Smart materials for green buildings and vehicles: towards energy efficiency, energy utilization, and a healthy interior environment

Resume : The development of new-generation high-performance energy-saving windows relies on the formation of utlra-thin metal films (commonly Ag), which exhibit low electrical resistivity upon the surface of the window glass. This requires film growth in a pronounced 2D fashion: an outstanding scientific challenge, since weak interaction (i.e., bond strength) between metals and oxide layers used in energy-saving windows(e.g., SiO2, ZnO, TiO2) provides a strong thermodynamic driving force that lead to the formation of 3D-island agglomerates. Thus,understanding the dynamics of the atomic-scale processes that govern 3D island formation and shape evolution is a key step toward controlling film morphology and, by extension, the functionality of metal layers in low-emissivity window stacks. This talk contributes to this understanding by means of kinetic Monte-Carlo (kMC) simulations, analytical modelling, and experiments. By establishing qualitative agreement between experimental and theoretical data it is found that a crucial mechanism for 3D island formation and growth is upward atomic diffusion (i.e., mass transport) via sidewall facets bounding the islands. It is also shown that the limiting atomic process which determines the island height is the temperature-dependent rate at which adatoms cross from sidewall facets to the island top. This notion provides insights for developing growth manipulation strategies for promoting 2D metal-layer growth on weakly-interacting oxide substrates.

Resume : The growing demand of new and sustainable energy harvesting concepts led to the increased interest in electric and electrochemical devices with improved performance derived from the use of nanostructures. Here we present the wok resulting from recent research concerning the engineering of structure and morphology of transition oxide nanoparticles aiming electrochromic, thermochromic and energy storage devices. First topic is related to nanostructured electrochromic printed films with controllable WO3 dual phase, which show an optical density 80% higher than amorphous ones, in parallel with improved coloration efficiency and response time (below 3s). Second topic is related with the application of VO2 on ceramic tiles aiming to control the reflected infrared radiation on smart roofs. The VO2 nanoparticles are transferred to the surface of ceramic glassy tiles by spray coating with posterior annealing treatments to promote the surface adhesion as well as the stabilization of monoclinic phase. The VO2 transition temperature was adjusted from 69 °C to 49 °C by doping with tungsten. Finally, we demonstrate the application of V2O5 nanosheets obtained either by exfoliation or hydrothermal synthesis as cathode in Li-ion batteries. Proper control of their morphology allows for an initial charge capacity of 216 mA h g-1 at 1C, with high reversible capacity of 201 mA h g-1 at the end of the 100 cycles, which corresponds to an extremely lower capacity loss of 0.07 %.

Resume : Given their closely coupled lattice, orbital, and spin degrees of freedom, binary and ternary vanadium oxides represent interesting platforms for realizing a variety of electronic and optical properties. In this lecture, I will focus on two examples where the properties of vanadium oxides have been tuned for specific applications related to sustainability. In the first example, I will focus on the binary vanadium oxide VO2, which exhibits a massive insulator—metal transition in close proximity to room temperature. The phase transition is accompanied by a pronounced change in near-infrared optical transmittance, which allows for deployment of these materials in thermochromic glazing for improving the energy efficiency of buildings. Challenges with tunability of the transition temperature, light scattering, and thermal cycling have been resolved through the design and fabrication of a polymeric nanocomposite incorporating doped VO2 nanocrystals. The role of dopants in modifying the transition temperature of VO2 will be examined considering substitutional tungsten doping and interstitial boron doping. In the second example, I will focus on the introduction of mid-gap states in the electronic structure of tunnel-structured ternary vanadium oxide bronzes with the composition, β-MxV2O5. The mid-gap states can be positioned for specific catalytic reactions based on choice of the intercalating cation M. A novel class of quantum-dot/β-MxV2O5 heterostructures have been prepared and represent a reconfigurable platform wherein the kinetics and thermodynamics of hole transfer can be systematically tuned. Such heterostructures provide a vast compositional space that can be rapidly sampled to arrive at photocatalysts for water splitting.

Resume : Typical reversible electrochemical mirror (REM) devices are limited to switchability between transparent and mirror states. We develop a Cu-based REM device, which offers reversible switching between transparent, blue and mirror states with judicious selection of electrolyte and controllable electrodeposition. This tri-state REM device is one of the first to demonstrate electrochemical tunability to achieve clear, colored and reflective modulations in a single electrochromic device. The blue colored state can be obtained when copper (II) chloride CuCl2 undergoes electrochemical reduction to form copper (I) chloride, CuCl. The mirror state is formed when CuCl undergoes electrochemical reduction to Cu0 metal. The clear state can be obtained when the electrodeposited Cu0 metal oxidizes upon application of reverse potential and dissolves back into the electrochromic solution, thus increasing the optical transmittance of the working electrode. The polymer host, PVA (poly(vinyl alcohol)) plays a critical role in reducing the surface roughness of the electrodeposited mirror film, improving uniformity of the film and sustaining the mirror state of the device during the voltage-off state. In addition, the tri-state REM device is operational using low potential with standard battery and allows memory effect for energy conservation application for electronic devices and green buildings.

Resume : Nanoscale photonic structures and metamaterials, by their sub-wavelength length scales, can manipulate light and heat in unprecedented ways, thereby enabling new technological possibilities for energy efficiency and generation. In this talk, I will show how metamaterials can control the broadband electromagnetic fields associated with mid-infrared thermal radiation and sunlight to harness an unexploited thermodynamic resource – the cold of space – to improve the efficiency of terrestrial energy conversion systems. I will introduce the concept of radiative sky cooling and present our body of theoretical and experimental results in enabling this passive cooling approach, and the result energy savings possible in real-world building-scale deployments. I will further show how it is possible to design artificial materials with specific wavelength and angular selectivity that can in turn enable remarkable performance, including passive cooling to 100°C below ambient. Applications to both energy efficiency as well as new energy generation possibilities will be presented. Finally, I will highlight new fundamental and applied research directions for controlling light and thermal radiation at the building-scale, particularly at mid-infrared wavelengths. New materials capabilities our research group has been exploring will further be assessed for their energy-savings potential. By better controlling the radiative heat flows around us, we have the opportunity to enable a dramatically smarter, and more efficient built environment.

Resume : Metallic nanostructures shine in bright colours due to excitation of plasmons, which are collective charge oscillations induced by light. This interaction leads to strong light absorption and heat generation, which makes plasmonic nanooptical systems suitable as light-induced nanoscale heat sources. Here, I will present our recent work on utilizing this effect for energy management and energy conversion. I will discuss the use of directional optical nanoantennas for solar-heated transparent windows [1] and present means for converting light-induced heat to electricity [2], including harvesting of energy from random light and heat fluctuations [3]. Finally, I will discuss new exciting directions related to systems in which light and matter are strongly coupled and provide hybridized light-matter states [4]. References 1. Solar Transparent Radiators by Optical Nanoantennas Jönsson et al. Nano Letters 2017, 17 (11), 6766–6772 2. Thermoplasmonic Semitransparent Nanohole Electrodes Tordera et al. Nano Letters 2017, 7 (5), 3145–3151 3. Hybrid Plasmonic and Pyroelectric Harvesting of Light Fluctuations Shiran Chaharsoughi et al. Advanced Optical Materials 2018, 6, 1701051 4. Strong Plasmon–Exciton Coupling with Directional Absorption Features in Optically Thin Hybrid Nanohole Metasurfaces Kang et al. ACS Photonics 2018, 5, 4046–4055

Resume : Different examples of material development for various application will be shown in this presentation. Starting with basic principles of magnetron sputtered electrochromic systems and their current performance. Requirements of electrochromic materials will be discussed and examples of recent developments, especially TiNb2O7 will be presented. This will be followed by a summary of material development with hot wire (filament) CVD in the field of diamond electrodes for water purification in addition to amorphous silicon layers (a-Si:H) for silicon heterojunction (SHJ) solar cells. Finishing with Atomic layer deposition technology (ALD) with a focus on crystalline TiO2 applications for photocatalytic degradation of harmful pollutants to improve indoor and outdoor air quality. Furthermore, the application of amorphous TiO2 as diffusion barriers for solid-state electrolytes to be used in batteries will be discussed.

Resume : The growing demand for a low ecological impact and high economic impact materials and devices drives the competitive development of related technologies. One of the challenges of the future buildings is the effective use of large window areas enabling both production of electricity and cleaning of air while retaining their transparency and price close to that of conventional glass. To succeed in large-scale, cost-effective technologies should be employed for the preparation of thin films and solar cell structures directly on the window glass. Among several thin film technologies, wet-chemical ultrasonic spray pyrolysis method offers unique resource saving and rapid approach to fabricate thin films and solar cells on large substrate areas for environmental and energy applications. Our recent results show that sprayed TiO2 thin films with a thickness of 200 nm effectively decompose several volatile organic compounds in air under UV-A and VIS light illumination. Semi-transparent hybrid solar cells based on Sb2S3 thin film absorber layer, produced within 1.5 hours, show power conversion efficiency of 5.5% under 1 sun full spectral illumination intensity of 100 mW cm-2 and efficiency of 10% at 3 mW cm-2. Thus, thin films and devices fabricated by ultrasonic spray method demonstrate excellent potential for air cleaning and window solar applications.

Resume : Smart windows have the potential to contribute substantially to energy savings in cooling and air conditioning of modern (glass-façade) buildings with added benefits like glare reduction and reduced cost for additional light control facilities. A possibility to realize these functionalities in a passive way are photochromic thin films, which can adapt their optical properties to the incoming solar radiation. A unique photochromic effect was discovered in semiconducting rare-earth (RE) oxyhydrides REOxHy showing reversible color-neutral photo-darkening in a wide spectral range that is triggered by UV/blue visible light [1]. While the REOxHy films prepared by reactive magnetron sputtering exhibit large optical contrast (up to ΔT=40% at 300nm film thickness) the origin of the photochromic effect and the performance limits are poorly understood. Recently, we established a ternary composition-phase diagram showing that photochromism exists for many different RE metals and in a wide range of O/H anion ratios [2]. Further, we find that the photo-darkening energy threshold is linked to the optical band gap which can be tuned by cation-alloying and/or modifying the anion ratio of REOxHy. The effect of this approach on the photochromic performance in terms of contrast and the temperature dependent bleaching kinetics will be discussed. [1] F. Nafezarefi et al. Appl. Phys. Lett. 111 (2017) 103903 [2] S. Cornelius et al., J. Phys. Chem. Lett. (2019) – submitted

Resume : Photochromic (PC) materials have multitude of applications in the industry, being PC ophthalmic lenses—also known as transition lenses—one of their most extended and celebrated applications. However, the vast majority of PC materials available are based on organic dyes, which present poor resistance to fatigue and degrade rapidly under UV illumination; due to this fact, state-of-the-art PC materials cannot be used in applications that require longer lifespan (such as, for example, windows). Nevertheless, the first PC industrial materials were based on inorganic compounds (silver halides), which exhibit good durability under UV illumination. However, silver halides gave way during the last decades—mainly due to a fabrication method incompatible with the float glass process and to the popularization of organic lenses—to organic dyes easier to fabricate. In this work we present an emerging group of inorganic PC compounds based on rare-earth oxyhydrides, which can be synthesized by magnetron sputtering and hence have the potential to change the existing scenario by providing durable and easy-to-fabricate PC coatings; in particular, PC oxyhydrides may open new possibilities such as the fabrication of PC smart windows. For this purpose, we will present a complete study on PC yttrium oxyhydride (considered here as the archetypical PC oxyhydride), including its deposition procedure, optical and electrical properties, crystalline structure and possible causes of the PC effect.

Resume : In recent years, the need for smart window materials that lower the energy consumption for heating, venting and air-conditioning of buildings has grown immensely. These smart materials undergo a reversible change in physical properties depending on various conditions. A material that fits this description is vanadium dioxide, a thermochromic material that changes from a monoclinic to a rutile phase when heated above a critical temperature. This metal-insulator transition (MIT) leads to the absorption of infrared radiation. By absorbing this, a lower amount of heating-up occurs inside buildings and less cooling is needed. During this work, the main focus is the development of novel and easy methods to synthesize thermochromically active vanadium dioxide nanoparticles. Microwave syntheses were performed and optimized. The influence of various reaction parameters on the morphology, crystal structure and thermochromic properties of the nanosized materials were studied. Stabilization materials and methods were investigated to obtain stable suspensions in various solvents.

Resume : Electrochemical devices equipped with nanocrystalline electrodes are known to perform much better in energy related all-solid-state devices like solid oxide cells, batteries or sensors in comparison with their microcrystalline counterparts. This is mostly related to high surface area of nanocrystalline grains significantly influencing efficiency of an electrode reaction. However, technologies allowing fabrication of nanocrystalline films are frequently too expensive and/or complicated for widespread industrial application. In this work a spray pyrolysis method, which allows cost effectively fabricating dense or porous a few hundred nanometers thick layers, is presented. Examples of layers fabricated by spray pyrolysis will be presented together with their electrical properties strongly dependent on post deposition heat treatment procedure. Acknowledgement: This work was supported by the National Science Centre Poland based on decision 2017/25/B/ST8/02275.

Resume : With a power conversion efficiency over 23%, perovskite solar cells (PSCs) are considered a rising star in the solar energy. Nowadays a lot of research is focused on the improvement of the device performance through the employment of new materials or architectures [1,2]. With regard to this, the importance of interfaces in such a system is well known and in particular a crucial role is played by the energy level alignment of the different layers [3]. A good match between the electronic bands is required in order to obtain high performance PSCs structures, to this purpose we functionalize the interface between the perovskite and the charge selective contacts within the device. We make use of specific molecule-to-substrate interactions to self-assembly perfluorinated small molecules on the perovskite surface. This not only leads to a shift in the perovskite work function and therefore to a reduction of the bands offset, but also to passivation and reduction of recombination [4]. Moreover, the formation of a nanometer thick perfluorinated layer results in hydrophobicity of the perovskite surface, which enhances stability by preventing the ingress of water from the atmosphere. Notably, such a functionalization can be done through scalable solution processing methods, which are compatible with fast output production including roll-to-roll and inject printing. We investigate the impact of the functionalization on material and device by characterizing the change in the energetics of the system and correlating them with the PSCs performance. Our results show that the interface functionalization with perfluorinated molecules is an effective new approach to improve energy levels alignment and enhance PSCs performance. Our aim is to implement this technique in order to create a universal tool to tune the work function and control its shift, which would lead to more flexibility in the choice of materials and structure. [1] G. E. Eperon, V. M. Burlakov, P. Docampo, A. Goriely and H. J. Snaith, Adv. Funct. Mater., 2014, 24, 151–157. DOI: 10.1002/adfm.201302090 [2] K. T. Cho, S. Paek, G. Grancini, C. Roldan-Carmona, P. Gao, Y. Lee, M. K. Nazeeruddin, Energy Environ. Sci. 2017, 10, 621. DOI:10.1039/C6EE03182J [3] P. Schulz, E. Edri, S. Kirmayer, G. Hodes, D. Cahen, A. Kahn, A. Energy Environ. Sci., 2014,7, 1377-1381. DOI: 10.1039/C4EE00168K [4] C.M. Wolff, L. Canil, N.L. Nguyen, P. Caprioglio, L. Fiedler, M. Stolterfoht, A. Abate & D. Neher, submitted

Resume : A novel multifunctional molecular BTE-CNPH was designed and synthesized by connecting (3',5'-Bis(trifluoromethyl)-biphenyl-4-yl)-acetonitrile to both side of the bisthienylethene (BTE), which exhibits excellent aggregation-induced enhanced emission (AIEE) and bistable photochromism. High-contrast (> 60) reversible fluorescence switching was achieved in the 1D nanowires, solid of BTE-CNPH and also in a PMMA film 1% loaded with BTE-CNPH under the altering irradiation by 365 nm and visible light. The FE-SEM images of the BTE-CNPH nanowires upon different irradiation time by the 365 nm light describe the interesting process of the nanowires melting, which is less reported and suggests a new kind of opto-electronic materials.

Resume : Electrochromic (EC) materials are able to change their optical properties such as transmission, absorption and reflection reversibly by application of an external voltage. EC metal oxides are divided into two groups: cathodic (coloring under ion insertion) and anodic (coloring under ion extraction). Tungsten oxide (WO3) is a well-known cathodic EC material and has been intensively studied in the last 30 years. EC materials and devices have been developed as an alternative to passive coating materials for light and heat management. Conventionally, an EC device is a construction with five-layers: transparent conducting oxide (TCO)/cathodic EC/ion conducting layer (liquid, gel or solid)/anodic EC/TCO, either all on one substrate or positioned between two substrates in a laminated configuration. Indium-tin oxide (ITO) coated substrates are used as a TCO electrode in EC applications due to their high conductivity and transparency. In this study, we deposited WO3 films onto ITO coated glass substrates with different sheet resistances (15, 30, 60 and 1000 Ω/□) by using DC magnetron sputtering technique. Optical and structural properties of ITO films were investigated. For durability studies, cyclic voltammetry data was recorded for up to 500 cycles between 2.0 and 4.0 V versus Li/Li at a scan rate of 20 mV s−1. Chronoamperometry measurements of the WO3 films were also performed. We measured the inserted and extracted charges as well as bleaching and coloring times of WO3 films with different ITO layer properties. Generally, ITO with low resistivity is preferred for the electrochemical measurements while absorption is low in the near-infrared region for ITO with higher resistivity. In this study, it is observed that the ITO with 60 Ω/□ sheet resistance is very suitable for optical and electrochromic measurements.

Resume : Weight reduction is an important aspect in the automotive and aerospace sectors to enhance fuel efficiency, where the advantages demonstrate themselves both in cost savings and reduced emissions. One way to achieve this is through the use of carbon nanotube (CNT) reinforced lightweight metal composites, which could be considered as the next generation of composites due to CNT’s remarkable mechanical and physical properties. However, the biggest limitations to CNT-composite advancement are the inhomogeneous dispersion of CNTs within the matrix, and weak CNT-matrix interfacial strength. In this work, a pre-dispersion step, followed by melt-stirring and rolling is used for fabrication. Magnesium was chosen as the matrix due to it being the lightest of all structural materials (1.8 g/cm3). However, Mg is limited by its weaker mechanical properties, compared to other metals such as aluminium, which is why reinforcements need to be added. The pre-dispersion step involves the use of a block co-polymer to improve the dispersion of the CNTs among the Mg chips. The melt-stirring technique offers the advantage of being a scalable and inexpensive method. The purpose of the final rolling step is to close the porosities that are formed during melt-stirring, and further improve the strength. The composites are then characterised through tensile tests and microscopy techniques such as SEM and TEM to study the effects on the interfacial bonding and on ductility and tensile strength.

Resume : Electrochromic (EC) and thermochromic (TC) materials exhibit reversible change of their optical transmittances in response to applied electric field and temperature, respectively. The integration of EC and TC systems is important for the realization of multifunctional smart windows, allowing alternatively or simultaneously the control of light transmittance and solar energy. Here, we fabricated all-solid-state multifunctional EC-TC hybrid smart windows where tungsten oxide (WO3)-based EC and vanadium oxide (VO2)-based TC cells are integrated into a single device. It was found that VO2 has TC behavior not only at H+-deintercalated state, but at H+-intercalated state. The TC behavior of the EC-TC hybrid device in its colored and bleached states indicates that luminous and solar transmittance of the device can be actively regulated by oneself with increasing and decreasing temperature. Finally, four-different optical states were realized by using EC reaction and TC behavior selectively, which make it suitable for use in smart windows applications.

Resume : Search of a solution to fulfil the increasing energy demand and great concern regarding environmental pollution caused by fossil fuels leads to immense attention on energy conversion and storage devices. Electrochemical water splitting which includes hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) serve as suitable alternatives for the inevitable issues. Compared to HER, the later has a much complex reaction kinetics involving multiple electron transfer process, thereby leading to challenge in designing an efficient catalyst for OER. Ru and Ir based oxides have been considered as potential electrocatalysts to drive OER. However, they suffer from drawbacks like high cost being rare earth elements and unstable irrespective of acidic or alkaline medium. Herein, we have synthesized 2-dimensional (2D) trimetallic Co, Ni and Mn based oxides nanostructures using simple one pot solution technique which show enhanced current density, low onset and overpotential, excellent stability and low Tafel slope suggesting more favourable electron transfer kinetics. The as-synthesized catalyst is comparable or better than the state of art catalyst. Moreover, the catalyst is eco-friendly and cost-effective. Hence, transition metal-based oxides catalyst can be a potential candidate for water oxidation.

Resume : A facile nucleation of PtCu alloy nanoparticles is done over the heavily reduced SrTiO3 (RSTO) support in different alloy compositions using a fast microwave-assisted synthesis technique. The nano-alloy compositions are checked using XPS, ICP-MS and STEM-EDS techniques. The PtCu decorated RSTO are compared with monometallic Pt-decorated supports for their activity in preferential CO oxidation reaction under excess hydrogen. This work isolates the effect of Cu dilution on Pt in a PtCu bimetallic alloy-based catalyst for PrOx reaction. The unprecedented enhancement in the selectivity on the addition of Cu, could be seen in all the compositions of PtCu alloy. The CO oxidation activity, on the other hand, decreased on the alloys compared to the monometallic Pt catalysts. In a nutshell. We report an efficient catalyst, Pt-Cu(40:60)-RSTO, showing a high selectivity and stable activity for preferential oxidation of CO in a temperature range of 60-130 degree Celsius.

Resume : Molecular precursor derived ceramics (PDCs) have garnered intense research interest as potential standalone as well as composite electrode materials for rechargeable alkali metal-ion batteries and supercapacitors. PDC based electrodes offer high surface area, improved electrical conductivity by heteroatom modification, and mechanical toughness along with added value of mass production. Here, we will present data on recent success in direct fabrication of self-standing molecular precursor-derived silicon oxycarbide (SiOC) ceramic battery and supercapacitor electrodes by two different routes--electrospinning and sol-gel. We will show that micro and nano-structuring of PDCs is an effective strategy in improving PDC’s electrochemical capacity, rate capability, and cycling efficiency.

Resume : Devoted from the strong binding motif of phosphonic acids with metal oxides, organophosphonates can covalently bind on the surface of superparamagnetic iron oxide (Fe3O4) nanoparticles instantly. By using this unique feature, a facile water purification methods were proposed and their effectiveness from the artificial and real water samples was demonstrated, which then can be collected by an external magnetic field. Collected nanoparticles were analyzed by infrared spectroscopy, thermogravimetric analysis, and dynamic light scattering, while the binding mechanism was investigated with molecular dynamics simulations. Moreover, the effective extraction was examined with liquid chromatography-mass spectrometry. From both experimental and theoretical results, it is clearly demonstrated that the contaminants in the water can be extracted with a permanent magnet and their yield was quite substantial compared with the conventional method. Furthermore, the extracted Fe3O4 nanoparticles can be recycled which enables a cost-efficient full-loop process.

Resume : In this study, we propose the structure of color glass for BIPV (Building Integrated Photovoltaic System) and develop process technology to realize it. It was verified through computer simulation based on wave optics that two different kinds of metal oxide thin films with different refractive indices could be integrated to realize different colors with good transmittance. To fabricate the structure, we used RF Magnetron deposition method to achieve the target thickness uniformly. The optical analysis of the samples was carried our by comparing with the results of computer simulations and it was found that this technique can be stably implemented on lab scale. The stability test over weeks was confirmed at room temperature. This method is expected to be very useful in BIPV buildings.

Resume : The electrochemical comparison of samples deposited in deuterium plasma BBD_D and hydrogen plasma BDD_H was conducted. The diamond films (BDD_D and BDD_H) were deposited on p-type (100) silicon (1 x 1 cm2) with a D2/CH4 and H2/CH4 gas mixture of 1% vol. with the overall gas flow of 300 sccm. The films were grown in Microwave Plasma-Assisted Chemical Vapour Deposition (MWPACVD) process at pressure 6.7 kPa and 1300 W of microwave power resulting in the high-density direct plasma at the region of the substrate stage. Diborane (B2H6) was used as a dopant precursor. The boron level expressed as the [B]/[C] ratio in the gas phase was 10,000 ppm. The growth time of BDD_D and BDD_H films was 6 hours, producing microcrystalline films with an average thickness of 500 nm and 2 µm, respectively. The synthesized samples were measured using cyclic voltammetry in 0.5 M Na2SO4 containing 5 mM K3[Fe(CN)6] vs. Ag/AgCl 3M KCl reference electrode. The archived peak to peak separation was equal ΔE = 100 mV which is a which is a good result for thin diamond polycrystalline electrodes. Next, electrochemical impedance spectroscopy measurements were carried out in the frequency range of 0,01 Hz to 100 kHz. Furthermore, detection of paracetamol in artificial urine on both electrodes and electrochemical mineralization of landfill leachate. This work was supported by the Polish National Science Centre (NCN) under the Grant No. DEC-2017/01/X/ST7/02045, the Provincial Fund for Environmental Protection and Water Management in Gdańsk under Grant No. RX15/13/2017 and National Centre for Research and Development (NCBR) TECHMATSTRATEG1/347324/12/NCBR/2017.

Resume : Vapor-compression refrigeration system (VCRS) technology has practical limitations to improve against environmental destruction such as destruction of ozone layer and global warming. Recently, proposals and researches on new cooling technologies to replace these past cooling technologies have been underway. Magnetocaloric effect (MCE) is a magneto-thermodynamic phenomenon where the temperature changes when material is exposed to changing magnetic fields. These properties can be combined with cooling technology. The cooling technology with MCE has been used in a variety of cryogenic applications, such as cryogenic technology in space science, liquefaction of hydrogen or other fuel gases. In this study, we investigate the MCE properties of Eu3 -doped Gadolinium Vanadate (GdVO4) with nanostructures by using microwave-assisted hydrothermal methods. In addition, it was compared with basic GdVO4 nanopowder for magnetic properties. The changes of Néel temperature (T_N), Curie-Weiss temperature, effective magnetic moment (μ_eff), and relative cooling power (RCP) were observed with and without Eu3 ions. Basically, GdVO4 and and Eu3 -doped GdVO4 nanopowder showed paramagnetism behavior in common. This is due to the weak influence of antiferromagnetic couplings between rare-earth ions. T_N and the Curie-Weiss temperature are shown to be slightly different, which is attributed to an additional magnetic contribution of the Eu3 component to the population of low-lying excited states. The synthesized GdVO4 and and Eu3 -doped GdVO4 nanopowders, when compared to the Bulk GdVO4, has a relatively low RCP, which is a measure of the MCE performance, due to the increased surface effects. The temperature at which the AFM-PM transition occurs decreases and ferromagnetic behavior occurs at low temperatures when an external magnetic field is applied. As the particle size decreases, the metamagnetic transition becomes second order

Resume : 3D printing allows fabrication of membranes beyond traditional tubular, hollow fibre and flat surface configurations. Multimaterial 3D printing (MM-3DP) facilitates the rapid production of complex devices with integrated materials of varying properties and functionality. Herein, MM-3DP was used for printing a passive sampling device consisting of non-porous device body using black polylactic acid and porous integrated membrane using commercial composite material, porous on dissolution of polyvinyl alcohol. The novel design of the device, consisting of two interlocking frames, each with integrated membrane, provided simple assembly and efficient sealing in comparison to the current commercial configurations (Chemcatcher, POCIS) containing several assembly parts e.g. membranes, O-rings/compression disks. Scanning electron microscopy confirmed an av. pore size of ∼30 nm and diffusion studies showed selectivity for anions (NO-3,) and neutral organic contaminants (atrazine). 3D printed sampler with 0.5 mm thick integrated membrane showed excellent performance with 87% depletion and a sampling rate of 0.19 Ld–1 for extraction of atrazine, under controlled conditions. Our recent studies focus on the fabrication and characterisation of highly advanced prototypes with multiple partitions, each consisting of a highly selective target specific receiving phase, and an integrated protective cage outside the membrane to filter marine debris. 3D printed passive samplers show a great potential of MM-3DP for the manufacturing of the highly selective and customised samplers with integrated components of variable properties (e.g., pore size, surface charge) for a broad range of environmental applications.

Resume : This study produced silica nanoparticle from palm kernel shell ash. A Palm kernel Shell Ash (PKSA) is a byproduct of the palm oil industry. Sol gel extraction method was used to produce the silica nanoparticle from PKSA. The Ash was characterized by XRF. The prepared silica nanoparticles were characterized using XRD, SEM with EDX, and FTIR techniques. SEM micrograph shows silica Nano particles of between 50-98nm. The EDX confirmed presence of SiO2 in the sample. Fourier transform infrared (FTIR) data indicated the presence of siloxane and silanol groups. The success of this means reduction of environmental pollution caused by the disposal of PKS and valuable nanosilica particles for advanced materials for high-tech applications.

Resume : In this study, we investigated the effects of the heat threatment on the anti-pollution properties of functional nano films synthesized on photovoltaic module cover glass BIPV(Building-integrated photovoltaics). The functional nano films prepared by coating the coating solution with a brush on a glass substrate were subjected to heat treatment using natural drying, hot air fan equipment, a furnace, and RTA(Rapid thermal anneal). Heat treatment was performed once or twice by the hot air fan equipment and 1 hour at 300°C in the furnace. In RTA, heat treatment was performed at 300°C for 10 minutes. Identified properties include anti-pollution properties, contact angle properties, optical properties, and mechanical properties such as hardness and adhesion. We identified the anti-pollution properties through self-cleaning tests. The contact angle of the functional nano thin films was measured by a contact angle analyzer (Phoenix 300 Auto, S.E.O.). The optical property of functional nano thin films was measured via UV-visible spectroscopy (Mega-700, Scinco), the hardness was measured by a standard hardness testing method (ASTM D3363) such as a H-9H, F, HB and B-6B pencil (Mitsubishi, Japan). Also, the adhesion of the functional nano thin films were measured by the standard adhesion testing method (ASTM D3359).

Resume : We describe a novel method of preparation of silica aerogel powder with uniform particle size of ~1-3 mm. The method is significantly less time-consuming and requires less solvents than any previously known method. In this method no expensive equipment nor toxic drying-control chemical additives like formamide or N-N´-dimethyl formamide are required, making it potentially the cheapest method for producing aerogel powders. This method relies on neither super- nor subcritical processing and by that opens up a new vista for aerogel synthesis. The measurements show that the aerogel powder has specific surface area of 610 m2/g (BET), average pore diameter of 12 nm and porosity of approx. 80-89%. The density of the pile of powder, if shaken to densely fill the container, is ~0.22 g/cm3 and the estimated density of the single powder particle is <0.3 g/cm3. The material is obtained in a straightforward manner and at low cost. Aerogel powders are usable as functional additives in advanced thermal insulation composites.

Resume : Noble metals, such as Pd, have been widely used for catalysis. Among the various Pd-based nanomaterials, 2D nanostructures have shown promising catalytic performance due to their high specific surface area and high density of exposed active sites. Herein, we report two kinds of ultrathin Pd-based nanosheets whose catalytic performances can be tuned through the surface and crystal phase engineering, respectively. Firstly, we synthesized ultrathin PdCu alloy nanosheets in high yield via a facile and mild wet-chemical method. The Pd-to-Cu ratio can be tuned by changing the precursor ratio. Impressively, after post-treatment with ethylenediamine (EN), the PdCu nanosheets show dramatically enhanced activity toward the electrocatalytic formic acid oxidation reaction. The excellent catalytic activity can be attributed to their ultrathin morphology, unique electronic structure, synergistic effect between Pd and Cu and post-treatment with EN. Moreover, we synthesized a series of amorphous/crystalline heterophase Pd nanosheets with different crystallinities by a mild wet-chemical method, which are used for selective hydrogenation of 4-nitrostyrene. The nanosheet crystallinity can be controlled by fine-tuning the reaction temperature, which strongly affects the chemoselectivity and catalytic activity. The Pd nanosheets with high percentage of amorphous phase exhibit an excellent chemoselectivity, while those with high percentage of crystalline phase show a higher catalytic activity. This work not only presents a novel synthetic method for hetero-phase nanomaterials, but also provides a new strategy in controlling the catalytic activity and selectivity for fine chemical industries.

Resume : Steels of the family 17-4 Precipitation Hardening (PH) stainless steels are often considered as potential candidates for applications requiring high levels of strength (typically above 600 MPa in tensile strength) and a moderate ductility. The aim of this work is the characterization of a 17 – 4 precipitation hardening stainless steel obtained through metal powder Hot Isostatic Pressing process (HIP). The main purposes of using HIP process are the better chemical composition and microstructure homogeneity, the finer grain size (allowing to higher mechanical properties), and the possibility to obtain net shape products, avoiding subsequent finishing operations. The HIP temperature does not seem to significantly influence the tensile properties, while, the aging temperature is a key factor: lower aging temperature brings to higher strength and lower ductility. However, a higher influence of the HIP temperature was detected on the toughness. Improved toughness both at room and at low temperature was obtained by optimizing the aging treatments. An improvement of 32 % in impact energy was obtained by the optimization of the aging process thanks to a higher austenite content, which shown a nanosized shape between the martensite platelets, in the steel structure.

Resume : High temperature superconductor material has been regarded as a promising material in many field, especially in maglev vehicle. Defects produced by ion irradiation can be effective pinning centers, thus enhancing the superconducting properties. Gd-doped YBCO (YGd0.2Ba2Cu3O7-x) coated conductors were irradiated by 1.83 GeV Ta ions at a wide range of ion fluences. The structure damage in the irradiated samples were characterized by TEM (Transmission electron microscopy). The critical current density and transition temperature were measured with PPMS (Physical Property Measurement System). Continuous columnar defects produced by incident ions can be observed from TEM image. With the increasing of fluence, transition temperature Tc is almost unchanged and then decreased significantly (△Tc=6.14 K) with the maximum fluence, which is arising from the combination of residual oxygen defects and the non-negligible strain around columnar defects. The maximum value of Jc and Fp with the fluence of 5.00×1010 ions/cm2 can be investigated, proving that this fluence is optimal for pinning vortices in Gd-doped YBCO coated conductors irradiated with 1.83 GeV-Ta ions. It is indicated that there exist one threshold fluence value for irradiated Gd-doped YBCO coated conductors. Superconducting parameters will increase with the increasing of fluence when fluence is less than threshold value, otherwise, both critical current and transition temperature will deteriorate badly.

Resume : Crystal-phase engineering offers great opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds for construction of heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as electrocatalysis. Here, we report a facile wet-chemical synthesis strategy to prepare binary and ternary hybrid noble metal nanostructures with controlled crystal phase and morphology. Specifically, crystal-phase heterostructured 4H/face-centered cubic (fcc) Au nanowires developed by our group are used as templates for epitaxial growth of Ru nanorods. Impressively, these Ru nanorods only grew on the 4H phase (~83.3%) and fcc-twin boundaries (~16.7%), resulting in hybrid Au-Ru nanowires. Moreover, this method can be used for the epitaxial growth of Rh, Ru-Rh and Ru-Pt nanorods on the 4H/fcc nanowires to form unique hybrid nanowires. Such highly controlled overgrowth relies on the highly active 4H and fcc-twin structures. Strikingly, the as-prepared Au-Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media, giving a high turnover frequency (TOF) of 0.31 H2 s-1 at 50 mV and a low overpotential of 25 mV at 10 mA cm-2, which outperform the Pt/C, Ru/C and most of the reported electrocatalysts. On the basis of this work, hierarchical 4H/fcc Ru nanotubes are synthesized by a hard template-mediated method. Specifically, 4H/fcc Au nanowires serve as sacrificial templates to enable the epitaxial growth of Ru nanorods, which are subsequently etched by copper ion (Cu2 ) in dimethylformamide. The resulting hierarchical 4H/fcc Ru nanotubes contain ultrathin Ru shells (5-9 atomic layers) and tiny Ru nanorods with length of 4.2 ± 1.1 nm and diameter of 2.2 ± 0.5 nm, which are vertically decorated on the surface of Ru shells. As an electrocatalyst for the hydrogen evolution reaction in alkaline media, the hierarchical 4H/fcc Ru nanotubes exhibit excellent electrocatalytic performance, giving a high exchange current density of 1.81 mA cm-2, as well as a low overpotential of 23 mV at 10 mA cm-1, which are superior to the 4H/fcc Au-Ru nanowires as introduced above, the commercial Pt/C, Ru/C, and most of the reported electrocatalysts. The aforementioned studies reveal the significance of crystal phase engineering in the controlled synthesis of novel heterometallic nanomaterials. We believe that the strategy presented here may shed light on the preparation of novel nanomaterials with desired structures, crystal phases and morphologies to tailor their electrical, optical, magnetic and catalytic properties.

Resume : Considerable interest in ferromagnetic shape memory alloys (FSMAs) is associated with their unusual physical and mechanical properties. FSMAs belong to the class of functional materials, which can change their shape and size under the influence of external factors: temperature, mechanical stress, magnetic fields or their combinations. These alloys have a high damping ability due to the thermoelasticity of martensitic transformations (MT). The present work attempts to control the value of superelastic strain in a nonthermoelastic shape memory alloy with wide (over 100C) temperature hysteresis using thermomechanical treatment (TMT) for nanoparticle formation to narrow the MT thermal hysteresis. Full reversibility and narrowing of the thermal hysteresis in Fe-Ni-Co-Ti alloys are achieved by creating micro- and nano-sized inhomogeneities of the structure and magnetic ordering To improve the functional properties of a ferromagnetic Fe-Ni-Co-Ti shape memory alloy, a thermomechanical treatment that includes drawing followed by quenching and high-temperature annealing was proposed, as a result of which a nanostructured state is formed. TMT increases the alloy thermoelasticity, although it is accompanied by a large temperature hysteresis of martensitic transformation and results in a significant hardening of the matrix, which, in its turn, enlarges the effects of shape memory and superelasticity. It has been established that TMT of Fe-Ni-Co-Ti shape memory alloy contributes to an increase in reversible superelastic deformation up to ~3%. In a superelastic cycle with wide mechanical hysteresis, a large dissipation energy per loading-unloading cycle was gained, that favours the use of this alloy as a damper of mechanical oscillations.

Resume : Vanadium dioxide is a well-studied thermochromic material, with a potential for integration in building materials such as concrete, clay, paints or glazings, in order to improve thermal efficiency on buildings, due to its passive temperature-dependent IR switching property. Major challenges such as cost-effective production, cost-efficient fabrication, and improved efficiency of synthesised smart materials are paramount in achieving their imminent application in the construction industry. In this current study a solution-based approach for nano-scaled thermochromic vanadium oxide powders, is presented. In order to fully optimise the synthetic parameters, the hydrothermal method, an adaptive, scalable and cost-effective solution-based method is deployed. Using vanadium precursor vanadium pentoxide, organic reducing agents, and promoting agents/additives in low concentrations, the synthesis of high fidelity nano-scaled thermochromic vanadium oxide is promoted. The thermochromic property / IR switching of the synthesised powders was studied by differential scanning calorimetry. Morphology of the synthesised powders was observed by scanning electron microscopy, whereas high resolution imaging was observed with transmission electron microscopy. The structural and chemical composition of the powders were deducted by x-ray diffraction, energy-dispersive x-ray spectroscopy and infrared spectroscopy data. Thermal degradation of the material was tested by thermogravimetric analysis.

Resume : Polymer electrolytes (PEs) are an important component of many electrochemical devices owing to some special features: good electrode?electrolyte contact, ease of processing into thin films, ability of accommodating a wide range of ionic salt concentrations, good mechanical properties and high ionic conductivity [1]. In the last years the community of PEs has turned its attention to the development of systems derived from renewable sources targeting the development of sustainable electrochemical devices, such as smart windows, batteries and fuel cells. Recently we proposed near-infrared (NIR) emitting electrolytes composed of red seaweeds-derived kappa-carrageenan (?-Cg) polysaccharide [2], glycerol (Gly) and erbium triflate (ErTrif3.xH2O), as a valuable technological solution for the development of smart windows providing less heating demand, less glare and more indoeors human comfort for the new generation of energy-efficient buildings [3]. In the present work we extend this study to the analogue Cg-based NIR-emitting electrolyte system doped with neodymium triflate (NdTrif3). The membranes were prepared by means of a simple, clean, fast and low-cost synthesis procedure performed in aqueous solution [2]. The surface morphology, the structure, the thermal behavior and the photoluminescence features of the Nd3+-based electrolytes were characterized. The ionic conductivity was calculated at variable Nd concentration and ion association was examined. Preliminary tests of the performance of electrochromic devices incorporating these electrolytes were carried out. Acknowledgment This work was supported by FEDER, through COMPETE and Fundação para a Ciência e a Tecnologia (FCT) (FCOMP-01-0124-FEDER-037271, Pest-OE/QUI/UI0616/2014, PEst-OE/SAU/UI0709/2014, project UniRCell (SAICTPAC/0032/2015 and POCI-01-0145-FEDER-016422)) and project LUMECD (POCI-01-0145-FEDER-016884 and PTDC/CTM-NAN/0956/2014). References [1] F.M. Gray, Solid polymer electrolytes: fundamentals and technological applications, 1991, New York: Wiley-VCH, Weinheim. [2] S.C. Nunes, R.F.P. Pereira, N. Sousa, M.M. Silva, P. Almeida, F.M.L. Figueiredo, V. de Zea Bermudez, Advanced Sustainable Systems, 2017, adsu.201700070. [3] S. C. Nunes, S. M. Saraiva, R. F. P. Pereira, S. Pereira, M. M. Silva, L. D. Carlos, E. Fortunato, R. A. S. Ferreira, R. Rego, V.de Zea Bermudez, unpublished work

Resume : Perovskite solar cells have been recognized as a newly emerging solar cell with the potential of achieving high efficiency with a low cost fabrication process. In particular, facile solution processed cell fabrication facilitated rapid development of optimum cell structure and composition. Over the last few years, the cell efficiency has exceeded 22%. A typical perovskite solar cell employs a perovskite layer sandwiched by p-type semiconductor (such as spiro-OMeTAD, PEDOT or NiO) and n-type semiconductor (such as TiO2, ZnO or PCBM) layers. Following light absorption, an electron and a hole are separated at the perovskite film interface, and are collected at the back electrodes. Choice of the most suitable solar cell structure is crucial to improve their performance. In this presentation, we will present parameters controlling charge separation and recombination dynamics at the perovskite interfaces employing a series of transient absorption and emission spectroscopies. Nanosecond transient emission spectroscopy (Vis-ns-TES) clarifies charge separation processes, while Vis-NIR submicrosecond-millisecond transient absorption spectroscopies (NIR-smm-TAS) identify charge separation efficiency and charge recombination rates. Correlation of the dynamics results with the solar cell performance will be discussed [1-3]. An optimum cell structure for methylammonium lead iodide (MAPbI3) perovskite sandwiched by TiO2 mesoporous and spiro-OMeTAD layers, among planar heterojunction, mesoporous structure and extremely thin absorber structure will be identified.[4] This work was financially supported by the JST PRESTO program (Photoenergy Conversion Systems and Materials for the Next Generation Solar Cells) and partly by JSPS KAKENHI Grant Number JP16K05885. The author also acknowledges Australian Research Council (ARC) LIEF grant (LE170100235) for the financial supports. References [1] S. Makuta, M. Liu, M. Endo, H. Nishimura, A. Wakamiya, Y. Tachibana, Chem. Commun., 52, 673 - 676 (2016). [2] Tachibana et al., J. Photopolym. Sci. Technol., 30(5) 577-582 (2017). [3] Y. Tachibana, et al. J. Photopolym. Sci. Technol., 31(5) 633-642 (2018). [4] Y. Tachibana, et al. ACS Appl. Energy Mater., 1(8) 3722-3732 (2018).

Resume : Electrospinning and Functionalisation of Silicon Oxide Nanofibres via Sol-Gel Technology for the Separation of Heterogeneous Azeotropes Eva Loccufier, Jozefien Geltmeyer, Lode Daelemans, Dagmar R. D'hooge, Klaartje De Buysser Karen De Clerck Electrospinning of silica nanofibers without organic polymer addition is regarded as a highly promising methodology for the production of thermal and chemical resistant nanofibrous materials applicable in various advanced applications. The combination of sol-gel technology and the electrospinning process allows for the production of ceramic nanofibrous membranes. By proper control of the sols rheology, addition of an organic polymer can be skipped in the nanofibres preparation procedure. It allows for functionalisation of these nanofibrous membranes with various components that would otherwise not withstand the heat treatment. The influence on viscosity, concentration and degree of cross linking will be described (1,2). These fibres show a shift from hydrophobic to hydrophic properties upon time and temperature. This peculiar feature opens room to use them as membranes for separation of heterogeneous azeotropes (3). 1. Geltmeyer, J., De Roo, J., Van den Broeck, F., Martins, J., De Buysser, K. and De Clerck, K., The influence of tetraethoxysilane sol preparation on the electrospinning of silica nanofibers, Journal of Sol-Gel Science and Technology 1-10 (2016) 2. Geltmeyer, J., Van der Schueren, L., Goethals, F., De Buysser, K. and De Clerck, K., Optimum sol viscosity for stable electrospinning of silica nanofibres, Journal of Sol-Gel Science and Technology 67 188-195 (2013) 3. Loccufier, E., Geltmeyer, J., Daelemans, L., D’hooghe D.R., De Buysser K., De Clerck, K. Silica Nanofibrous Membranes for the Separation of Heterogeneous Azeotropes, Advanced Functional Materials 28 https://doi.org/10.1002/adfm.201804138 (2018)

Resume : In recent years, lightweight materials such as aluminium and carbon fiber reinforced plastics have been used to reduce the weight of vehicles, and structural adhesives for fastening them with steel have been actively developed. Structural adhesives also could improve the overall performance of the vehicle, such as reduction of fuel consumption and gas emission, reduction of running resistance, improvement of braking performance and steering stability. These are improved by reducing the vehicle weight. Structural adhesives are mainly prepared with epoxy-based and polyurethane-based resins. However they still have some drawbacks in mechanical properties, especially their impact peel strength should be improved according to the car manufacturer’s requirements. Therefore, many studies have been actively carried out to improve their impact performance as well as processing conditions. In this study, highly toughened structural adhesives were developed based on bisphenol A-based epoxy resins and a dicyandiamide curing agent. To improve the impact peel strength and shear strength of the epoxy-based structural adhesives, urethane-based polyol was added and their effects were investigated. The viscosity changes and glass transition temperatures of the resulting structural adhesives were also examined with respect to polyol amounts.

Resume : The potential of high energy efficient windows with low-e glass has been presented for energy saving in building refurbishment. We investigated and compared conventional glass and low-e glass. In this study, we proposed amorphous oxide/metal/amorphous oxide (OMO) thin films as low-e glass which was fabricated using amorphous silicon-indium-zinc-oxide (a-SIZO) and Ag metal layer (SIZO/Ag/SIZO) on a glass substrate at room temperature. Thermal transmittance and optical properties of the samples were measured and used in building simulations. At single glazing system, the U-value is significantly lower than that of conventional glass (5.8 W/m2·K) and low-e glass (3.3 W/m2·K). Likewise, the U-value is decreased from 2.7 W/m2·K to 1.8 W/m2·K with the double glazing in interspace only 12 mm in thickness. Even though the U-value was lowered because Ag blocks the infrared area the visible light transmittance (550nm) did not change to 93%. Energy simulations for research at annual cooling and heating power consumption showed that the energy requirements have been saved for heating and cooling for single and double glazing systems using low-e glass. The low-e glass is a suitable solution for building refurbishment, showing low U-values, high visible light transmittance, and low power consumption.

Resume : Using energy from the sun to produce a fuel and finally obtaining only water as an exhaust is a promising future technology for renewable energy and environmental sustainability. Solar driven water splitting is a method to produce hydrogen from solar energy. Coupling a solar cell with an electrolyzer is the approach with highest technological readiness. CuInxGa1-xSe2 (CIGS) is here a promising solar cell material for water splitting because it is possible to tune the band gap between 1.0 and 1.7 eV by changing the ratio between Ga and In, thus enabling maximum power point matching with an electrolyzer. Tungsten oxide is known as a photocatalytic material and mainly used for the oxygen evolution reaction in a water splitting process. However, WO3 films also show electrochromic activity together with hydrogen evolution. This result is interesting because it shows that WO3 films can be used as bifunctional materials for both hydrogen and oxygen evolution in water splitting, and provide additional functionalities to the system. In this study, WO3 films coated at different sputtering conditions on Ni foam and indium tin oxide substrates were investigated in the potential range of the hydrogen evolution reaction. The best overpotential of 164 mV vs. RHE at 10 mA/cm2 was obtained for WO3 films on Ni foam in 0.5 M H2SO4. The lowest potential needed for 10 mA/cm2 was measured 1.768 V for the electrolyzers consisting WO3 films on Ni foam as the cathode and non-coated Ni foam as the anode. Optimum solar-to-hydrogen (STH) efficiency of the CIGS solar cell modules and the electrolyzers was examined for different band gaps of the CIGS modules and sputtering conditions of WO3 films. Operation points of the combined system were calculated from the intersection of the voltage-current density curves for the CIGS modules and the electrolyzers. The results showed that the detailed sputtering conditions were not very critical to obtain high STH efficiency, indicating that the system could be robust and easily manufactured. The best-matched band gap of the CIGS was 1.19 eV and the highest STH efficiency of the CIGS driven WO3-based electrolyzers was 12.98 %.

Resume : Performance and life time of battery system of electrical vehicle critically depend on the temperature of battery system. Transportation integrated photovoltaic (TIPV) system combined with cooling circuit was investigated to optimize performance of battery system and minimize electric power to cool-down battery overheating. Photovoltaic (PV) module was integrated on the roof of a car. Using sensor network and multiprotocol communication chip, efficiency of PV and temperature of each battery system were analyzed in real time. The maximum voltage and current of PV module were 92.54V and 7.46A, respectively. The output power of the module was 1.2 kWh/day. To enhance total performance of air conditioning system we combined heat pump system with TIPV. COP value of heat pump could be optimized to be larger than 3.0. Our research results may suggest potential alternative for currently used air conditioning system of electric vehicle.

Resume : The carbon-based nanofillers have recently attracted enormous attention as potential fillers to enhance the thermal conductivity of polymer composites due to their high intrinsic thermal conductivity. A lot of researches made into hexagonal boron nitride (hBN), an analog of graphite with layered hexagonal structures due to its high thermal conductivity (up to 300 W·m-1·K-1) and good insulation property (bandgap of ~5.5 eV). In this study, the silane functionalized hexagonal boron nitrides was assembled with carbon nanotubes (oCNTs@fBN) via electrostatic interaction to improve the thermal conductivity of the epoxy composites. The dispersion of hybrid fillers was improved by the introduction of the immobilized CNTs on the edges of hexagonal boron nitride (hBN). The thermal conductivity of oCNTs@fBN filler loaded epoxy composites were measured and compared with the epoxy composites with a filler of hBN, a mixed filler of oCNTs, and silane functionalized hBN (fBN). The thermal conductivity of the epoxy composites containing 10 wt% of oCNTs@fBN10 was 0.6 W·m-1·K-1. The significant improvement in thermal conductivity was attributed to the formation of linkages between oCNTs and fBN and the good compatibility of oCNTs@fBN in the epoxy matrix. *This research is supported by Korea National University of Transportation in 2018.

Resume : We compared thermal/chemical stability of VO2 nanoparticles in several polymeric host matrixes that are widely used in current thermochromic smart coating. The mixture of VO2 nanoparticles and several polymers in solvent were used to make slurry for thermochromic coating. And the coating was fabricated by directly casting the slurry on the slide glass by bar coating. The coating was put in high temperature air or acid solvent to check thermal/chemical stability. Among the polymers, PDMS shows the highest thermal/chemical stability but show the lowest thermochromic performance due to poor dispersion of VO2 nanoparticles. This results will present necessary properties of polymeric host matrixes for thermochromic smart coating.

Resume : Polyurethane (PU) foams are used in a widespread range of applications such as insulators and dielectric materials, but their applicability is limited due to their poor mechanical properties. It seems appealing to modify PUs using nanoparticles. One-dimensional carbon nanotubes (CNTs) and two dimensional graphene nanoplatelets (GNPs) owing to their unique properties can be used as hybrid nanofillers to form well dispersed three-dimensional networks, which can overcome the dispersion problem of single nanofillers. CNTs and GNPs have a self-assembling ability due to the π –π interaction, which could decrease aggregations, resulting in enhancing the contact area between nanofillers and the polymer matrix. Micromechanical modeling and mechanical properties of PU hybrid nanocomposite foams with MWCNTs and GNPs were studied by mean of tensile strength and modified Halpin–Tsai equation. Three types of GNPs with various flake sizes and specific surface areas (SSA) were used to study GNP types dependence on the synergistic effect of MWCNT/GNP hybrid nanofillers. The results exhibit an outstanding synergetic effect between MWCNTs and GNPs with a flake size of 1.5 μm and a higher SSA, which tensile strength of PU was enhanced by 43% as compared to 19% for MWCNTs and 17% for GNPs at 0.25 wt%.

Resume : Y2W3O12 and AlN rich aluminium matrix hybrid composites (AMHCs) are prepared via solid state powder metallurgy technique. The hardness, compressive strength, coefficient of thermal expansion (CTE), thermal stability and thermal conductivity of all the composites are measured. The hardness and wear resistance of Y2W3O12 rich and AlN rich composites increase with increasing amount of Y2W3O12 and AlN reinforcement, respectively. A high compressive strength (500-520MPa) along with a low CTE (12-14 × 10-6 K-1) is achieved by adjusting the amount of individual reinforcement. Dilatometry measurements reveal that the composites are thermally stable. The Y2W3O12 rich and AlN rich AMHCs show improved mechanical properties without significant sacrifice of thermal conductivity compared to other composites reported in literature. These novel AMHCs demonstrate the desired set of properties which render them as suitable candidates for heat sink and thermal management applications in green buildings and vehicles.

Resume : Buildings contribute around 40% of the world’s total annual energy consumption. The unwanted transmission in the infra-red region causes heat loss or gain through glass windows, requiring heating and cooling systems to accommodate this. The extensive use of electricity to operate these systems leads to increased carbon dioxide emissions. Hence there is a growing need to find solutions for radiation loss through glass. An alternative method that can control radiation losses is to coat glass with a vanadium dioxide thin film to construct ‘smart windows’. These thin coatings are thermochromic and change their optical properties upon reaching a critical transition temperature which helps control radiation transmittance in the building. This transition temperature needs to be close to room temperature between 18-25°C to be an effective thermochromic coating. Vanadium dioxide’s transition temperature of 68°C still remains too high to be used in smart window applications. Here, F has been incorporated into VO2 coatings to lower its transition temperature. F doped vanadium oxide thin films exhibited a successful decrease in the transition temperature of VO2 to 58°C. The critical transition temperature of thermochromic VO2 was lowered by 10°C. As well as reducing the critical transition temperature, F doping also improved the aesthetics of the thin film displaying a more appealing transparent light blue coloured film. Thermochromic coatings present a promising solution to the reduction of electricity usage in buildings.

Resume : The detection and control of CO2 levels in the environment has become necessary, since the emission of CO2 has greatly increased due to human activities. The advantages of chemoresistive CO2 sensors based on metal oxides are low cost, small size, and reliability. The sensing performance of metal oxides depend on their structure, particle size, and morphology. Therefore, hollow nanostructured materials can be used to enhance the performance of gas sensors due to the high specific surface area, and efficient diffusion and adsorption of gases. Herein, a microwave-assisted solvothermal approach followed by thermal annealing was used to synthesize hollow Pr6O11 nanospheres. The spheres are 670 nm in diameter and their hollow nature was confirmed by STEM images. In addition, the crystallinity, crystal and electronic structures and composition of the material were determined by PXRD, HERFD-XANES, and PDF analysis. The CO2 sensing properties were evaluated upon exposure to 2000 ppm of CO2 over 10 cycles at 250°C and 50% relative humidity. The sensing tests revealed that the hollow Pr6O11 nanospheres are sensitive to CO2 and the responses are maintained during the cyclic CO2 exposure, indicating a long-term reproducibility. This research was funded by São Paulo Research Foundation (FAPESP) – grants 2018/08271-7 and 2017/01267-1.

Resume : Over the last few decades new ingenious methods have been developed in the sol-gel processing of materials, combining knowledge and material processing methods from different fields of research and pushing the boundaries of conventional xerogel/oxide or aerogel preparation from a wet gel in a typical film, fiber or bulk material form. Notable examples of the reinvention of the sol-gel technique include the synthesis of oxide foams, which form an important class of materials due to their wide applicability for catalysis, electrochromic devices and high performance thermal insulation. This work reports a novel method for the preparation of thick silica foam films that combines an alkoxide-based hydrolytic sol-gel process and in situ catalytic decomposition of hydrogen peroxide on a catalyst-coated support. A hydrogen peroxide/nitric acid aqueous solution was used to carry out acid-catalysed hydrolysis of tetramethoxysilane. The H2O2-loaded sols were sprayed on MnO2-coated substrates, resulting in heterogeneous catalytic decomposition of H2O2 and effective foaming and simultaneous gel formation due to oxygen gas and water formation. Silica foam films with a well-defined closed-cell porosity were annealed at 600°C without any damage to the closed-cell porous film morphology. Up to 530 µm thick films were prepared with macropore sizes in the range of 29–47 µm, exceptionally thin macropore wall thicknesses of 16–50 nm and a bulk density as low as 64 kg/m3, comparable to that of the aerogels. The lowest measured thermal conductivity of the prepared foams was 0.018±0.001 W/(m*K), which is also similar to silica aerogels, enabling the prepared foams to be used as efficient thermal insulation materials.

Resume : Electrochromic (EC) materials are able to change their optical properties such as transmission, absorption and reflection reversibly by application of an external voltage. EC metal oxides are divided into two groups: cathodic (coloring under ion insertion) and anodic (coloring under ion extraction). W oxide is a well-known cathodic EC material and its color changes from transparent to dark blue when ions are inserted. A desirable electrochromic material must have and maintain a high optical modulation, high coloration efficiency, fast coloration/bleaching switching kinetics and a stable charge/ discharge reversibility. In this study, W oxide films with different nitrogen levels were deposited by using reactive DC sputtering onto glass and ITO coated glass in Ar+O2+N2 atmosphere. For all films, the total gas pressure was set to 4.0 Pa, the Ar flow rate was kept at 50 ml/min, and the O2+N2 flow rate was kept at 7.5 ml/min. The optical, structural and electrochromic properties of undoped and N-doped W oxide films were investigated. The concentration of nitrogen in the films changes from 2 at. % to 12 at.%. The optical studies revealed that the average optical transmittance and band gap decreased (from 3.43 to 3.08 eV) due to N doping. It is shown that a small amount of nitrogen has promising effects on the EC performance (i.e. charge/discharge reversibility, optical modulation, coloration efficiency) of the WO3 films. It is observed that CE values increased by increasing N2 flow rate and its maximum value was 33.8 cm2/C. The maximum ΔT at 537 nm was 73.6% for an optimized N doped W oxide film.

Resume : The detection of volatile organic compounds (VOCs) has attracted great attention because they can be toxic, explosive, flammable or exhaled in human breath, acting as biomarkers. Among the different ways of detecting VOCs, the use of semiconductor metal oxides is the most promising. These materials have their simple operation mechanism based on conductance change, simple production and low cost. However, these materials have some limitations such as low analyte selectivity, low sensitivity, and humidity interference. The present study proposes the synthesis of hollow structures of ZnO to detect VOCs in the presence of humidity, similar to human breathing conditions. The sample presented an excellent performance in the detection of VOCs, due to the effect of hollow structures, which promote an increase in diffusion and surface area. The sample was exposed to different VOCs, including methanol, ethanol, isopropanol, acetone, 2-butanone, acetaldehyde, benzene, toluene, and m-xylene. The material presented higher selectivity and sensitivity for n-butanone, showing a response (Rair/Rgas) range of 1.72-846 to the concentration range of 100ppb to 200ppm. The result is promising, and its application under real conditions is plausible.

Resume : Due to the fact that development of efficient near-infrared (NIR) molecular luminophore is a demanding task, the cornerstone of this study is to investigate the energy transfer (EnT) between 2,2’-bipyridine-6,6’-dicarboxylate as ligand and lanthanide ions (Ln3+) e.g. Yb3+ and Er3+. Measuring UV-Vis spectrum of the complexes indicates a broad absorption band of the ligand starting at deep-UV and extending up-to ≈345nm. The steady-state and time-resolved photoluminescence (PL) measurements under 300nm excitation at room temperature (RT) and 77K are performed to obtain PL spectrum, PL quantum yield (QY), and PL lifetime (LT). As for Yb3+, although the energy of the ligand’s S1 is not close to the accepting 2F7/2 level, the successful sensitization process extends to yield its RT NIR emission with high PLQY of 3.1%, while the efficiency of the EnT (ƞEnT) is 81.9%. The LT of the 1012nm emission is 72μs at RT and 96μs at 77K. In case of Er3+, under 300nm excitation at RT the green and NIR emissions are captured extremely weak, whereas, ƞEnT is 82.2%. Further, measuring in the zero-phonon mode of the ligand (at 77K) the green and NIR emissions are observed much more intense and LT of the 1526nm emission is 2.88μs. Moreover, the effect of the presence of oxygen in the atmosphere on the PL is examined which does not show any meaningful difference. Accordingly, the most probable result would be that the EnT is stemming from the singlet states of the ligand and not from its triplet states.

Resume : Electrical energy demand is constantly increasing. On the other hand, environment friendly technologies for energy production and management are expected to replace conventional methods based on large power plants. One of such alternative is decentralized system based on fuel cells. Molten Carbonate Fuel Cells (MCFC) became attractive to the marked due to their high efficiency and low cost comparing to other types of fuel cells. Materials development is of key importance when performance and durability of such devices are considered. The cathode is the bottleneck due to the slowest chemical reactions rate taking place there. Thus, one of the most promising ways to increase the efficiency of molten carbonate fuel cell is to ensure an upswing of the catalytic activity of the cathode, which will result in improvement of kinetic for oxygen reduction reaction. In the present study, we investigated the influence of the chemical composition of cathode on the efficiency of molten carbonate fuel cell. Addition of metal oxides or rare earth elements embedded into the volume or at the surface of the cathode is utilized within these studies. The results of detailed microstructure analysis and single cell performance tests are described in order to get deeper insight into understanding the catalytic mechanisms at the cathode side and their role in overall device efficiency.

Resume : In this study, we have demonstrated the fabrication of novel material called boron-doped carbon nanowalls (B-CNW) which is characterized by remarkable electrochemical properties like high standard rate constant k° and low surface resistivity. The B-CNW samples were deposited by the microwave plasma assisted chemical vapor deposition (CVD) using a gas mixture of H2:CH4: B2H6 and N2. Growth results in a sharp edge, flat and long carbon nanowalls rich in sp2 as well as sp3 hybridized carbon phases. The synthesis parameters were tuned to vary the electrical and optical properties of such CNWs. We have demonstrated the direct growth of highly transparent boron-doped nanowalls (B-CNW) on optical grade fused quartz. The effect of growth temperature and boron doping on the behavior of boron-doped carbon nanowall grown on quartz was particularly studied. Temperature and boron inclusion doping level allow for direct tailoring of the CNW morphology. It is possible to operate with both parameters to obtain a transparent and conductive film; however, boron doping is a preferred factor to maintain the transparency in the visible region, while a higher growth temperature is more effective to improve conductance. Light transmittance and electrical conductivity are mainly influenced by growth temperature and secondarily by the boron doping. Tailoring the B-CNW has important implications for potential applications of such electrically conductive transparent electrodes. Acknowledgments The authors gratefully acknowledge financial support from the National Centre for Science and Development Grant Techmatstrateg No. 347324. The DS funds of the Faculty of Electronics, Telecommunications, and Informatics and the Faculty of Chemistry at the Gdansk University of Technology are also acknowledged.

Resume : Nanocomposite membranes present versatile opportunities for membrane fabrication with unique and useful functionalities. Although several studies have shown that nanocomposite membranes can be used for highly efficient water purification while preventing biofouling. Most current methods to generate such nanostructured membranes are suitable only for lab-scale production, limiting their widespread adoption by the industry. A critical bottleneck is the lack of robust methods to enable the cost-effective/large-scale fabrication of nanocomposite membranes while maintaining the precise control over their nanoscale structures. Here we present a strategy to overcome these challenges by developing capillary rise infiltration (CaRI) of polymers into the interstices of vertically aligned ZnO nanowire (NW) arrays to enable the scalable fabrication of nanocomposite membranes. This study describes the effect of the structure of ZnO NW arrays on the CaRI of polymers. The structural features of ZnO NW arrays including aspect ratio and alignment are varied by changing the growth conditions (e.g., precursors concentration and growth time) of the ZnO NWs and controlling the number of ZnO seed layers used for preparing ZnO NWs. We also study the wetting properties and photocatalytic activity of these polymer/ZnO NW composite membranes. Because of the vertical alignment of NWs, such nanocomposite membranes are expected to have unique transport properties, giving high permeability and selectivity.

Resume : The cool pigments (PGs) based on metal oxides are promising for commercial cool painting applications, due to their high reflectance for near infrared (NIR) radiation, which considered the direct consequence of heat up in solar radiation. Indeed, the darker colors are preferred in real usage for their aesthetics. Nevertheless, the addition of the colored element to white PGs lead to limitation of their high reflectivity to NIR radiation. Many research works were done to synthesize the colored PGs based on nanostructured metal oxides to increase the number of reflectance points, which improves the scattering of radiation and compensates the limitation of reflectivity due to the addition of colored elements. In fact, amorphous materials have a high surface area due to their high-roughness surface. To date, amorphous nanosized TiO2 was not used in pigment applications. In this respect, we realized Cr:TiO2 nanosized amorphous with Cr concentrations up to 25 Cr at. % at 100oC as well as crystalline structure ones at different annealing temperatures up to 700oC. The diffuse reflectance measurement according to the ASTM (G173-03) revealed high NIR solar reflectance (R*) for the amorphous PGs in comparison to the crystalline PGs. The obtained values of R* of amorphous PGs exhibited small reduction from 81 to 72.5% with the increase of Cr concentration, However, dramatic reduction in R* from 82.1 to 20.4% and from 93.5 to 20.87% for crystalline PGs annealed at 500oC and 700oC, respectively. The obtained results will be interpreted using the variation of the surface area and porosity as well as microstructure of the investigated PGs. The obtained results enable to fabricate novel and cost effective cool-colored nanopigments based on amorphous TiO2.

Resume : Ion conductors act as components of many electrochemical applications, mainly in the field of energy conversion, for example, in photoelectrochemical solar cells and fuel cells, in energy storage devices like batteries, electrochromic devices, supercapacitors and electrochemical sensors. Studies of solid polymer electrolytes (SPEs) based on biopolymers have seen an upsurge of interest in recent years, due to the appealing properties of biopolymers and environmental concerns. Biopolymers are biodegradable, renewable, abundant, and non-hazardous compared to synthetic polymers. Among the existing biopolymers, carrageenans (Cg) are very attractive, because they are abundant in nature, renewable, biocompatible and cost effective. Cgs are linear high-molecular-weight sulfated polysaccharides made up of repeating galactose units and 3,6-anhydrogalactose, both sulfated and non-sulfated [1], joined by alternating alpha 1-3 and beta 1-4 glycosidic linkages. Few works have been reported in literature of SPs based on Cg [2-6]. As Cg exhibits relatively low ionic conductivities (10-7 S/cm) [6], we introduced synthetic or natural plasticizers in the present work with the aim of enhancing the thermal and mechanical properties, as well as the ionic conductivity. A new series of green blended electrolytes composed of Cg and glycerol and/or polyethyleneglycol (PEG) and/or Aloe Vera have been prepared by solvent-casting technique. Scanning Electronic Microscopy, X-ray diffraction, Differential Scanning Calorimetry, Fourier transform Infrared spectroscopy and complex impedance spectroscopy were used to characterize the composites. Acknowledgment This work was supported by FEDER, through COMPETE and Fundação para a Ciência e a Tecnologia (FCT) (FCOMP-01-0124-FEDER-037271, Pest-OE/QUI/UI0616/2014, PEst-OE/SAU/UI0709/2014, project LUMECD (POCI-01-0145-FEDER-016884 and PTDC/CTM-NAN/0956/2014), and project UniRCell (SAICTPAC/0032/2015 and POCI-01-0145-FEDER-016422)). S.C. Nunes and R.F.P. Pereira thank FCT for grants (Post-Ph.D. Fellowship of LUMECD project and SFRH/BPD/87759/2012, respectively). References 1. Kariduraganavar, M. Y.; Kittur, A. A.; Kamble, R. R., Chapter 1 - Polymer Synthesis and Processing. In Natural and Synthetic Biomedical Polymers, Kumbar, S. G.; Laurencin, C. T.; Deng, M., Eds. Elsevier: Oxford, 2014; pp 1-31. 2. Mobarak, N. N.; Ramli, N.; Ahmad, A.; Rahman, M. Y. A., Chemical interaction and conductivity of carboxymethyl κ-carrageenan based green polymer electrolyte. Solid State Ionics 2012, 224, 51-57. 3. Bella, F.; Mobarak, N. N.; Jumaah, F. N.; Ahmad, A., From seaweeds to biopolymeric electrolytes for third generation solar cells: An intriguing approach. Electrochim Acta 2015, 151, 306-311. 4. Christopher Selvin, P.; Perumal, P.; Selvasekarapandian, S.; Monisha, S.; Boopathi, G.; Leena Chandra, M. V., Study of proton-conducting polymer electrolyte based on K-carrageenan and NH4SCN for electrochemical devices. Ionics 2018, 24, (11), 3535-3542. 5. Moniha, V.; Alagar, M.; Selvasekarapandian, S.; Sundaresan, B.; Hemalatha, R.; Boopathi, G., Synthesis and characterization of bio-polymer electrolyte based on iota-carrageenan with ammonium thiocyanate and its applications. J Solid State Electr 2018, 22, (10), 3209-3223. 6. Nunes, S. C.; Pereira, R. F. P.; Sousa, N.; Silva, M. M.; Almeida, P.; Figueiredo, F. M. L.; de Zea Bermudez, V., Eco-Friendly Red Seaweed-Derived Electrolytes for Electrochemical Devices. Advanced Sustainable Systems 2017, 1, (9), 1700070.

Resume : Electrostatic double-layer capacitors (EDLCs) are electrical storage devices still in development, which require new methods of their state-of-health assessment. Thermographic imaging is one of the methods which may be applied for this aim due to its popularity and high negative impact of overheating on EDLCs parameters. Moreover, thermographic imaging may be easily applied to identify any hot spots, present during intense charging and discharging when working. These devices comprise of porous carbon electrodes and electrolyte, and during charging/discharging an extensive heat may be generated and dissipated there. We have observed temperature fluctuations and were able to identify inhomogeneity of the tested structures. Electrical parameters (capacitance C and resistance ESR) were measured as well and compared with temperature distribution during cyclic charging/discharging process. X-ray examination of the samples was also performed. Bot techniques indicated areas where eventual overheating took place due to their electrodes shape, suggesting their further optimization. The proposed method is much less accurate than the calorimetric methods but is still sufficient to identify problems with heat dissipation in the developed EDLCs structures. Finally, some conclusions about ability of applying this method in practice to monitor the EDLCs during exploitation were presented.

Resume : A facile nucleation of PtCu alloy nanoparticles is done over the heavily reduced SrTiO3 (RSTO) support in different alloy compositions using a fast microwave-assisted synthesis technique. The alloy compositions are checked using XPS, ICP-MS and STEM-EDS techniques. These PtCu decorated RSTO are compared with Pt-decorated supports for their activity in preferential CO oxidation reaction under excess hydrogen. This work isolates the effect of Cu dilution on Pt in a PtCu bimetallic alloy-based catalyst for PrOx. The unprecedented enhancement in the selectivity on the addition of Cu, could be seen in all the compositions of PtCu alloy. The CO oxidation activity, on the other hand, decreased on the alloys compared to monometallic Pt catalysts. In a nutshell, we report an efficient catalyst, Pt40Cu60-RSTO, showing a high selectivity and stable activity for preferential oxidation of CO in a temperature range of 60-130 degree Celsius.

Resume : Electronic wastes (e-waste) is to be a major concern since various kinds of materials including metals (basic and pernicious metals), polymers and ceramics are combined elaborately and too hard to be separated readily. Printed circuit boards (PCBs) are considered as one of the main splits of e-wastes containing around 35% metals. Disregarding ceramics and polymers, the metallic portion includes Cu, Zn, Ni, Sn, and Fe, making the waste valuable as a secondary source of row materials after the initial processing of separation and purification. In this research, we focused on the metallic portion of waste PCBs to turn them into a value-added alloy usable in a practical application. The main goal was transforming squeezed metallic particles with different composition to homogenous nano-structured particles. To achieve the aim, we used mechanical alloying in room temperature and liquid N2 (cryomilling) in different milling time. After the initial mechanical separation, the metallic portion was subjected to ball milling. The parameters such as powder to ball ratio, rotation speed, time and temperature were optimized followed by characterization. The heat input energy was calculated to indicate the formation of a nano-structured alloy. The powder characterized by TEM, STEM and SAED patterns which revealed a homogenous nano-crystalline (<100nm) alloy of (Cu79-Zn13-Fe3-Sn3-Ni1). Lattice parameters, grain size (40nm) and lattice strain (0.73%) were measured by XRD analysis. High-resolution XPS analyses approved the presence of an insignificant oxide on the surface. A broad peak between 350-650 nm in UV-Vis spectrum confirmed the chemical homogeneity of the particles. Finally, the particles were applied in nanofluid application by dispersion into deionized water followed by monitoring pH and conductivity variations. The conductivity of optimized particles was 10 times more than deionized water. To conclude, using this method, waste PCBs were transformed to an applicable alloy without using any solution or heat.

Resume : The global supply of rare earth elements (REEs), is under considerable strain. As many countries have no suitable ore deposits within their territories, and deposits elsewhere are both limited and finite, the recovery of REEs through recycling is essential. Currently, less than one percent of REEs are recovered via recycling. Nd-Fe-B permanent magnets are now one of the most widely used type of rare-earth magnets which are implemented in a variety of applications such as electric power generation (computer and laptop hard drive) and transportation (hybrid and electrical vehicles). Given the growing demands for lightweight products with high magnetic strength to support the miniaturization of equipment in many existing and emerging applications, demand for Nd-Fe-B magnets is, likewise, expected to continue to rise, particular for the clean energy/transport sectors. In this study oxidation-reduction process was used for the recovery of rare earth elements (REEs) (i.e. Nd, Pr, and Dy) from Nd-Fe-B permanent magnets. Nd-Fe-B permanent magnets collected from e-waste were subjected to an oxidation process at 1000oC for 60 minutes followed by carbothermal reduction at 1450oC for 90 minutes using waste tyre rubber-derived carbon (WTR-DC) as a reducing agent. Fe-based metal and rare earth oxides (REO) phases were successfully separated from the original magnets. The distribution of elements (i.e., Nd, Dy, Pr, Fe, B, Al, and C) between the Fe-based metal and oxide phases were investigated via Inductively Coupled Plasma (ICP), Energy-Dispersive X-ray Spectroscopy EDS/Electron Probe Microanalysis (EPMA) elemental mapping. REEs were confirmed as the main components of the oxide phase and it was shown that the REEs did not remain in the Fe-based metal phase. The oxide phase mainly contained REEs (i.e., Nd, Dy and Pr) and a minor amount of B and Al. Using REEs (i.e., Nd, Pr and Dy) derived from Nd-Fe-B magnets we applied a low temperature urea-based homogeneous precipitation method and synthesized crystallized RE (i.e., Nd, Pr and Dy) OHCO3 nanoparticles with diameters of 40-50 nm and high specific surface area of 60 m2.g-1. The synthesized REOHCO3 was used as a precursor for the synthesis of REO nanoparticles through a thermal degradation process at 700oC. FE-SEM images revealed that the synthesized REO nanoparticles inherited their parent’s morphology. X-ray diffraction spectrum of the synthesized REO nanoreplicas showed cubic phase of Nd2O3 with no additional peak corresponding to the secondary phases of Pr and Dy. High resolution TEM (HRTEM) micrographs and electron diffraction of the selected area (SAED) of the as-synthesized REO nanoparticles exhibited the deformation in crystalline structure, shrinkage of the crystalline size and decrease in interplanar distance value indicating that Nd3+ in Nd2O3 host lattice were replaced with dopants of Pr3+ and Dy3+.

Resume : A novel luminescent thermometer based on thermal shifting of the charge transfer band (CTB) in europium-doped gadolinium oxysulphide (Gd2O2S:Eu3 ) is presented. The Gd2O2S:Eu3 phosphors, synthesized via flux-assisted solid-state reaction, exhibited intense red emission and a high photoluminescence quantum yield of 64.5% under 375nm excitation. Temperature-dependent photoluminescence (PL) and lifetime studies for the temperature range (100-873K) under 375nm excitation led to the development of a temperature-dependent-charge-transfer (TDCT) model. The TDCT model fully explains the anomalous PL and lifetimes which increase with increasing temperature from cryogenic to roughly 353K, and then decrease with further temperature increase. Interestingly, the depth of the charge-transfer states leads to lifetimes in the hundreds of milliseconds regime around room temperature. This means that the emission decay can easily be captured with a standard smartphone camera. Based on this, we used UV LED pulsed excitation source and a smartphone camera to record the sample emission. The as measured afterglows were found to vary by more than a factor of two with temperature in the 273-330 K range. This provided a new inexpensive route for temperature detection relative to the expensive lifetime-based detectors. We plan to extend the temperature range by further developing the phosphors and introducing more sophisticated analysis of the decay curves.

Resume : A facile nucleation of PtCu alloy nanoparticles is done over the heavily reduced SrTiO3 (RSTO) support in different alloy compositions using a fast microwave-assisted synthesis technique. The nano-alloy compositions are checked using XPS, ICP-MS and STEM-EDS techniques. The PtCu decorated RSTO are compared with monometallic Pt-decorated supports for their activity in preferential CO oxidation reaction under excess hydrogen. This work isolates the effect of Cu dilution on Pt in a PtCu bimetallic alloy-based catalyst for PrOx reaction. The unprecedented enhancement in the selectivity on the addition of Cu, could be seen in all the compositions of PtCu alloy. The CO oxidation activity, on the other hand, decreased on the alloys compared to the monometallic Pt catalysts. In a nutshell. We report an efficient catalyst, Pt40Cu60-RSTO, showing a high selectivity and stable activity for preferential oxidation of CO in a temperature range of 60-130 oC. Keywords: PrOx, PtCu, bimetallic, SrTiO3.

Resume : Combined frequency-resolved techniques are suitable to study electrochromic (EC) materials. We present an experimental setup for simultaneous electrochemical and color impedance studies of EC systems in transmission mode, and conceive a simple method for determining the experimental background noise which is based on the measurement of a sample with negligible or absent EC response. We define the frequency-dependent variables that are relevant in the combined measurement scheme, and a special emphasis is given on the complex optical capacitance and the differential complex coloration efficiency, which provide the relation between the electrical and optical responses. Results of a test measurement on amorphous WO3 with LED light sources of peak wavelengths of 470 nm, 530 nm, and 810 nm are shown and discussed. We study the effect of the excitation voltage amplitude on the linearity of the electrical and optical responses for the case of WO3 at 2.6 V vs. Li/Li+, where a trade-off should be made between the signal-to-noise ratio of the optical signal and the linearity of the system. In the linear regime, the optical capacitance could be distinguished from the background noise for frequencies below ~10 Hz. Furthermore, the amplitude of the differential complex coloration efficiency presented a monotonous increase down to ~1 Hz and was close to a constant value for lower frequencies. In the non-linear regime, using high excitation voltage amplitude values, it was possible to distinguish the optical signal from the background noise for frequencies as high as ~300 Hz. The different optical wavelengths presented similar qualitative results, however, the magnitudes of the complex optical capacitance and the differential complex coloration efficiency increased towards the infrared.

Resume : Electrochromic W–Ti oxide thin films were prepared by reactive DC magnetron sputtering and cycled voltammetrically in an electrolyte comprised of lithium perchlorate in propylene carbonate. The films were degraded for up to 500 voltammetric cycles in the voltage ranges 1.5–4.0, 1.6–4.0, 1.7–4.0 and 2.0–4.0 V vs. Li/Li+. The films were subjected to potentiostatic rejuvenation at a constant voltage of 6 V for 20 h to accomplish ion de-trapping. Optical changes were recorded during the electrochemical degradation and rejuvenation. The degradation kinetics was parametrized by a power-law model based on dispersive chemical kinetics. The results showed that optical transmittance contrast between bleached and colored states was regained after the ion de-trapping. It was also found that Ti containing films were more stable than pure W oxide ones.

Resume : Spectrally selective nanocoatings that exhibit synergistically enhanced solar light modulation, luminous transmittance and catalytic properties can be made by combining dielectric film stacks with complementary optical and structural properties. It is here shown that enhanced photocatalytic properties can be achieved by combing anatase TiO2 films with solar absorbing and thermochromic films in bilayer configurations. We present two case studies: TiO2/TiAlN and TiO2/VO2 bilayer films made by reactive dc magnetron sputtering. The TiO2/VO2 bilayer exhibits enhanced near-infrared light absorption and heats the TiO2 film resulting in a 2-fold increase of the photocatalytic reaction rate. The TiO2/VO2 bilayer stack exhibits anti-reflective properties, and enhanced solar modulation (∼ 9%) compared to VO2, and ∼ 20% increased solar absorptance compared to TiO2. In addition the TiO2 chemically protects the VO2 layer avoiding oxidation to pentoxide. In the second example, bilayer TiO2/TiAlN films yielded an almost 10-fold enhancement of the quantum yield for acetaldehyde removal (on par with state-of-the-art, heterojunction photocatalysts), and an associated temperature rise larger than 120 degrees. Both findings can be understood by a dual role of thermally enhanced reaction kinetics and desorption of water from the catalyst surface which otherwise acts as a diffusion barrier. A proposed implementation of our results would be a new windows technology for indoor air cleaning.

Resume : Formaldehyde (HCHO) and acrylamide (C3H5NO) are besides their wide commercial use recogized as harmfull for the humans health, however up to date no commercial sensor for C3H5NO is available, and for the HCHO the comercial sensors are scarce and oriented towards its gas detection. Here we present the development of electrochemical sensors based on screen printed electrodes based on nanostructued KOH modified NiOOH nanowires (NWs) for HCHO and moleculary inprinted polyaniline for detecting C3H5NO in aqueus solutions. Taking into account the determined Aecsa of NiOOH NWs the calculated the sensitivities: 0.3419 mA L cm-2 mmol-1 and 0.0458 mA L cm-2 mmol-1 and the sensing element has a detection capabitility of 0.8 μmol L-1 down to 0.1 μmol L-1 for smaller NWs diameter, that surpasses all of up to date Ni-based HCHO receptor elements. For the detection of AA, conductive polymer polyaniline (PANI) nanofibers were prepared by electropolymerization in HCl to elemardine salt, which is the most conductive form of polyaniline (confirmed by FTIR). Imprinted PANI was prepared by adding template molecule – propinoamide (PAM – structural analogue to acrylamide) into starting polymerization suspension. FTIR results showed two new peaks in the range of 2849 and 2924 cm-1, characteristic for alkanes, which confirms successful imprinting of propanamide that is a dummy molecule for final C3H5NO detection.

Resume : Chromogenic materials exhibit tunable properties as a consequence of an external stimulus such as light (photochromism), temperature (thermochromism) or voltage (electrochromism). Those smart compounds find applications in buildings and automobile industry by controlling light and heat transfer through windows for transmissive devices while colour changes in reflective devices offer great interest in the field of displays and printed electronics. In this presentation, through various examples, we will illustrate the key role played by the synthesis or deposition route on the physico-chemical properties of mostly oxides powders and thin films as well as on their chromogenic properties. In particular, multichromism, namely thermochromism and electrochromism, in vanadium oxides will be discussed in respect of the oxide stoichiometry. Beside the influence of shaping in form of nanopowders synthesized through the polyol process, thin films of few hundred nanometers by RF sputtering method or thick films of few micrometers by doctor blading on the chromogenic properties will be illustrated focusing more specifically on electrochromism (V2O5) and thermochromism (VO2). The content of our presentation will be of interested for an audience concerned with energy saving, thermal management and the use of smart materials.

Resume : The benefits provided by energy to society have resulted in a substantial increase of energy demand. The building sector offers excellent prospects to reverse this tendency. In particular, windows will contribute to solve the global energy problem, as they are responsible for ca. 10% of the total energy consumed in the building. Estimates indicate that smart window technology [1] will reduce up to 40% of the building’s energy needs. Currently, one of the greatest challenges of this field is to fabricate windows enabling the control of sunlight transmittance (visible radiation) and solar heat gain (near-infrared (NIR) radiation) to reduce energy use, increase indoors thermal/visual comfort, and improve outdoors view. Here we demonstrate that the combination of conducting oxides transparent in the visible and NIR regions (amorphous indium zinc oxide [2-4] and indium molybdenum oxide [5]) with sol-gel derived hybrid electrolytes [2,5], or a seaweeds-derived k-carrageenan electrolyte [3], or a nanofluid based on glucose-derived carbon dots functionalized with a thermotropic ionic liquid [4], are extremely attractive approaches to produce sustainable electrochromic [2,3,5], thermotropic [4] or integrated thermotropic/electrochromic [4] devices with outstanding performance. Acknowledgment This work was supported by FEDER, through COMPETE and Fundação para a Ciência e a Tecnologia (FCT) (FCOMP-01-0124-FEDER-037271, Pest-OE/QUI/UI0616/2014, project LUMECD (POCI-01-0145-FEDER-016884 and PTDC/CTM-NAN/0956/2014), and project UniRCell (SAICTPAC/0032/2015 and POCI-01-0145-FEDER-016422)). References [1] C. G. Granqvist, M. A. Arvizu, İ. Bayrak Pehlivan, H. Y. Qu, R. T. Wen, G. A. Niklasson, Electrochim. Acta, 2018, 259, 1170-1182 [2] M. A. Cardoso, R. F. P. Pereira, S. Pereira, H. Gonçalves, M. M. Silva, L. D. Carlos, S. C. Nunes, E. Fortunato, R. A. S. Ferreira, R. Rego, V. de Zea Bermudez, Adv. Sustainable Syst. 2018, 1800115 [3] S. C. Nunes, S. M. Saraiva, R. F. P. Pereira, S. Pereira, M. M. Silva, L. D. Carlos, E. Fortunato, R. A. S. Ferreira, R. Rego, V.de Zea Bermudez, unpublished work [4] H. M. R. Gonçalves, R. F. P. Pereira, S. Pereira, A. J. M. Valente, E. Fortunato, A. J. Duarte, V. de Zea Bermudez, unpublished work [5] M. Fernandes, V. Freitas, S. Pereira, R. Leones, M. M. Silva, L. D. Carlos, E. Fortunato, R. A. S. Ferreira, R. Rego, V. de Zea Bermudez, Energies 2018, 11(12), 3513; https://doi.org/10.3390/en11123513

Resume : Electrochromic (EC) materials can be reversibly changed in optical properties by an applied electric field due to electrochemical oxidation and reduction. Nickel oxide (NiO) is generally used as a counter electrode material with enhancing coloration efficiency of whole device with a pair of tungsten oxide. However, NiO films have been suffered from charge degradation during electrochemical cycling, resulting in insufficient device lifetime. Especially, due to complicated reaction with Li+-conducting electrolytes on cycling, the decay of the charge exchange, and hence of the optical modulation span of NiO films still limits the commercialization of EC devices (ECDs). In this study, we report the enhancement of cycling stability of ECDs with excellent EC properties using tungsten-doped NiO (Ni-W oxide). We confirmed the effect of compositional modulation by means of specific electrochemical tests and structural characterization using cyclic voltammetry (CV), X-ray diffraction (XRD), and scanning electron microscope (SEM). And we proposed a reaction mechanism that accounts for the observed degradation in the EC performances of optimized Ni-W oxide films. Finally, we demonstrated flexible ECDs using graphene-supported transparent conducting electrode which offers requirements for practical applications, that is, high-contrast optical modulation, good electrical conductivity and mechanical flexibility. Fabrication strategy of highly stable Ni-W oxide films on flexible electrodes provide a general framework for designing optically and mechanically high- performance EC devices.

Resume : Chromogenics refers to different types of coatings and devices that use the effect of their repeatable and reversible coloring/bleanching, which occurs under the influence of such external factors as temperature (thermochromic effect), electric field (electrochromic effect), lighting (photochromic effect) or gas atmosphere (gasochromic effect). Such coatings are increasingly used, among others, in the construction of modern windows in intelligent buildings, automobiles, planes or in gas sensing devices. Based on the review of available literature, it can be concluded that in the vast majority of scientific publications on chromogenic phenomena, the authors focus solely on presenting only the effects of measuring the characteristics of light transmission (or reflection). On the other hand, much less often, one can find publications in which the authors undertake to explain the mechanism of the phenomenon itself. The subject of this work is the analysis of optical properties occurring in such optical coatings with the gasochromic effect. The paper presents a proposal to link the change in the optical properties of a gasochromic material to a gas medium based on the analysis of dispersion of the complex refractive index. As a prototype material used in the study was thin film of tungsten trioxide (WO3) covered with the platinum catalyst and ethanol vapor as an active volatile medium. It has been shown that the proposed method allows not only to explain the reasons for the observed changes in the transparency of such materials, but may also be useful in the design of such coatings for various applications.

Resume : Electrochromic materials are able to change their optical properties as a response to an externally applied electric potential. Along with the other members of smart chromogenic materials such as thermochromics and photochromics, they have been long considered as a subset of the “solar energy materials”, thanks to their impact in energy savings and sustainability in the building and transportation sector. An ideal smart window, based on electrochromic materials, must independently and selectively control the transmittance of visible sunlight and solar heat into a building and should be globally applicable across different building types and climate zones. The novel concept of “dual-band electrochromism” offers this capability of dynamic control over the entire solar spectrum, which has led to an exciting development of new generation of advanced glazing systems. Full understanding and optimisation of this unique electrochromic device is crucial for energy efficient building envelopes, which can massively contribute to reducing energy use in buildings and ensure occupant comfort. Herein we combine two spectrally complementary electrochromic materials, through the potentiodynamic electrochemical deposition of a polyaniline film onto a nanocrystalline large surface area ITO electrode, to realize a dual-band electrochromic system that synergistically embodies both the plasmonic features of ITO nanocrystals and the peculiar electrochemical redox prerogatives of PANI. Its optical and electrochemical properties have been exhaustively investigated and exploited to realize a three-state electrochromic device. It provides a high selective modulation both in the VIS range (ΔT=80% upon -1.4V/+0.8V) and in the NIR range (ΔT=90% upon +0.2V/+0.8V) accompanied with high electrochemical stability.

Resume : TiO2 has been widely investigated as photocatalyst because of its environmentally and economically advantages with high chemical stability, earth abundant and bio compatible properties. However, its large band-gap for the activity to only UV light region, and the high recombination rate of photogenerated electron and hole pairs have to be overcome to utilize effectively sunlight, and to enhance the photocatalytic performance. Recent enormous efforts to overcome the above-mentioned drawbacks have resulted in the one-dimensional TiO2 nanotubes, nanofibers and nanorods to suppress the carrier recombination, and/or the heterojunction structure of TiO2 with another semiconductor to achieve larger separation of the photogenerated electron and hole, as well as the modification of TiO2 nanoparticles with gold clusters to expand the light conversion from UV to visible and near-infrared region. Another interesting approach on black TiO2 nanoparticles succeeded in narrowing the band gap of pure white TiO2 nanoparticles, however, it required the hard treatment condition of a 2 MPa hydrogen atmosphere at ca. 200 C for 5 days. In order to synthesize the hydrogenated TiO2 nanoparticles, the thermal treatment under hydrogen and plasma treatment have mostly relied on the reduction of TiO2 nanoparticles. But, these processes have drawbacks such as high temperature over 1,000 C, vacuum system for hydrogen plasma and long treatment time. After thermal treatment, the sintered nanoparticles should be crush to follow multistep processes. Thus, alternative approaches have been highly demanded in the reduction of TiO2 with keeping its nano-sized particle. The in-liquid plasma processing, which is named as solution plasma, is a non-thermal plasma discharged in liquid for synthesizing catalytic nanoparticles and preparing low molecular weight polymers. The present study focused to treat pristine TiO2 nanoparticles by the discharge in water-based solution and to investigate the material properties as well as the photocatalytic activities for decomposing organics.

Resume : Semiconductor based photocatalysts are identified as one of the effective materials for disinfecting the bacteria present on various surfaces. The ability of the photocatalysts to yield long-lasting electrons or holes and the formation of various free radical species are the two major determining factors for the efficiency of the photocatalytic process. As part of a research programme to prepare highly efficient photocatalytic materials, current investigations were aimed at preparing new visible light activate antimicrobial materials. Thermal stability of these catalysts at elevated temperatures is one of the essential properties required for making coatings on ceramic surfaces. Anatase phase of the titania nanoparticles, which are stable above the annealing temperature of the substrate (e.g., sanitary wares, bathroom tiles etc.) is hugely important for the development of anti-bacterial building materials. A range of novel photocatalytic materials prepared by modifying the band-gap of TiO2 using various dopants such as N, S, C and F will be presented. A range of visible light active photocatalysts with high temperature stability will also be discussed. References 1. P.Ganguly, C. Byrne, A. Breen and S.C. Pillai. Applied Catalysis B: Environmental, 225 (2018) 51-75. 2. C. Byrne, , L. Moran, , D. Hermosilla, N. Merayo, Á. Blanco, , S. Rhatigan, S.Hinder, P. Ganguly, M. Nolan and S. C. Pillai, Applied Catalysis B: Environmental, 246, 5, (2019) 266-276 3. V.Kumaravel, , S.Mathew, , J.Bartlett, and S.C Pillai, Photocatalytic hydrogen production using metal doped TiO2: A review of recent advances. Applied Catalysis B: Environmental, 244, (2019), 1021-1064 4. V. Etacheri, C. Di Valentin, J. Schneider, D. Bahnemann, and S. C. Pillai , Journal of Photochemistry and Photobiology, 25 (2015) 1–29 5. S. Banerjee, S.C. Pillai, P. Falaras, K. E O'Shea, J. A Byrne, D. D Dionysiou, J. Phys. Chem. Lett. 5 (2014) 2543–2554. 6. S. Banerjee, D. D. Dionysiou, and S. C. Pillai, Applied Catalysis B: Environmental 176 (2015) 396–428 7. R. Fagan, D. E. McCormack, D. D. Dionysiou, and S.C. Pillai Materials for semiconductor processing 42 (2016) 2–14 8. J. Podporska-Carroll, E. Panaitescu, B. Quilty, L. Wang, L. Menon, S. C. Pillai, Applied Catalysis B: Environmental 176, (2015) 70-75.

Resume : Ammonia photocatalytic oxidation into nontoxic N2 represents an unconventional and effective way to detoxify wastewaters originated from livestock manure. However, besides innocuous N2, also pollutant species even more noxious than NH3 itself, such as nitrite and nitrate anions, can be formed during the process. The deposition of metal nanoparticles (NPs) on the TiO2 photocatalyst surface, acting as efficient traps of photoexcited electrons in the semiconductor and thus ensuring better photoproduced charge carriers separation, was found to be beneficial in ammonia abatement. Furthermore, both ammonia conversion and its photodecomposition mechanism were found to be affected by the type of metal deposited on TiO2 as well as by its relative loading. Here we first focus on the effects that the chemical route employed to deposit Pt NPs on TiO2 has on photocatalytic NH3 abatement and explore strategies of properly combining Pt NPs with Ru NPs on the TiO2 surface for a synergistic exploitation of the two metal co-catalysts. Indeed, while the presence of Pt NPs may increase the overall ammonia conversion yield, Ru has peculiar effects in improving the selective photocatalytic performance of titania.

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. Nanostructured metal oxides and composite materials are promising candidates for effective photoanodes, which are fabricated using CVD, PE-CVD and ALD techniques for producing multilayered electrodes as oxygen evolution reaction catalysts. 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 and forms has intensified the research on the integration of different functional material units in a single architecture to obtain new photocatalytic materials. In addition, new concepts of enhancing charge transduction by surface functionalization are promising strategies to promote specific chemical interactions. This talk will present how chemically grown and designed thin films and bilayers of different metal oxides open up new vistas of material properties, which can be transformed into advanced material technologies.

Resume : The microwave hydrothermal and photo-reduction method were used to synthesize the plasmonic photocatalyst, silver spherical nanoparticles (Ag NPs) decorated α-Nickel molybdate (NiMoO4) nanorods. Antibiotics, tetracycline (TC) was used as target pollutant to evaluate the photocatalytic activity under visible light irradiation. The observed degradation efficiency of Ag NPs decorated α-NiMoO4 for TC degradation (80 % within 180 min) is 8 folds as compare to α-NiMoO4, respectively that is associated with increase in visible light absorption or reduction of band gap, surface plasmon resonance (SPR) effect, and efficient separation of electron-hole pairs. The excellent photodegradation stability was found which was also further supported by XRD and FESEM measurements of photocatalyst after three cycles. In addition, the scavenger experiment suggests that OH• plays a major role whereas O2•- and h+ show the minor role for TC degradation. Furthermore, ultra-performance liquid chromatography-photodiode array (UPLC-PDA) and high resolution-quadruple time of flight electrospray ionization mass spectroscopy (HR-QTOF ESI/MS) techniques were employed to find out the transformation products of TC in water as well as degradation pathways. The five degradation pathways were proposed for TC degradation which was explained on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. The efficient mineralization of TC was found in the basis of total organic carbon (TOC) analysis. Therefore, this efficient photocatalyst can be applied for removal of pharmaceuticals pollutants. Also, this work presents the insight into photocatalytic mechanism, transformation products and degradation pathways of TC in water.

Resume : Increasing global energy consumption and intensive use of fossil fuels have resulted in greenhouse gas generations and serious environmental problem. Photocatalytic water splitting is regarded as one of the most promising green methods for generating hydrogen fuel from water, owing to its simplicity and the merit of using free and infinite solar energy. The principle of water splitting is to utilize photogenerated electron and hole carriers for reduction and oxidation reactions of water molecules. The most important factor to enhance the photocatalytic activities of semiconductors is efficiency of charge separation. For separations of photoexcited electron and hole carriers, many efforts of materials design have been suggested. Among them, heterostructuring is the most common method. The most widely studied heterostructures are Pt- and Au- decorated TiO2 and Fe2O3 nanostructures (particle, film, wire) and junction of two or more semiconductors which have substantial band offsets. However, these heterostructure costs too much for processing and/or raw materials. For realistic commercialization of photocatalysts for commercial use, a breakthrough for mass producible strong photocatalytic material should be found. As our breakthrough strategies, we suggested photocatalysts that are structurally heterogeneous and homogeneous in elements: 1) crystal-amorphous junctioned titania and 2) iron oxides junction with changed oxidation states of iron. These systems are synthesizable through cost-effective ways and have enhanced photocatalytic activity for water splitting. The enhanced photocatalytic activities of the systems were successfully explained as the results of the charge separation at interfaces by the band offsets and interface dipole moment formations, respectively, which were revealed by density functional theory (DFT) calculations.

Resume : The PECSYS project aims to build very first large area demonstration systems for hydrogen production from solar energy via integrated photovoltaic (PV) and electrolyzer (EC) systems. In this work, a general model was developed to determine best PV and EC combination for hydrogen yield. The solar-to-hydrogen (STH) efficiency was calculated for the climate of Jülich; Germany, which will be the installation site. The effect of alkaline and acidic electrolysis on the performance of the installation was analyzed. The modelling included collection of current-voltage data for PVs and ECs. The data used for modelling were from PVs with crystalline silicon with passivated emitter rear totally diffused, thin film silicon triple junction, silicon heterojunction, and thin film CuInxGa1-xSe2 (CIGS). The EC data for acidic electrolysis was from an EC with IrO2 (anode)/Pt (cathode). One dataset for alkaline electrolysis was from an EC consisted of NiO (anode)/NiMoW (cathode) and a second dataset from EC with Ni foam (anode)/Pt-Ni foam (cathode). Co-optimization of operation currents for the systems were performed by analyzing the PV-performance matching with the load curve of the catalyst system. The acidic EC with silicon heterojunction and a thin film CIGS resulted in similar electricity to hydrogen efficiency (ETH) and the best combinations resulted in 74% ETH, 12% STH, and 36 kg yearly hydrogen production for a 10 m2 PV-EC. For alkaline electrolysis, up to 73% ETH, 13% STH, and 35 kg hydrogen production was possible with NiO/NiMoW EC and a silicon heterojunction combination. The results showed that the catalyst area did not play any significant role in the outcomes for the acidic electrolysis, while it was more crucial for the alkaline electrolysis.

Resume : Sub-wavelength dielectric nanostructures offer new or added light manipulation functionalities in surface optical coatings and interfaces for a variety of application contexts ranging from photovoltaic devices, photocatalysis to customized glass. Light manipulation functions desired in several of these applications include structural colors, broad-band anti-reflection, light trapping, light scattering, UV blocking and spectral down-shifting. We present our recent research on optical coatings and films based on semiconductor-based subwavelength structures (meta-surfaces) focusing on their optical properties, fabrication technologies and selected application examples. We discuss different methods for nanostructuring such as top-down methods, self-assembly, transfer printing, infilling, soft-imprinting and embedding nanostructures in transparent films. Broad-band anti-reflection and structural colors from spatially ordered and disordered assemblies of sub-wavelength nanodisk, nanopillars and nanoholes in different materials (metal oxides, III-Vs and Si), including hierarchical structures, are reported. Surface structuring by packing sub-wavelength metal-oxide nanoparticles from solution into specific geometric shapes is investigated as a generic low temperature method to “add-on” functional optical coatings on pre-fabricated devices/surfaces. Such coatings on glass and solar cells are shown to be promising for broad-band antireflection, UV-blocking and structural colors.

Resume : Tin monosulfide (SnS) is an earth-abundant and non-toxic compound semiconductor showing promise as an absorber layer in photovoltaic applications, due mainly to its near optimal band gap and high absorption coefficient. Moreover, SnS is an excellent candidate for the realization of ultrathin plasmonic solar cells, since it has a very high optical damping and refractive index, which enables effective interaction between the plasmon resonances of Au nanodot arrays and electron-hole pair generation in nanoscale SnS coatings. To gain further insight into the realization of efficient devices based on this compound, it is of interest to investigate the photovoltaic behavior of ultrathin SnS heterojunctions fabricated with various stack configurations. These may involve different back contact materials, buffer layer compositions and SnS crystal phases, as well as variations of buffer and absorber layer thicknesses. We have investigated Ti, Mo and Al back contacts for heterojunctions based on both cubic (π-) and orthorhombic (o-) SnS, where Mo and Ti show promise for further device development. The tunable wide bandgap semiconductor Zn(O,S) ALD has further been studied as a buffer layer to create a SnS/Zn(O,S) heterojunction. We investigate the relations between the ZnO:ZnS atomic layer deposition (ALD) cycle ratios and chemical composition, and the structural, optical and electronic properties of the resulting thin films. Devices based on -SnS and a pure ZnO ALD buffer layer is found to yield a higher photocurrent and open circuit voltage than those with o-SnS, although the higher bandgap of the cubic phase would be expected to result in a lower photocurrent. Higher sulfur content in the Zn(O,S) ALD buffer layer leads to a higher open circuit voltage of up to 611 mV, while the short circuit current decreases. This demonstrates a bottleneck in the current-voltage parameters where devices with a good voltage have low current and vice versa. Numerical device simulations are deployed to cast light on this situation and a possible route forward.

Resume : Materials in the A2BX6 structure that adopt the Fm-3m space group are being increasingly investigated as lead free, air stable analogues of the famous hybrid halide pervoskite solar absorbers. However, whilst the structural and electronic properties of the ABX3 perovskites are well understood, the A2BX6 structure has been less intensively studied. Here we present a study of the structural, optical and electronic properties of Cs2SnX6 and (CH3NH3)2SnX6 mixed halide compounds. We show that mixed chloride-bromide and bromide-iodide compounds are stable at all compositions and form single phase materials. We show that the local structure of the Sn-halide octahedra can be quantitatively modelled using Raman vibrational spectra, and that the local halide distribution has an impact on the optical properties - a new lower energy absorption is observed in mixed halide compounds that is not present in the pure halide equivalents. We observe and quantify for the first time the distortion of the A2SnX6 structure that occurs when ions of mismatched size are combined - we identify that instead of octahedral tilting which is observed in the ABX3 analogues, materials with the A2BX6 structure can remain cubic but distort via increasing separation of the BX6 octahedra. We also show that this distortion, whilst not reducing the symmetry, is implicated in generation of point defects and charge carriers in the material. These results may be important in design of new PV materials.

Resume : FeS2 has attracted considerable attention as a potential non-toxic absorber material in lieu of widely used but toxic CdTe and CIGS for thin-film solar cells. Interest in FeS2 is intrigued by its exotic electronic and optical properties that include a bandgap of 0.95 eV and an absorption coefficient of 5x105 cm-1. A theoretical energy conversion efficiency of over 30% is expected for FeS2 with a very thin absorber layer of thickness < 20 nm. However, the conversion efficiency of experimental solid-state and photoelectrochemical FeS2 solar cells never exceeded 3% to date owing to limitation of photovoltage generation above 200 mV. A possible S-deficiency and surface inversion have commonly been discussed in the literature to be responsible for this limitation. Disappointingly, the last 35 years of research surprisingly could not increase the solar energy conversion efficiency of FeS2 solar cells above 3%, and there is no unambiguous evidence of correlating low photovoltage with S-deficiency or with surface inversion. With debates and inconsistency in scientific finding, we here present a deductive reasoning to dissect whether the direct or indirect association with S-vacancies and/or with surface inversion are stepping us back or moving us forward. Our finding will answer the must asked question- are we awkwardly happy to sitting in a comfort zone and overlook the darkness beneath the lamp using bare FeS2?

Resume : Solar control coatings are materials designed to reflect the near-infrared part of the solar spectrum, while being transparent in the visible range. Blocking the near-infrared part allows for improved thermal management in buildings especially in warm climates, at the same time maintaining good visible light conditions. Conventional solar control coatings, widely used in glazing industry, rely on multilayer thin film stacks. The near-infrared blocking behavior of these coatings is good, although the transmission in the visible can be compromised. In the current work a novel approach for solar control coatings based on a nanostructured ultrathin silver film, embedded between two dielectrics, is presented. The silver nanostructure causes a broadband plasmonic resonance associated with increased reflectance in the near-infrared part of the spectrum, while the dielectrics allow for improved visible transmittance. Optical finite-difference time-domain (FDTD) simulations are presented elucidating the origin of the plasmonic resonance. Fabrication is realized by nanoimprint lithography and subsequent physical vapor deposition without additional lift-off processes, allowing for efficient upscaling possibilities by roll-to-roll technologies. The optical characterization reveals a good stability towards change of incidence angle and an excellent agreement with simulation is achieved. Due to the low sheet resistance of 7.0 Ω/sq, the coating holds further potential for application as multi-functional transparent electrode.

Resume : The recent development of less expensive, solarisation resistant fibres has opened new possibilities for their use in technologies for green buildings such as daylighting systems and high concentration photovoltaics (HCPV). Even if many studies have been carried out to investigate the resistance of OFs to pulsed laser irradiation, there is a lack of literature regarding the evolution of their guiding properties when high-power UV/visible light is injected. The aim of this work is to evaluate the resistance of various classes of doped and pure-silica fibres to concentrated light for applications in HCPV and indoor lighting systems. To this end, both commercial and prototype OFs have been exposed to high-power white light and the time evolution of their transmission properties has been characterised. In particular, the spectral dependence and growth kinetics of the photodarkening losses have been measured. While fluorine-doped silica-core fibres proved to be resistant to prolonged irradiation, phosphorous- and aluminium-doped fibres showed a drastic reduction of the transmitted signal even after few hours of light exposure. The irradiation of telecom-grade germanium-doped OFs also resulted in a darkening in the UV domain which, however, may not compromise the use of these low cost fibres in solar applications. The reported results give an insight into possible ways of studying the response of OFs to high-power continuous light and represent a first attempt to identify a potential candidate for solar and laser applications among the plethora of commercially available fibres.

Resume : Additive manufacturing (AM) of ceramics is an emerging technology with first technologically viable and economically profitable industrial applications e.g. in the area of bio-medicine and energy technologies. Different techniques to obtain the best printed ceramics material are currently under investigation, using micro- or nano-particle slurries out of which ceramics green bodies are created using lasers to either cure binder additives or to initiate the collapse of charge stabilized suspensions. Depending on process parameters, the resulting green bodies are of varying stiffness and thus shape fidelity, homogeneity and density prior to compaction within the sintering process. The AM produced ceramic parts with the lowest possible crack- or pore density with mechanical properties close to conventionally produced ceramics are targeted. Materials and device optimization will rely on advanced correlated electron microscopy and spectroscopy (CORRMIC) containing x-ray microscopy (XRM) and electron- and ion-microscopies (FIB-SEM, HIM) with analytical techniques such as energy dispersive x-ray spectroscopy, time-of-flight mass spectrometry, electron backscatter diffraction and in-situ mechanical testing. Complex microscopy and spectroscopy data sets will be utilized in combination with machine learning approaches to further advance materials and devices.

Resume : Many smart materials with applications in the fields of solar energy and energy-efficient buildings are structured and exhibit significant light scattering. To facilitate optical design of materials and devices for these applications, knowledge of their basic optical parameters, describing light scattering and absorption is necessary. Previous methods to extract these coefficients from experimental data either relied on unverified approximations or required extensive computational effort. In certain cases the obtained scattering and absorption coefficients could even not accurately reproduce the experimental spectra. In this paper we present a novel method for determining scattering (S) and absorption (K) coefficients from total transmittance and reflectance measurements by inversion of the Kubelka-Munk theory. The reflectance parameters appearing in this theory depend on the angular distribution of scattered light inside the material. We present an approximation for this distribution that was verified by comparison with angle resolved scattering measurements. The versatility of our method is demonstrated by a reanalysis of experimental data for several materials of interest in energy-related applications. Specifically we report spectra of S and K for: (a) pigmented polymer foils for radiative cooling applications; (b) suspended particle devices for smart windows; (c) selective solar absorbing paints for solar collectors and (d) solar reflecting TiO2-pigmented paints.

Resume : Both energy and material consumption of buildings are and will remain a major concern for the next decades. In every buildings, either residential or commercial, the overall energy use can significantly be lowered through optimization of heat accumulation and heat loss of façades and windows. This leads to research devoted to novel materials for smart windows which can be conceived as affordable multifunctional systems that offer enhanced energy control. As well other scientific fields can contribute to lower the external energy demand of buildings such as photovoltaics or efficient lighting. All of these technologies need transparent electrodes which should be thoroughly investigated and optimized for an efficient integration into buildings. The present contribution focuses on the different technologies associated to transparent electrodes. The various studied materials are for instance the classical transparent conductive oxides (TCO) and more recently metallic nanowire networks. We will describe and compare the main structural, optical and electrical properties of the different materials developed for transparent electrodes in multifunctional windows. The main scientific challenges associated with transparent electrodes for improving performance of multifunctional windows, as well as their stability, will be discussed. Stability can indeed be a crucial issue, involving electrical and/or thermal aspects, ageing or chemical degradation.

Resume : Thin films of vanadium dioxide show a phase transition from semiconducting to metallic that can be used for designing multilayer window coatings with designed optical transmittance behaviour which varies with temperature. In the low-temperatur state the thin films are in a monoclinic phase while they are in a tetragonal phase at high temperature.The phase transition occurs at a critical temperature of 68 °C for bulk material and about 55 °C for thin films. Due to this transition the transmittance in the infrared region of the natural sunlight spectrum changes from transmitting to reflecting behaviour. This thermochromic effect can be used to passively control the climate in buildings. It can be seen, that the transition temperature and also the optical properties of pure vanadium dioxide thin films do not match the requirements for window glazings, for example their brownish colour and the high critical temperature are unsuitable. We present different ways of improving, on the one hand, the critical temperature and, on the other hand, the optical properties of rf-sputtered thin films. Co-doping with W and Sr is one way to achieve improvements for application as smart window. Doping with tungsten drastically influences the transition temperature by stabilizing the monoclinic low-temperature phase. Adding strontium affects the bandstructure, influences the band gap and with this the optical impression can be improved. Another approach is to integrate the vanadium dioxide thin films into a multilayer system including buffer-, antidiffusive- and antireflective-layers in addition to the active thermochromic layer. We will discuss different kinds of buffer layers, for example, produced with the technique of ion beam sputtering deposition (IBSD), and their influence on pure vanadium dioxide thin films as well as on co-doped thin films. Also we discuss the effect of adding layers onto the thermochromic films and compare the properties of such multilayer systems with the single layer thin films.

Resume : The reflector is important for blocking the near-infrared(NIR) radiation because NIR region in the solar spectrum is the main cause of heat generation. To obstruct NIR bands, Metal reflector has been used. However, the reflector has a limitation of device size because of the metallic film on a thick substrate. To solve this problem, reflectance of NIR region was improved by using metasurface with ultrathin optical element. Initial metasurface reflector consists of metallic nanostructure by creating a plasmonic resonance. However, these nanostructures are difficult to manufacture due to their complicated structure as well as ohmic loss. To prevent these problems, all of the compoents of the metasurface were replaced by the dielectric materials. In this work, we report the novel metasurface, composed of nanostructures with different geometries. The metasurface can prevent NIR radiation by Mie resonance. To qualify the performance of the reflector, we used the transmittance fraction before and after passing the reflector in a specific wavelength range at solar irradiance spectrum. To improve the reflectance in NIR region, we conducted Rigorous coupled wave analysis (RCWA) simulation. As a result, the reflectance of metasurface is about 80% in the NIR region on the simulation. This metasurface can be used in outdoor devices with transparent window such as solar cell, due to prevention of heat generated by NIR rays.

Resume : The Room-temperature switching effect is of great interest for many applications, such as smart buildings, sensors, thermal energy storage and automatic temperature control. In this paper, we summarized the recent progresses in room-temperature switchable composites and all-organic systems. Electrical conductivity, thermal conductivity and permittivity of the CNT/hexadecane composites can be regulated around 18˚C and the maximal switching ratio reaches 5 orders of magnitude, 3 times and 106.4, respectively. In the Span80/ hexadecane HD-PET film system, the dielectric switch can be triggered at 13.8 ºC and the highest switching ratio reaches 270.5. The switching behavior of composites is caused by rearrangement of the carbon nanotube fillers in hexadecane matrix during liquid-solid phase transition. The dielectric switching of all- organic system is caused by the self-formed blocking layer during the first-order phase transition.

Resume : The fundamental physical effects for the transformation of heat to electrical energy are known for a long time. However, it was only recently that the idea of re-gaining energy, for example from hot exhaust gases, has attracted remarkable attention. This interest is certainly driven by the need of a more effective and sustainable use of energy. A good thermoelectrical material should on one hand behave as a very good electrical conductor, on the other hand its ability for the conduction of heat should be bad. These needs are usually contradictory because electrical conductors are in most cases also very good heat conductors. A plethora of compounds has been prepared meanwhile and some of them show impressive effects. Besides, of the strength of the physical effect, however, another aspect is gaining increasing attention, i.e. the availability of the chemical elements used for the preparation of the compounds. For example, some of the best thermoelectrical materials are based on the elements bismuth and tellurium. However, the abundancy of these elements is quite low, i.e. their usage is limited. In general, elements which have low abundancies (or which are hard to mine) are called "critical elements". Those elements which are available more or less unlimited are called the "elements of hope". Thus, it is a big topic for chemists nowadays to substitute the critical elements by the elements of hope in devices that are needed in great numbers. For thermoelectrics such elements are, for example, zinc and sulfur. The chemical approach to new materials based on such elements will be discussed.

Resume : At present, many different ferroelectric (PbZr1-xTixO3 (PZT), BaTiO3 (BTO), K1-xNaxNbO3 (KNN), etc.) and non-ferroelectric (AlN, ZnO) piezoelectric materials in the form of films, nanostructures and ceramic/crystals bonded on wafers are explored for the fabrication of piezoelectric vibrational energy harvesters (PiViEHs). However, in future, PZT maybe has to be replaced by lead-free materials, even for thin films. Ferroelectric material, such as LiNbO3 (LN) presents FoM similar to that of PZT. Moreover, LN is compatible with high-temperature applications of transducers (up to 1000 °C) and EHs (at least up to 500 °C) while PZT, BTO and KNN loss their piezoelectric properties at these temperatures. Moreover, LN presents very high pyroelectric coefficients. However, the application of these materials in PiViEHs is still very little studied and considerable efforts have to be done towards their integration to the conventional processing of MEMS. In this work, piezoelectric and pyroelectric transducers based on single-crystalline LN films on Si substrates were designed, fabricated and characterized. Good agreement between simulations and experimental results was demonstrated. In the future, we aim to develop a hybrid system with dedicated electronics able to harvest energy from both thermal and vibrational sources.

Resume : In general, particle-polymer composite nanogenerators, in which the particles are dispersed in the polymer matrix, are less power generation than the oriented particle composite because of the particle randomness and a thick insulating polymer layer. If the nanoparticles are unidirectionally oriented in a polymer matrix to form a bundle of chains, the stress-induced energy can be more concentrated and easier transferred to the electrodes. Here, we present a facile electrical orientation method to obtain vertically aligned BaTiO3 nanoparticle arrays in a polymer matrix for the improved piezoelectric power generation. Compared to the randomly dispersed nanoparticle composite, the vertically aligned BaTiO3 array film has an excellent electrical output performance (ca. 3 V and 650 nA) and more than twice the transparency because of reducing light scattering by gathering BaTiO3 nanoparticles. In addition to the improved piezoelectric performance and transparency due to the alignment of the nanoparticles, we found that the (200) diffraction plane of BaTiO3 is transformed by an electric field. Furthermore, it is demonstrated that electric power generated by a mechanical micorloading of 4 μm denting depth using a nanoindenter equipment can pass through the polymer insulating layer in the well-aligned composite system but no the dispersed system.

Resume : Organic-inorganic hybrid thermoelectric materials have attention because of enhancing thermoelectric performance by utilizing the low thermal conductivity of organic thermoelectric materials and the high Seebeck coefficient of inorganic thermoelectric materials. Moreover, the interfacial effects including the energy filtering effect and interfacial interactions to align the polymer chains for a favorable hopping mechanism have known to influence the thermoelectric performance of the hybrid composites. Herein, we report on the template-assisted fabrication of PEDOT:PSS/Ge2Sb2Te5 (GST) nanowires hybrid composites for improvement in electrical conductivity and Seebeck coefficient. The GST nanowires array fabricated by a solvent-assisted nanotransfer printing technique was participated as a template to align the PEDOT:PSS. Significantly enhanced thermoelectric performance of PEDOT:PSS/GST nanowires hybrid composites compared to their individual counterparts is because of energy filtering effect at the GST nanowire/PEDOT:PSS interfaces. The alignment effect of PEDOT:PSS chains on the electrical conductivity was elucidated by measurement in parallel and perpendicular to the GST nanowires. The details will be presented in the session.

Resume : Metal Organic Frameworks (MOFs) are porous crystalline hybrid solids with a huge chemical and structural diversity leading to thousands of porous architectures with micro or meso-pores and tunable sorption properties. This paves the way for a wide range of potential applications from catalysis, sensing, biomedicine to separation, among others.[1] These materials have also been recently proposed for applications related to their adsorption/desorption properties of water such as heat reallocation [2] or fuel cells [3]. In both cases one shall consider only cheap MOFs not only bearing a very good hydrothermal stability [4] but also produced and shaped under green conditions not only to compete with benchmark materials but also in order to integrate them within new processes. [5] We will report here our latest results in this field with a particular emphasis on the synthesis and characterization of these new high valence metal polycarboxylate MOFs. [6-7] References [1] G. Maurin, C. Serre, A. Cooper, G. Férey, Chem. Soc. Rev., 2017, 46(11), 3104 , MOFs theme issue and references therein [2] A. Cadiau, J.S. Lee, D.D. Borges, P. Fabry, T. Devic, M.T. Wharmby, C. Martineau, D. Foucher, F. Taulelle, C.H. Jun, Y.K. Hwang, N. Stock, M.F. De Lange, F. Kapteijn, J. Gascon, G. Maurin, J.S. Chang, C. Serre, Adv. Mater., 2015, 27(32), 4775-4780 [3] D.D. Borges, S. Devautour-Vinot, H. Jobic et al.; Angew. Chem. Int. Ed., 2016, 55(12), 3919 [4] H. Assi, G. Mouchaham, N. Steunou, T. Devic, C. Serre, Chem. Soc. Rev., 2017, 46(11), 3131 [5] A. Permyakova, O. Skrylnyk, E. Courbon, M. Affram, S. Wang, U.H. Lee, A.H. Valekar, F. Nouar, G. Mouchaham, T. Devic, G. De Weireld, J.S. Chang, N. Steunou, M. Frère, C. Serre, ChemSusChem, 2017, 10(7), 1419-1426 [6] S. Wang, J. S. Lee, M. Wahiduzzaman, J. Park, M. Muschi, C. Martineau-Corcos, A. Tissot, K. H. Cho, J. Marrot, W. Shepard, G. Maurin, J. S. Chang and C. Serre, Nat. Energy, 2018, 3, 985 [7] S. Wang, M. Wahiduzzaman, L. Davis, A. Tissot, W. Shepard, J. Marrot, C. Martineau-Corcos, D. Hamdane, G. Maurin, S. Devautour-Vinot and C. Serre, Nat. Comm., 2018, 9, 4937

Resume : Metal-organic frameworks (MOFs) and other nanoporous hybrid materials have potentially widespread applications in energy and environmental domains; viz., their potential use as an alternative solid electrolyte for fuel cells and water adsorption based heat pumps which are essential components in the solar cooling systems. However, the pathway from laboratory synthesis to such practical implications is substantially challenging. More specifically, the structure determination of these framework materials is often a tedious task due to their relatively poor crystallinity, low symmetry, and large unit cell volumes that make the indexation of their powder X-ray patterns very complex. Inspired by the concept of Secondary Building Units (SBU) and the Automated Assembly of Structure Building Units (AASBU) method we have developed a software to facilitate the structure solution of such complex systems.[1] In this communication, first, we will present few example cases of structure determination of novel MOFs that have been solved by our structure prediction toolbox where ab initio methods were unsuccessful. We will then highlight the structure-property relationship for a series of hydro-chemically stable novel MOFs in terms of water adsorption based proton conduction and heat reallocation performances.[2,3] 1. Wahiduzzaman et al. Chem. Commun. 54, 10812–10815 (2018) 2. Wang et al. Nat. Commun. 9, 4937 (2018) 3. Wang et al. Nat. Energy 3, 985–993 (2018)

Resume : Supercapacitors of high capacity, better cyclic stability and good rate capability can be the perfect solution to fulfill the growing, worldwide, energy storage, harvesting and generation demands. Nanostructured materials have already been proven to be efficient electrode materials in supercapacitor applications as they provide a large specific surface area and short transport/diffusion path for mass and carriers, leading to a faster kinetics and high charge–discharge capacities. The nanostructured material can be well-controlled with their sizes, architectures, shapes, and compositions which make them as versatile electrodes materials in electrochemical supercapacitor applications. In this presentation, our, ongoing research activities to develop electrochemical supercapacitors of inexpensive and environmentally friendly transition metal oxide electrode materials as positive and negative materials Co3O4, NiO, MnO2, CuO and Fe2O3, Bi2O3 and V2O5 etc., in microspheres, needles, nanorods, and nanobelts morphologies can be envisaged with remarkable capacitive performance. Finally, well-controlled nanostructures employed for commercial symmetric/asymmetric supercapacitor devices will be proposed through practical demonstrated.

Resume : Block copolymer (BCP) elf-assembly can generate dense, periodic nanopatterns with sub-10-nm scale pattern precision for nanolithography application. One critical limitation of BCP lithography is intrinsic two-dimensional characteristic. Well-established processing steps for the BCP lithography generally include the solution casting of BCP thin films and subsequent thermal/solvent annealing, which have been regarded incompatible to three-dimensional or flexible substrate geometry. In this presentation, BCP lithography for three-dimensional, flexible and complex geometry will be introduced. Mechanically robust but compliant chemically modified graphene (CMG) films prepared by substitutional heteroatom doping of graphene plane are utilized as a transferrable and disposable substrate for the BCP nanopatterning for nonplanar, flexible, and even multi-stack structures. Taking advantage of the high chemical/thermal stability, atomic scale flatness, and mechanical robustness with compliance, the graphene based materials can be versatile substrates for nanopatterning. While pristine graphene has a low surface energy, CMG with non-carbon elements, may have a controllability of surface energy to tune the wettability for BCP thin films. Direct implementation of conventional BCP lithography process on the spin cast CMG film and subsequent transfer onto flexible or nonplanar geometries accomplishes various surface nanopatterned structures on flexible or three-dimensional geometry, including metal nanopatterns stabilized on conventional PET or PDMS substrates. Significantly, strong light absorption and photothermal efficiency of CMG layer can be exploited for area-selective BCP lithography by means of the irradiation of focused IR/visible laser beam or large-area flash light. The ultrafast photothermal process makes it possible to build up steep thermal gradient at the boundary of the focused laser beam, whose lateral scanning in the BCP film plane may induce spontaneous lateral alignment of nanoscale vertical BCP lamellar or hexagonal cylinder patterns over large-area. Taken together CMG substrate based BCP lithography offer enormous opportunity for highly ordered self-assembled nanopatterns on nonplanar and flexible geometry.

Resume : Diverse techniques for depositing and patterning colloidal quantum dots (QDs) to demonstrate individual RGB QD pixels have been developed in past years to realize electroluminescent QD light-emitting diodes (QLEDs) as next-generation displays. However, previously reported patterning technologies have limitations in demonstrating large-area, full-color pixel arrays of sub-micrometer feature size with high fidelity and low edge-roughness. At the first part, we present a highly practical transfer-printing technique, which allows patterning and printing of QD array in omni-resolution scale; QD array in single-particle resolution to the entire film can be fabricated and transfer-printed. Polychromatic array with unprecedented resolutions up to 200 PPD is demonstrated by utilizing sequential aligning and printing of individual RGB pixel arrays. Our transfer-printing technique effectively reduces tradeoffs of conventional QD patterning method, suggesting possibilities for fabrication of full-color electroluminescent QLED displays. At the second part of this talk, highly interconnected porous QD/block copolymer (BCP) nanocomposites is demonstrated to achieve enhancement of photoluminescence. The QD/BCP nanocomposites with strong emission characteristics have the potential to be used in photoluminescence devices of display application with simple and cost-effective fabrication method. Block copolymers (PS-b-P4VP) forms highly inter-connected porous structure via the mechanism of spinodal decomposition among BCP, water, and solvent. The porous QD/BCP nanocomposites effectively enhanced absorption of QDs inside the BCP matrix by the multiple light scattering and trapping effect, resulting in a 21-fold enhancement in photo-luminescence is achieved compared to reference quantum dot films.

Resume : Unique self-amplification enhanced photo responsivity has been reported at a graphene-silicon hetero interface when the band bending is properly managed by an external gate. In this work, same principle is applied to the photodetector having graphene/germenium hetero junction. Very high photoresponsivity over 20A/W has been reported with a competitive dark current level at infrared wavelength range (950-1550nm). Detail characteristics of IR detector at an array level will be presented and the enhancement mechanism will be discussed.

Resume : The metal-insulator transition attracts the crystallographic issues because the phenomena are coupled to a symmetry-lowering structural phase transition. Structural phase transition is accordingly related with various types of emergent functional properties, implying that the atomic modification and control can promise the new paradigms for electronics and photonics. Amongst them, vanadium dioxide (VO2), an archetypal correlated oxide, show a metal‒insulator transition (MIT) near room temperature and thus it can be regarded as a potential material to realize the metal insulator transition in our real life. In the recent effort in our group, the variety of VO2 model experiments has been revealed through the intensive collaborations. Most of results were carried out through the combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling, in order to reveal the controllable parameters affecting metal insulator transition in VO2, such as strain, composition, electronic coupling, structural coupling, and so on. In this talk, I will summarize and introduce four papers in VO2 system that we have recently published [1-4]. [1] D. Lee, B. Chung, Y. Shi, G.-Y. Kim, N. Campbell, et al., Isostructural metal-insulator transition in VO2, Science 362, 1037 (2018). [2] H. Yoon, J. Park, S.-Y. Choi, D. Lee, and J. Son, “Facet-Dependent Phase Control by Band Filling and Anisotropic Electron-Lattice Coupling in HVO2 Epitaxial Films”, Advanced Electronic Materials 4, 1800128 (2018) [3] D. Lee, J. Lee, K. Song, F. Xue, S.-Y. Choi, et al, “Sharpened VO2 Phase Transition via Controlled Release of Epitaxial Strain,” Nano Letters 17, 5614 (2017) [4] H. Yoon, M. Choi, T.-W. Lim, H. Kwon, K. Ihm, et al, “Reversible phase modulation and hydrogen storage in multivalent VO2 epitaxial thin films”, Nature Materials 15, 1113 (2016)

Resume : Energy storage devices for future hybrid plug-in electric vehicles (EVs) and pure EVs must satisfy more challenging standards in energy and power densities over long repeated charge/discharge cycles. Currently, the dominating electrochemical energy storage remains on a lithium ion battery (LIB) with high energy density although an electrochemical capacitor (EC) with high power density along with robust cycle life has great potential for many energy storage devices. Meanwhile, it was found that the sole usage of a LIB or an EC could not give simultaneously high energy and power densities because of its complementary ion storage mechanism. Therefore, hybrid electrochemical energy storages are of great interest as they have the potential to achieve both high energy and power densities. Herein, we propose high-performance hybrid full-cell capacitors on a new class of paradigm materials for anode and cathode electrodes. These results support that assembling the cathode with many metal encapsulated anode structures could pave a new route to realize the hybrid full-cell energy storage devices requiring both high energy and power densities over long repeated charge/discharge cycles along with excellent rate capability, in addition to design a new class of high-performance energy storage structures.

Resume : Zinc-air alkaline battery is a century-old battery technology but has attracted revived interest as one of the most viable future options to powering electric vehicles. Zinc-air battery clearly shows benefits in terms of safety, price and feasible to be commercialized in near future. However, the major obstacle of Zn-air battery is the slow kinetics in air cathode, which terms as oxygen reduction reaction (ORR). Normally, Pt or Pt-Ni alloy is applied as electrocatalysts yet the high capital cost and instability of the materials limits the practical installation in electrical vehicles. Non-platinum electrocatalysts including transitional metal, heteroatom-doped carbon and organo-metallic catalysts have currently being proposed to be potential substitute ORR electrocatalysts. Among all, transitional metal nanoparticles generally show advanced in ORR catalytic activity, where heteroatom-doped carbon demonstrates superior durability. In this study, we synthesized a hybrid metal/nitrogen-doped carbon as efficient and economical electrocatalyst in Zinc-air battery. The type of C-N bonding states can be prepared by choosing the structure of the original precursor, where the transitional metal (Fe, Ni, Co) nanoparticles were synthesized via a one-step process. In this research, amine and quinoline was applied as precursor for selective amino N-doped and graphitic-N carbon. The effects of the structure of CN precursor on the chemical bonding states and electroatalytic activities were investigated. From the electrochemical measurement, the current density was proportional to the content of graphitic-N, where higher percentage of amino-N shifted the ORR onset potential positively. The ORR catalytic activity was further enhanced by doping Fe or Co nanoparticles on N-doped carbon. The highest onset potential and current density of Co/N-C 0.95 V (V vs R.H.E) and 6.72 mA/cm2, which is comparable to that of 20 wt.% Pt/C. The discharge specific capacity of Co/N-C in a Zinc-air battery cell was 633 m A h g-1. We believe our Co/N-C hybrid materials could be one of the potential candidates as electrocatalyst in air cathode of Zinc-air battery.

Resume : Advanced rechargeable batteries with low cost, high safety, good operational capacity, and eco-friendly materials must be implemented in large-scale energy storage systems (ESSs). In this respect, rechargeable multivalent ion batteries, namely, Zn-ion, Mg-ion, Al-ion, and Ca-ion are considered promising and risk-free charge-storage devices compared to unsafe and expensive Li-ion batteries. 1D nanorods of the layered material K2V6O16•2.7H2O (KVO) are implemented for the first time as cathode materials in secondary aqueous rechargeable Zn-ion batteries (ARZIBs) and exhibit excellent electrochemical Zn storage properties. This cathode material delivers a reversible capacity of 296 mA h g-1 over 100 cycles. At current densities of 1000, 3000, and 5000 mA g-1 for 700 cycles, the electrode displays reversible capacities of 223, 177, and 138 mA h g-1, for approximately 170, 300, and 230 cycles, respectively. In addition to these properties, it withstands over 500 cycles at an applied current density of 6000 mA g-1 with nearly 82% capacity retention. The battery offers a specific energy of 128Wh kg-1 at a specific power of 5760 W kg-1, revealing the advantages of the material in an ecofriendly atmosphere.

Resume : Crystalline and porous Metal-Organic Frameworks (MOFs) are currently of great interest and importance among the existing classes of porous solids. In spite of versatile advantages of porous MOFs, most of MOFs suffer from several stability issues which could be a critical hurdle for practical applications. Conversely, highly porous MOFs with good hydrothermal and chemical stability could represent candidates of industrially-viable sorbent materials. Gas, vapor or liquid sorptions with porous materials provide one of essential tools for energy and environmental applications to realize a sustainable society and industry. These include energy-efficient water sorption, heat allocation, gas separation, storage of light gases containing energy values, removal of toxic gases and chemicals, etc. In particular, water sorption technologies are used commercially in many contexts, including industrial or indoor desiccant applications such as desiccant dehumidifiers, adsorptive air-conditioning systems, evaporative cooling, and fresh water production. Besides this, the energy-efficient separations of gases such as olefins/paraffins, N2/CH4, N2/O2, etc. are always important subjects to replace conventional cryogenic distillation processes, which require high energy consumption, by MOF-based adsorbents or mixed matrix membranes. This presentation will cover several examples of energy-efficient and sorption-driven applications such as water sorption and gas separations by robust MOFs.

Resume : The device performance of inverted planar perovskite solar cells (IPSC) is directly affected by the quality of the perovskite active layer, which is related to the crystallinity, extent of coverage, and grain size of the layer. However, the fundamental mechanism of grain growth evolution in the fabrication process from the precursor phase to the perovskite phase which determines quality of grains is not fully understood. This study deals with understanding the fundamental mechanism of grain growth evolution in the fabrication process from the precursor phase to the perovskite phase. Furthermore, on the basis of these studies, we developed a simple and effective method to tailor grain properties including the crystallinity, size, and number of grain boundaries, and then utilized the film with the tailored grains to develop perovskite solar cells. By monitoring the film forming process, we found that highly crystalline perovskite generates a nanorod intermediate aggregation in film formatting process and the nanorod intermediate aggregation plays an important role in producing highly crystalline perovskite with enlarged grains. The nanorod intermediate phase can be easily obtained by retarding the solvent evaporation speed and it helps in grain to get merged with neighboring grains leading to enlarged grains with high crystallinity. Based on these observations, we have newly developed a simple and effective method for tailoring grain properties including crystallinity, size, and numbers of grain boundaries. Using the tailored perovskite film, we have successfully conducted comparative study of grain size effect on PESC performance. The best device performance is obtained in the PESC with the largest grain size. The device shows a high short-circuit current (Jsc) of 21.78 mA cm-2, a open-circuit voltage (Voc) of 0.97 V and fill factor (FF) of 0.82, yielding a power conversion efficiency of 17.20%. We believe that our work provides an alternative way and new insight towards the optimization of the perovskite crystallization kinetics, which is beneficial in further enhancing the performance of IPSCs and other optoelectronic applications.

Resume : Using first-principles calculations we establish big data to utilize machine learning method for high-throughput screening of efficient energy materials. Efficient nanoscale electrocatalyts for oxygen/hydrogen redox reactions are identified with multicomponent alloys. Low-dimensional transition metal dichalgenides support with single atom catalysts are proposed as a novel method to extremely reduce Pt loading for fuel cell systems. It is clearly shown that the first-principles-based machine learning can make a breakthrough for conventional development of new functional materials on the aspect of temporal and monetary costs.

Resume : Nanomaterials are important in the modern society since they can provide solutions in several fields of knowledge. One of these fields is related to gas sensors, in which a material has its resistance modulated based on the presence of an analyte gas. Gas sensors are important in monitoring environmental pollution, and controlling processes having gases as a limiting step, such as in chemical industry. In this work will be presented gas sensor devices produced using tin oxide nanostructures. Besides the most known stannic oxide (SnO2), we were able also to produce stannous oxide (SnO) and the less stable, mixed valence oxide, Sn3O4. The morphology of materials can be nanobelts or micro-disks, and the gas sensor properties are dependent on the morphology. Moreover, the gas sensor response also changes when using surface functionalization by adding noble metal nanoparticles (Pd, Ag, Pt). Materials were tested in carpet mode and using the single element sensor device. Although SnO2 is a standard material in the gas sensor field, results showed that both SnO and Sn3O4 have better sensor response and selectivity than SnO2, opening a new class of materials to be explored. A sensor signal around 1000 was obtained for SnO micro-disks when detecting 100 ppm of NO2, and this giant sensor response was attributed to the presence of lone pairs on the material surface. Moreover, it is possible to change the analyte gas to be detected using the surface functionalization process. A mechanism

Resume : The electrical conversion and storage of solar energy is crucial for assuring the world energy supply. Besides solar fuels such as hydrogen, the possibility of storing energy in other kinds of redox pairs has recently attracted attention, giving rise to the so-called solar-powered electrochemical energy storage (SPEES). In particular, photoelectrochemical redox flow batteries are promising alternatives, considering their inherent higher energy density versus other redox pairs. This integration is not seamless unless the photovoltage is customized to the voltage needs of the battery, which unlike artificial photosynthesis, continuously increase with the state-of-charge. We have for the first time developed integrated solar vanadium redox flow battery (VRFB) with tailor-made low-cost CIGS light absorbers, and considering the voltage requirements (1.3-1.6V), we have evaluated the influence of the photovoltaic operation on the final efficiency of the solar VRFB. Full unbiased photocharge under 1 Sun illumination has been achieved reaching high energy (77%), solar-to-charge (7.3%) and overall round trip energy conversion efficiencies (5%), excelling values reported in literature for other solar RFB. Considering the voltage tenability of redox flow batteries, the latest results of a non-vanadium based chemistry to achieve a bias-free solar charging using monolithic tandem photoelectrodes will be presented. The work was funded by MINECO project WINCOST (ENE2016-80788-C5-5-R).

Resume : Our modern life demands automations and a network of sensors that could provide continuously information about our living surroundings. Various types of sensors have been developed embedded in smart devices, glass windows at homes/cars and flexible wearables. A crucial parameter is to monitor and recognize fast, air pollutants that can affect people’s health. Ozone is one of such pollutant and its concentrations up to 50 ppm could present risks to life due to its toxicity at the respiratory system. The most of the developed gas sensors require high temperatures or/and UV triggering in order to provide accurate concentration values. Very recently, hybrid perovskites have been suggested as promising sensing materials. In this work, we demonstrate a rapid, room-temperature operated, without UV external stimuli, ozone sensor of all-inorganic halide perovskite, developed in few steps on work-bench. Ligand-free nanocubes of CsPbBr3 synthesized directly on InterDigitated platinum Electrodes. The ozone gas sensor demonstrates high sensitivity (54% for 187 ppb), fast response and recovery time (143 & 319 s) and stability over 3 months exposed at ambient conditions. Our nanoparticulate system could be exploited in other gasses and open the way to research and develop environmental lead-free perovskite-based sensors. This research is co-financed by Greece and E.U. (ESF) through the Operational Program «Human Resources Development, Education and Lifelong Learning 2014-2020» MIS 5004411

Resume : This talk demonstrates programmable gas phase electrodeposition for air quality sensor fabrication. Smart buildings employ a variety of gas sensors to create a temporal profile for each gas. The developed device demonstrates a room temperature operated sensor chip that can integrate an array of different nanostructured materials arranged in a pre-decided pattern on the substrate. Each gas sensitive structure is a 3D nanobridge, composed of porous but electrically conducting nanoparticle network. Method of gas phase electrodeposition has been reported [1] and used as interconnects in nanoelectronics. Extending the basic principles for self-aligned growth of nanobridges with a new substrate design, it is possible to grow bridges of different materials on a single substrate. 1080 Platinum, Nickel oxide and Gold nanobridges were grown on a photoresist patterned glass substrate with gold electrodes showing excellent selectivity towards Ammonia, Carbon Monoxide and Hydrogen Sulfide gases, respectively. Gas phase electrodeposition has established itself as a material-efficient method, achieves high material yield, which means that expensive materials such as Platinum or Gold, are used economically and efficiently. [1] Fang, J.; Schlag, L.; Park, S. C.; Stauden, T.; Pezoldt, J.; Schaaf, P.; Jacobs, H. O., Approaching Gas Phase Electrodeposition: Process and Optimization to Enable the Self-Aligned Growth of 3D Nanobridge-Based Interconnects, Adv. Mater. 2016, 28 (9), 1770–1779.

Resume : Titania nanotube (TNTs) is a unique low-dimensional oxide and expected as energy production and environmental purification material because of its synergy of photochcemical property and of high adsorptivity of ions/molecules derived from its multilayered tube-structure. In this paper, low-dimensional nanohybrids based on TNT have been investigated to improve their properties and to add new functions. Oxide-carbon nanocomposites consisted of TNT and nanostructured 1-dimensional (1D) or 2-dimensional (2D) carbons were synthesized via solution chemical processing. When carbon nanotube (CNT) was chosen, unique core-shell 1D/1D CNT/TNT nanocomposite could be successfully obtained, where CNT core was surrounded by rolled shell form of TNT. In contrast, 1D/2D nanocomposites could be fabricated by combining graphene oxide (G0), where TNT decorated on the graphene substrate. Electrical resistivity was decreased with the addition of nanocarbon. In addition, these nanocomposites exhibited better gas sensing properties, implying the carrier transport performance of titania which intrinsic mobility is sufficiently low might be greatly enhanced. On the other hand, organic-ingorganic hybrid nanotubes have been synthesized in the system of TNT and polyaniline (PANI) which is well-knopwn conductive polymer. Additionally, we proposed the new synthesis method of nano-hybridizing TNTs and PANI by photopolymerization without any polymerization initiator used in the existing method. Polyanilines have successfully be polymerized by radical species generated from TNTs by photo-irradiation, which result is the first case for hybridizing nanostructure-oxide (TNT) and PANI by simple self-photopolymerization route without using any iniciating agent. Electrical conductive PANI was obtained under the controlled pH during photopolymerization process. Further tuning of nanohybrids was attempted for the TNT/PANI system; oganic linker molecules were immobilized on TNT surfaces, and the PANI was well formed on TNT to make core-shell structures. Materiaps processings and nanohybrid structures as well as fundamental and photochemical properties wil lbe discussed for these low-dimensional nanohybrids. Keywords: titania nanotubes, nanohybrids, nanocrbon, polyaniline, photopolymerization, photocatalyst

Resume : Superhydrophobic surfaces (SHS) possess a water contact angle greater than 160°. They have attracted tremendous interests due to their potential application in areas such as self-cleaning, anti-icing, anti-bio-fouling and anti-corrosion. In general, superhydrophobicity can be achieved by a synergistic effect of a week surface energy and a high roughness. Many studies have been devoted to understand this effect to prepare SHS films and it has been proven that the well-known lotus leaf can enhance both effects by their hierarchical roughness with nanometric and micrometric roughness. Herein, we present the sol-gel based fabrication of a micro/nano dual-roughness film made of a micrometer scale network composed of zinc oxide nanowires (ZnO NWs). The rough ZnO NW network was then grafted with hexadecyl trimethoxysilane (C16) to yield SHS without fluorination. We confirmed that the micro/nano-roughness ZnO NW film maintained superhydrophobic feature of above 170o over more than a month. In addition, the micro/nano-porous ZnO NW film with superhydrophobic property was also studied on anti-icing and anti-fouling abilities.

Resume : In order to enhance performance and reliability of photovoltaic modules (PV) it is very essential to keep the PV modules clean. Although there are good number of available technologies to clean the glass cover of solar panels but self-cleaning coatings, with extreme wettability, is emerging as one of the most reliable solution which can be easily applied and at the same time comes with low cost. Such coatings should be not only good at keeping the PV modules clean but at the same time should maintain the transparency of solar glass covers so as to allow maximum light to enter the surface of encapsulated solar panels. Most importantly such self-cleaning glazing structures have become very much useful in diverse field of solar energy application areas such as solar radiation transmission, building integrated photovoltaics (BIPV), solar panel, concentrated solar power (CSP) systems. Here we have developed a facile sol-gel based highly transparent and self-cleaning coating with tunable wetting property, by synthesizing single component silane modified base and acid catalyzed mixed silica sol. The sol is coated by following dip-coating approach on glass substrates. A static contact angle as high as 150° and rolling angle of ~2° has been achieved with these coatings. It also increases the maximum transmission of glass used in solar glass cover from 91.8% to 95.5% and concomitantly reduced the minimum reflectance from 8.7% to 3.2%. Such antireflection property has been further investigated by making ellipsometry studies, where we found the refractive index of1.21 and film thickness 82 nm.

Resume : Taking inspiration from the superhydrophobic properties of different plants (e.g., Asparagus setaceus, Nuphar luteum, Viola tricolor, and Strelitzia reginae) and insects (e.g., Hydrometra stagnorum, Aquarius remigis, and Dolomedes triton), we were able to process different polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(ethylene terephthalate) (PET), polyamide (PA), and polytetrafluoroethylene (PTFE) using various plasma technologies from P300, BSET EQ NT-1, and GDIS plasma devices, to obtain self-cleaning properties for vehicular interior applications. The samples were characterized by contact angle measurements, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and optical profilometry. Plasma processing effects such as surface etching and surface functionalization were observed on the polymeric materials and the observed superhydrophobic (with water contact angle as high as 161°) or enhanced hydrophobic or hydrophilic properties of the plasma-processed polymeric materials can be attributed to the changes in the physicochemical properties such as the increase in the average and r.m.s. surface roughness, changes in the material’s chemistry, and the creation of surface micro and nanostructures. The polymeric materials that exhibited self-cleaning properties in accordance with the Cassie-Baxter wetting model showed a sliding angle of as low as 3°. The changes in the properties of the polymeric materials due to plasma processing are also useful in terms of possible applications of the material as an antimicrobial and an antibiofouling surface.

Resume : Polymer electrolyte fuel cells (PEFCs) have attracted attention as a clean and efficient power source for generating electricity using air and hydrogen. A design of active interface on cathode is required for development of high quality PEFCs for fuel cell vehicle application. In the present work, the promotion effects of formation of Pt-CeOx hetero-interface on the oxygen reduction reaction (ORR) activities on Pt cathode was examined. And we already observed the clear promotion effect of surfaces of CeOx particle and CeOx nanowire (NW) for improvement of ORR on Pt in electrochemistry measurement method. However, the performance of membrane electrolyte assembly (MEA) with Pt-CeOx NW/C cathode was not enough as compared with our expectation level. In order to activate the active sites on Pt-CeOx NW/C cathode in MEA of PEFCs, we used the electron beam irradiation technique for creation of active sites on the surface of Pt-CeOx NW/C cathode in MEA. Our experimental results indicate that the active three phase boundaries which was suggested by both of microanalysis and surface atomistic simulation in our work was formed by electron beam irradiation. And the performance of MEA with Pt-CeOx NW/C was conspicuously improved by formation of our expected defect sites on electron beam irradiated Pt-CeOx NW/C cathode surface. Therefore, it is expected that the performance of MEA with Pt-CeOx NW/C cathode will be maximized by optimization of fabrication condition in the present method.

Resume : The microwave hydrothermal and photo-reduction method were used to synthesize the plasmonic photocatalyst, silver spherical nanoparticles (Ag NPs) decorated α-Nickel molybdate (NiMoO4) nanorods. Antibiotics, tetracycline (TC) was used as target pollutant to evaluate the photocatalytic activity under visible light irradiation. The observed degradation efficiency of Ag NPs decorated α-NiMoO4 for TC degradation (80 % within 180 min) is 8 folds as compare to α-NiMoO4, respectively that is associated with increase in visible light absorption or reduction of band gap, surface plasmon resonance (SPR) effect, and efficient separation of electron-hole pairs. The excellent photodegradation stability was found which was also further supported by XRD and FESEM measurements of photocatalyst after three cycles. In addition, the scavenger experiment suggests that OH• plays a major role whereas O2•- and h+ show the minor role for TC degradation. Furthermore, ultra-performance liquid chromatography-photodiode array (UPLC-PDA) and high resolution-quadruple time of flight electrospray ionization mass spectroscopy (HR-QTOF ESI/MS) techniques were employed to find out the transformation products of TC in water as well as degradation pathways. The five degradation pathways were proposed for TC degradation which was explained on the basis of demethylation, hydroxylation, dehydroxylation, oxidation, and deamination organic reactions. The efficient mineralization of TC was found in the basis of total