Emerging bismuth stannate semiconductor and its photocatalytic applications in pollutant degradation via Z/S-scheme...

Bismuth stannate (Bi₂Sn₂O₇) has emerged as a promising compound for heterostructure applications due to its outstanding photocatalytic, structural, and optical properties. As a pyrochlore-type semiconducting material, Bi₂Sn₂O₇ demonstrates a suitable bandgap, strong visible-light absorption, and high chemical stability, making it attractive for environmental remediation. Heterostructures based on Bi₂Sn₂O₇ have gained significant attention because of their enhanced charge carrier separation efficiency, improved charged carrier mobility, and synergistic effects that boost photocatalytic performance. Different strategies have been utilized to construct Bi₂Sn₂O₇-based heterostructures, including doping, vacancies generation, coupling with other semiconductors to form Z-scheme and S-scheme heterojunctions. These engineered interfaces effectively reduce charge recombination, thereby enhancing photocatalytic efficiency for pollutant degradation. Furthermore, various synthesis techniques have been reviewed viz. hydrothermal, solvothermal solid-state reaction method, in-situ, and co-precipitation, etc for Bi₂Sn₂O₇ photocatalyst in which the hydrothermal method was most preferable due to yield efficiency, crystallinity, morphology, cost-effectiveness, eco-friendly, and energy conserving. This review highlights the structural, and optical properties, synthesis, modification strategies, and application of Bi₂Sn₂O₇-based heterostructures in environmental technologies. The challenges as well as future prospects of these materials are also analyzed, emphasizing their potential for next-generation photocatalysts. Further research is required to optimize material stability, enhance charge transport, and develop scalable synthesis methods for commercial applications.