Nanoscale oxide layer protected semiconductor photoelectrodes show enhanced stability and performance for solar fuels generation, although the mechanism for the performance enhancement remains unclear due to a lack of understanding of the microscopic interfacial field and its effects. Here, we directly probe the interfacial fields at p-GaP electrodes protected by n-TiO₂ and its effect on charge carriers by transient reflectance spectroscopy. Increasing the TiO₂ layer thickness from 0 to 35 nm increases the field in the GaP depletion region, enhancing the rate and efficiency of interfacial electron transfer from the GaP to TiO₂ on the ps time scale as well as retarding interfacial recombination on the microsecond time scale. This study demonstrates a general method for providing a microscopic view of the photogenerated charge carrier’s pathway and loss mechanisms from the bulk of the electrode to the long-lived separated charge at the interface that ultimately drives the photoelectrochemical reactions.

中文翻译：

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纳米级 TiO2 保护层增强了 GaP 光电极的内置场和电荷分离性能

纳米级氧化物层保护的半导体光电极显示出增强的太阳能燃料发电稳定性和性能，尽管由于对微观界面场及其影响缺乏了解，性能增强的机制仍不清楚。在这里，我们通过瞬态反射光谱直接探测受 n-TiO ₂保护的 p-GaP 电极上的界面场及其对电荷载流子的影响。将 TiO ₂层厚度从 0 增加到 35 nm 会增加 GaP 耗尽区的场，从而提高从 GaP 到 TiO _{2的界面电子转移速率和效率}在 ps 时间尺度上以及在微秒时间尺度上延迟界面复合。本研究展示了一种通用方法，用于提供光生电荷载流子的路径和从电极主体到最终驱动光电化学反应的界面处的长寿命分离电荷的损失机制的微观视图。