Slow charge transfer kinetics and poor stability are two critical issues for silicon (Si) photoanodes in photoelectrochemical (PEC) water splitting. Herein, a facile and ultrafast interfacial reaction was performed on n-Si/Ni for stable and high-performance Si photoanode by regulating both the Ni electrocatalyst and Si surface. The calculated and experimental results reveal that highly catalytic oxygen vacancies-rich Fe:NiOOH layer will be formed on Ni surface during the hot Fe ions exchange reaction, which can create abundant active sites for oxygen evolution reaction (OER). The interfacial reaction also can modulate the interfacial state of Si photoanode to increase barrier height for n-Si/Ni/Fe:NiOOH photoanode, thereby accelerating the charge separation and transportation. More significantly, a thin iron silicide (FeSi₂) layer will be generated on Si surface (Ni-free region), which is beneficial for the stability of Si photoanode. This work provides a low-cost and straightforward approach to design high-performance Si photoanodes by interface engineering and electrocatalyst defects regulation.

缓慢的电荷转移动力学和较差的稳定性是光电化学（PEC）水分解中硅（Si）光电阳极的两个关键问题。本文中，通过同时调节Ni电催化剂和Si表面，在n-Si / Ni上进行了简便而超快的界面反应，从而获得了稳定，高性能的Si光阳极。计算和实验结果表明，在热的Fe离子交换反应过程中，Ni表面会形成高催化氧空位的Fe：NiOOH层，从而为氧释放反应（OER）创造了丰富的活性位。界面反应还可以调节Si光电阳极的界面状态，以增加n-Si / Ni / Fe：NiOOH光电阳极的势垒高度，从而加速电荷的分离和传输。更重要的是，薄硅化铁（FeSi₂）在Si表面（无Ni区域）上将产生层，这有利于Si光电阳极的稳定性。这项工作提供了一种通过接口工程和电催化剂缺陷调节设计高性能Si光阳极的低成本直接方法。