Surface modification with CoFe-based overlayers has been widely studied to improve the performance of WO₃/BiVO₄ photoanodes for photoelectrochemical water oxidation because such overlayers can increase the photocurrent and shift the onset potential to more favorable values. Herein, we present a transient absorption spectroscopic analysis of WO₃/BiVO₄ photoanodes coated with cobalt iron oxide or cobalt iron Prussian blue overlayers, designed to establish the underlying mechanisms for these enhancements on the picosecond-to-second time scale. The data reveal that the overlayer suppresses recombination of trapped holes in BiVO₄, with free and trapped electrons, and accepts photogenerated holes. These results show that the observed boost in efficiency for water oxidation can be explained by the dual role of the overlayer in inhibiting charge recombination and enhancing charge extraction.

中文翻译：

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Co-Fe 覆盖层对 WO3/BiVO4 异质结载流子动力学的影响：皮秒至秒光谱分析

_{使用CoFe基覆盖层进行表面改性已被广泛研究，以提高用于光电化学水氧化的WO 3} /BiVO ₄光阳极的性能，因为此类覆盖层可以增加光电流并将起始电位转移到更有利的值。在此，我们对涂有钴铁氧化物或钴铁普鲁士蓝涂层的 WO ₃ /BiVO ₄光阳极进行瞬态吸收光谱分析，旨在建立皮秒到秒时间尺度上这些增强的基本机制。数据表明，覆盖层抑制了 BiVO ₄中俘获空穴与自由电子和俘获电子的复合，并接受光生空穴。这些结果表明，观察到的水氧化效率的提高可以通过覆盖层抑制电荷复合和增强电荷提取的双重作用来解释。