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In this study, a series of optimization steps were performed in the production of Al-doped ZnO (AZO) thin films to tailor their properties as efficient transparent heaters and for near-infrared (NIR) reflectance. The films were produced on 50 x 75 mm(2) glass substrates via magnetron sputtering and capped with a protective SiO2 layer. Processing parameters such as deposition temperature, film thickness, and annealing conditions were all optimized in terms of structure, morphology, optical/electrical properties, and heating/deicing behavior. Electro-thermal characteristics of the films were investigated using a thermal imaging infrared camera under various input voltages. The optimized AZO/SiO2 coatings displayed impressive room-temperature electrical conductivity (sigma) of nearly 3774 S/cm with a sheet resistance (R-s) of 3.53 Omega/square, carrier concentration (eta) of 1.14 x 10(21), and Hall mobility (mu) of 20.48 cm(2)/Vs. These films exhibited very high optical transmittance (above 96%) in the visible range and reflectance (73% at 2500 nm) in the NIR region. The highest figure of merit (FOM) was achieved as 237 (x 10(-3) omega(-1)). Deicing tests were performed with samples cooled to - 40 degrees C and resulted with complete removal of ice/water only within 3 min. In addition, the heater exhibited a high surface temperature of 161 degrees C (12 V), a good thermal resistance value (219 degrees C cm(2)/Watts) with stable and reversible heating behavior. More importantly, these results reveal the potential of optimized AZO/SiO2 coatings as alternatives to transparent tin-doped indium oxide heaters and NIR reflecting mirrors for vehicular applications.

Herein, the long-term stability of vacuum-deposited methylammonium lead iodide (MAPbI(3)) perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of around 19% is evaluated. A low-temperature atomic layer deposition (ALD) Al2O3 coating is developed and used to protect the MAPbI(3) layers and the solar cells from environmental agents. The ALD encapsulation enables the MAPbI(3) to be exposed to temperatures as high as 150 degrees C for several hours without change in color. It also improves the thermal stability of the solar cells, which maintain 80% of the initial PCEs after aging for approximate to 40 and 37days at 65 and 85 degrees C, respectively. However, room-temperature operation of the solar cells under 1sun illumination leads to a loss of 20% of their initial PCE in 230h. Due to the very thin ALD Al2O3 encapsulation, X-ray diffraction can be performed on the MAPbI(3) films and completed solar cells before and after the different stress conditions. Surprisingly, it is found that the main effect of light soaking and thermal stress is a crystal reorientation with respect to the substrate from (002) to (202) of the perovskite layer, and that this reorientation is accelerated under illumination.

Double layer glass/fluorine-doped tin oxide (FTO)/aluminum-doped zinc oxide (AZO) multifunctional thin films were achieved via ultrasonic spray pyrolysis (USP) method without employing a post-deposition annealing. Transparent heater and near-infrared heat reflection behaviors were investigated. The samples were characterized in terms of their structural, morphological, optical, and electrical properties. The top AZO layer exhibited a polycrystalline structure without any preferred orientation. The double layer structure showed very high average transmittance (87%, 400-700 nm) in the visible and reflectance (55%, 2500 nm) in the near-infrared, regions. In addition, the sheet resistance and resistivity of the film were measured as 14.85 (Omega sq(-1)) and 1.78 x 10(-3) (Omega cm), respectively. The saturation temperature, response time, surface temperature uniformity, areal power density, and thermal resistance values were found to be 111 degrees C, 174 s, 11.42%, 0.299 W/cm(2), and 282.8 degrees C cm(2) W-1 for a sample with an active area of 31.5 cm(2) and input voltage of 9 V. In addition, dry-ice cooled samples (-25 degrees C) showed impressive deicing performance depending on the input power. In case of 12 V, all ice was defrosted, and water droplets were evaporated within 2 min and 10 s. During this process, a heating rate of similar to 43 degrees C/min was achieved.

In the current study, sulfide based ternary and quaternary thiospinel nanocrystals were synthesized by using a simple hot injection method and used as catalyst instead of Pt in a DSSCs application for the first time. CuNiCoS4, CuCo5S8, and CuCo2S4 as thiospinel nanocrystals have been synthesized in crystalline structure, single phase, nearly stoichiometric, and having narrow size distribution below 10 nm. Comparative studies showed that, Carbon Nanotube (CNT)-CuCo2S4 based DSSCs yielded the most favorable results as a potential counter electrode showing very similar power conversion efficiency (eta = 4.99%) in comparison with Pt based DSSCs produced under identical conditions. Therefore, this study implies that the thiospinel nanocrystals and their CNT supported composites can be proposed as novel counter electrode materials for low-cost platinum-free solar cells., TUBITAK (The Scientific and Technological Research Council of Turkey) [217M212]; TUBITAK [217M212], This work is supported by TUBITAK (The Scientific and Technological Research Council of Turkey) under project number 217M212. This paper was prepared from Ph.D. thesis of Adem SARILMAZ, which supported also by TUBITAK (217M212).

A study was carried out to tailor the properties of ultrasonic spray pyrolysis deposited Al-doped ZnO (AZO) thin films suitable for transparent heater applications. For this purpose, the influences of solvent/precursor type and molarity, Al-doping concentration, nozzle to substrate distance, solution flow rate, carrier gas flow, substrate temperature, and post-deposition annealing on the microstructure, electrical, optical properties, and heating/ deicing behaviors of the films were investigated. The optimized heaters were produced on 50 x 75 mm(2) glass substrates at 400 degrees C with 750 nm thickness and annealed under forming gas for 90 min. This sample revealed a good sheet resistance value of 38.7 Omega/square and 83% transmittance in the visible region. Heating/deicing tests showed that the maximum achievable surface temperature was 76 degrees C under an applied potential of 12 V and all ice/water can be removed completely within 250 s. In addition, the AZO heater exhibited a very high thermal resistance value (409 degrees C cm(2)/Watts) with stable and reversible heating behavior.

Ternary and quaternary structured thiospinel nanocrystals are important materials for energy applications based on their outstanding characteristics such as earth abundant components, non-toxic nature and simple production. In this study, CuNiCoS4, CuCo5S8 and CuCo2S4 nanocrystals have been successfully synthesized via hot injection-method with generalized synthesis conditions and detailed structural, optical and electrochemical characterizations were performed for the first time. The characterization results indicated that the nanocrystals were single phase, nearly stoichiometric composition and a mean size below 10 nm. Moreover, the synthesized nanocrystals have been used for the photocatalytic hydrogen evolution as a catalyst under visible light irradiation. In these reactions, CuNiCoS4 nanocrystals exhibited higher photocatalytic activity and stability than the others. CuNiCoS4 and CuCo5S8 catalyst have firstly been proven as valuable alternatives to CuCo2S4 structure and Platinum in hydrogen evolution reactions and are of particular interest due to lower costs, ease of fabrication and comparable evolution performance. (C) 2020 Elsevier Ltd. All rights reserved.

Tetragonal BaTiO3 nanoparticles have been hydrothermally synthesized using the electrospun TiO2 nanofibers as the Ti-source. Microstructural and compositional analyses have been carried out using XRD, SEM, TEM, XPS, and Raman spectroscopy. Characterization studies confirmed that the BaTiO3 nanoparticles had a tetragonal structure with an average particle size of 100 nm. Photocatalytic activities of the nanoparticles were investigated via the decolorization of methylene blue dye aqueous solutions under visible light and UV-A irradiations. The degradation efficiency reached to 13 and 35% after exposing to light for 60 min with visible and UV-sources, respectively. Effect of sintering temperatures on the dielectric properties was also investigated. Among all the sintering temperatures employed, 1473 K was the optimum sintering temperature for these ceramics in terms of high relative density (95.3%), high dielectric constant (3162 at 1 MHz), and low loss tangent (15 × 10−3 at 1 MHz). Experimental results showed that electrospun TiO2 fibers can be used as a precursor template to produce nano-scale BaTiO3 particles which are suitable for various applications such as photocatalysis and capacitors.

In this study, we introduce a new concept for the highly efficient tandem p-n photoelectrochemical cell consisting of coumarin6 organic dye-anchored p-type CuCrO2 delafossite semiconductor as photocathodes coupling with traditional n-type TiO2 based photoanodes. Also, we have systematically studied the photovoltaic performance of tandem cells as a function of post-annealing of CuCrO2 films before sensitization. Hydrothermally synthesized CuCrO2 nanocrystals exhibited a high surface area with small crystallite size of 12 nm, phase-pure and well-crystalline after the optimized post-annealing conditions. The experimental results indicated that the optimal post-annealing temperature was 450 °C for 1 h due to the larger active surface area, lower Rct, and higher Jsc and Voc values. This tandem cell, fabricated by employing the CuCrO2 photocathodes, iodide-based redox mediator and a coumarin6 organic dye, afforded an impressive efficiency of 2.33% with Voc of 813 mV, Jsc of 4.83 mA cm−2, and fill factor of 0.59. The obtained parameters are acceptably high in comparison to NiO photocathode-based tandem cells previously reported in literature under similar experimental conditions. Therefore, this work opened the way for developing highly-efficient tandem photoelectrochemical solar cells.

CuCrO2 nanoparticle decorated SnO2 nanofiber composites have been prepared as novel p–n heterostructured semiconductor photocatalysts for the degradation of organic pollutants in wastewater. The composite structure was achieved via drop casting of various amounts of hydrothermally derived CuCrO2 nanoparticles on electrospun SnO2 nanofibers. The microstructural and morphological features of each semiconductor and the formation of p–n heterojunctions between them were characterized. In addition, the photo-response and electrochemical properties of the samples were determined. The photocatalytic activity of the heterostructured photocatalysts was investigated systematically as a function of the amount of CuCrO2 nanoparticles in the samples. Experimental results showed that the optimal decoration amount was 0.6 wt% CuCrO2 on SnO2. This composite photocatalyst displayed a 41% higher rate constant value compared to pure SnO2 nanofibers in the degradation of methylene blue dye molecules and reached 83% degradation under UV/visible light irradiation after 1 h. The increase in the photocatalytic activity was ascribed to the incorporation of Cr3+ and Cu+ cations into the SnO2 host lattice and the more effective electron–hole pair separation in the heterostructured sample. The presented data here are highly convincing in comparison to those of UV active p–n heterostructured photocatalysts reported previously in the literature. Therefore, this work opens the way to develop visible light active p–n heterostructured semiconductor photocatalysts using p-type delafossites with n-type oxides.

Effective charge separation is of importance in increasing the efficiency of photocatalysts used in removing common industrial toxic dye in wastewater. The alternative spatial electric field produced by the piezoelectric effect, when combined with the semiconductor photocatalyst, can significantly accelerate the charge separation. In this study, lead magnesium niobate-lead titanate 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT) nanoparticles and tin dioxide (SnO2) nanofibers were synthesized using colloidal coating method and electrospinning synthesis methods, respectively. PMN-PT@SnO2 composites were prepared as a novel heterostructured photocatalyst for the degradation of dye molecules in wastewater. Degradation of an organic dye pollutant in the presence of SnO2 nanofibers or PMN-PT@SnO2 nanocomposite photocatalysts were investigated under magnetic stirring and/or ultrasonic wave vibration conditions. Morphologies and electrical properties of pure and composite samples were also investigated. It was observed that the photocatalytic efficiency of PMN-PT@SnO2 piezoelectric-based photocatalysts could be increased by about 29% in the magnetic stirring and 32% in the ultrasonic wave vibration, respectively.

A study was carried out on the synthesis of CuAlO 2 at temperatures below 1000 °C, using a simple approach based on mechanical mixing of chemically precipitated CuO and Al(OH) 3 nanoparticles. Synthesis of precursor powders was achieved at low temperatures ( 2 samples with high crystallinity formed only after 5 h of firing at 900 °C under flowing nitrogen. Electron microscopy images revealed a loosely packed microstructure with high surface area consisting of nanosized grains after the heat treatment. The achieved relative density was 45% of the theoretical density. The crystallite size was estimated to be 39 nm and the specific surface area of the sintered sample was measured as 9.67 m 2 /g. The bandgap was calculated as 3.07 eV with a transmittance of 60% in the visible region. The measured electrical conductivity was 4×10 −3 mS/cm at room temperature and showed an increase with increasing measurement temperature, which indicates semiconducting behavior. The conductivity was shown to increase by an order of magnitude with a higher degree of densification by sintering at 1150 °C.

In this study, it is aimed to develop a hybrid bi-functional material which will enable the removal of common industrial toxic dyes in wastewater via adsorption/photocatalysis reactions. For this purpose, WO3 nanofibers and CuO particles were synthesized using electrospinning and hydrothermal synthesis methods, respectively. WO3 nanofibers were combined with different amounts of CuO particles by a simple dispersion dropping technique. Structural, morphological and optical properties of the samples were characterized by XRD, Raman, FT-IR, XPS, SEM, TEM, UV–vis, and Mott-Schottky measurements. The adsorption capacity and photocatalytic behavior of the hybrids were compared with pure WO3 nanofibers under visible light irradiations. Experimental results have shown that the hybrid samples containing only 0.75 wt.% CuO could adsorb 38.4% higher and degraded 25.7% faster the methylene blue dye compared to pure WO3 nanofibers. This improved adsorption and degradation behavior of the hybrids were discussed in detail based on the structural properties, Z-scheme heterojunction formation, and using Langmuir/Freundlich isotherm and kinetic models.

CuO–TiO2 p-n heterostructures with tailored compositions were fabricated using hydrothermally derived plate-like CuO particles and electrospun TiO2 fibers and further applied for photocatalytic degradation of typical water pollutants such as methylene blue and 4-Nitrophenol. Effect of varying amount of CuO decoration on TiO2 fibers on microstructure, on phase constitution, and on the optical and photocatalytic properties was investigated. Photocatalytic testing results indicated that the degradation behavior was affected by the amount of CuO particles in the samples. Among all compositions studied, the samples with 1.25 and 0.5 wt% CuO exhibited the highest photocatalytic efficiency under UV (3.3 times higher compared to pure TiO2) and visible light irradiations (3.75 times higher compared to pure TiO2), respectively. The improved photocatalytic performance compared to pure fibers was attributed to particle-fiber architecture, increased and extended light harvesting ability, more efficient charge separation due to staggered band structure and p-n junctions of the heterostructured samples.

In this study, Mg-doped CuCr1-xMgxO2 (x=0, 0.01, 0.03, 0.05) fibers are synthesized via electrospinning process followed by a two-step heat treatment in air and Ar atmospheres. The produced samples are all crystalline with a fiber diameter ranging from 120 to 140nm. The effect of Mg2+ substitution for Cr3+ on the structural, morphological, and optical properties of CuCrO2 fibers is investigated systematically. Structural characterizations indicate that the solubility limit of Mg2+ is around 3at.% and beyond this concentration the formation of MgO phase is observed. This also leads to the formation of Cu cations with ((+)2) oxidation state. In addition, the incorporation of Mg into the CuCrO2 lattice hinders the formation of perfect hexagonal-shaped isolated grains and contribute to the preservation of fiber morphology after the final sintering step. Further, the optical transmittance in the visible range decreases with increasing Mg-doping ratio. The corresponding optical band gaps are determined to be 3.53, 3.47, 3.30, and 3.22eV, respectively, for x=0, 0.01, 0.03, 0.05.

An investigation was carried out into Pd–Ag separation membranes to check whether a reduction in their Pd content was possible through the incorporation of a third element, namely Ti. For this purpose a combinatorial thin film deposition system was developed incorporating three sputter targets arranged in triangular form. The system had a substrate in the form of a magazine, 6 inch in diameter, accommodating 21 discs arranged again in triangular form aligned with the targets underneath. With this geometry, a library of thin film membranes was obtained in a single experiment covering a wide compositional field, Pd content up to of approx. 75%. The thin film library was then screened with respect their tendency to react with hydrogen. This was accomplished by the resistivity measurements carried out on the membranes, while they are subjected to heating–cooling cycle under hydrogen, the values being compared with identical cycle carried out under argon. Since permeability is a product of hydrogen solubility and diffusivity, membranes that react with hydrogen, i.e. either forming a solid solution or a hydride, delineate compositions which are candidates for separation membranes. In the present work, this procedure was applied to a portion of Ag–Ti–Pd ternary system aiming for separation membranes with f.c.c. crystal structure. Mapping based on the resistivity measurement indicated, Ag35Ti22Pd43, Ag13Ti25Pd62 and their near compositions as possible candidates for separation membranes.

WOS: 000401815800017, Micropollutants are found in all water sources, even after thorough treatments that include membrane filtration. New ones emerge as complex molecules are continuously produced and discarded after used. Treatment methods and sorbent designs are mainly based on non-specific interactions and, therefore, have been elusive. Here, we developed swellable covalent organic polymers (COP) with great affinity towards micropollutants, such as textile industry dyes. Surprisingly, only cationic dyes in aqueous solution were selectively and completely removed. Studies of the COPs surfaces led to a gating capture, where negatively charged layer attracts cationic dyes and moves them inside the swollen gel through diffusive and hydrophobic interaction of the hydrocarbon fragments. Despite its larger molecular size, crystal violet has been taken the most, 13.4 mg g(-1), surpassing all competing sorbents. The maximum adsorption capacity increased from 12.4 to 14.6 mg and from 8.9 to 11.4 mg when the temperature of dye solution was increased from 20 to 70 degrees C. The results indicated that disulfide-linked COPs are attractive candidates for selectively eliminating cationic dyes from industrial wastewater due to exceptional swelling behaviour, low-cost and easy synthesis., Scientific Research Foundation (BAP) of Selcuk UniversitySelcuk University; Scientific and Technological Research Council of Turkey (TUBITAK MAG)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [214M232]; Academic Staff Training Program (OYP)Ministry of National Education - Turkey [2015-OYP-128]; National Research Foundation (NRF) of KoreaNational Research Foundation of Korea [NRF-2016R1A2B4011027], This study was carried out as a Master thesis by Mehmet Sahin Atas at the Graduate School of Natural and Applied Science at Selcuk University, Konya, Turkey. Support for this work is provided by the Scientific Research Foundation (BAP) of Selcuk University, Scientific and Technological Research Council of Turkey (TUBITAK MAG) (Project Number 214M232) and Academic Staff Training Program (OYP) (Project Number 2015-OYP-128), which authors gratefully acknowledge. C. T. Y. thanks for the support from National Research Foundation (NRF) of Korea, No: NRF-2016R1A2B4011027.

Mg thin films with various thicknesses ranging from 50 to 1000 nm capped with Pd have been prepared by thermal evaporation and their hydrogen sorption properties were examined following the electrical resistance change. The study showed that the hydrogenation and dehydrogenation temperatures correlate with the film thickness, thinner films reacting with hydrogen at reduced temperatures. It is concluded that films thinner than 200 nm react fully with hydrogen, while a considerable portion of the thicker films remain unreacted. The significance of this is discussed with reference to the design of hydrogen storage systems based on thin films or nanoparticles.

Polycrystalline BaTiO3 thin films have been prepared by hydrothermal reaction with sputter-deposited nanostructured reactive Ti templates designed to control net diffusion direction and distance. Templates were prepared in two morphologies, i.e., planar and nanopillar. The samples produced from flat templates showed sluggish transformation kinetics and an eventual termination of reaction without fully consuming the Ti metal. Templates with pillar morphology, on the other hand, could be transformed to phase-pure BaTiO3 independent of the template thickness. In the as-precipitated state, those films revealed a permittivity of ~1000 and loss tangent values around 0.1 with mild dispersion in the kilohertz frequency range. Annealing these films under forming gas containing 1 vol% H2 balance N2 for 3 h at 200 °C decreased high-field losses to 0.06 and reduced dispersion. Mn incorporation as an in situ acceptor dopant was also explored. Addition of Mn during hydrothermal treatment further improved the electrical properties. Annealing under the same postgrowth conditions virtually eliminated the frequency dispersion in the range of 1 kHz to 1 MHz, while maintaining permittivity values in the range of 350.

A study was carried out to examine the hydrogenation behavior of 300 nm, Pd-capped, Mg–Cu thin films with Cu contents of 5, 10 and 15 at.%. The films were produced via thermal evaporation of Mg and Cu co-deposited onto glass substrates at two different temperatures: 298 and 223 K. The samples produced at 298 K were all crystalline, the structure being refined with increase in the Cu content. The films deposited at 223 K developed structures that were either refined, i.e. Mg 95 Cu 5 ; or amorphous, i.e. Mg 90 Cu 10 and Mg 85 Cu 15 . The hydrogen sorption of the films was followed by resistance measurements, with the samples heated isochronally, initially under hydrogen and then under vacuum. The resistance data have shown that an increase in Cu content, or a decrease in the substrate temperature, improves the sorption characteristics of the films by reducing both the absorption and desorption temperatures. The lowest desorption temperature achieved was 323 K. The study suggests that an amorphous alloy of Mg 90 Cu 10 could be used as hydrogen storage medium as it would store 5.9 wt.% hydrogen in near-ambient conditions and could desorp it at around 100 °C.

A study is carried out for hydrogenation of Mg based thin films produced via thermal evaporation. Films produced were pure Mg, Mg capped with Au–Pd, Mg–Cu co-deposited and Mg–Cu multilayered. The films under the experimental conditions employed were crystalline with columnar grains with some degree of preferred orientation. In multi-component systems, the films in the as-deposited state were made of individual elements, but upon hydrogenation at temperatures greater than 473 K, the elements react with each other yielding the intermetallic phases. The study showed that, of the systems studied in this work, Mg–Cu multilayer yielded the most favorable result as useful storage system, for Mg portion of the film can be converted totally into MgH 2 , this occurring at temperatures not greater than 473 K. The study implies that if the as-deposited structure were to be used and preserved as hydrogen storage medium, there is a narrow temperature window for hydrogenation.

Magnesium thin films of 350 nm, capped with Pd, were deposited on glass substrates and hydrogenated in two different conditions; namely isochronal and isothermal. As-deposited films were highly textured with Mg (001) parallel to the glass substrate. Experiments have shown that under isothermal conditions starting from 333 K, Mg films can absorb hydrogen producing MgH(2) with a random texture. When the films were heated slowly starting from the room temperature, hydrogenation gives rise to a textured MgH2, where (110) parallel to the substrate. (101) is also present in this texture as a minor component. Formation of the textured hydride in isochronal loading was discussed within the context of the lattice mismatch in a Mg to MgH(2) transformation. (C) 2010 Elsevier B.V. All rights reserved.