Modification strategies of BixOyBrz-based photocatalysts for enhanced environmental applications: A review

Bismuth-rich oxybromide (Bi x O y Br z ) photocatalysts feature distinctive layered structures, adjustable electronic properties, and effective visible light response, positioning them as promising candidates for environmental remediation and solar energy conversion. Nonetheless, practical applications are still limited by rapid recombination of charge carriers, insufficient light absorption, and unfavorable conduction band position. This review provides a systematic summary of the latest advances in Bi x O y Br z -based photocatalysts, focusing on synthesis methods, including hydrothermal/solvothermal, calcination, in situ synthesis, precursor, and chemical vapor deposition methods, and their effects on morphology, defect formation, and catalytic performance. Key enhancement strategies, including element doping, defect engineering, morphology control, and the construction of heterojunctions (Type II, Z-Scheme, and S-Scheme), are discussed with emphasis on their roles in improving light absorption, charge separation, and redox capability. The environmental applications of Bi x O y Br z -based photocatalysts in organic pollutant degradation, heavy metal removal, and photocatalytic CO 2 reduction are highlighted, along with the underlying reaction mechanisms. By synthesizing current findings, this review concludes with a forward-looking perspective on addressing existing stability challenges, scaling up laboratory synthesis, and leveraging advanced characterization and theoretical simulations to design the next generation of high-efficiency Bi x O y Br z -based photocatalytic systems.