Surface/Interface Engineering of Si-Based Photocathodes for Efficient Hydrogen Evolution

Solar-driven photoelectrochemical (PEC) water splitting into hydrogen fuel is a promising avenue for renewable energy conversion to overcome energy crises and environmental concerns. Earth-abundant Si semiconductors with excellent light-harvesting capabilities are suitable photocathode candidates for the PEC hydrogen evolution reaction (HER), but suffer from intrinsic instability and sluggish kinetics. Extensive studies have demonstrated that surface/interface engineering can serve as an effective strategy for fabricating Si-based photocathodes with sufficient surface catalytic activity and facile interfacial carrier transport. In this Review, we first briefly introduce the current status of PEC HER using Si-based photocathodes and summarize their fabrication techniques. Subsequently, a systematic overview of recent achievements in surface/interface engineering of Si-based photocathodes is presented to illustrate their distinct roles in boosting the PEC-HER performance. Finally, the perspective views regarding the further development of practical Si-based photocathodes are discussed. This Review aims to promote an in-depth understanding and technical evaluation of surface/interface engineering strategies for efficient Si-based PEC HER.