Template-free self-assembly of three-dimensional porous graphitic carbon nitride nanovesicles with size-dependent photocatalytic activity for hydrogen evolution

Abstract

The vesicle structure of g-C3N4 with various unique properties for photocatalysis, but its current synthesis method with complex and environmentally unfriendly still needs to be further optimized. Herein, a facile template-free self-assembly method was reported to synthesize three-dimensional (3D) porous g-C3N4 nanovesicles (PCNNVs) for achieving efficient and durable photocatalytic H2 evolution. In addition, the photocatalytic H2 activities of as-prepared PCNNVs photocatalysts are size-dependent, the large-size PCNNVs-L exhibits the best H2 production rate of 10.3 mmol h−1 g−1, which is 7 times as high as than that of bulk g-C3N4. The improvement of PCNNVs photocatalysts is mainly from the following points: (i) the porous hollow cavity structure enables it to absorb more photons and form multiple reflections; (ii) the high specific surface area that increases the active site and accelerates the photocatalytic reaction; (iii) ultra-thin shell structure provides a short diffusion channel for electrons’ migration from the volume to the surface; (iv) the hydrophilicity of PCNNVs evidently accelerates electron transportation, resulting in the fast seperation of photo-induced charge carriers. Given the potential and superiority of PCNNVs themselves, this research provides design ideas and reference for developing diverse morphologies of g-C3N4-based photocatalysts.