Pyrochlore Bi₂Sn₂O₇ photocatalysts: a systematic review on performance tuning and multifunctional applications

Given the limitations of traditional photocatalysts in terms of the light absorption range and carrier recombination rate, Bi₂Sn₂O₇ (BSO) has attracted widespread attention due to its unique crystal structure, tunable band characteristics, and defect-rich chemistry. This review systematically summarizes progress in pyrochlore-type oxide BSO-based photocatalysts for energy and environmental applications. We start with methods for preparation of BSO materials and the exploration of their growth mechanism. Then, different strategies, such as morphology control, elemental doping, heterostructure construction, metal deposition, and defect engineering, have been summarized to tune the photocatalytic performance of BSO by addressing the main issues of poor charge separation efficiency and sluggish surface reaction kinetics. Furthermore, advancements of BSO-based photocatalysts in versatile photocatalytic applications are discussed with an emphasis on the structure-activity relationship, including hydrogen evolution reactions, nitrogen fixation, CO₂ reduction, H₂O₂ generation, organic pollutant degradation, sterilization, and nitric oxide removal. Finally, the current challenges and future development prospects in BSO-based photocatalysts are also presented to produce new opportunities for future research.