conductive Ti support. Morphological and structural characterizations indicate that NWs of several microns in height with rutile structure are formed. The photocatalytic properties were studied by using the decoloration rate of methylene blue dye under UV light. NWs revealed 2 times improvement of the decoloration rate compared to flat sample. Moreover, we realized a photo-catalytical monolithic cell composed by TiO2 NWs on the front-side and a Pt nanoparticles sheet on the back-side of the conductive Ti foil. An improvement of photocatalytic activity of 6 times is measured. This increase is discussed considering the transfer of electrons from the cell to the solution.

Resume : Continuous flow hydrothermal synthesis (CHFS) represents a green and scalable approach to the synthesis of many inorganic nanomaterials. In this study, a two-mixer setup was developed for the synthesis of pure ZnS nanoparticles. This approach allowed to pursue a tight control over the experimental conditions, as the sulfur precursor decomposition and the crystallization occurred in subsequent parts of the flow reactor and were optimized independently. The syntheses were performed in water, using cheap and commercially available precursors (zinc nitrate and thiourea), and without the addition of any surfactant or stabilizing agent. The obtained samples consisted of rounded ZnS nanoparticles of approx. 20 nm having a mixed cubic (sphalerite) and hexagonal (wurtzite) stacking. The formation of the faulted nanoparticles was evidenced by both HRTEM and XRD analyses. By maintaining stable decomposition conditions for the sulfur precursor, and gradually increasing the reaction temperature from 241 °C to 335 °C, a regular increase of the hexagonal stacking probability was obtained, as confirmed both by XRD and Raman analyses. At the same time, the TEM analysis revealed that nanoparticles’ size remained nearly unchanged. Thus, the crystallographic features of the particles were changed independently form size and morphology. The XPS analysis indicated that particles were made of ZnS with no detectable surface oxidation, thus showing the effectiveness of the adopted route in achieving pure ZnS. The Raman analysis was performed by identifying the prevalent features of the two phases by simulating the individual spectra via DFT-LDA. Then, the evolution of the experimental spectra was followed by principal component analysis (PCA). The efficiency of the samples as photocatalyst for the hydrogen evolution reaction (HER) was tested, evidencing a general increased efficiency of nanoparticles having a larger hexagonal stacking probability.

Resume : Here, we have tried to apply the surface treated TiO2 support to VOx based SCR catalysts with high thermal stability, dispersion characteristics, and specific surface area properties. The VOx as active materials dispersed on the surface of support with smaller size without any aggregation, and support should be chemically stable preventing sintering of the active materials even at high temperatures based on its thermal stability. In order to improve the dispersibility of active particles, two types of TiO2 anatase phase were synthesized. The first is the synthesis of defective TiO2. This method could disperse VOx on the surface of defective TiO2, preventing particle growth and crystallization. The other method is to synthesize nitrogen-doped TiO2, so that surface nitrogen functional groups can improve thermal stability and anchors the active materials. The N-TiO2 support can be synthesized by a simple impregnation method using commercial TiO2, and which can contribute to the mass production of the catalyst. The characteristics of the surface treated TiO2 support were analyzed by XPS, XRD, and BET analysis, and the dispersion properties of VOx and the morphology of the catalysts were confirmed by SEM and TEM analysis.

Resume : Tungsten trioxide is a metal oxide which possess many appealing properties for sensing, electrochromic and energy applications. A facile synthesis leading to controlled properties of WO3 in nanostructured shape is highly demanded. Chemical methods like, electrodeposition or hydrothermal growth, represent simple, environmental compatible and low cost routes giving nanostructured tungsten trioxide. This work aims at identifying the role of the synthesis parameters and at modelling the WO3 nanostructures nucleation and growth. The structural, chemical and physical properties have been measured by Scanning Electron and Atomic Force Microscopy, X-Ray Diffraction, Rutherford Backscattering Spectrometry, UV/Vis-NIR Spectrophotometry, Electrochemical Impedance Spectroscopy. Thin film of compact WO3 grains (50 nm in size, regardless of the electrodeposition parameters) have been obtained with thickness ranging from 34 to 270 nm, and an optical bandgap of 3.51 eV. By investigating the early stage of electrodeposition, the current profiles have been explained by using the Scharifker and Hills’s model, which is a general model used for the description of the nucleation process during electrodeposition. In our cases this model has pointing out an instantaneous nucleation process. Further development of WO3 nanostructures synthesis through pulsed electrodeposition and hydrothermal growth have been tried, to improve the control of physico-chemical properties.

Resume : Selective catalytic reduction (SCR) catalyst is typically used to remove nitrogen oxides (NOx) in stationary sources. The catalyst which has a function of NOx trap below activation temperature (350 ~ 380 °C) was synthesized. Baria was impregnated into the catalyst as a NOx adsorbent, and Ceria was used to improve the performance, NOx storage and removal efficiency, as a promoter. V2O5-WO3/TiO2 was selected as a control group to compare the characteristics by the diverse contents. Baria/Ceria-added V2O5-WO3/TiO2 catalysts were impregnated as a comparison. As a result, the Ceria-added catalyst showed 95% efficiency, and the Barium-added catalyst showed that the lowest efficiency is 67%. Especially, Baria/Ceria added catalyst showed 94% NOx removal efficiency at 300 °C. The catalyst’s properties were improved due to the impregnated Ceria. By comparing the adsorption characteristics, the NOx storage capacity of V2O5-WO3/TiO2 catalyst was calculated as 2 μmol/g, and 85 μmol/g for Baria/Ceria added catalyst. NOx desorption behavior was investigated with NOx-TPD (Temperature programmed desorption) analysis. Baria-added catalysts started the desorption of NOx at 250 °C and peaked at 350 °C. In addition, physical properties of the catalysts were characterized from XRD (X-Ray diffraction), XRF (X-Ray fluorescence) and SEM (Scanning electron microscope) analysis.

Resume : The decoration with noble metals is emerging as an efficient methodology to add new functionalities in nanomaterials, maintaining the properties of the individual components. In particular, it was demonstrated that the catalytic activity of a nanomaterial can be strongly enhanced by surface decoration with noble metals. Among the most promising metal oxide nanostructures, Ni-based ones are particularly interesting for potential application in sensing and catalysis, due to their low-cost fabrication and high performances. In this work, NiO nanowalls are obtained through Chemical Bath Deposition (CBD) on various substrates and low-temperature thermal annealing in inert atmosphere. Then, a novel, low-cost and environmentally friendly Electroless Deposition (ELD) method is tested to decorate the NiO nanowalls with Au clusters. The effects of pH, temperature and substrates have been investigated, and a simple model for ELD is developed. The analysis shows that in order to enhance the charge transport at the semiconductor nanostructure, a bulk metal substrate is the ideal choice. By Electrochemical Impedance Spectroscopy (EIS) the reduction of charge transfer resistance between an electrolyte solution and the Au decorated samples was observed, opening the way to improve the performances of semiconductor nanostructures by Au decoration.

Resume : In this article, the UV photoresponse and H2 sensing characteristics of dumbbell-shaped ZnO at different temperatures were measured and examined systematically. The structural, morphological, chemical states and optical properties of the synthesized ZnO sample was investigated via using various characterization tools. XRD result confirmed that the synthesized ZnO sample has a hexagonal wurtzite structure and morphological studies revealed that the obtained sample exhibited uniformly distributed horizontal dumbbell-shaped morphology. Our experimental outcomes indicate that the surface adsorbed oxygen species and increasing operating temperature (OT) can improve the UV photoresponse as well as the response time of dumbbell-shaped ZnO. The highest UV photosensitivity has been observed approximately~10580% at optimum OT 358.15K, below and above this temperature, sensitivity was found to be reduced. The maximum H2 sensor response was observed ~20% for 100 ppm H2 concentration at OT of 358.15K. The dumbbell-shaped ZnO sensor is highly selective to H2 gas and attains better stability along with fast response/recovery time. The present work confirms that the dumbbell-shaped ZnO will offer great avenues to the research and development for the fabrication of MSM UV photodetector and selective H2 sensor. Therefore, our experimental findings may become pioneering examples for researchers around the globe regarding further development and fabrication of ZnO based photodetector and gas sensor

Resume : The metal oxide nanoparticles based on their special characteristics have proven their ability to be used in medical applications and biotechnological developments. In this context, a particular interest is presented by the nanoparticles of ZnO, CuO, Y2O3, TiO2, etc., which being functionalized with different chemical groups allow the conjugation with ligands, antibodies and drugs of interest. One of the most common and accessible methods for synthesizing oxide nanoparticles (especially for ZnO, CuO) has proven to be the coprecipitation synthesis by using (Zn (NO3)2, Cu (NO3)2) inorganic salts, (NaOH) precipitating agent and different surfactants (CTAB, PVP), the method allowing a rigorous control over the process parameters. The precipitates formed after the intermediate steps (filtration, washing and drying) were subjected to the heat treatment at 550 ° C. The morphological and structural analysis of the synthesized powders was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and the Fourier transform infrared spectroscopy (FTIR). Based on the obtained results, it was shown the formation of particles with average dimensions of 40 nm, which are in agreement with the average size of the crystallites, the presence of the main elements (Zn, Cu, O) and the presence of the band attributed to the vibration mode corresponding to the M-O bond, depending on the sample type.

Resume : The development of the plating technology of nanopowders with ultra-thin (nano-thin in the limit) layers of oxides requires optimization of deposition modes, including the solution of the problem of pre-agglomeration of silicon nitride. For plating of silicon nitride nanoparticles there were co-precipitation method, Pechini method (with the addition of citric acid), precipitation in the gelatin matrix, granulation by spray drying considered. The obtained powders were investigated by the methods of X-ray diffraction analysis and scanning electron microscopy, qualitative composition of samples was determined, the influence of the synthesis method on garnet phase formation and plating character was studied. The reported study was funded by RFBR, project number 19-33-60084.

Resume : Micron size silica mesoporous particles with a controlled morphology can be fabricated by precipitation in solution. They can exhibit highly anisotropic shapes, like long rods or platelets, or even curved toroidal shapes [1]. Iron oxide nanocrystals have been grown inside the nanochannels of such particles, using impregnation of molten iron nitrate followed by thermal decomposition [2,3]. Versatile magnetic properties are obtained due to the different polymorphs of Fe2O3 iron oxide that have been stabilized: the superparamagnetic γ phase and the rarest multi-ferroic ε phase. The confinement inside the nanochannels also induces a preferred crystallographic orientation of the iron oxide nanocrystals. As a result, we obtained mixed silica/iron oxide particles with a highly anisotropic rod-like shape (aspect ratio ~ 10). When dispersed in a solvent, these particles can be easily oriented and displaced by a magnetic field. A macroscopic orientation of all the particles is achieved, with their long axis parallel to the field, due to the shape anisotropy of the particles. This opens new possibilities for the design of macroscopically oriented mesoporous nanocomposites with anisotropic magnetic properties with prospective applications such as drug delivery or remediation assisted by magnetic fields. We are currently exploring the possibility to lock the orientation of the particles inside hydrogels polymerized under magnetic field, for which a macroscopic anisotropy of the magnetic response is expected [4]. [1] Moulin, R.; Schmitt, J.; Lecchi, A.; Degrouard, J.; Impéror-Clerc, M. Soft Matter, 9, 11085 (2013). [2] Li, J.G.; Fornasieri, G.; Bleuzen, A.; Gich, M.; Gloter, A.; Bouquet, F. and Impéror-Clerc, M. Small, 12, 43 (2016) DOI 10.1002/smll.201602272 [3] Li, J.G.; Fornasieri, G.; Bleuzen, A.; Gich, M. and Impéror-Clerc, M. submitted to chemnanomat [4] Goldmann, C.; Li, J.G.; Bleuzen, A.; Gich, M. and Impéror-Clerc, M. in preparation

Resume : Zinc oxide (ZnO) is considered as one of the most promising material for applications in optoelectronics, energy conversion and sensors for several decades. ZnO films doped with transitional metal such as Ni, Co or Fe are considered as a candidate for fabrication of diluted magnetic semiconductors which are promising for spintronic applications and magnetoelectronic devices. In this work we have studied Ni doped ZnO films synthesized by electrochemical deposition. The results of Raman spectroscopy and XRD study showed that obtained films consist of crystalline ZnO doped with Ni atoms. The ZnO/Ni films have a high quality crystal lattice. The set of peaks and their relative intensity indicate the presence of a highly developed nanostructured surface of the film. Despite the high quality of crystal, a single intense photoluminescence band in visible range on all spectra was observed. The band corresponds to radiative transitions through three main group of deep levels in the band gap of semiconductor ZnO: a oxygen atoms in zinc interstitial (2,28 eV or 523 nm); a complex of an oxygen vacancy and zinc interstitial (2,16 eV or 576 nm) and oxygen vacancy (2,00-1,62 eV or 640-765 nm). Annealing leads to redshift of the photoluminescence band. It was shown that obtained ZnO films also exhibit magnetic properties at high Ni concentration. The work has been supported by the Belarus Government Research Program grants 2.1.02 and 1.15.

Resume : Surface-Enhanced Raman Scattering (SERS) spectroscopy is a sensitive method for detection of organic molecules. Nowadays, variety of SERS-active substrates are used for the detection of specific molecules, however all of them, despite of efficient Raman scattering signal enhancement, suffer from irreproducibility of SERS spectra and inability to act as multipurpose SERS-active substrates. In our work, we present experimental results of a new approach to fabrication of SERS-active substrate based on deposition of silver nanoparticles from colloidal solution on porous silicon substrate. Silver nanoparticles were synthesized following the Turkevich protocol. Morphology of the prepared substrates was studied using Scanning Electron Microscopy. SERS activity was determined using 3D scanning optical spectrometer with a 633 nm laser excitation wavelength using a 0,01 µM Rhodamine 6G solution as the analyte. Silver-covered porous silicon demonstrated higher Raman signal enhancement in comparison with crystalline silicon, as due to developed surface more silver nanoparticles were able to be kept and arranged very close to each other, leading to the formation of a high density of hot spots. We demonstrate that synthesis of noble nanoparticles solutions with different plasmonic properties and their subsequent deposition onto porous silicon is efficient method to produce SERS-active substrates with tunable optical properties.

Resume : Most high efficiency optoelectronic device architectures include indium tin oxide (ITO) as the transparent electrode. ITO, however, has an inherent limit in its range of applications due to its brittle nature, cost and its low-throughput method of production. It is therefore desirable to replace ITO with other transparent conductive electrodes [1]. This is especially important with regard to the high throughput production processes necessary in large-scale manufacturing. For these processes, the fabrication on low cost flexible substrates, such as polyethylene terephthalate (PET), is of particular interest. In this contribution we highlight our recent work on three possible approaches to this. We deposit copper nanoparticles by inkjet-printing in order to form conducting structures after chemically treating them using a reductive sintering approach that is fully compatible with flexible substrates [2]. We implement silver nanowires as transparent electrodes sprayed on PET and implemented in light-emitting devices [3]. The performance parameters are superior to those of PET/ITO reference devices in terms of flexibility, conductivity and luminance, as well as processing and material cost. Finally, we show dielectric-metal-dielectric (DMD) electrodes sputtered at low temperature on glass and modified PET [4]. The resulting DMD electrodes consisting of TiOx/Ag/AZO were incorporated in solution-processed light emitting devices for the first time and yield 2.6 times higher current efficacy compared to devices based on commercial PET/ITO [3]. [1] Hermerschmidt et al., Adv. Mater. Technol. 4, 1800474 (2019). [2] Hermerschmidt et al., Adv. Mater. Technol. 3, 1800146 (2018). [3] Kinner et al., in preparation. [4] Kinner et al., Mater. and Design 168, 107663 (2019).

Resume : Within the last decades, the use of chemical solution deposition method and in particular the Metal Organic Decomposition (MOD) approach for producing epitaxial YBa2Cu3O7-δ (YBCO) superconducting film has played an increasing role in the development of scalable processes. MOD route consists in preparing a single precursor solution made of metalorganic salts in organic solvent. Then, YBCO precursor solution, deposited on oriented substrate, undergoes a two steps thermal treatment that promotes film nucleation and growth. Film properties are highly dependent on the precursor solution quality and stability. A detailed understanding of the involved chemical equilibria and solution reactivity is necessary to ensure good structural and superconducting properties to the films, as well as, high reproducibility of the results. Only recently, High Resolution Nuclear Magnetic Resonance (HR-NMR) analysis was applied to the characterization of YBCO and YBCO+5%BaZrO3 precursor solutions and allowed us to identify the chemical species formed during solution aging [1]. In the present work, further insights into precursor solution reactivity have been carried out. Different mixtures of YBCO compatible solvents, i.e. methanol and propionic acid, have been analyzed by HR-NMR over 50 days. Then, a kinetic model of reactions occurring during solutions degradation has been proposed and verified with our experimental data both of solvent mixtures and YBCO precursor solutions. The present work confirms the relevance of a proper optimization of YBCO precursor solution composition through NMR technique. [1] V. Pinto, et al, IEEE TAS, 2018. DOI: 10.1109/TASC.2018.2800767 Acknowledgments This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

Resume : A highly efficient black TiO2 photocatalytic materials, active under both UV and visible light illumination, was synthesized by sol-gel method followed by the chemical reduction of pristine white TiO2. Pristine titanium oxide nanoparticles have been synthesized using the sol-gel method from precursors of titanium isopropoxide, ethanol and nitric acid following by annealing at different temperatures between 400 and 800°C, in air and argon atmospheres. At high temperature, larger particles grow at the smaller particles leading to more nucleation of the nano-clusters and more growth centres. Heat treatment in the synthesis process affects anatase-rutile ratio, crystalline nature of the particles, morphology, and porosity. Colour change of pristine TiO2 powder has been monitored under chemical reduction targeting a higher photocatalytic activity for pesticides, phenolic compounds and drugs degradation under UV and solar irradiation. The narrower bandgap of black TiO2 extends the photoresponse to the visible light region. The black titanium oxide nanoparticles show excellent visible-light photocatalytic activity for pollutants degradation.

Resume : The conversion of CO2 in aqueous media is a promising approach toward carbon recycling. Although many catalysts have been demonstrated in electrolyte purged with pure CO2 gas, efforts to develop catalysts that reduce the industrial CO2 gas are limited. Here, we fabricated the copper sulfide nanoparticles (CuSx NPs) which were spontaneously formed by immersing the Cu foil into industrial CO2-purged in 0.1 M KHCO3 electrolyte. Since the industrial CO2 contains H2S gas, sulfur species dissolved in the electrolyte can easily react with Cu foil. As the amount of dissolved H2S species in electrolyte increases from 0 to 320 ppm, the reaction between Cu foil and sulfur species was enhanced. As a result, the average particle size and surface density of CuSx NPs increased to 133.2 ±33.1 nm and 86.2 ±3.3%, respectively. Due to the larger concentration of sulfur species and the enlarged electrochemical surface area of CuSx NPs, faradaic efficiency of formate were improved from 22.7 to 72.0% at -0.6 VRHE. Moreover, CuSx catalysts showed excellent stability of reducing the industrial CO2 gas to formate. Change in faradaic efficiency was hardly observed even after long-term (12 h) operation. This study experimentally demonstrated that spontaneously formed CuSx NPs are the efficient and stable catalysts for reducing the industrial CO2 gas reduction to formate.

Resume : Modern advanced technologies allow to synthesize new 2D materials of various composition and unexpected structure like silicene[1], stanene[2], borophene[3] and 2D layers of CuO[4], Fe[5], FeO[6], CoC[7] etc. Alkali halides are well-known type of materials, widely used in many practical applications and fundamental studies. The most common among them is sodium chloride, table salt. During the last decades a series of experimental and theoretical studies were performed to investigate the possibility to synthesize different NaCl thin films with cubic structure on different substrates. The possibility of non-stochiometric Na_xCl_y thin films was also observed [8]. Here formation of exotic hexagonal thin NaCl films on the (110) diamond surface were theoretically predicted based on ab-initio evolutionary algorithm USPEX. Using experimental synthesis methods existence of α-hexagonal NaCl thin film was confirmed. It was found that formation of exotic atomic structure is possible due to the high binding energy between (110) diamond substrate and NaCl thin film. Work was supported by Russian Science Foundation (№ 18-73-10135). 1. Sone, J., Yamagami, T., Aoki, Y., Nakatsuji, K. & Hirayama, H. Epitaxial growth of silicene on ultra-thin ag (111) films. New Journal of Physics 16, 095004 (2014). 2. Saxena, S., Chaudhary, R. P. & Shukla, S. Stanene: atomically thick free-standing layer of 2d hexagonal tin. Scientific reports 6, 31073 (2016). 3. Mannix, A. J. et al. Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs. Science 350, 1513-1516 (2015). 4. Kano, E. et al. One-atom-thick 2d copper oxide clusters on graphene. Nanoscale 9, 3980-3985 (2017). 5. Zhao, J. et al. Free-standing single-atom-thick iron membranes suspended in graphene pores. Science 343, 1228-1232 (2014). 6. Larionov, K. V., Kvashnin, D. G. & Sorokin, P. B. 2d feo: a new member in 2d metal oxide family. The Journal of Physical Chemistry C 122, 17389-17394 (2018). 7. Larionov, K. V., Popov, Z. I., Vysotin, M. A., Kvashnin, D. G. & Sorokin, P. B. Study of the new two-dimensional compound coc. JETP Letters 108, 13-17 (2018) 8. Shi, G. et al. Two-dimensional Na-Cl crystals of unconventional stoichiometries on graphene surface from dilute solution at ambient conditions. Nature chemistry 10, 776 (2018).

Resume : The search for high-energy density batteries especially stimulates the design of electrode materials with enhanced electrochemical storage properties. Downsizing the material to extend its electrochemically active surface as well as creating vacancies to create more available insertion sites are common approaches to improve the performance of electrode materials.[1] In this work, our strategy is to maximize the cationic vacancies into nano-sized spinel Fe2O3 through substituting iron by molybdenum, with the final objective of extending the electrochemical insertion domain and accessing higher specific capacities. Our electrode materials were prepared by a simple solvothermal route which allows a carefully tuning of the cationic precursors.[2] The stabilization of molybdenum cations inside the spinel structure, and consequently the creation of cationic vacancies, were characterized by a wide range of complementary techniques, including pair distribution function analysis, X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy. Interestingly, it is possible to tune both size and crystallinity of such nanomaterials by modifying the iron precursors and the synthesis conditions. The positive influence of this nanoscale engineering was firstly verified by evaluating the synthesized materials as positive electrodes in lithium batteries, with a significant enhancement of the initial specific capacity (from 40 to 100 mAh/g) for Li insertion. As magnesium-ion batteries are emerging electrochemical storage systems that are still facing lack of positive electrode materials, we are also currently evaluating the magnesium insertion inside the Mo-substituted nanosized Fe2O3. References [1] B. P. Hahn, J. W. Long, and D. R. Rolison, “Something from nothing: Enhancing electrochemical charge storage with cation vacancies,” Acc. Chem. Res., vol. 46, no. 5, pp. 1181–1191, 2013. [2] B. P. Hahn, J. W. Long, A. N. Mansour, K. A. Pettigrew, M. S. Osofsky, and D. R. Rolison, “Electrochemical Li-ion storage in defect spinel iron oxides: The critical role of cation vacancies,” Energy Environ. Sci., vol. 4, no. 4, pp. 1495–1502, 2011.

Resume : NiO is a transition metal oxide p-type semiconductor with a wide bandgap (3.6-4.0 eV). It is antiferromagnetic in the bulk. When the particle size of antiferromagnetic materials is reduced, the uncompensated spins on the surface gives a non-zero net magnetic moment. This makes NiO a prototype material for both ferromagnetic and antiferromagnetic spintronics. In this work, NiO nanoparticles were synthesized by a sol-gel method followed by thermal annealing at different temperatures and time to vary the size and stoichiometry. Raman scattering is a rapid probe of both the structure and magnetism at a microscopic level. The phonons and magnons observed in the Raman spectrum reflect the effect of finite size and surface effects and helps to identify the super-exchange mechanism associated with the short-range magnetic interactions. The phonon-magnon (1P+1M) mode, splitting of the optical phonons, and the two-magnon (2M) peak observed in the Raman spectra are signatures of the magnetic properties. Their occurrence and size dependence are correlated with magnetization measurements which show an increasing component of ferromagnetism with decreasing size. The increasing intensity of 2M mode with higher crystallite size is attributed to an increase of antiferromagnetic spin correlations.

Resume : TiO2 nanopowders are generally used in photocatalysis because of their higher activity if compared to thin films. However, coatings that are prepared from nanopowders are less mechanically stable, i.e. have weaker than thin films adhesion to the substrates. In this study, TiO2 compact layers are fabricated by chemical spray pyrolysis method. Chemical spray pyrolysis method is an easy, fast, low-cost and resource-saving deposition process which does not require sophisticated apparatus, process is performed in air. Applied technological processes use low concentrations of Ti-precursor solution; process is easily industrially scalable and enables to cover large areas. Significant advantage is that the TiO2 layers are directly grown onto a substrate and do not need any further immobilization. The films’, with an area of 600 cm2, photocatalytic activity for the degradation of volatile organic compounds was studied in multi-section plug-flow reactor. The process operating parameters, like air humidity, residence time, content of pollutants and irradiation source were varied. The recent results show that sprayed TiO2 thin films with a thickness of 200 nm effectively decompose several volatile organic compounds with concentration up to 40 ppm, such as acetone, formaldehyde, heptane and toluene in air under UV-A and VIS light illumination. Thus, thin films fabricated by spray method demonstrate excellent potential to replace TiO2 nanopowder coating in air cleaning devices.

Resume : ZnAl2O4 spinel is a promising luminescent host that can act as blue and white emitter without the incorporation of rare-earths and as NIR emitter doping with Cerium and Neodymium. These color-tunable emissions make this material a suitable host for a wide range of applications, e.g, bio-imaging, security markers, imaging devices, optical coatings and solar cells. Using a cost-effective and flexible route such as the sol-gel, ZnAl2O4 nanofibers were synthesized, being the average diameter about 60 nm. By virtue of processing conditions and the incorporation of different rare-earths concentrations, it is possible to tune the ratio between Ce3+ and Ce4+in the material and their functional response. To clarify the role of trivalent and tetravalent Cerium on the modulation of NIR emission and the establishment of the luminescence mechanism, photoluminescence and Ce L3-edge X-ray absorption near edge structure analysis; determining the relative amount of the two-oxidation states. In addition, the cytotoxicity studies point out that the nanofibers are biocompatible with human cells.

Resume : Halide perovskite solar cells (PSCs) have revolutionized the photovoltaic arena providing power conversion efficiencies currently above 25 %, low cost and ease of fabrication. Their combination in tandem architectures with Silicon solar cells will permit to build a terawatt-scale energy production required in a low-carbon economy, shaping the energy future of our society. However, it is imperative that we ensure the application of materials that are compatible with low-cost solution processable techniques and, most important allows for stable PSCs devices. In this talk, I will briefly review the most important aspects of PSCs to take into account to fabricate solution processable devices. For example, I will describe the advantages behind the use of semiconductor oxides as transport layers and our newest results on the effect of ferroelectric oxides on the halide perovskite grain size. I will also include the application of additives, the importance of defect control and passivation in the halide perovskite absorber or the effect of device architecture, among others. I will present the most recent results developed in our laboratory related to the development of novel materials and methods to fabricate solution processable PSC which we currently fabricate as efficient devices (21.1%) that can retain near 100 % of their original performance after 1,000 h of continuous operation at maximum power point under 1 sun illumination.

Resume : Inorganic perovskites display an enticing foreground for their wide applications in photovoltaics (PVs). For efficient and robust PV devices, a dense, homogeneous and stable perovskite film is required. Recently, supercrystals (SCs) of inorganic perovskite nanocrystals (IP-NCs) have been reported to possess highly ordered structure as well as novel collective optical properties, opening new opportunities for high-efficiency PV films. Here, we report firstly the large-scale assembly control of spherical, cubic, and hexagonal SCs of inorganic perovskite NCs through templating by oil-in-oil emulsions. We show that the competition between nanocrystal shape and droplet surface tension sets the superstructure morphology, and we exploit this interplay to design hexagonal close-packed hyperlattices of SCs. The SCs show remarkable morphological stability for at least two months without obvious structural degradation and minor optical changes. The assembly of perovskite NCs into well-defined superstructures, deposited into a dense and highly ordered film, provides new prospects for bottom-up production of optoelectronic devices based on the microfluidic production of mesoscopic building blocks.

Resume : Nowadays, visible quantum dots have already become the essential nanomaterials to increase color gamut for display devices, for example, cadmium selenide (CdSe), perovskites (CsPbBrxI1-x) or indium phosphide (InP). Among these nanomaterials, InP QDs are regarded as high-end emitting nanomaterials in the future display industry due to their non-heavy-metal property. However, the relationship between optical properties and shell conditions has not been fully understood. Here, we present a robust method to synthesize InP core-shell QDs with high reproducibility. In particular, we remove residual water from the reactive solvent by using sodium metal adsorption method to synthesize InP QDs with high photoluminescence quality. The as-prepared InP QDs with further ZnSeS shell could provide higher PLQY (>70%). The results suggest the PLQY value is independent of shell composition but it related to shell coverage for InP core-shell QDs (when shell thickness <2 monolayers). Furthermore, the uniformity of QD size (size deviation needs <1 nm) would determine the final PLQY value for InP core-shell-shell QDs (when shell thickness <3 monolayers). This study provides a possible way to reproducibly synthesize high quality InP-based QDs and the effect of shell thickness, composition and uniformity on optical properties are also discussed.

Resume : Colloidal quantum dots (QD) have opened pathways for novel infrared (IR) image sensors, which are essential for emerging technologies such as biometric sensors, augmented/virtual reality. QD based sensors can overcome the limits of state-of-the-art IR sensors, such as the Si absorption cut-off at 1 µm or the high cost of InGaAs. While great advances have been achieved the last years in the synthesis and processability of QD, the main challenge remains the surface passivation. Here, we focus on PbS QD and demonstrate the major effect of the ligand termination in their optoelectronic properties. First, all optical constants of QD films using various organic and inorganic ligands are measured by ellipsometry. This allows to model the photogenerated carrier profiles and drift-diffusion transport. The correlation with steady-state photoluminescence (PL) experiments on different stacks comprising a quenching layer allows to extract the carrier diffusion length and lifetime accurately from the experimental data. We show that the diffusion length improves from 9 nm for thiol ligands to 150 nm for mixed halides. However, this is attributed to the increased mobility due to the decreased inter-dot spacing, while the effective lifetimes remain always in the range of a few hundred nanoseconds. Finally, the mapping of the transient PL data with the solutions of the time-dependent drift-diffusion equation enables to estimate the speed limitations of QD based absorbers.

Resume : Metal chalcogenide quantum dots (QDs) are promising materials for light harvesting in photocatalytic water splitting. However, these materials are typically synthesized through high temperature, multi-step processes that utilize organic solvents and expensive precursors, increasing the complexity and economic and environmental costs of scale-up; especially considering the desired scale of photocatalytic hydrogen production. In contrast, biomineralization, the process by which biological systems produce structural nanomaterials, occurs under ambient conditions in aqueous media. We have developed an enzymatic biomineralization route to the direct, scalable, size-controlled synthesis of QDs in numerous forms; from single component materials, to alloys, and core-shell heterostructures. We have also developed an analogous route to the synthesis of reduced graphene oxide (r-GO) utilizing biologically generated reductant. A key step in the green synthesis of high performance QD/r-GO photocatalysts is to efficiently couple these two components via a linker that facilitates photoexcited electron-transfer from the QD to the r-GO. In addition to these individual components, we have overcome this challenge to achieve an enzymatic, room temperature, aqueous phase synthesis of QD/r-GO photocatalysts that provides solar hydrogen production rates equivalent to the best chemically synthesized materials. This presentation will discuss the origin of size control in the QD synthesis process, the optimization of the biomineralization processes and linker molecules, and demonstrate the activity of the resulting photocatalyst for solar hydrogen generation.

Resume : The design and synthesis of solution processable, atomically controlled and tunable multi-component nanomaterials is crucial to advance many applications, spanning from catalysis to plasmonics, nanoelectronics and energy harvesting. Yet, interfacing domains of different chemical nature poses new synthetic challenges for chemists and material scientists. Here, the ability to tailor-make material platforms with tunable morphological characteristics in an unrestricted compositional range is critical for providing understanding of the performance sensitivities to different structural parameters. Our work highlights how colloidal chemistry can aid to construct such nanomaterials and to develop new concepts for storing energy into chemical bonds. After a general introduction on colloidal chemistry and an overview on the tools that we have developed to study the reaction mechanisms [1,2], this talk will focus on our recent efforts on the growth of metal oxide coatings on semiconductor quantum dots both in solution and in thin films.[3,4] We will discuss how these coatings enable studies of nanoscale phenomena, including anion exchange and solar-to-chemicals conversion, which were not possible otherwise. [4,5] References [1] M. Strach, V. Mantella, J.R. Pankhurst, P. Iyengar, A. Loiudice, S. Das, C. Corminboeuf, W. van Beek, R. Buonsanti Insights into reaction intermediates to predict synthetic pathways for shape-controlled metal nanocrystals J. Am. Chem. Soc. 2019, 141, 16312 [2] C. Gadiyar, M. Strach, P. Schouwink, A. Loiudice, R. Buonsanti Chemical transformations at the nanoscale: nanocrystal-seeded synthesis of β-Cu2V2O7 with enhanced photoconversion efficiencies Chem. Sci. 2018, 9, 5658 [3] A. Loiudice, S. Saris, E. Oveisi, D.T.L. Alexander, R. Buonsanti CsPbBr3 QD/AlOx inorganic nanocomposites with exceptional stability in water, light and heat Angew. Chem. Int. Ed. 2017, 56, 10957 [4] A. Loiudice, M. Strach, S. Saris, D. Chernyshov, R. Buonsanti Universal Oxide Shell Growth Enables In-situ Structural Studies of Perovskite Nanocrystals during the Anion Exchange Reaction J. Am. Chem. Soc. 2019, 141, 8254. [5] S. Sarys, A. Loiudice, M. Mensi, R. Buonsanti Exploring Energy Transfer in a Metal/Perovskite Nanocrystal Antenna to Drive Photocatalysis J. Phys. Chem. Lett. 2019, 10, 7797.

Resume : Multimetal oxides, especially those of the perovskite family, have a very broad field of applications from catalysis, to sensing and energy conversion. In order to benefit from this, and propose reliable alternative solutions to noble metals, the surface characteristics of the materials such as porosity, surface area and more importantly reactivity need to be carefully optimized. Surprisingly, the synthesis procedures for such materials in the last years did not undergo major changes and still relies on solid-state strategies or sol-gel-like procedures as the well-known Pechini method, mostly employed to get bulk structures. Herein, we present novel synthesis strategies for the preparation of nanostructured and nanoporous perovskite oxides with improved catalytic properties through the design of polymer precursors[1–3]. The combination of citric acid with polyols of increasing length resulted in polymers with highly cross-linked structure, thus leading to Fe-doped SrTiO3-based materials with substantial mesoporosity and specific surface area [1]. Due to their hydrophilicity, the polymers intimately combined with siliceous endotemplates thus originating phase pure perovskites with up to four times higher specific surface area [2]. The outstanding material mesostructure along with the shorter diffusion path length for the charge carriers provided enhanced thermal and photo-catalytic properties to the synthetized materials[1–3]. [1] B. Kayaalp, S. Lee, K. Klauke, S. Jongsu, L. Nodari, A. Kornowski, W. Jung, S. Mascotto, Appl. Catal. B Environ. 2019, 245, 536–545. [2] B. E. Kayaalp, Y. J. Lee, A. Kornowski, S. Gross, M. D’Arienzo, S. Mascotto, RSC Adv. 2016, 6, 90401–90409. [3] J. Scholz, A. Garbujo, B. Kayaalp, K. Klauke, A. Glisenti, S. Mascotto, Inorg. Chem. 2019, 58, 15942–15952.

Resume : Metal oxide nanostructures with hetero-contacts and phase boundaries offer unique platform for designing materials architectures for energy harvesting applications. As viable alternative to water electrolysis, photoelectrochemical (PEC) water splitting has emerged as a competitive technology being capable of converting solar energy directly into chemical energy using stable and efficient photocatalysts for solar hydrogen production. Besides the size and surface effects, the modulation of electronic behaviour due to junction properties leads to modified surface states that promote selective decomposition of analytes and adsorbates. The growing possibilities of engineering nanostructures in various compositions (pure, doped, composites, heterostructures) and forms has intensified the research on the integration of different functional material units in a single architecture to obtain new photocatalytic materials. Even though the potential of hematite thin films for water splitting applications are widely accepted, researchers are still tackling the ‘rust challenge’. We report here on the influence of external magnetic fields applied parallel or perpendicular to the substrate during plasma enhanced chemical vapor deposition (PECVD) of hematite (α-Fe2O3) nanostructures. Hematite films grown from iron precursors showed pronounced changes in crystallographic textures depending upon whether PECVD was performed with or without the influence of external magnetic field. Investigations on the water splitting properties of the hematite films in a photoelectrochemical reactor revealed superior photocurrent values of hematite photoanodes deposited in external magnetic field.

Resume : Noble metal nanomaterials are well known in the field of catalysis for various inorganic and organic chemical reactions. Besides common catalyst design strategies based on the modulation of nanomaterial morphology, size, and composition, a rapid transition on noble metal-based catalysis research has been made toward the crystal phase engineering approach in the past two decades, which opens up a huge opportunity for the exploration of unusual crystal structures of noble metals with fascinating and exotic physiochemical properties [1]. The first few reported synthetic methods of thermodynamically metastable phases of noble metals often required high-temperature and high-pressure treatment, and the morphology of resulting nanomaterials were mostly particles [2-4]. Since then, the synthesis of unusual noble metal crystal structures has been extended to the use of the solution-phase system, which provides a much more flexible platform to fine-tune the structural parameters of the resulting nanomaterials. For example, hexagonal close-packed (hcp) 2H Au nanosheets and 4H nanoribbons were formed in organic solvents with appropriate use of surfactants and reaction temperature to control the reaction pathway kinetically and induce the formation of such thermodynamically metastable crystal structures [5, 6]. On the other hand, unconventional crystal phases of Pd have only been achieved in the solution phase by using other nanostructures with unusual crystal phase as the template [7]. However, this approach is limited by the choice of the substrate and the resulting nanostructures often adopt the crystal phase of the starting template. It is also complicated to design two different synthetic routes for each component in this approach. To overcome this problem, in our work, we have successfully developed a one-pot wet-chemical method to synthesize PdM (M = Zn, Cd, ZnCd) nanosheets. The nanosheets of less than 5 nm thick crystallized into unconventional face-centered tetragonal crystal structure with the presence of grain boundaries and dislocations within a single nanosheet which are potentially active for catalytic reactions. The introduction of Zn and Cd atoms in Pd nanosheets also caused a noticeable change in the electronic structure of the resulting alloyed nanostructures according to the shift of Pd 3d XPS peaks compared to pure Pd nanosheets. With the large surface area of the 2D structures as well as the abundance of defects on the nanosheets, PdZn alloyed nanosheets exhibited significantly enhanced catalytic activity toward ethanol oxidation reaction in alkaline solution in comparison to pure Pd nanosheets and commercial Pd black. The mass activity of PdZn nanosheets is about thrice that of Pd black and the current density retained 20.7% of its initial value after 1 h chronoamperometric stability measurement. References 1. Cheng, H., et al., Syntheses and Properties of Metal Nanomaterials with Novel Crystal Phases. Adv Mater, 2018. 30(26): p. e1707189. 2. Sun, S., et al., Monodisperse FePt Nanoparticles and Ferromagnetic FePt Nanocrystal Superlattices. Science, 2000. 287(5460): p. 1989-1992. 3. Wang, D., et al., Structurally ordered intermetallic platinum–cobalt core–shell nanoparticles with enhanced activity and stability as oxygen reduction electrocatalysts. Nature Materials, 2013. 12(1): p. 81-87. 4. Guo, Q., et al., Cubic to Tetragonal Phase Transformation in Cold-Compressed Pd Nanocubes. Nano Letters, 2008. 8(3): p. 972-975. 5. Huang, X., et al., Synthesis of hexagonal close-packed gold nanostructures. Nat Commun, 2011. 2: p. 292. 6. Fan, Z., et al., Stabilization of 4H hexagonal phase in gold nanoribbons. Nat Commun, 2015. 6: p. 7684. 7. Chen, Y., et al., High-Yield Synthesis of Crystal-Phase-Heterostructured 4H/fcc Au@Pd Core-Shell Nanorods for Electrocatalytic Ethanol Oxidation. Adv Mater, 2017. 29(36).

Resume : Piezocatalyst is one of the most innovative catalysts for renewable energy production in recent years. It has attracted broad interest due to its ultra-high efficiency and renewability. In this study, the cost-effective, eco-friendly and high stability piezoelectric quartz microrods were successfully synthesized from rice husks for effective hydrogen evolution reaction (HER). After the post-annealing treatment in argon and hydrogen mixture gaseous atmosphere, the hydrogen generation rate has effectively enhanced 80%, from 3178 μmol/g/h to 5729 μmol/g/h. While after three times cycling test, the hydrogen generation efficiency remained 87%, indicating its high mechanical durability and stability. The piezoelectric property of the as-synthesized quartz microrods has been confirmed by piezoresponse force microscopy (PFM). Based on x-ray photoelectron spectroscopy (XPS), the chemical states of Si and O have been changed. It is deduced that partial reduction of Si leads to improve the conductivity and thus contribute to the significant enhancement of hydrogen generation efficiency. The process is under a completed dark environment without an additional illumination, which provides a unique opportunity for industry applications.

Resume : This work, Ca(ZrYCeCrAg)O), modified from pristine CaZrO3, owning inner heterostructure, which was sonicated with visible light has been confirmed it can enhance piezo-photo catalytic activity for organic dye degradation. CaZrO3(CZO) demonstrate remarkable optical information storage application due to possessing numerous intrinsic traps and ferroelectricity, which imply long recombination lifetime. However, the large band gap (3.3eV) restrict its photo-catalytic efficiency for dye degradation. Herein introduction of several transition metal elements into CZO nanoparticles has been synthesized by a sol-gel process and forms heterojunction nanostructure(fluorite-((Zr,Y,Ce)O2) & perovskite-CaZrO3) with porous nano particle. The time-resolved photoluminescence (TRPL) reveals that recombination lifetime have already improved up to 620% compared to pristine CZO. CZO, which belong to Pnma group of perovskite structure, display unique ferroelectricity which has spontaneous polarization for prolonging lifetime and enhance piezo-photo activity. Besides, modified-CZO surrounded by silver nanoparticles, demonstrating localized surface plasmon resonance (LSPR) effect as observed by surface enhanced raman spectrum(SERS) Through ultraviolet-visible (UV-Vis) spectrophotometer measurement, modified-CZO is achieving almost 200% degradation performance compared to pristine CZO. The vast enhancement arises from piezo-photo activity, which was combined through ferroelectricity, charge transfer mechanism for prolonging recombination lifetime, and induced local electric field for generating numerous electron-hole pair. The COMSOL software was employed to simulate the charge distribution. The mechanism on LSPR enhanced piezo-photo catalytic dye degradation will be investigated. Keywords: CaZrO3, Ag, Ferroelectricity, Lifetime, Surface Plasmon Resonance, Dye Degradation

Resume : Dielectric nanoparticles have recently attracted extensive attention, because they exhibit ultralow absorption losses and support strong electric and magnetic resonances simultaneously. Dielectric nanoparticles are expected to complement or even replace plasmonic components in many applications, such as directional light scattering, nonlinear optics and functional metasurfaces. However, there are still challenges in controlling the sizes and shapes of dielectric nanoparticles. Here we report on a wet-chemistry growth method for the synthesis of colloidal Cu2O nanospheres with uniform sizes and shapes. The diameters of the Cu2O nanospheres can be adjusted from ~100 to ~350 nm, supporting both electric and magnetic resonances in the visible region. The spectrally overlapped electromagnetic resonances endow Cu2O nanospheres with excellent directional light scattering property. In practice, for most semiconductor devices and metamaterials, dielectric nanoparticles need to be deposited on various substrates. Investigating the substrate effects on the optical resonances of dielectric nanoparticles is of great importance for engineering their resonances and designing devices. In our studies, the substrate-modulated electromagnetic resonances in colloidal Cu2O nanospheres are explored. When supported on ITO-coated ITO glass and Si wafers, the color of the nanospheres varies gradually from blue to red with their diameters increase, covering almost the entire visible region. When deposited on Au films, their electromagnetic resonances redshift and a new effective magnetic resonance mode appears. The enhanced Raman scattering reveals that large electromagnetic field enhancements are produced in the gap region.

Resume : Abstract: The large-scale temperature-responsive nanomaterial composite sponge was synthesized by a dip-coating method and served as a highly-efficient adsorbent to removal environmental pollution ─ dibutyl phthalate (DBP) and parachlormetaxylenol (PCMX) from water sample. Cu based metal-organic nanotubes (Cu-MONTs) which contain the advantages of carbon nanotubes and metal-organic frameworks were fabricated though solvothermal method and chosen as model nanomaterial. After connection the nanomaterial with temperature-responsive polymers poly(N-isopropylacrylamide) (PNIPAM), its surface could exhibit “ON-OFF” state through conformation change. Like the majority of nanoscale materials, MONTs-PNIPAM were obtained as powders. However, for their actual application, the powders must be fabricated into other form. In this work, a rapid and convenient method for large-scale synthesis of new composite material that comprise nanoscale MONTs-PNIPAM and macroporous 3D sponge structure was reported. By interaction of electrostatic charges, Cu-MONTs-PNIPAM and a macroporous 3D sponge were constructed. The nano material composite sponge was characterized by Fourier Transform Infrared Spectra (FT-IR), Scanning Electron Micrographs (SEM), X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS) and N2 sorption-desorption. The maximum adsorption capacities for DBP and PCMX were 101.29 mg/g and 163.93 mg/g, respectively. Kinetics and equilibrium adsorption parameters illustrated the adsorption fitted the pseudo-second-order kinetic model and Langmuir isotherm. Moreover, this nanomaterial composite sponge was recycled and its adsorption efficiency only decreased by 8.2-10.3% after 10 times “adsorption-desorption” cycles. This resulting Cu-MONTs-PNIPAM sponge achieved large-scale fabrication, excellent adsorption, chemical stable and recycle which is an ideal adsorbent for actual application of environmental pollution removal.

Resume : Silica aerogel is fascinating solid materials with very low density, high meso-porosity and ultralow thermal conductivity. However, the actual aerogel applications have been hindered seriously due to low density and fragility which also complicate handling or processing aerogels. Because, the silica aerogels have poor mechanical strength owing to its nanoporous structure and high porosity. One of the good methods to solve these problems and also to expand the application of aerogels is the combination of aerogel powders or hydrophobic gel with woven fiber. In this research, the hydrophobic gel solution was prepared through solvent exchange and surface modification process on the hydrogel produced by adding isoprophyl alcohol to form gelation from water glass added inorganic acid, namely, silicic acid. The hydrophobic gel solution added to hexane of constant amount was carried out various pre-treatment conditions in order to disperse hydrophobic gel in the solution using agitator or homogenizer. Then the pre-treatmented hydrophobic gel solution was used to impregnate into the blanket and finally the silica aerogel blankets were fabricated by ambient pressure drying on the blanket. The total process time of the aerogel blanket preparation could be drastically reduced to 8hrs. Also the silica aerogel powders were synthesized for investigation on change of aerogel properties according to various pre-treatment conditions like the blanket preparation process on the hydrophobic gel solution. The silica aerogel was prepared by a sol-gel process using waterglass as silicon derivative, n-hexane as solvent, and trimethylchlorosilane as surface modification agent, followed by ambient pressure drying. The chacracterizations of silica aerogel powders and aerogel blankets were evaluated for the microstructure, tap density, specific surface area, pore size distribution and thermal conductivity.

Resume : Recently, the fully inorganic CsPbX3 NCs (X= Cl-, Br-, I-) have been extensively attracted because of their high PLQY, narrow size distribution, low cost, simple preparation, high reproducibility and narrow emission width as well as their easy color tunability via control of their composition. Despite many advantages, the instability and anion-exchange reaction are still issue that hinder their practical application such as LEDs. Therefore, we first report a simple and easy polymeric encapsulation method for CsPbX3 NCs based on the self-assembly of oxidized polyethylene (PE) wax. Our approach can be divided into three experimental steps: (1) the oxidized PE wax was dissolved in toluene with heating, (2) CsPbX3 solution was injected into the hot PE wax solution, and (3) the mixed solution was cooled at a constant cooling rate using a water bath. Consequently, a pumpkinseed shaped polymeric microcapsule composed of multi-lamellar structure was formed and CsPbX3 NCs were entangled in an amorphous region located between the crystalline regions. Our results that CsPbX3 NCs can be a potential candidate for optoelectronic device for next generation materials.

Resume : The cost-effective fabrication of nanostructured cathodes for solid oxide fuel cells (SOFCs) that catalyze the oxygen reduction reaction effectively is a milestone to be achieved. Infiltration being the conventional method for the fabrication of nanostructured SOFC cathodes requires many infiltration and calcination cycles due to the low catalyst loading per infiltration cycle. Chemically assisted electrodeposition (CAED), a new means of fabricating nanostructured SOFC cathodes in a single loading step, provides the advantage of the simultaneous deposition of multiple cations while using dilute aqueous solutions of readily available salts. In this study, CAED is demonstrated by fabricating a cobalt-free LNO (LaNiO3)/GDC composite cathode. The LNO/GDC composite cathode prepared by CAED exhibits superior electrochemical properties compared to LNO/GDC composite cathodes fabricated by sintering or self-assembly (a recently introduced low-temperature SOFC cathode fabrication method) approaches. An anode-supported SOFC with a LNO/GDC composite cathode fabricated by CAED shows a high power density of 974 mW cm-2 at an intermediate operating temperature of 750 °C. Low-temperature nano-fabrication by CAED, producing a cathode with a high surface area while avoiding the formation of insulating phases, is believed to play an important role in achieving better SOFC performance.

Resume : Nowadays, population growth and human development as well as industrial activities have led to the environmental pollution. So, the solar energy is one of the most promising technologies due to its potential applications to address those issues. Much effort has been focused on semiconductors photocatalysis, which utilizes solar energy to decompose various organic contaminants in waste water. An important example is the Ag3PO4 photocatalyst, which possesses high visible-light photocatalytic activity in O2 evolution and organic contaminant degradation, especially, for the color substances degradation. To widen the solar use of such a photocatalyst, we use Cu-doping to reduce its bandgap energy in order to benefit from the entire solar radiation spectrum. In this work, Cu-doped Ag3PO4 photocatalysts were successfully prepared via traditional Sol-Gel method. Structural and morphological characterization techniques (XRD, UV-Vis, TEM and FT-IR) were used to quantify the particles size and molecular bonding. The effects of Cu doping on the photocatalytic performance of Cu-Ag3PO4 was also studied. Density functional theory calculations have been performed to complement the experimental results and understand the physical behavior of the electronic and optical properties involved.

Resume : Electrochromic (EC) windows undergo changes in light transmittance in response to an applied voltage, enabling the dynamic control of daylight and solar heat passing through buildings. This technology can improve building energy efficiency by as much as 20%. Commercially available EC windows are produced by sputtering, which is a high-cost and energy-intensive technique that involves high vacuum conditions and sophisticated instrumentation. The high manufacturing cost of sputtered EC windows has prevented their widespread deployment. Here we developed a cost-effective solution-based photodeposition method for accessing amorphous metal oxide films for electrochromic layers and charge-balancing counter electrode layers, enabling the fabrication of full EC devices that show state-of-the-art performance.[1-2] This method uses UV irradiation to convert solution-processed metal chlorides to desired amorphous metal oxides. We found that UV-light and UV-induced reactive oxygen species such as ozone can drive the liberation of chloride ions in metal chloride precursor films and the formation of amorphous metal oxide films. Importantly, this method is amenable to scalable solution deposition techniques such as spray-coating, which enables us to fabricate large-area electrochromic devices. This scalable technique also has other advantages including low temperature processing, rapid deposition, inexpensive instrumentation, and easy operation which meet the industrial production requirements. Therefore our photodeposition method has the potential to expedite commercial large-scale deployment of EC windows. [1] W. Cheng, J. He, K. E. Dettelbach, N. J. J. Johnson, R. S. Sherbo and C. P. Berlinguette, Chem, 2018, 4, 821-832. [2] W. Cheng, M. Moreno-Gonzalez, K. Hu, C. Krzyszkowski, D. J. Dvorak, D. M. Weekes, B. Tam and C. P. Berlinguette, iScience, 2018, 10, 80-86.

Resume : This study reports the highest BET surface area (1312 m2/g), and the highest total pore volume (1.41 cm3/g) that has been reported for Fe-BTC to date. More importantly, a CO2 adsorption capacity of 27.5 wt.% (6.24 mmol/g) is achieved at 8.5 bar and 298 K that is the highest of the reported for Fe-BTC. A perturbation assisted nanofusion mechanism is used to synthesize Fe-BTC that forms hierarchical pores. Synthesis parameters are optimized to enhance the amount of CO2 adsorbed. The highest CO2 adsorption capacity of 27.5 wt.% (6.24 mmol/g) is achieved by Fe-BTC that has ultramicropores (pore diameter<0.7 nm) in its pore structure. The measured CO2 uptake capacity (1 bar and 298 K) is higher than those of MOFs (MOF-177, UMCM-1, MIL-101(Cr), ZIF-8, and MOF-5) reported in literature. Herein, we experimentally prove the significant contribution of ultramicropores, and narrow micropores (pore diameters<1 nm) on the adsorbed CO2 amount. In conclusion, this study i) reports a strategy that increases BET surface area (1.6 times), total pore volume (3.1 times) and CO2 adsorption capacity (1.66 times); and ii) shows the critical role of ultramicropores, volume and distribution of narrow micropores on the adsorbed CO2 amount. The reported synthesis strategy leads the way to synthesize highly porous sorbents with enhanced BET surface area, total pore volume and CO2 sorption capacity which should be further examined on other porous sorbents to achieve the aimed CO2 sorption goals.

Resume : The prevalence of pathogenic microbes and superbugs in the environment is a worldwide health concern.1-3 Development of efficient antimicrobial system is need of the time. Immobilization of the antimicrobial metal oxide nanomaterials on paper matrices as a cost effective and biodegradable substrate is advantageous as leaching of the nanoparticles is also negligible. Herein, Ag+ doped ZnO nanowires (Ag:ZnO NWs) have been immobilized on the paper matrices using a facile single step hydrothermal method, which deactivation E. coli and G. trabeum. The immobilization of Ag:ZnO NWs on the paper matrices has been confirmed by the XRD, XPS, TGA, FESEM and TEM. The paper matrices deactivated 108 CFU E. coli within 2h of visible light exposure and also desisted the G. trabeum growth for 7 days. The doping of Ag+ in the lattice of ZnO NWs have shown to improve the antimicrobial activity against E. coli and G. trabeum. References: 1. G.D. Wright, Chem. Biol. 7 (2000) R127-R132. 2. C. Willyard, Nature 543 (2017) 15. X. Zeng, D.T. McCarthy, A. Deletic, X. Zhang, Adv. Funct. Mater. 25 (2015) 4344-4351.

Resume : Recently, all-inorganic perovskite nanocrystals emerged as an efficient material for optoelectronic applications. However, the presence of trap states at the surface hinders their optical and electrical properties. Along with this, the NCs are surrounded by organic ligands, which prevent the effective injection of charge carriers in the devices. So, to integrate these NCs into the devices, it is essential to address the issues mentioned above. Herein, we report the post-synthetic treatment of CsPbBr3 NCs with phenethylammonium bromide. This treatment results in highly stable and luminescent CsPbBr3 NCs with an increase in photoluminescence quantum yield (PLQY) from 69.1% to 92.4% without changing the shape and size of NCs. Time-resolved photoluminescence decay traces and ultrafast transient absorption measurements confirm the removal of defect states after the treatment, which are responsible for non-radiative recombination of charge carriers. Additionally, this treatment efficiently removes ligands from NCs surface while sustaining their colloidal stability. Finally, photodetectors were fabricated by using pristine as well as phenethylammonium bromide treated CsPbBr3 NCs. The treated CsPbBr3 NCs based photodetector shows a high on-off ratio with fast response time as compared to a very weak photoresponse of pristine CsPbBr3 photodetector. This work provides a simple but effective way to make high-quality NCs for optoelectronic applications.

Resume : Transparent conducting materials are one of important components in many electronic devices such as liquid-crystal displays, organic light emitting diodes, touch screens, photovoltaics, thermoelectrics, and so on. For practical applications, both n-type and p-type transparent conducting materials should exhibit a low electrical resistivity with a wide bandgap whose energy value should be larger than those of visible light. Indium tion oxide (ITO) has been recognized as a standard n-type transparent conducting oxide (TCO) the most widely used in industry that shows a high electrical conductivity σ of ~10000 S cm-1 and a transmittance of >80 %. However, TCOs have some critical drawbacks including an expensive and fluctuating cost of indium metal in the case of ITO, inapplicability of flexible plastic substrates due to its high synthetic temperature of >400 °C, and difficulty in obtaining high-performance p-type TCOs. Copper iodide (CuI) has been recently reported to be a highly conductive p-type transparent conducting material at room temperature (RT). Furthermore, a transparent CuI thin film has been prepared near RT by various chemical and physical methods, allowing it to be compatible for both organic electronics and flexible electronics. However, a facile, reliable, scalable, and large-area CuI thin film has been elusive for a practical application of p-type transparent electronics. Here we report a simple, quick, and mild chemical process for making a highly conductive CuI thin film at RT. In this study, we present various investigations of electrical measurements as well as structural data on CuI thin films. The highly conductive CuI thin films are successfully realized and its origin will be discussed.

Resume : The aims and tasks of this work were to investigate or define more precisely equilibria in conventional alkaline solutions of electroless copper deposition as well as influence of the nature of Cu(II) ligands on the copper deposition process and properties of deposited films. This research report deals with the results obtained by means of dc-polarography, vis-spectrophotometry, voltammetry, potentiometry, pH-metry, 1H and 13C NMR spectroscopy, scanning electron microscopy, X-ray diffractometry and gravimetry. The composition, stability and the values of the diffusion coefficient of Cu(II) complex compounds with ligands (EDTA, DTPA, pyridine-2,6-dicarboxylic acid and 4-hydroxypyridine-2,6-dicarboxylic acid, Quadrol, L(+)-, D(–)- and DL(-/+)-tartrate, glycerol, saccharose and OH- ions) which are used or usable in alkaline electroless copper deposition solutions were established. The formation of mixed complex compounds between Cu(II) complexonates and K4Fe(CN)6, as well as between Cu(II) tartrate complexes and methanediol was investigated. The interaction of methanediol with L(+)-tartrate alongside with the influence of the ionic strength and cation nature on the deprotonation of methanediol in alkaline solutions were studied. The kinetic data on electroless copper films formation from solutions containing above-mentioned ligands are presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.

Resume : Chalcogenide glasses are attractive optical materials due to their high transmittance and low losses in the near infrared spectrum. Many applications of these glasses require patterning with micro/nano- structures, e.g. diffraction gratings, antireflection morphologies, or waveguides. These patterns can be imprinted due to the low glass transition temperature (Tg) of those glasses. However, high imprint pressure and temperature deforms the imprinted substrate. Here, we demonstrate a novel approach for the direct imprint of chalcogenide glasses, by which the glass solution is spin coated on the glass substrate, and baked to produce a plasticized film whose glass transition point is below that of the bulk chalcogenide glass. The film is then imprinted with soft mold at the temperature below that of the Tg of the bulk chalcogenide glass, thereby maintaining the original substrate shape.  We demonstrated this approach by imprinting As2Se3. First, we characterized Tg of the solution-deposited As2Se3 films using nano-indentation, to optimize the conditions for the film formation. We then fully characterized the chemical composition and optical properties of the frim and imprinted structures, and verified that they are similar to that of bulk As2Se3. Finally, we patterned As2Se3 surface with diffraction grating and moth-eye antireflective coating. Our approach opens a novel route for facile micro-processing of chalcogenide glasses and enables their numerous future applications.

Resume : Nanostructuring of electrode materials is considered as a promising way to achieve high specific capacity and rate capability in lithium-ion batteries. Most of the synthesis of nanostructured material for electrodes usually involve complex processing and high energy consumption. Here, we report a facile and reproducible method to synthesize dual phase Li4Ti5O12-TiO2 nanostructures at low temperature as superior anode materials. We make use of potassium-doped titanate nanostructures as precursor produced from Ti metal via the wet corrosion process (WCP) at room temperature. Owing to the 2D layered crystal structure, titanates ideally provide the possibility to modify the precursor through ion-exchange. Li4Ti5O12-TiO2 nanowires were produced by WCP, ion-exchange and calcination. In particular, the calcination condition controls the phases present in nanowires. The nanowires annealed at 450ºC maintained the nanowire structure and showed the presence of TiO2 and Li4Ti5O12 phases with a fraction of 7:3. These nanowires yielded the highest specific capacity of 180mAh/g at 0.5C, 105 mAh/g at 5C and a remarkable capacity retention of ~95 % after 150 cycles at 5C. They are the best electrochemical behavior among previous Li4Ti5O12-TiO2 anode material studies. We demonstrate that these dual phase nanowire structures effectively provide the synergy to shorten the diffusion path of lithium ions and to accelerate ion/electron migration owing to abundant interfaces/grain boundaries.

Resume : The requirements for the environmental monitoring, industrial and domestic safety necessitate the rapid and accurate detection of different air pollutants at the TLV level and below. The main requirements for the gas sensor materials are high sensitivity, selectivity, resistance to air humidity (RH) changes and thermal stability, which insure the long-term sensor operation. Among n-type wide-gap semiconductor oxides, SnO2 is the most widely used sensor material. To prevent the sintering of nanoparticles during operating in different temperature regimes, as well as to reduce the effect of air humidity on sensor properties, it was proposed to modify SnO2 with SiO2. Nanocomposites SnO2/SiO2 with Si content of 3 – 86 mol.% were synthesized by hydrothermal method and characterized by XRD, low-temperature N2 adsorption, HRTEM, thermogravimetric and mass-spectral analysis, TPR-H2, XPS, IR and EPR spectroscopy. It was shown that amorphous SiO2 layer not only decelerates the growth of SnO2 nanoparticles during high temperature annealing but also alters the active sites on SnO2 surface that influences the conduction mechanism and gas sensing properties. Nanocomposite SnO2/SiO2 with Si content of 13 mol.% was found to be the least sensitive to the RH change. Additional modification of this material with Pd, Ru and Au results in selective sensitivity to CO, NH3 and VOCs, respectively, in humid air conditions. The work was supported by Russian Science Foundation grant 19-13-0024.

Resume : Due to its unique soft and complex structure, it has been difficult to analyze the exact crystal structure of the layered double hydroxides (LDHs), which has been a major obstacle in understanding and improving the catalytic properties of LDHs. In this report, we present a new analytic method to characterize the crystal structure of LDHs using Rietveld refinement, XPS, and XANES. Using this analytic method, we found that ZnCo LDH nanoplates prepared by a new facile synthetic route had a Zn3.1Co1.9Cl2(OH)8∙H2O structure and contained a large portion of divalent Co cation, unlike the previously reported ZnCo LDHs. Thanks to this accurate crystal structure analysis, we found that the cause of the enhanced electrochemical properties of the ZnCo LDH nanoplates toward oxygen evolution reaction was due to the large portion of divalent Co cation.

Resume : CO2 methanation is a vital reaction for converting waste energy into alternative fossil fuels. Among existing catalysts, nickel is a promising player regarding its high selectivity and low cost. In this research, acidified carbon nanotube (A-CNT) supported Ni@Pd nanoparticles (NPs) with surface decoration of Tetramethoxysilan (TMOS) is synthesized by two steps wet chemical reduction method as a thermocatalyst in the CO2 reduction reaction (CO2RR). Upon thermal reduction, the H2 from the feed gas triggers the polymerization of CO2 into high carbon chain as C3 products found in CO2 and H2 mixing gas.

Resume : The study of radiation damages in solid systems is crucial in order to understand the degradation and recovery mechanisms in irradiating environments such as space, military applications, fission reactor structural components and for nuclear waste disposal issues. Due to the hazardous nature of radioactive materials, the practical studies of radiation damage, which are conducted to confirm existing theoretical models, are very limited. Deposition of small amounts of a radioactive element such as 228Th, makes the radiation damage research much safer for the surrounding, and opens the option to perform internal (or “self”) irradiation studies which can be carried out in a regular laboratory environment due to the small dose of radiation. We have previously reported incorporation of thorium in thin films of semiconductors (PbS)[1,2], yet metallic systems are simpler for interpretation and for testing of theoretical models. In this research, an electroless chemical solution deposition process is developed, in which a thin layer of nickel is deposited together with small amounts (0.5%at) of the stable isotope of thorium, Th^232 (T^0.5~1.4×〖10〗^10 years). Although electroless nickel bath has been well studied, [3, 4] addition of 232Th to the film has not been reported to date, and it presents several challenges; Thorium ions tend to react with phosphides and hydroxides, thus inhibiting their incorporation within the film which was overcome by complexation with tri-sodium-citrate and by decreasing the reducing agent concentration. As a result, we have developed and optimized a procedure in which small amounts of 232Th are incorporated in nickel thin films (0.1-0.5 at% homogenously distributed in the film), and gained understanding of the reactions between thorium and other bath components. 1. Templeman, T., Shandalov, M., Schmidt, M., Tal, A., Sarusi, G., Yahel, E., Kelson, I. & Golan, Y. A new solid solution approach for the study of self-irradiating damage in non-radioactive materials. Sci. Rep. 7, 1–9 (2017). 2. Biton, M., Shamir, A., Shandalov, M., Arad-Vosk, N., Sa’ar, A., Yahel, E. & Golan, Y. Chemical deposition and characterization of thorium-alloyed lead sulfide thin films. Thin Solid Films 556, 223–229 (2014). 3. Wang, W., Ji, S. & Lee, I. A facile method of nickel electroless deposition on various neutral hydrophobic polymer surfaces. Appl. Surf. Sci. 283, 309–320 (2013). 4. Schlesinger, M. & Paunovic, M. Modern electroplating. vol. 30 (wiley, 1990).

Resume : Sensors that recognize acetone selectively and sensitively from human expired air have attracted great attention, because they may detect a sign of diabetes noninvasively. Tungsten oxide is known to have a great potential as a base material for acetone sensors. In particular, single crystal tungsten oxide nanowires (NWs) are considered to be promising, because they can be easily grown by hydrothermal synthesis and the NWs have properties of high surface-to-volume ratio and easy formation of low-resistance electrical contacts. Additives in hydrothermal synthesis are known to modify characteristics of NWs. In previous studies, it is shown that tungsten oxide NWs synthesized with sodium sulfate have a space group of P6/mmm and grow in the [001] direction, whereas those synthesized with ammonium sulfate have a space group of P63/mcm and grow in the [110] direction. The space group of P63/mcm indicates a non-uniform distribution of electron clouds, leading to greater adsorption of larger dipole-moment molecules; acetone, to (002) planes of tungsten oxide. However, in hydrothermal synthesis of the NWs synthesized with ammonia sulfate, pH dependencies of the morphology and crystal structure have hardly been investigated. In this study, we firstly investigated these pH dependencies. Then, the pH dependencies of concentrations of dissolved chemical species were calculated using stability constants. The relationship between the former and the latter pH dependencies will be discussed.

Resume : Among additive manufacturing (AM) technologies, powder-based 3D printing produces workpieces that could be used in a great variety of applications, such as architecture, prototypes, foundry molds, medical device, and others. This technique includes the powder deposition to form the layers, and post-processing to enhance mechanical properties. Cement can be mixed with traditional raw material powder in order to produce composite parts that are stronger. Calcium sulfoaluminate (CSA) cement is considered to be powdery binder in composites because of their rapid production capability, high strength, and dimensional stability. This study examines a dry cementitious mix comprised of silicate beads and fine CSA cement. Also accelerators were added to increase the mechanical properties of as-printed (green) parts with hydration by jetting binder. During an experimental study on the hydration behavior of several cement component reaction with an accelerator, we found hydration time reduction of the green parts as an accelerator controlled. The result show that the compressive strengths and a density increase with the increasing of accelerator contents, indicating that the accelerator chemically interacts between watery binder and cement. In order to study the interaction between the accelerator and saturated part, some morphological (FE-SEM), crystal-chemical (XRD), physical-chemical (hydration temperature profile) and chemical (ICP) analyses on green parts samples were carried out.

Resume : Membrane photocatalytic reactor (MPR) can be considered as one of the promising methods for Palm oil mill secondary effluent (POMSE) polishing treatment. However the utilization of green synthesis Zinc Oxide-Cymbopogon Citratus (ZnO-CC) nanoparticles to improve the performance in MPR for POMSE treatment rather limited. In this study the effects of operating conditions (pH, initial concentrations, and catalyst loadings) for treating POMSE via MPR in the presence of ZnO-CC nanoparticles were elucidated. The behaviour of membrane fouling was evaluated through the normalize flux, colour removal, water quality and membrane surface characteristics. The results showed that the colour removal reached 99.9% normalized flux up to 0.33 and the water quality parameters attained in this study are within the acceptable discharge limit of wastewater, thus verified the effectiveness of POMSE treatment via MPR in presence of ZnO-CC nanoparticles. In addition, the best performance in terms of flux, colour, chemical oxygen demand (COD), and turbidity removal efficiency was achieved after six cycles of POMSE treatment via MPR. Hence, a cleaning of membrane is able to recover the quality of POMSE permeate at a certain extent and resulting in the reusability of membrane, which can serve as an alternative to improve severe membrane fouling.

Resume : A new generation of hybrid plasmonic sensors have arised from the synergistic combination of metal nanoparticles (NPs) with supramolecular receptors.1 AuNPs are ideal scaffolds because of their highest surface-to-volume ratio combined with their unique optical and electrical properties.2 On the other hand, supramolecular recognition has proven to be the key for the next generation of sensors exhibiting detection limits down to ppm/ppb levels with fast response speed combined with unprecedented selectivity.3 Here we have devised a novel chemiresistor device architecture and exploited it for real time ion sensing in liquid state. Such devices are based on the use all-covalent 3D networks of AuNPs connected with dithiolated crown ether linkers as active material in a microfluidic cell. These devices can detect analytes as a result of a reversible chemical adsorption/desorption process occurring onto the functionalized AuNP-based network. Such interaction can determine a modification of the network’s structure (e.g. via swelling) or electronic properties (e.g. via a change in the device resistance). The ultimate goal is to develop a technology that can be implemented in portable optoelectronic sensing devices featuring sensitivity, selectivity, response time, multiplex sensing, reusability and stability beyond the state-of-the-art. 1J. Liao, et al., Chem. Soc. Rev., 2015, 44, 999 2K. Saha, et al., Chem. Rev., 2012, 112, 2739 3R. Pinalli, et al., Chem. Soc. Rev., 2018, 47, 7006

Resume : Different nanostructures based on ZnO and SiO2 (composite and by layer SiO2-TiO2 films), were deposited on langasite or quartz SAW structures and used as sensitive layer materials for ammonia detection. Zinc oxide consisting of small nanorods with diameters under 50 nm were obtained through solvothermal method using surfactants. SiO2 component were obtained by RF sputtering (in case of layered structure) and chemical method (in composite case). Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) were used to investigate the morphology and structure of the obtained nanostuctures. The sensing performance of the prepared microdevices towards ammonia was investigated. The gas response of these complex nanostructures was superior compared with those of piristine ZnO reported in the literature. The tested materials have proven good sensitivity and stability, reversibility at room temperature. Also, possible ammonia sensing mechanism were proposed for each nanostructure type.

Resume : The non-stoichiometric misfit layered compounds (MLC) of the general formula ((MX)1+y)m(TX2)n (abbreviated herein as MX-TX2) have been investigated quite extensively over the last 30 years. Here MX is a monoatomic slab of a material with distorted rocksalt structure and TX2 is a layered compound with hexagonal (octahedral) coordination between the metal T atom and the chalcogen X atom. Recognizing the mismatch between the two (MX and TX2) sublattices, nanotubes from the MLC of different compositions were described in the past. In particular, semimetallic nanotubes belonging to the family LnX-TaX2 with Ln= rare earth atom and X=S, Se, Te have been studied in the past. While some of them, like LaS-TaS2 were obtained with moderately high yields, others like YbS-TaS2 were scarce. In the present study, a new strategy for promoting the yield of such MLC nanotubes by alloying the LaS sublattice with another Ln atom is proposed. Detailed transmission electron microscopy investigation of the (mixed) LnxLa(1-x)S-TaS2 (Ln= Pr, Sm, Ho, Yb) nanotubes show clearly that the substituting Ln atom resides in the rocksalt LaS sublattice of the nanotubes. Raman measurements show distinct differences between mixed tubes with open-shell (Pr, Sm, Ho) and close-shell (La, Yb) rare-earth atoms. Density functional calculations show that the interplay between two important factors determine the enhanced stability of the mixed nanotubes- the size and electronic structure of the substituting rare-earth atom. The smaller is the substituting rare-earth atom (larger Z number), the more dissimilar it is to the original La atom. This dissimilarity enhances the incommensurability between the LnxLa(1-x)S and the TS2 subunits, promoting thereby the stability of the mixed MLC. However, the electronic structure of the Ln atom was found to play a more significant role. The MLC lattice of the LaS-TaS2 is electron-rich and consequently the 4dz2 level of Ta is full. The unoccupied 4f levels of the substituent open-shell atoms (Pr, Sm, Ho), which are positioned below the Fermi level, serve as electron acceptors. Consequently, the Ln substitution is found to enhance the stability of the mixed lattice and nanotubes thereof. This strategy can be employed for enhancing the yield of these and other misfit nanotubes using different substituents of the right size and energy profile.

Resume : Phase separation is well-known as a nanofabrication method mainly in polymer blends. Thin films coatings can lead to sub-wavelength photonic patterns or even porous structures after a step of selective etching. Besides some applications need robust nanostructures so glass appears to be suitable material. Phase separation has already been studied in bulk glasses where morphological evolution and growth of domains during the coarsening stage are of particular interest. However, few experimental studies have been reported so far for glass phase separation in confined media. The present study investigates phase separation in glass thin films as a large-scale nanostructuring method. Thin layers of a model glass, barium borosilicate, are deposited by magnetron sputtering to mimic industrial processes for functionalization. Layers between 20 and 200nm thick are studied after annealing at high temperature around 600-1000°C. Preliminary in-situ SEM helps to determine interesting time and temperature ranges. A quantitative data analysis is then performed by image processing, showing a good agreement between post-mortem SEM and AFM on etched sample. Controlled composition and temperature impact phase separation mechanisms. Added to initial layer thickness, they allow to control morphology and size of the final objects. Three kinds of nanostructures are obtained: holes and pillars due to nucleation and growth process, and interconnected rough patterns induced by spinodale decomposition.

Resume : The optoelectronic devices industry is built on transparent conductive oxides (TCOs) such as ITO, ZnO, and TIO2. Most popular TCOs exhibit an n-type characteristic that is why the synthesis and development of p-type TCOs is a challenge and interesting research point, which opens up new fields such as transparent diode and p-n homojunction. P-type conducting CuFeO2 thin films deposited on fused quartz substrates by chemical spray pyrolysis technique that advantage by its low equipment cost, simple and safe technique, low-temperature processing, and the possibility of preparing large area. The heat treatment in nitrogen (N2) atmosphere for two hours at annealing temperature 850°C is an essential step to achieve the delafossite phase. The effects of the thickness (t) and the Cu/Fe various ratio in precursor solutions were studied on the structural, morphological, optical and electrical properties to achieve optimal parameters for the deposition process. The CuFeO2 post-annealed films are polycrystalline with a rhombohedral structure and growth orientation (012). The optical transmittances of post annealed thin films are range 80-30 % in VIS-IR spectrum and the direct bandgap value was various from 2.36 eV to 1.48 eV. The highest electrical conductivity of CuFeO2 film obtained with t= 738 nm and Cu/Fe ratio 1:1 was found to be 0.15 S/cm and carrier concentration 7.4Х1018cm-3 which is a new record for spray CuFeO2 films up to date.

Resume : Vanadium pentoxide (V2O5) is quite promise as an electrode material for lithium batteries and electrochromic devices, due to its high lithium ion intercalation. Because of the fascinating properties and wide application range of V2O5 thin films, these have attracted significant attention over the past decades. V2O5 has a wide optical band gap, layered structure, good chemical and thermal stability and excellent electrochromic properties However, it is still challenging to develop uniform, large-scale thin films. We have prepared V2O5 films by spraying a precursor solution of metavanadate onto FTO coated glass obtaining nanostructured thin films with excellent morphology, electrical, optical and electrochromic properties. Compared with V2O5 films developed with other methods, sprayed films exhibited similar transmittance values and comparable charge storage capacity. At the same time, sprayed V2O5 films showed a reproducilble wall-like structuring, grown onto granular uniformely distributed grains, a property resulting in large active surface. In conclusion, these properties in correlation with the advantages in both cost and control of the development make spraying a very suitable approach for preparing large-area films for electrochromic devices.

Resume : Among the most useful techniques for medical diagnosis are luminescent imaging (LI) and X-ray computed tomography (CT). These techniques usually require the use of external probes to increase the contrast between the target and its surrounding. Ln-based nanoparticles have been proposed as ideal probes for such purpose. Thus, the high atomic number of lanthanides makes these kind of materials excellent X-ray attenuators and therefore, optimum CT probes. In addition, when nanoparticles of lanthanide compound are doped with Nd3+, luminescent probes with excitation and emission within the biological windows (NIR region) result, which are of special interest for in vivo imaging due to the penetration deep of NIR radiation. In this communication, we report on the synthesis of uniform Nd3+-doped LuVO4 nanophosphors by homogeneous precipitation in ethylene glycol/water media. After optimizing the Nd doping level, these phosphors present intense luminescence in the near-infrared biological windows. The X-ray attenuation capacity of the optimum nanophosphor is much higher higher than that of a commercial X-ray computed tomography contrast agent. After surface coating with polyacrylic acid, such nanoparticles present a high colloidal stability in physiological pH medium and high cell viability, thus fulfilling the main requirements for their use as a bimodal probe for NIR luminescent bioimaging and X-ray computed tomography.

Resume : Due to the growing interest of one-dimensional nanostructures (nanowires) of ZnO, it is necessary to optimize the parameters involving in their elaboration. In this work, we have focused on hydrothermal growth of ZnO nanowires, thermally treated in different pH of growth solution ranging from 3 to 11 by adding precise amounts of hydrochloric acid (HCl) or sodium hydroxide (NaOH) to the aqueous solution as pH controlling agents. The synthesized ZnO nanowires were characterized in terms of their structural, morphological and optical properties respectively by X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and UV-Vis spectrophotometry. The XRD spectrums show well that the ZnO nanowires were grown along the c-axis direction according to the wurtzite hexagonal phase at inherent pH. For pH acid solution higher than 5.5 the structures take also the form of nanowires with however eroded zones, whereas for pH solution lower than 5.5 no structure appears. Moreover, a clear anisotropy has shown of the samples prepared at alkaline pH, which gives rise to various ZnO structures of flower-like and urchin-like morphology. The transmittance spectra show that the ZnO nanostructures are transparent in the near ultraviolet and visible regions with an average level about 90% that decreases going from alkaline to acidic pH. It is to note that the gap energy of the elaborated nanowires presents a blue-shift compared to the ZnO thin films in accordance to the quantum confinement effect.

Resume : Ultrasmall single-crystal gold nanorods are an appealing class of plasmonic material, which has attracted considerable interest in biomedicine and catalysis. Unfortunately, their high-quality synthesis remains challenging, impairing their practical implementation in technology. One of the most critical parameters in the synthesis of ultrasmall single-crystalline gold nanorods is the size dispersity of the 1.5 nm nuclei used to seed the growth process. Moreover, the reduced dimension of the seeds the use of high surfactant concentration to preserve their stability and to assist the nanorod growth complicate their characterization. Here we investigated the effect of the seed size distribution in the formation of ultrasmall gold nanorods using multiwavelength analytical ultracentrifugation, a useful technique for characterizing unstable small crystalline seeds in the presence of surfactants. The analysis of their sedimentation behavior under an applied centrifugal field enabled the obtention of accurate information on its size distribution, which was employed for further optimization of the seed synthesis. Thereby we were able to grow high-quality ultrasmall nanorods with dimensions ranging from 4 to 6 nm in width and 6 to 12 nm in length.

Resume : 2,2’-(Ethylenedioxy)bis(ethylamine)-functionalized graphene quantum dots (GQDs) were prepared under mild conditions from graphene oxide (GO) via oxidative fragmentation.The as-prepared GQDs have an average diameter of ca. 4 nm, possess good colloidal stability, and emit strong green-yellow light with a photoluminescence (PL) quantum yield of 22% upon excitation at 375 nm. We also demonstrated that the GQDs exhibit high photostability and the PL intensity is poorly affected while tuning the pH from 1 to 8. Finally, GQDs can be used to chelate Fe(II) and Cu(II)cations, scavenge radicals, and reduce Fe(III) into Fe(II). These chelating and reducing properties that associate to the low cytotoxicity of GQDs show that these nanoparticles are of high interest as antioxidants for health applications.

Resume : Semiconductor nanocrystals (NCs), thanks to tunability and control afforded by quantum confinement effects with unique properties, have been broadly applied in light emitting diodes displays, chiral sensing and asymmetric catalysis, etc. However a systematic control of these NCs was extremely difficult not to say impossible. Thus, it is still mandatory and relevant to find out an effective synthetic approach to achieve semiconductor NCs with tunable properties. In this work, we studied the precise control of quantum rods synthesis, and used them for chirality and laser-induced deposition purposes. Herein, we chose cysteine as a chiral ligand and dot-in-rod CdSe/CdS NCs (DRs) as the phosphors, with highly tunable shape and luminescence properties. The anisotropic factor of circularly polarized luminescence (CPL, glum) and circular dichroism (CD, g-factor) can reach 10-4. The anisotropic factors can be further increased by one order of magnitude (10-3) after doping in poly(vinyl alcohol) films, probably because of the enhanced anisotropy degree, crystal orientations, and ordered morphologies. Hybrid semiconductor-metal nanoparticles (HNPs) have gained great interest in a variety of research fields and applications, including optics, electronics and catalysis. Compared with the thermal induced growth of multi-sites gold particles, the more energy efficient light-induced growth leads to a highly selective deposition of gold in HNPs. Therefore, we investigate the shape anisotropy DRs coupling with blue laser to study the mechanism of noble metal in situ-photodeposition. Various parameters are studied: laser intensity, wavelength, and reaction time. Such anisotropic semiconductor-metal hybrids are of great potential for self-assembly and photocatalysis and as building blocks in optoelectronic devices.

Resume : Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide (PI), PEEK or transparent conductive polyester film. In this study, we investigated the electroless copper deposition on the flexible substrate – polyimide from the alkaline formaldehyde-containing solution using ethylenediaminetetraacetic acid (EDTA) as Cu(II) ligand at temperatures, mainly lower than room temperature. Influence of the solution pH, temperature, and ligand concentration on the rate of electroless copper deposition as well as on the surface morphology has been investigated. It was found that the highest copper plating rate of ca. 4 μm h-1 was obtained from Cu(II)-EDTA plating solution at pH 12.5. The surface roughness factor Rf of deposited copper coatings reaches ca. 39. Acknowledgement This research was funded by a grant (No. 01.2.2.-LMT-K-718-01-0004) from the Research Council of Lithuania.

Resume : Photoelectrocatalytic(PEC) reduction of CO2 could efficiently reduce carbon dioxide because the applied external voltage can facilitate the separation of photogenerated carriers. Recently, Au and Ag were reported as cathode for reducing CO2, but these metals are expensive and are therefore not appropriate for limited use in scalable production. Bi is a promising electrode for reducing CO2 because it is environmental friendly, nontoxic and has low hydrogen evolution characteristics. In this work, we fabricated Bi photocathode with nanostructures. First, the TiO2 layer was deposited on the p-Si substrate by electron beam evaporator and then rapid thermal annealing was conducted at various temperatures for 5min under N2 flow. For improve adhesion between annealed TiO2/p-Si and Bi nanostructure, bismuth seed layer was deposited by thermal evaporator. As the final process Bi nanostructure was produced on the annealed TiO2/p-Si using photo-assisted electrodeposition of Bi in electroplating solution. Bi nanostructured photocathode showed excellent properties for PEC CO2 reduction reaction compared to planar Bi photocathode. The Bi nanostructured photocathode shows highly selective HCOO- production (FEHCOO- > 90%) could be demonstrated at potential of −1.0 VRHE in CO2-pureged 0.1M KHCO3. In addition, it exhibited about two times higher formic acid partial current density (~8mA/cm2) compared to the planar bismuth photocathode (4.4mA/cm2).

Resume : Ag is one of the promising oxygen reduction reaction (ORR) catalysts in the alkaline environment because of its cost-effectiveness, stability in alkaline electrolyte, and appropriate binding energy with intermediates of ORR pathway. To enhance the ORR activity of Ag, the nanostructured Ag such as Ag nanoparticles and Ag nanowire (NWs) were extensively investigated, but they exhibited low onset potential in the range of 0.84 - 0.87 VRHE because those powdery catalysts must be attached on a carbon support using a binder. The insulating binder covers the catalytically active sites and lowers the electrical conductivity, resulting in deterioration of catalytic performance. Here, self-supported and vertically-aligned Ag nanowires (NWs) were developed as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The electrochemical reduction of the vertically-aligned AgCl NWs grown on plastic film enables to produce of binder-free Ag NWs. During the reduction, the extraction of Cl atoms from AgCl produced aggregated nanoparticles at the side wall of Ag NWs, resulting in numerous active sites and high electrochemical surface area. Consequently, the Ag NWs have 79 times higher electrochemical surface area and 24 times lower charge transfer resistance than those of the Ag film. As a result, the Ag NWs exhibit a remarkable enhancement in onset potential of the ORR up to 0.97 VRHE, which is comparable to or better than planar Pt film (0.96 VRHE).

Resume : Electrochemical CO2 reduction reactions (CO2 RR) at metal surface in aqueous solution is promising method for the use of CO2 as a source for energy storage because the system is simple and the product can be selectively controlled by changing the metal electrode. Metallic Cu and Zn have been assessed as efficient catalysts because of its abundant reserves and particularly selective production of CO. Several studies have manipulated morphology to enhance the catalytic activity of Zn compared to bulk metal electrodes. Multilayered Zn nanosheets directly grown on Zn foil by repeated of oxidation and reduction achieved FECO as high as 86 %, but required a large potential (> -1.1 VRHE). Here, we demonstrated nanoporous Zn catalysts via sequential process of hydrothermal growth of ZnO and electrochemical reduction of the ZnO. The ZnO nanowires were hydrothermally grown on the Zn foil, and then, the ZnO nanowires were electrochemically reduced to nanoporous Zn by electrochemical reduction in N2-purged 0.1 M KHCO3 electrolyte. During the electrochemical reduction, a localized electric field was focused on the tip of ZnO nanowires, resulting in metallic nanoporous structure. The morphology of nanoporous Zn catalysts were controlled by varying the reduction potential and the time. As a result, we identify the relationship between size of nanoporous and catalytic activity of CO2 RR. The relationships would guide the optimization of these materials and achieve breakthrough advances.

Resume : Lithium metal (Li), regarded as the "holy grail" of anode materials for high energy density batteries, has attracted high attention as an advanced anode material due to its high specific theoretical capacity (3860 mAh g-1), light weight (0.53 g cm-3), and the lowest electrochemical potential (-3.04 V vs standard hydrogen electrode). Despite various advantages, practical use of lithium metal anodes faces hurdles which are infinite dimensional change due to low dendritic lithium growth, "dead" lithium formation, and low coulomb efficiency during repeated stripping / plating. To address the above issues, three major approaches are being intensively investigated. i) Mechanically suppress dendritic lithium growth. ii) Adjustment of interfacial Li ion flux. iii) Engineering of interfacial stability at electrochemically highly reductive condition. Research on controlling interfacial layers, such as the solid electrolyte interface (SEI) and artificial protective layers can have a chance to improve all three approach mentioned above. Here we propose a very simple and scalable methodology to form a uniform and dense Li metal protective layer on Li metal using a simple reaction between alkali metal (Li) and sacrificial fluoropolymer film. During the reaction, the mechanical energy caused by the pressing process triggers the reaction, forming a mixed layer of ceramic and carbon chains. Li anodes with artificial protective layers exhibit lower over voltages and better cycle life than bare samples in both Li || Li symmetric and Li || LCO full cells.

Resume : The quest for novel photoelectrocatalytic (PEC) materials is very active, in the global attempt to find renewable energy sources: solar water-splitting is one of the most heavily investigated applications, with working materials based on III-V semiconductors and/or metal oxides. However, some of the developed materials either require fabrication techniques that are energy-expensive and carbon-positive, or present significant challenges in recycling and disposal. Therefore, an ongoing question on PEC water-splitting is the realization of materials by using a sustainable route. Water-splitting materials require co-catalysts, such as Pt or RuO2, to facilitate charge transfer and lower the reaction overpotential. We developed a photodeposition procedure that allows the deposition of Pt[1], Au and RuOx[2] nanoparticles on thin films (titania and hematite), both in presence and in absence of methanol, without any galvanostatic assistance. In particular, the presence and the concentration of methanol as a hole scavenger affected strongly the morphology, the size and the density of the nanoparticles, allowing therefore a reproducible control over the co-catalyst load. [1] C. Tossi, L. Hällström, J. Selin, M. Vaelma, E. See, J. Lahtinen and I. Tittonen, Journal of Material Chemistry A 2019 (7), 14519-14525, DOI: 10.1039/C8TA09037H. [2] E. See, C. Tossi, L. Hällström and I. Tittonen, Facile Morphologically Controllable Photodeposition of RuOx Nanostructures on TiO2 Films (submitted).

Resume : Controlling the growth and properties of ZnO nanowires (NWs) is critical for their efficient integration into nanoscale engineering devices.1 ZnO Wurtzite structure exhibits spontaneous polarization along the c axis. The resulting polarity is known to affect the growth and properties of ZnO single crystals and epitaxial films,2 but the polarity-induced effects are mostly unknown in NWs. ZnO NWs grown by chemical bath deposition (CBD) can be of either O- or Zn-polarity,3 which opens the way for more deeply investigating these effects. In this context, we address the issue of the polarity-dependent growth and properties of ZnO NWs by CBD following the selective area growth approach.4 Well-ordered O- and Zn-polar ZnO NW arrays with high structural uniformity are grown. The comparison of their typical dimensions unambiguously reveals that Zn-polar ZnO NWs have significantly higher growth rates than O-polar ZnO NWs for fifteen different domains .4 The origin of the difference is discussed in the light of surface configurations and interactions in aqueous solution at the top polar c-faces of the ZnO NWs. Four-point probe resistivity as well as low-temperature cathodoluminescence and Raman scattering measurements are performed on these NWs showing the high electrical conductivity originating from the massive incorporation of hydrogen in different forms and its relationship with their polarity.5 These findings show the relevance of considering polarity as an important quantity to control the growth and physical properties of ZnO NWs by CBD. 1 J. Michallon et al., Nanotechnology 26, 75401 (2015) 2 J. Zúñiga-Pérez et al., Appl. Phys. Rev. 3, 41303 (2016) 3 V. Consonni et al., ACS Nano 8, 4761-4770 (2014) 4 T. Cossuet et al., Langmuir 33, 6269-6279 (2017) 5 T. Cossuet et al., JPPC122, 22764-22775 (2018)

Resume : Metal–nitrogen–carbon (M-NC) catalysts have been reported as promising electrocatalysts to replace noble-metal catalysts (Pt/C, Au/C, Ru/C etc.) in many industrial processes. In this regard, carbonized zeolite imidazole frameworks (ZIFs), as precursors of M-NC catalysts, have been extensively studied because of their porosity and ligand composition containing nitrogen and carbon. In this study, we synthesize Co-doped ZnO@ZIF-8 particles from a Co-doped ZnO sphere via the spray pyrolysis method and pseudomorphic replication. Ultrasonic spray pyrolysis is an attractive approach to operate mass production with high-purity homogeneous structures. Further, pseudomorphic replication makes it possible to control the morphology of the metal–organic framework (MOF) particles and easily prepare MOF composite particles. In the study, the pyrolyzed ZIF particles are applied to oxygen reduction reactions in alkaline media, and our results indicate that particles show a high half-wave potential of 0.904 V, which makes them suitable for diverse electrochemical applications.

Resume : One of the simplest and most thoroughly studied ionic crystals is sodium chloride, also known as table salt. It is well established that NaCl has a B1 (“rock-salt”) structure that transforms into a CsCl-type structure (the B2 phase) at about 30 GPa and room temperature. [1] A number of theoretical [2] and experimental [3] studies confirm that only these two phases exist in the 0-300 GPa pressure range. The available reference data show that the most energetically favorable surface of NaCl is (100). [4–6] We have predicted stable reconstructions of the (100) and (111) surfaces of NaCl using the global optimization algorithm USPEX [7]. For the cleaved bare (100) surface, pure Na and pure Cl are the only stable surface phases. The study of the (111) surface shows that a newly predicted Na3Cl-(1×1) reconstruction is thermodynamically stable in a wide range of chlorine chemical potentials. It has a sawtooth-like profile where each facet reproduces the (100) surface of a rock-salt NaCl, hinting on the preferred growth of the (100) surface. We used the Bader charge analysis to explain the preferable formation of this sawtooth-like Na3Cl-(1×1) reconstruction of the (111) surface of NaCl. We find that at a very high chemical potential of Na, the polar (and normally absent) (111) surface becomes a part of the equilibrium crystal morphology. At both very high and very low chemical potentials of Cl, we predict a large decrease of surface energy and fracture toughness (the Rehbinder effect) References 1. Bassett W.A. et al. Pressure-Induced Phase Transformation in NaCl // J Appl Phys. 1968. Vol. 39, № 1. P. 319–325. 2. Froyen S., Cohen M.L. Structural properties of NaCl // Phys Rev B. 1984. Vol. 29, № 6. P. 3770–3772. 3. Li X., Jeanloz R. Measurement of the B1-B2 transition pressure in NaCl at high temperatures // Phys Rev B. 1987. Vol. 36, № 1. P. 474–479. 4. Tasker P.W. The surface energies, surface tensions and surface structure of the alkali halide crystals // Phil Mag A. 1979. Vol. 39, № 2 DOI-10.1080/01418617908236887. P. 119–136. 5. MacDonald R.J., Taglauer E.C., Wandelt K. Surface Science - Principles and Current Applications. 1st ed. Springer Berlin Heidelberg, 1996. 374 p. 6. Surface Science: Foundations of Catalysis and Nanoscience. 3rd ed. / ed. Kolasinski K.W. Wiley, 2002. 572 p. 7. Kvashnin A.G., Kvashnin D.G., Oganov A.R. Novel Unexpected Reconstructions of (100) and (111) Surfaces of NaCl: Theoretical Prediction // Sci. Rep. 2019. Vol. 9, № 1. P. 1–9.

Resume : Compared with multi-phosphor blends for phosphor-conversion white light-emitting diodes (pc-LEDs), multicolor-emitting phosphors with a single phase can diminish the self-absorption, leading to an enhancement in luminous efficacy of pc-LEDs. The multiple-photoluminescence can be obtained by co-doping the Mn2+ ions with the Eu2+ ions. It has been suggested that Ba2-δCaδSiO4 (δ = 0.450.8) compounds are suitable for the co-doping of Eu2+ and Mn2+. In this study, we have prepared Ba1.3-x-ySrxCa0.7+ySiO4:Eu2+,Mn2+ powders using a sol-gel combustion process. The photoluminescence spectra of the powders consisted of two emission bands in the blue-green (Eu2+) and red regions (Mn2+). The red emission resulted from an energy transfer from Eu2+ to Mn2+. The ratio of the divalent cations (Ba2+, Sr2+, and Ca2+) affected the crystal structure and multiple-photoluminescence properties. Accordingly, the emission colors were tunable by adjusting the cation ratio, and thus warm-white light emissions could be achieved from the single-phase compound. The results were discussed using the crystal structure refinement, efficiency and critical distance of the energy transfer from Eu2+ to Mn2+, quantum efficiencies, crystal field strength, and thermal quenching.

Resume : Dry reforming of methane (DRM) is highly endothermic process that uses two GHGs to produce syngas (CO and H2). Then syngas can be used to produce high-value fuels and chemicals. The use of noble metal based catalysts makes it economically infeasible. Conversely, Ni based catalysts provide a cheaper alternative. The major issue with Ni-based catalysts is deactivated due to the carbon deposition which is formed from the CO disproportionation and CH4 decomposition reactions that occur simultaneously with DRM. 5 wt. % Ni supported on Ce-X-10Cu (X=La, Sm) supports were synthesized to see their performance towards DRM. The catalytic supports were synthesized by enhanced microwave (EMW) technique coupled with reflux cooling then they were ball-milled at different environmental conditions and durations. Finally, Ni was deposited via wet impregnation method. Various characterization techniques were used to analyse the effect of milling conditions (time, atmosphere) on the catalyst’s performance and the intrinsic properties of the catalysts. It was also observed that dry BM conditions resulted to beneficial characteristics compared to wet BM in terms of acidity/basicity and exhibited higher catalytic activity. It was also noticed that the oxygen vacant sites. 16O/18O transient isotopic exchange experiments (TIIE) was used to record surface/bulk diffusion of lattice oxygen (16O). Temperature-programmed oxidation (TPO) was also used to examine the reactivity of carbon species formed by the two reaction routes.

Resume : Сopper chalcogenides have opened a novel challenged direction last decade in the field of nanoscaled semiconductors due to appearance of localized plasmonic resonance generated by the high carrier concentration. Major researches for such copper chalcogenides have been performed with colloidal nanoparticles those allow a wide control of their chemical composition, size, and surface state. An incorporation of the particles into solid matrices is more complicated task, however, a facile synthesis of plasmonic materials is of interest for application in near-IR optics and ultrafast photonics. An original version to fabricate plasmonic copper chalcogenide nanoparticles within silica glass was elaborated through the sol-gel technique. Copper selenides of various stoichiometry were synthesized by selenization of the copper nanoparticles incorporated into porous silica followed by annealing towards the transparent silica glass state with the pronounced near-IR optical response. The glasses were characterized with TEM, XPS, XRD, FTIR, and SANS techniques to conclude on structural features of the nanoparticles with controlled IR-band. An origin of the near-IR band usually associated with the localized plasmon is discussed also in relation to the effect of Cu(II) impurity-generated intraband levels providing observable linear and non-linear optical response of these materials.

Resume : Zirconium-based MOF (UiO-67) possesses excellent intrinsic properties (high BET surface area, exceptional chemical and thermal stabilities) which are suitable to apply for separation process. For production of UiO-67, however, it was mainly carried out in a batch reactor assisted by conventional solvothermal process. In this study, UiO-67 was prepared by using a continuous tubular reactor under microwave radiation, which is easy to scale-up and reduce production cost, consequently increasing productivity. The precursor solutions were continously transfered by a syringe pump system into a PTFE tubular reactor placed in the microwave oven. The effects of manufacturing conditions such as resident time, concentration of modulator and kind of modulator on morphology, crystallinity, porosity, and thermal stability were consistently examined. The results showed that a large quantity of UiO-67 was produced with a high quality and a high yield within a short reaction time of 10  30 min at 120 oC under ambient pressure. The obtained UiO-67 showed an outstanding adsorption performance with gaseous toluene uptake amount of 465.6 mg/g at room temperature, higher than that of various adsorbents such as UiO-66, ZIF-8, ZIF-67, MOF-199, MOF-5, etc.

Resume : Multi-component nanocomposites are highly attractive in heterogeneous catalysis and photocatalysis, owing to the integrated benefits of quantum and synergistic multiphasic interactions in producing unprecedented properties (e.g. charge transport, selectivity, recyclability) that are superior to those of the single constituents. [1] For heterogeneous metal-oxide semiconductor systems, the formation of nanosized heterojunctions by means of bulk solution processing (e.g. one-pot sol-gel and assisted-solvothermal methods), is largely dominated by faceting interactions (i.e. epitaxy), and crystal growth effects (e.g. size and kinetics) that are often tedious to control and tune, due to the multivariate nature of the synthesis conditions. In such case, a statistical design of experiments (DOE) becomes a powerful tool for optimizing several variables simultaneously by shedding the light not only on the major parametric effects but also locating significant intercorrelations, which are typically overlooked by single-variable empirical approaches for material advancement. [2-3] In this work, ceria-rich CeO2-TiO2-CuxO nanocomposites, with fixed copper and titanium loadings are prepared by sol-gel assisted hydrothermal synthesis, using a one-pot methodology, and a post- air calcination step. The materials are produced by mixing precursor alkoxide and salts, namely titanium(IV) n-propoxide, cerium(III) nitrate and copper(II) nitrate in hydro-organic medium, in the presence of acetic acid (AA) and fatty acid (FA) to control the growth conditions and induce nano-hetero-structuring and faceting. Using a systematic factorial design approach with central points, we particularly screen the effects and interactions of critical synthesis variables such as the (i) relative mol ratio of the structure-directing additives (FA/AA, 0-0.06), (ii) duration of the hydrothermal treatment (12-36 hours, 120 °C), and (iii) calcination isotherm (300-500 °C), on the microscopic morphology, texture, crystal structure and surface composition of the resulting materials. These properties are evaluated from electron microscopy, nitrogen porosimetry, X-ray and Raman spectroscopy measurements, and correlated with the synthesis variables via a response surface methodology. Preliminary results evidence the formation of flower and lamellar-shaped microscopic features that have a macro/mesoporous texture and relatively uniform distribution of the various metal oxides. The impact of the thermal treatment conditions on relevant physicochemical properties of the ceria-rich ternary metal oxide system is explicated. [1] J. Shi, Chemical Reviews 113 (2013) 2139-2181. [2] M. Abi Jaoude et al., Analytical and Bioanalytical Chemistry 403 (2012) 1145–1155. [3] H. Eskandarloo et al., Industrial & Engineering Chemistry Research 53 (2014) 7847-7855.

Resume : Along with the demanding of the design and highly efficient catalysts for the renewable and clean energy, the core-shell bimetallic nanoparticles are high expectations. But, to construct an appropriate catalyst with tailored compositions and structure by green and continue way is still challenging. In this study, Pd@M (M=Pt,Ru,Fe,Cu) nanocubes were synthesized via unified direct seed-mediated growth in aqueous solution at low temperature without washing process. This work showed the green and continue approach to prepare core-shell bimetallic nanoparticles exposed most catalytically active transitional metals (Pt,Ru,Fe and Cu) on the shell with low facet. The X-ray absorption spectroscopy, high-resolution transmission electron microscopy and Energy Dispersive Spectroscopy were employed to character the structural and comprehensive electronic of those nanocrystals. And, their Methanol Oxidation Electrocatalytic Activity and stability were recorded by cyclic voltammetry and chronoamperograms.

Resume : CO2-to-synfuels manufacturing based on renewable electricity could enable a net-zero-emission-economy future. To achieve this ideal, we are engaged in developing new technologies that can efficiently and selectively convert CO2 into fuels and chemicals. However, the estimated market prices of CO2-based synfuels, even with state-of-the-art performance metrics, remain 2-4 times higher than today's selling prices, which calls for additional effort towards building a more powerful CO2 electroreduction system. The core of such a system would be a catalyst capable of CO2 reduction to fuels with high selectivity, activity, and energy efficiency. Cu, amongst various electrocatalysts, has been the most efficient and selective in converting CO2 to hydrocarbon fuels such as ethylene. Its selectivity towards hydrocarbons on Cu catalysts was reported by Hori. Y (1). The effect of facets on the product distribution was subsequently discovered in the 1990s, with Cu(100) facets consistently enabling the highest C2+ hydrocarbon selectivity among the low-index Cu facets. This later served as a design principle for improving Cu catalysts (2-4). One route to Cu(100)-rich catalysts is the colloidal syntheses of nanocubes, during which capping agents adsorb on the Cu surface to lower the surface energy of Cu(100) facets and stabilize its cubic morphology (5). A conjecture that entered our minds was that CO2 reduction intermediates could, similarly to the capping agents in colloidal syntheses, absorb on Cu surface to stabilize Cu(100) facets (6). We therefore investigated the effect that adsorbed CO2RR intermediates have on the energetics of Cu facets through density functional theory calculations. We found that increasing the coverage of CO2RR intermediates lowers surface energy of Cu(100) facets; We then proceeded to synthesize Cu catalysts under CO2 reduction conditions via an electrodeposition approach. Using the grazing-incidence wide-angle X-ray scattering and hard X-ray absorption spectroscopy beamlines, we observed that the Cu growth was decelerated in the presence of CO2 by ~60% compared to synthesis under the usual H2 evolution conditions. A CO2-rich environment increased the Cu(100):Cu(111) ratio up to 1.4:1, as verified by both OH- electroabsorption and Pb underpotential deposition, which is a 70% increase in the ratio of Cu(100) facets to total facet area. This is in agreement with the picture presented by our theoretical studies, wherein the unique energetics of Cu facets under CO2 reduction conditions alter the Cu surface. Finally, we equipped alkaline flow cells and a membrane electrode assembly systems with Cu catalysts fabricated under CO2 reduction conditions. We achieved a 90% Faradaic efficiency toward C2+ products at current densities of 580 mA cm-2. A 37% full-cell energy efficiency at 300 mA cm-2 was achieved in alkaline flow cells. Consistent high-selectivity-at-high-current-density performance was demonstrated in 65-hour operation using the membrane electrode assembly systems. References 1. Hori, Y., Kikuchi, K., Suzuki, S. Chem. Lett. 14, 1695-1698 (1985); 2. Jiang, K. et al. Nat. Catal. 1, 111-119 (2018); 3. Roberts, F. S., Kuhl, K. P., Nilsson, A. Angew. Chem. Int. Ed. 54, 5179-5182 (2015); 4. Huang, J. et al. Nat. Commun. 9, 3117 (2018); 5. Jin, M. et al. Angew. Chem. Int. Ed. 50, 10560-10564 (2011); 6. Wang, Y. et al. Nat. Catal. DOI: 10.1038/s41929-019-0397-1, 2019.

Resume : There is increasing demands of material developments for high electrical performance, high photosensitivity, novel mechanical functionality, high electrical stability, and exotic chemical stability under harsh condition. Although the organic materials and oxide materials have been investigated with diverse approaches, there have been increasing demands for alternative semiconductors with superior intrinsic properties and low cost processing methods. The metal chalcogenides have been investigated with superior properties and compositional diversity for various electronic and optoelectronic applications. In this presentation, I will discuss about our recent works on the general strategy of solution-processing of metal chalcogenides and nanomaterials based hybrid devices for high performance TFT and photosensor devices.[1,2] 1. Science Advances, 2019 2019, 5, eaax8801 2. Sci. Adv. 2018, 13, eaap9104

Resume : The optimization of a material functionality requires both the rational design and precise engineering of its structural and chemical parameters. [1] Colloidal chemistry is an excellent synthetic choice for the synthesis of homogeneous and compositionally complex novel nanostructured systems with potential application in several fields. [2] We have exploited here a room temperature surfactant-assisted synthetic strategy in order to chemically transform our starting silver and copper chalcogenide nanocrystals into compositionally more complex nanostructured systems. More specifically, the Au-Ag-chalcogen and the the Pt-Cu-chalcogen systems have been explored from a synthetic point of view, leading to a set of chalcogenide-based hybrid and ternary I-I-VI semiconductor nanocrystals with different stoichiometries. Our results indicate that the chemical nature of the surfactant assisting the synthesis radically determines the type of nanocrystals obtained. Considering the complex chemical distribution of the species in the materials, the use of advanced atomic-resolution electron microscopy techniques was key for their appropriate characterization and elucidation of formation mechanisms. The work is complemented with the assessment of their potential as active materials for energy conversion devices and as contrast agents in clinical diagnosis. [1] M. V. Kovalenko, L. Manna, A. Cabot, Z. Hens, D. V. Talapin, C. R. Kagan, V. I. Klimov, A. L. Rogach, P. Reiss, D. J. Milliron, P. Guyot-Sionnnest, G. Konstantatos, W. J. Parak, T. Hyeon, B. A. Korgel, C. B. Murray, W. Heiss, ACS Nano 9 (2015) 1012-1057. [2] R. Costi, A. E. Saunders, U. Banin, Angew. Chem. Int. Ed. 49 (2010) 4878-4897.

Resume : Chalcogenides thermoelectrics materials based on semiconducting colloidal nanocrystals is of great interest in thin-film and flexible thermoelectrics, both from a fundamental and applications perspective. In recent years, the prevailing need for facile fabrication which is solution-processable, and transport property optimization for high thermoelectric figure-of-merit, has driven the development of chalcogenides colloidal quantum dots, whose electrical and thermal transport can readily modulated by dimensional constraints via. Quantum confinement effect. Herein, we summarize recent progress in the development of chalcogenides quantum dots as prospective thermoelectric materials with focus on fundamental breakthroughs in synthesis, surface chemistry, and characterization techniques that facilitates the use of these nanostructures into future thermoelectric device architectures and their rapidly emerging applications.

Resume : All-solid-state batteries (SSBs) represent a promising next-generation energy storage technology, potentially delivering higher energy density and exhibiting better safety characteristics than today’s liquid-electrolyte-based lithium-ion batteries [1]. Ni-rich layered oxide cathode materials and lithium thiophosphate solid electrolytes are being considered as a viable combination of materials for SSB applications. However, interfacial side reactions and chemomechanical degradation, among others, constitute a significant obstacle toward commercialization of bulk-type cells [2,3]. In this presentation, I will demonstrate the importance of tailoring Ni-rich layered oxide cathode materials in terms of size and composition to improve the cycling performance and stability [4,5]. Moreover, I will show recent findings on the effect that the protective surface coating chemistry has on the gas evolution in high-loading SSB cells [6,7]. 1. J. Janek, W. G. Zeier, Nat. Energy, 1 (2016) 16141. 2. R. Koerver, W. Zhang, L. de Biasi, S. Schweidler, A. O. Kondrakov, S. Kolling, T. Brezesinski, P. Hartmann, W. G. Zeier, J. Janek, Energy Environ. Sci., 11 (2018) 2142−2158. 3. F. Strauss, D. Stepien, J. Maibach, L. Pfaffmann, S. Indris, P. Hartmann, T. Brezesinski, RSC Adv., 10 (2020) 1114−1119. 4. F. Strauss, T. Bartsch, L. de Biasi, A.-Y. Kim, J. Janek, P. Hartmann, T. Brezesinski, ACS Energy Lett., 3 (2018) 992−996. 5. F. Strauss, L. de Biasi, A.-Y. Kim, J. Hertle, S. Schweidler, J. Janek, P. Hartmann, T. Brezesinski, ACS Mater. Lett., 2 (2020) 84−88. 6. T. Bartsch, F. Strauss, T. Hatsukade, A. Schiele, A.-Y. Kim, P. Hartmann, J. Janek, T. Brezesinski, ACS Energy Lett., 3 (2018) 2539−2543. 7. A.-Y. Kim, F. Strauss, T. Bartsch, J. H. Teo, T. Hatsukade , J. Janek, P. Hartmann, T. Brezesinski, Chem. Mater., 31 (2019) 9664−9672.

Resume : The recent discovery of ferroelectric behavior in ultra-thin hafnia-based films[1] has revived interest in ferroelectric memories. Recently, the authors have demonstrated the chemical solution deposition (CSD) of 1 µm thick piezoelectric La:HfO2 films, which is very encouraging for pyro- and piezoelectric applications. However, a common problem of low density (around 80 % of the theoretical value) of solution-derived hafnia and zirconia films has been raised.[2] Here, we report an in-depth optimization of the CSD process to tackle this issue. The typical adjustments of drying and pyrolysis steps as well as the maximum temperatures accessible in common rapid thermal annealing are insufficient to achieve dense, high-quality dielectric films. The final density remains surprisingly unaffected by these parameters. Using X-ray reflectivity, we show that significant improvements rely on crystallizing the films every spinning and on decreasing the deposited thickness per spinning. With this, an improved relative density of 88 % could be achieved giving rise to an increase of remanent polarization and maximum electric field from 7 to 12 µC/cm² and 3 to 4.5 MV/cm, respectively. The origins, such as shifting from a homogeneous to a heterogeneous nucleation regime, and prospective routes for even further improvement will be discussed in the contribution. [1] T. Böscke et al. Appl. Phys. Lett., 99, 102903, 2011. [2] T. Schenk et al., Phys. Status Solidi Rapid Res. Lett., 2019 https://doi.org/10.1002/pssr.201900626

Resume : Double perovskite structure (A2BB’O6) oxides exhibit a breadth of multifunctional properties with a huge potential range of applications in fields as diverse as spintronics, magneto-optic devices or catalysis, and most of these applications require the use of thin films and heterostructures. The physical properties of these materials are strongly dependent on the ordered arrangement of cations in the double perovskite structure. Therefore, the synthesis of ordered double perovskite oxides by environmentally friendly methods combining high performance, with high throughput and low cost is an important and interesting challenge worth to be addressed. In the present work, our recent achievements using polymer assisted deposition (PAD) of environmentally friendly, water-based solutions for the growth of epitaxial ferromagnetic insulating double perovskite La2CoMnO6 and La2NiMnO6 thin films on SrTiO3 and LaAlO3 single-crystal substrates are presented. We show that the particular crystallization and growth process conditions of PAD (very slow rate, close to thermodynamic equilibrium conditions) promote high crystallinity and quality of the films, as well as favors spontaneous B-site cationic ordering. La2CoMnO6 epitaxial thin films exhibit a single magnetic phase with high saturation magnetization (Ms) values, indicative of full Co2+/Mn4+ B-site cationic ordering, whereas the La2NiMnO6 films showed a more complex magnetic behavior suggesting the persistence of anti-site defects lowering Ms with respect to the spin only maximum theoretical value.

Resume : We report on the solution-based preparation of thin oxide films e.g. ferroelectric BaTiO3 or ferrimagnetic CoFe2O4. The films were synthesized by spin coating of solutions with a DMF/HOAc mixture as solvent followed by thermal decomposition and crystallization steps. Each coating step enhances the film thickness by approximately 30 nm. Thus, by varying the number of coating steps, different total thicknesses and stacking sequences (e.g. bilayers or sandwich structures) are available. Phase evolution was monitored by XRD and Raman spectroscopy and the resulting films were investigated by X-ray (q/2q, rocking curve and pole figure scans) and SEM/TEM in combination with EDX. Platinum coated Si-wafers and (001)-SrTiO3 single crystals were used as substrates. On Pt-coated silicon highly oriented ferrite films with a columnar particle growth were obtained and the samples show a pronounced magnetic anisotropy. In contrast, with SrTiO3 substrates an epitaxial growth (STO(001)[100]||BTO(001)[100]) can be realized and polarization loops indicated the formation of the ferroelectricity tetragonal modification of BaTiO3.

Resume : The in-field superconducting properties of YBa2Cu3O7-δ (YBCO) film can be significantly improved through the introduction of nanosized defects that may have a beneficial effect on film properties in the conditions generally adopted for fusion applications, i.e. low temperatures and high magnetic fields. Incorporation of different metal oxides as secondary phases into YBCO has been extensively investigated in the past. On the contrary, Nanodiamond (ND) introduction in YBCO film (YBCO-ND) has never been reported until our preliminary study on chemical solution deposited YBCO-ND film grown by metal organic decomposition approach and the “ex situ” route using ND as preformed nanoparticle. Our first attempts showed ND potential for the improvement of YBCO transport properties [1]. In fact, ND suspension in YBCO compatible solvent, i.e. propionic acid, was prepared and nanoparticles with uniform size below 10 nm were obtained. Despite the uncertainty and the low amount of nanoparticles concentration, ND suspension was used for YBCO precursor solution preparation and epitaxial films were obtained. An improvement of film morphology and superconducting properties was observed. Therefore, further investigations of ND influence on YBCO nucleation and growth appeared to be necessary. In the present work, studies on the effect of ND on YBCO nucleation mechanism have been carried out in order to elucidate the role of ND in promoting film growth. Furthermore, ND functionalization has been attempted with the aim of favoring the interaction between nanoparticle and solvent and, consequently, obtaining higher and precise ND concentration, as well as more stable precursor solution. Different routes have been explored and results will be discussed. [1] Pinto et al., Thin Solid Films 2020. Doi.org/10.1016/j.tsf.2019.137696 Acknowledgments This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission

Resume : Chemical solution deposition (CSD) has been proven as a scalable method to fabricate YBa2Cu3O7-δ (YBCO) films in coated conductor (CC) architecture with high performance and low manufacturing cost. However, the implementation of YBCO CCs in moderate magnetic field applications is limited due to the strong reduction of the critical current density (Jc) when the magnetic field is increased. Nevertheless, this reduction of the Jc can be lowered by the introduction of nanometre-sized defects in YBCO matrix that prevent vortex motion. In this work, bimetallic oxide nanocrystals of 2-10 nm in diameter were synthesized via microwave-assisted heating of bimetallic alkoxide precursors, stabilized in polar solvents and added to the low-fluorine YBCO precursor solution. Superconducting YBCO nanocomposite films deposited on LaAlO3 single crystal substrates with a Jc of around 5 MA/cm² at 77 K and a thickness of 300 nm were obtained. These YBCO nanocomposites showed a reduced decay of the Jc with increasing magnetic field as a result of the increase in pinning force by a factor of 3-4 compared to pristine films. The challenging upscaling of these results to long industrial tapes was carried out as a part of the Horizon2020 project SynFoNY (www.synfony.eu). CC nanocomposites were deposited for the first time via full-CSD process in up to 100 m long tapes reaching high self-field Jc comparable to pristine commercial tapes and showing a smoother decay of the Jc with the magnetic field.