Metal selenides for solar-driven photocatalytic and photoelectrochemical hydrogen production: Progress, challenges, and perspectives

Solar-driven photocatalytic (PC) and photoelectrochemical (PEC) water splitting are promising techniques for producing sustainable and clean hydrogen. Metal selenides have recently gained considerable attention and have been extensively investigated as semiconductor materials to catalyze these processes because of their favorable optoelectronic properties, higher electronic conductivity, suitable band gaps, exceptional light-harvesting capabilities, and high photostability. This review comprehensively analyses recent research progress in metal selenide-based photocatalysts and photoelectrocatalysts, highlighting key synthesis and modification strategies, structure-performance relationships, and elucidating activity mechanisms. It begins with fundamental structural and electronic properties of metal selenides, followed by an introduction to synthetic methods. Subsequently, the basic concepts and principles of PC and PEC water splitting are discussed, along with recent advances in developing metal selenides for solar hydrogen production, with various architectures and strategies to improve solar-to-hydrogen (STH) efficiency and stability highlighted. Finally, the key challenges, opportunities, and future perspectives for advancing solar-driven hydrogen production are briefly presented. • Comprehensive review of metal selenides for photocatalytic and photoelectrochemical H 2 production. • Synthetic strategies enable tunable metal–selenium bonding for efficient and stable photocatalysts/photoelectrodes. • Structure–composition–activity relationships across Cu-, Fe-, Cd-, Zn-, Ag-, and 2D transition-metal selenides highlighted. • Integration of DFT and machine learning for accelerated discovery of selenide catalysts. • Perspectives on stability, scalability, and emerging directions for solar hydrogen technologies.