Important role of carbon doping in photocatalytic peroxymonosulfate activation of carbon nitride for efficient 4-Chlorophenol degradation

In order to improve the photocatalytic activity of pristine carbon nitride while maintaining its metal-free property to achieve the activation of peroxymonosulfate (PMS), a series of carbon-doped g-C 3 N 4 (BCN) with different carbon contents were synthesized in this paper by adding benzotriazole to urea. The catalyst obtained by this approach significantly promoted PMS activation and enhanced the degradation efficiency of 4-chlorophenol (4-CP). Experiments and theoretical calculations showed that the introduction of carbon not only narrowed the band gap, but also accelerated the separation of photoinduced electron-hole pairs, which greatly improved the photocatalytic activity of g-C 3 N 4 . In the degradation of pollutants, free radicals and non-free radicals acted simultaneously, with non-free radicals playing a dominant role. This study explained the origin of 1 O 2 by Density functional theory (DFT) calculations, visible light excited photocatalysts to form holes, while carbon introduction decreased the valence-electron density around the area, inducing electron transfer from PMS toward g-C 3 N 4 directed to generate 1 O 2 . The 1 O 2 -dominated degradation process improved the application of the catalysts in complex aqueous matrices. In addition, we proposed 4-CP degradation pathways, and the toxicity of intermediates derived from 4-CP degradation process reduced.