Improved water-splitting performances of CuW1−xMoxO4 photoanodes synthesized by spray pyrolysis

CuW1−xMoxO4 solid solution of CuWO4 and CuMoO4, which is a copper-based multi-component oxide semiconductor, possesses much narrower band gap than CuWO4. In theory, it can absorb a larger part of the visible spectrum, widening the use of solar spectroscopy and obtaining a higher photo-to-chemical conversion efficiency. In this study, CuW1−xMoxO4 thin-film photoanodes on conducting glass were prepared using a simple and low-cost spray pyrolysis method. The resulting CuW1−xMoxO4 photoanodes perform higher photocurrent than CuWO4 photoanodes under AM 1.5G simulated sunlight illumination (100 mW cm−2) in 0.1 mol L−1 phosphate buffer at pH 7. Combined with IPCE and Mott-Schottky analysis, the enhancement of the photocurrent is due to the improvement of photon utilization and the increase of carrier concentration with the incorporation of Mo atoms. Moreover, with the optimal Mo/W atomic ratio, the photocurrent density increases obviously from 0.07 to 0.46 mA cm−2 at 1.23 VRHE bias. In addition, compared with particle-assembled thin-film photoanodes prepared by solidphase reaction and drop-necking treatment, the photoanodes prepared by spray pyrolysis have obvious advantages in terms of reducing resistance and facilitating charge transport.摘要CuWO4和CuMoO4的固溶体CuW1−xMoxO4是一种铜基多组分氧化物半导体, 拥有比CuWO4更窄的带隙. 理论上, 它可以拓宽对太阳光谱的响应范围, 吸收更大部分的可见光, 获得更高的太阳能-化学能转换效率. 本研究通过简单、 低成本的喷雾热裂解法在导电玻璃上制备了CuW1−xMoxO4薄膜光阳极. 在AM 1.5G模拟太阳光(100 mW cm−2)照射下, 制备出的CuW1−xMoxO4光阳极在pH 7的0.1 mol L−1磷酸缓冲液中产生了比CuWO4光阳极更高的光电流. 结合IPCE和莫特-肖特基分析可知, 光电流的增长来源于Mo原子的加入所造成的光子利用率的提高以及载流子浓度的增加. 而且, 在最优的Mo/W原子比例下, 1.23 VRHE偏压时的光电流从0.07 mA cm−2显著地增加到 0.46 mA cm−2. 与对应的颗粒组装薄膜光阳极(通过固相反应结合涂覆-粘结后处理得以制备)相比较, 喷雾热裂解法所制备的光阳极有利于降低电阻和促进电荷传输.

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