Recent advances, application and prospect in g-C3N4-based S-scheme heterojunction photocatalysts

Semiconductor photocatalytic technology has great potential in solar energy utilization and conversion and meets people's demand for sustainable development. In recent years, graphitic carbon nitride (g-C3N4) has been considered as a potential photocatalyst due to its unique electronic band structure, excellent optical and electronic properties, cheap raw materials and easy synthesis. However, the single g-C3N4 faces the high recombination rate of photogenerated electron-hole pairs and its low reduction and oxidation capacity, which limits its practical application in the field of photocatalysis. The emerging S-scheme heterojunction can overcome the problems existing in the traditional type-II and Z-scheme heterojunctions and has great advantages in improving the photocatalytic activity by photo-generated electron transfer. Hence, the design mechanism of the S-scheme heterojunction and the proof of its charge transfer mechanism are presented in detail in this review. In addition, the synthesis methods, modification strategies and related applications of g-C3N4-based S- scheme heterojunctions are discussed and summarized. Finally, the limitations of current research on S-scheme heterojunction photocatalysts are discussed and prospected.