Powerful combination of 2D g-C3N4 and 2D nanomaterials for photocatalysis: Recent advances

As a fascinating metal-free conjugated polymer semiconductor, 2D graphitic carbon nitride (g-C3N4) has been widely used as a visible-light-responsive photocatalyst. Generally, g-C3N4 exhibits some appealing properties, such as exceptional thermal and chemical stability, appropriate band structure, as well as low cost. However, the pristine g-C3N4 is limited by the fast recombination of the photoinduced electron-hole pairs, limited surface area, and insufficient sunlight absorption. Very recently, the construction of 2D/2D heterojunctions has attracted widespread attention owing to their distinct advantages, including the intimate interface, high surface area, suitable band potential and so forth. Therefore, this review summarized the latest progress in the coupling g-C3N4 with other 2D nanomaterial systems, including 2D graphene-like materials, 2D transition metal dichalcogenides, 2D metal oxides, 2D bismuth-based semiconductors and 2D phosphorous. Furthermore, the photocatalytic mechanism of g-C3N4 based 2D/2D heterojunctions was systematically studied and their corresponding charge-transfer pathways on the interface surface were elaborated. In addition, the photocatalytic applications of the g-C3N4 based 2D/2D composites in the realm of hydrogen generation, carbon dioxide reduction, pollutant degradation, and photocatalytic disinfection were also reviewed. Finally, the current challenges faced by the formation of g-C3N4 based 2D/2D composite and the opportunities for further development are also proposed.