Hydroxyl decorated g-C3N4 nanoparticles with narrowed bandgap for high efficient photocatalyst design

Abstract

Zero-dimensional graphitic carbon nitride nanoparticles (0D g-C3N4 NPs) possess the advantages of non-toxicity, metal-free, and rich surface catalytic active sites. However, the complex preparation process, wide bandgap structure, easily particle aggregation and rapid carriers’ recombination still limit their development in photocatalysis. Herein, these issues are addressed by synthesizing a novel hydroxyl (-OH) modified g-C3N4 NPs with a simple hydrothermal method without using any etching agents. Besides the high hydrophily and small particle size, the OH decorated 0D g-C3N4 NPs possess obvious narrowed bandgap and high reduction potential. To further improve their dispersity and carriers’ separation rate, 0D/3D g-C3N4 NPs/ZnS type II heterojunction is fabricated, which simultaneously improves the hydrophily, passivates the surface defects and extends the sunlight absorption range of ZnS. As a result, a high and cyclable photocatalytic activity of 112 μmol h−1 (5.6 mmol h−1 g−1) is achieved under visible light irradiation without any co-catalysts, which is 140 times higher than that of pure ZnS and much better than the pure 0D g-C3N4 NPs. A systematic study of photocatalytic mechanism is proposed by combining the theoretical calculations and experimental results. This work offers a new sight for the design of 0D g-C3N4 NPs based photocatalysts for H2 production.