Copper vanadates have been important to the development of new-generation photoelectrodes for solar water splitting and hydrogen generation. Of these, copper pyrovanadate (β-Cu₂V₂O₇), the 2:1 ternary compound derived from CuO and V₂O₅, has been of particular interest to the solar fuel community. This n-type semiconductor has shown the highest photocurrent for water oxidation at 1.23 V versus reversible hydrogen electrode and exhibits good photostability in aqueous media of pH 9.2. However, further successful application of this material in photoelectrochemical (PEC) devices hinges on a comprehensive understanding of its optical, electrochemical, and optoelectronic attributes. This was done in this study by a combination of density-functional theory (for the structural, magnetic, and optical characterization) and experiments, with the latter using both small-signal (intensity-modulated photocurrent spectroscopy, IMPS) and large-signal, transient photocurrent (TP) analyses. Both IMPS and TP measurements yielded complementary and self-consistent insights into the rate constants for hole transfer and carrier recombination at the irradiated β-Cu₂V₂O₇/electrolyte interface, specifically their dependence on the applied bias potential. The information from PEC data analyses was also self-consistent with that garnered from the optical (diffuse reflectance spectroscopy) data.

中文翻译：

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焦钒酸铜的光学、电化学和光电化学行为：统一的理论和实验研究

钒酸铜对开发用于太阳能水分解和制氢的新一代光电极非常重要。其中，焦钒酸铜（β-Cu ₂ V ₂ O ₇），一种由 CuO 和 V ₂ O ₅衍生的 2:1 三元化合物, 一直是太阳能燃料社区特别感兴趣的。与可逆氢电极相比，这种 n 型半导体在 1.23 V 下显示出最高的水氧化光电流，并且在 pH 9.2 的水性介质中表现出良好的光稳定性。然而，这种材料在光电化学 (PEC) 器件中的进一步成功应用取决于对其光学、电化学和光电属性的全面了解。在本研究中，这是通过结合密度泛函理论（用于结构、磁性和光学表征）和实验完成的，后者同时使用小信号（强度调制光电流光谱，IMPS）和大信号，瞬态光电流 (TP) 分析。₂ V ₂ O ₇ /电解质界面，特别是它们对施加的偏压的依赖性。来自 PEC 数据分析的信息也与从光学（漫反射光谱）数据中获得的信息自洽。