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Photoelectrochemical (PEC) water splitting is an eco-friendly method for producing clean and sustainable hydrogen fuels. Compared with the fabrication of solar hydrogen using n-type metal oxide semiconductor photoanodes, that of solar hydrogen using p-type metal oxide semiconductor photocathodes has not been researched as thoroughly. Therefore, this study investigated the effect of drop casting time on the PEC performance of a prepared CuBi2O4 photocathode. XPS, HRTEM, UV-DRS, Raman spectroscopy, XRD, and SEM analyses were used to characterize the prepared CuBi2O4 photocathode. Owing to the high charge separation and transfer, the photocurrent density of the CuBi2O4 photocathode was ~0.6 mA cm−2 at 0.3 V vs. RHE. The nanoporous CuBi2O4 photocathode exhibited a high photocurrent density of up to 1.2 mA cm−2 at 0.3 V vs. RHE with H2O2 as a sacrificial agent. Mott–Schottky and impedance measurements were also performed on the CuBi2O4 photocathode to estimate its acceptor density and charge-transfer resistance. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) emissions are an important environmental issue that causes greenhouse and climate change effects on the earth. Nowadays, CO2 has various conversion methods to be a potential carbon resource, such as photocatalytic, electrocatalytic, and photo-electrocatalytic. CO2 conversion into value-added products has many advantages, including facile control of the reaction rate by adjusting the applied voltage and minimal environmental pollution. The development of efficient electrocatalysts and improving their viability with appropriate reactor designs is essential for the commercialization of this environmentally friendly method. In addition, microbial electrosynthesis which utilizes an electroactive bio-film electrode as a catalyst can be considered as another option to reduce CO2. This review highlights the methods which can contribute to the increase in efficiency of carbon dioxide reduction (CO2R) processes through electrode structure with the introduction of various electrolytes such as ionic liquid, sulfate, and bicarbonate electrolytes, with the control of pH and with the control of the operating pressure and temperature of the electrolyzer. It also presents the research status, a fundamental understanding of carbon dioxide reduction reaction (CO2RR) mechanisms, the development of electrochemical CO2R technologies, and challenges and opportunities for future research. [ABSTRACT FROM AUTHOR]

In the current investigation, Al/Cu/SiC composites with different reinforcement contents were prepared for thermal applications via powder metallurgy and hot pressing technique to study the effects of reinforcement content and structure on the thermal behavior of the samples. Microstructural characterizations showed that SiC and Cu particles were uniformly distributed, and a continuous Cu network structure was formed in the Al matrix. Density measurements revealed that the samples Al/15Cu/10SiC and Al/45Cu/20SiC had the highest and lowest relative density (97% and 90%), respectively. Microhardness evaluations displayed that the composite hardness improved as the Cu and/or SiC contents increased. Besides, the coefficient of thermal expansion of the composites increased nonlinearly by elevating the temperature and it reduced with increasing the SiC content. A comparison of thermal expansion coefficient values to the Turner and Kerner models showed a slight difference (lower that 8%) only for Al/15Cu/10SiC and Al/45Cu/20SiC samples. Thermal cycles examination exhibited that as the number of cycles increased, the thermal strain of the composites increased. Furthermore, the thermal expansion coefficient of Al/45Cu/20SiC reduced to values lower than 7 ppm that indicates the significance of Cu network structure. Image 1 • Al/Cu/SiC composites were prepared for thermal applications by powder metallurgy. • SiC particles were uniformly distributed and a continuous Cu network was obtained. • A comparison of CTE values to the thermoelastic models showed a slight difference. • CTE values lower than 7 ppm indicated the efficiency of reinforcement structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin and single crystal of WO 3 nanoplates synthesized by a one-step hydrothermal technique. • This study shows a collaborative approach of facet engineering and p-n Junction of WO 3 /MoS 2 -MoO X. • Depth, surface, and interface of the WO 3 /MoS 2 -MoO X investigated by TOF-SIMS analysis. • The obtained WO 3 /MoS 2 -MoO X photoanode exhibits highly efficient and stable PEC H 2 generation. • H 2 and O 2 productions of the WO 3 /MoS 2 -MoO X after 2 h were 54.5 and 25.8 μmol cm−2, respectively. In this paper, we demonstrate a facet-controlled WO 3 nanoplate heterojunction with MoS 2 -MoO X nanosheets that produces extremely efficient and stable photoelectrochemical H 2 production. Furthermore, the effect of the hydrothermal process time (t = 1, 2, and 3 h) for the WO 3 photoanode and drop-casting process of the MoS 2 nanosheets (4, 8, and 12 times) to obtain the optimum amount of the material (MoS 2 and MoO X) for the PEC performance of the WO 3 /#n-MoS 2 and WO 3 /#n-MoS 2 -MoO X (n = 4, 8, and 12) photoanodes were investigated. The photocurrent density of the WO 3 /MoS 2 -MoO X photoanode was approximately 2.15 mA.cm −2 at 1.23 V vs. RHE, which was 8.6 and 1.2 times higher compare to pure WO 3 and WO 3 /MoS 2 photoelectrodes, respectively. The incident photon current efficiency of the WO 3 /MoS 2 -MoO X photoanode is approximately 27.5%, which is a significant improvement over that of bare WO 3. The WO 3 /MoS 2 -MoO X photoanode produced 54.5 μmolcm−2 of H 2 and 25.8 μmolcm−2 of O 2 after 2 h, at 1.23 V vs. RHE and 100 mWcm−2. The electrochemical kinetics clearly showed that water oxidation reaction was accelerated. The WO 3 /MoS 2 -MoO X photoanode, which was developed through simple and facial drop casting of MoS 2 nanosheets onto WO 3 photoanode, resulted in effective photogenerated carrier separation and enhanced oxygen evolution reactions on the anode surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin and single crystal of WO 3 nanoplates synthesized by a one-step hydrothermal technique. • This study shows a collaborative approach of facet engineering and p-n Junction of WO 3 /MoS 2 -MoO X. • Depth, surface, and interface of the WO 3 /MoS 2 -MoO X investigated by TOF-SIMS analysis. • The obtained WO 3 /MoS 2 -MoO X photoanode exhibits highly efficient and stable PEC H 2 generation. • H 2 and O 2 productions of the WO 3 /MoS 2 -MoO X after 2 h were 54.5 and 25.8 μmol cm−2, respectively. In this paper, we demonstrate a facet-controlled WO 3 nanoplate heterojunction with MoS 2 -MoO X nanosheets that produces extremely efficient and stable photoelectrochemical H 2 production. Furthermore, the effect of the hydrothermal process time (t = 1, 2, and 3 h) for the WO 3 photoanode and drop-casting process of the MoS 2 nanosheets (4, 8, and 12 times) to obtain the optimum amount of the material (MoS 2 and MoO X) for the PEC performance of the WO 3 /#n-MoS 2 and WO 3 /#n-MoS 2 -MoO X (n = 4, 8, and 12) photoanodes were investigated. The photocurrent density of the WO 3 /MoS 2 -MoO X photoanode was approximately 2.15 mA.cm −2 at 1.23 V vs. RHE, which was 8.6 and 1.2 times higher compare to pure WO 3 and WO 3 /MoS 2 photoelectrodes, respectively. The incident photon current efficiency of the WO 3 /MoS 2 -MoO X photoanode is approximately 27.5%, which is a significant improvement over that of bare WO 3. The WO 3 /MoS 2 -MoO X photoanode produced 54.5 μmolcm−2 of H 2 and 25.8 μmolcm−2 of O 2 after 2 h, at 1.23 V vs. RHE and 100 mWcm−2. The electrochemical kinetics clearly showed that water oxidation reaction was accelerated. The WO 3 /MoS 2 -MoO X photoanode, which was developed through simple and facial drop casting of MoS 2 nanosheets onto WO 3 photoanode, resulted in effective photogenerated carrier separation and enhanced oxygen evolution reactions on the anode surface. [ABSTRACT FROM AUTHOR]