Engineered Graphitic Carbon Nitride-Based Photocatalysts for Visible-Light-Driven Water Splitting: A Review

Graphitic carbon nitride (g-C 3 N 4 ), a polymeric semiconductor, has become a rising star for photocatalytic energy conversion because of its facile accessibility, metal-free nature, low cost, and environmentally benign properties. This work reviews the latest progress of g-C 3 N 4 -based materials in visible-light-driven water splitting to hydrogen. It begins with a brief history of g-C 3 N 4, followed by various engineering strategies of g-C 3 N 4, such as elemental doping, copolymerization, crystalline tailoring, surface engineering, and single-atom modification, for elevated photocatalytic water decomposition. In addition, the synthesis of g-C 3 N 4 in different dimensions (0D, 1D, 2D, and 3D) and configurations of a series of g-C 3 N 4 -based heterojunctions (type II, Z-scheme, S-scheme, g-C 3 N 4 /metal, and g-C 3 N 4 /carbon heterojunctions) were also discussed for their improvement in photocatalytic hydrogen production. Lastly, the challenges and opportunities of g-C 3 N 4 -based nanomaterials are provided. It is anticipated that this review will promote the further development of the emerging g-C 3 N 4 -based materials for more efficiency in photocatalytic water splitting to hydrogen.