Photoelectrochemical Properties and Behavior of α-SnWO4 Photoanodes Synthesized by Hydrothermal Conversion of WO3 Films

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• 作者：Zhehao ZhuPranab Sarker ; Chenqi Zhao ; Lite Zhou ; Ronald L. Grimm ; Muhammad N. Huda ; Pratap M. Rao
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：9
• 期：2
• 页码：1459-1470
• 全文大小：741K
• ISSN：1944-8252

文摘

Metal oxides with moderate band gaps are desired for efficient production of hydrogen from sunlight and water via photoelectrochemical (PEC) water splitting. Here, we report an α-SnWO₄ photoanode synthesized by hydrothermal conversion of WO₃ films that achieves photon to current conversion at wavelengths up to 700 nm (1.78 eV). This photoanode is promising for overall PEC water-splitting because the flat-band potential and voltage of photocurrent onset are more negative than the potential of hydrogen evolution. Furthermore, the photoanode utilizes a large portion of the solar spectrum. However, the photocurrent density reaches only a small fraction of that which is theoretically possible. Density functional theory based thermodynamic and electronic structure calculations were performed to elucidate the nature and impact of defects in α-SnWO₄ prepared by this synthetic route, from which hole localization at Sn-at-W antisite defects was determined to be a likely cause for the poor photocurrent. Measurements further showed that the photocurrent decreases over time due to surface oxidation, which was suppressed by improving the kinetics of hole transfer at the semiconductor/electrolyte interface. Alternative synthetic methods and the addition of protective coatings and/or oxygen evolution catalysts are suggested to improve the PEC performance and stability of this promising α-SnWO₄ material.