Recent Advances in Metal–Organic Halide Perovskite-Based Photoelectrodes for Efficient Solar-Driven H ₂ production

Metal–organic halide perovskites (MHPs) are attracting strong interest for solar energy conversion because of their favorable optoelectronic properties, including strong light absorption, tunable band gaps, and long carrier diffusion lengths. This review outlines recent advances in perovskite-based photoelectrodes for photoelectrochemical (PEC) H2 production. We describe the intrinsic properties of MHPs and the fundamental principles involved in PEC water splitting. Strategies for designing and optimizing perovskite-based photoelectrodes are discussed, with a focus on material composition, structural engineering, and interface modulation. The distinct roles of perovskite-based photoanodes and photocathodes in driving the O2 and H2 evolution reactions are summarized. Recent developments in bias-free PEC systems using perovskite-based photoelectrodes are also reviewed, showing pathways toward solar-driven water splitting without external power input.