Solar-rechargeable battery based on photoelectrochemical water oxidation: Solar water battery

As an alternative to the photoelectrochemical water splitting for use in the fuel cells used to generate electrical power, this study set out to develop a solar energy rechargeable battery system based on photoelectrochemical water oxidation. We refer to this design as a "solar water battery". The solar water battery integrates a photoelectrochemical cell and battery into a single device. It uses a water oxidation reaction to simultaneously convert and store solar energy. With the solar water battery, light striking the photoelectrode causes the water to be photo-oxidized, thus charging the battery. During the discharge process, the solar water battery reduces oxygen to water with a high coulombic efficiency (>90%) and a high average output voltage (0.6 V). Because the reduction potential of oxygen is more positive [E0(O2/H2O) = 1.23 V vs. NHE] than common catholytes (e.g., iodide, sulfur), a high discharge voltage is produced. The solar water battery also exhibits a superior storage ability, maintaining 99% of its specific discharge capacitance after 10 h of storage, without any evidence of self-discharge. The optimization of the cell design and configuration, taking the presence of oxygen in the cell into account, was critical to achieving an efficient photocharge/discharge. © The Author(s) 2016.1

Effect of temperature on the photocatalytic production of H-2 on Pt/TiO2

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Investigation on Photocatalytic Reaction of Sugar Alcohol-adsorbed TiO2

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TiO2 complexed with dopamine-derived polymers and the visible light photocatalytic activities for water pollutants

Visible light-induced chemical transformation using inexpensive photocatalytic materials has been proposed as an eco-friendly method for energy and environmental applications. In this work, we employed polymers of environmentally benign derivatives of dopamine (DA) as low-cost sensitizers of titania and systematically investigated their properties for the visible light photocatalytic transformation in aquatic environment. DA and its derivatives (norepinephrine and nitrodopamine) were chosen as monomers, and their polymers (pDA, pNE, and pNDA) were synthesized and subsequently complexed with TiO2. Visible light-induced catalytic transformations were successfully demonstrated for the reduction of Cr(VI) to Cr (III), dechlorination of CCI4, oxidation of As(III) to As(V), and H2O2 production via dioxygen reduction using polymer-complexed TiO2. pDA-TiO2 exhibited the highest activities, much higher than those of DA-TiO2 in all tested cases, which indicates that the polymerized form of DA forms a stronger and more efficient surface complex on the TiO2 surface for visible light sensitization. DA-derived polymers could efficiently transfer electrons to the TiO2 conduction band under visible light to initiate reductive transformations, whereas the oxidative transformation of organic substrates was largely inhibited because the organic polymer layer on TiO2 should scavenge any oxidizing radical species. pDA and pNE exhibited far higher activity than pNDA due to the extensive it electron delocalization induced by the 5,6-dihydroxyindole structure. This was also supported by the higher photon-to-current conversion and lower charge transfer resistance obtained with pDA-TiO2 and pNE-TiO2 (compared with pNDA-TiO2), which was observed with photoelectrochemical measurements. pDA should be an attractive visible light sensitizer for aquatic transformations. (C) 2016 Elsevier Inc. All rights reserved.111711sciescopu

Optimization of porous BiVO4 photoanode from electrodeposited Bi electrode: Structural factors affecting photoelectrochemical performance

In this study, BiVO4 photoanode is prepared via the chemical reaction of electrodeposited Bi metal electrode with a vanadium precursor, and the electrodeposition conditions for the Bi electrode are modified to optimize the resultant BiVO4's photoelectrochemical performance. The nucleation and growth kinetics of Bi dendrites are varied by changing the applied potential and temperature during electrodeposition. This affects the structure and morphology of Bi as well as the properties of the resultant BiVO4 after the chemical reaction. Specifically, the morphology, particle size, porosity, and facet exposure of BiVO4 are changed according to the applied potential and temperature during the electrodeposition of Bi. The decrease in particle size and increase in porosity and active facet exposure under optimized conditions are responsible for the improved photoelectrochemical performance. The photocurrent density of BiVO4 prepared under optimized condition is over 5 mA cm-2 at 1.25 VRHE for sulfite oxidation; this represents an improvement of almost 2.5 times compared to that of non-optimized BiVO4. Furthermore, the BiVO4 samples prepared under different deposition conditions only show changes in structural properties and not in other intrinsic properties such as the light absorption, energy level, and carrier density. Therefore, the structural effect of BiVO4 on the performance can be elucidated clearly. © 2015 Elsevier Ltd. All rights reserved.

Ice-templated synthesis of tungsten oxide nanosheets and their application in arsenite oxidation

Tungsten oxide (WO3) nanosheets were prepared as catalysts to activate hydrogen peroxide (H2O2) in arsenite (As(III)) oxidation. Ice particles were employed as templates to synthesize the WO3 nanosheets, enabling easy template removal via melting. Transmission electron microscopy and atomic force microscopy revealed that the obtained WO3 nanosheets were plate-like, with lateral sizes ranging from dozens of nanometers to hundreds of nanometers and thicknesses of <10 nm. Compared to that of the WO3 nanoparticle/H2O2 system, a higher efficiency of As(III) oxidation was observed in the WO3 nanosheet/H2O2 system. Electron spin resonance spectroscopy, radical quenching studies, and As(III) oxidation experiments under anoxic conditions suggested that the hydroperoxyl radical (HO2●) acted as the primary oxidant. The WO3 nanosheets possessed numerous surface hydroxyl groups and electrophilic metal centers, enhancing the production of HO2● via H2O2 activation. Various anions commonly present in As(III)-contaminated water exhibited little effect on As(III) oxidation in the WO3 nanosheet/H2O2 system. The high oxidation efficiency was maintained by adding H2O2 when it was depleted, suggesting that the catalytic activity of the WO3 nanosheets did not deteriorate after multiple catalytic cycles. © 2022 Elsevier B.V.FALS