Bismuth Chalcogenide-Based Photocatalysts for Nitrogen Reduction: Recent Progress and Prospects

Bismuth chalcogenides and related bismuth-based materials have recently attracted considerable attention as promising photocatalysts for sustainable nitrogen reduction reaction (NRR) due to their unique electronic structures, visible-light responsiveness, stereochemically active Bi 6s² lone pair, and tunable band positions that facilitate nitrogen adsorption and activation. This review summarizes recent advances in the rational design of bismuth chalcogenide-based photocatalysts for light-driven ammonia synthesis. Fundamental aspects of photocatalytic N₂ reduction and reliable methodologies for ammonia quantification are critically discussed. Material engineering strategies, including defect modulation, elemental doping, heterojunction construction (Type-II, Z-scheme, and S-scheme systems), and hybrid structural design, are analyzed with respect to charge separation and band alignment. Key challenges, such as low N₂ activation efficiency, competing hydrogen evolution reaction, charge recombination, and reproducibility concerns, are highlighted. Future perspectives emphasize electronic structure regulation, operando mechanistic studies, standardized evaluation protocols, and integration with photoelectrochemical systems for improved efficiency and selectivity.