Carbon Defects Induced Delocalization of π Electrons Enables Efficient Charge Separation in Graphitic Carbon Nitride for Increased Photocatalytic H2 Generation

作者：Niu, Ling; Du, Jianmei; Jiang, Daochuan^*; Du, Haiwei; Lin, Xiangang; Xu, Jiahui; Li, Zhongjun; Zhu, Chuhong^*; Gu, Lina; Bi, Hong; Yuan, Yupeng

来源：Catalysis Letters, 2022, 152(3): 669-678.

DOI：10.1007/s10562-021-03674-w

• Graphitic carbon nitride
• Carbon defects
• pi electron
• Hydrogen
• Photocatalysis

Carbon defects in graphitic carbon nitride (g-CN) can modulate the electronic structure for efficient separation of electronhole pairs, and thereby potentially enhance the photocatalytic H-2 generation. However, the mechanism on the separation of electrons and holes in C defect-modified g-CN still remains unclear. Here we report an autogenic ammonia gas route via in-situ urea decomposition to create carbon defects in g-CN for realizing increased photocatalytic H-2 generation rate of 36.62 mu mol h(-1) under visible light exposure, which is 10 times higher than that of g-CN obtained in the absence of autogenic ammonia gas (similar to 3.63 mu mol h(-1)). Illustrated by the density functional theory calculations, the C defects can not only reduce the band gap for increased light harvesting, but also delocalize the pi electrons in valence band (VB) and conduction band (CB) for efficient charge transfer. Such delocalization of pi electrons facilitates the efficient separation of electrons in LUMO and holes in HOMO, then promoting the photocatalytic H-2 generation. Therefore, the creation of C defects can be used as an effective route to delocalize the pi electrons in g-CN for efficient photocatalytic H-2 generation.