Efficient synthesis of monolayer carbon nitride 2D nanosheet with tunable concentration and enhanced visible-light photocatalytic activities

A versatile and scalable mixed solvent strategy was developed to prepare monolayer C₃N₄ nanosheets with tunable concentration for the first time. This approach could also be used to prepare other 2D nanosheets from their layered materials (such as MoS₂, BN, WS₂ etc.). The structural features and intrinsic semiconductor properties of the as-prepared C₃N₄ nanosheets have been investigated in detailed. The photocatalytic activities were evaluated by photocatalytic oxidation of both benzyl alcohol and rhodamine B (RhB) under visible light irradiation. Results showed that the as-prepared monolayer C₃N₄ nanosheets with thickness of 0.4 nm still retained the structural features of g-C₃N₄ layer. The functionalities of C₃N₄ nanosheets well inherited from the layered parent counterpart. Furthermore, due to the exceptionally high 2D anisotropy, C₃N₄ nanosheets showed the distinctive physicochemical properties and unique electronic structures, such as high surface area, lower surface defects, stronger reduction ability of the photogenerated electrons, increased photoelectric response, and promoted the charge-carrier migration and separation. All of these favorable factors co-contributed to the greatly improved photocatalytic activities over C₃N₄ nanosheets compared with those of its bulk counterpart.