The water oxidation capability of the promising photoanode bismuth vanadate (BiVO₄) is hampered by poor bulk electron transport and by high rates of charge recombination at the semiconductor/electrolyte interface. Here, we demonstrate that a dual modification of BiVO₄ by: (i) annealing in a hydrogen-containing environment and (ii) coating with FeOOH overlayer substantially enhances the water oxidation ability of BiVO₄ photoanodes. Hydrogen treated, FeOOH coated BiVO₄ photoanodes exhibit a water oxidation photocurrent density of 2.16 mA cm⁻² at 1.23 V_RHE, which is 5 times higher than for untreated BiVO₄ films. Moreover, they showed an impressive low photocurrent onset potential of −0.11 V_RHE. A stable photocurrent was observed for 1 h of water oxidation measurement at 1.23 V_RHE under 1 Sun illumination. The enhanced photocurrent of FeOOH/H:BiVO₄ photoanode is ascribed to an improved bulk charge transport, as confirmed by impedance spectroscopy measurements and Mott-Schottky analysis. The cathodic shift of the onset potential originates from a lowering of the flat band potential and from an improvement of the charge transport at the semiconductor/electrolyte interface. The dual modification strategy used here offers a simple but effective approach of improving the water oxidation performance of BiVO₄.

有前景的光阳极钒酸铋（BiVO ₄）的水氧化能力受到不良的体电子传输和半导体/电解质界面处高电荷复合率的阻碍。在这里，我们证明了BiVO ₄的双重改性：（i）在含氢环境中进行退火，以及（ii）用FeOOH覆盖层进行涂覆，实质上增强了BiVO ₄光电阳极的水氧化能力。经过氢气处理的FeOOH涂层BiVO ₄光电阳极在1.23 V _RHE下的水氧化光电流密度为2.16 mA cm ^-2，是未经处理的BiVO _4的5倍电影。此外，它们显示出令人印象深刻的低光电流起始电位-0.11 V _RHE。在1个阳光照射下，在1.23 V _RHE下水氧化测量1小时，观察到稳定的光电流。FeOOH / H：BiVO ₄光电阳极的增强光电流归因于整体电荷传输的改善，如通过阻抗谱测量和Mott-Schottky分析所证实的。起始电位的阴极位移源自平带电位的降低和半导体/电解质界面处电荷传输的改善。这里使用的双重修饰策略提供了一种简单而有效的方法来改善BiVO ₄的水氧化性能。