Recent advances in TiO2-based S-scheme heterojunction photocatalysts

The green and sustainable photocatalysis technique turns out to be a promising route to settle the urgent energy and environmental issues. As a representative semiconductor photocatalyst, the titanium dioxide (TiO2) with numerous advantages has attracted worldwide attentions and already applied in various fields. To settle the inherent limitations of single-component photocatalyst, the emerging step (S)-scheme heterojunction system offer a desirable answer, which could extend light-harvesting, accelerate spatial charge separation and simultaneously maintain their strong redox abilities. This review tends to offer a comprehensive introduction of S-scheme heterojunction mechanism and recent advances in TiO2-based S-scheme photocatalysts. The design concepts and advanced characterization techniques for high-efficiency TiO2-based S-scheme catalysts are summarized. Moreover, various energy and environmental fields including hydrogen production, CO2 reduction, H2O2 production and water treatments achieved by TiO2-based S-scheme heterojunctions are reviewed and listed in tables. Lastly, we propose some outlook in aspects of targeted S-scheme heterojunction design and preparation, interfacial charge transfer channels, stability issues, in-situ or operando characterization techniques, and device design, which can contribute to a deeper understand and development of efficient S-scheme photocatalysts.