Passivation strategies for enhanced photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is an efficient method of absorbing solar energy and converting it to hydrogen energy. However, in actual applications, the photoelectric conversion efficiency is significantly lower than the theoretical value due to the high recombination of photogenerated carriers in the semiconductor and its own instability. Surface passivation strategies can reduce the impact of surface defect states on the actual photoelectric performance and achieve effective protection of the inner layer materials. This article reviews the recent advances in the passivation strategies for mainstream PEC photoanode materials, such as TiO₂, BiVO₄, Fe₂O₃, and photocathode materials such as Cu-based and silicon-based materials. The main functions of the passivation layer strategies are discussed, such as reducing surface recombination and maintaining semiconductor stability. The state of the art of passivation strategies is presented. The research achievements on passivation strategies are summarized, and their challenges and possible future development directions are projected.