Co-modification of carbon and cyano defect in g-C3N4 for enhanced photocatalytic peroxymonosulfate activation: Combined experimental and theoretical analysis

Carbon substitution of nitrogen is considered as a non-toxic and stable way to improve the availability of pi electrons in g-C3N4. In this paper, a simple one-step calcination method was adopted to prepare carbon and cyano co-doped g-C3N4 (C-CND), photocatalytic experiments, characterization and excited state calculations showed that carbon substitution of bridging nitrogen greatly improved the pi-conjugated system and synergistically modulated the electronic structure of g-C3N4 with cyano, enhancing the photocatalytic activation towards peroxymonosulfate (PMS) by C-CND. Both radicals and non-radicals play an essential role in the C-CND/PMS/Vis system, where 1O2 dominates, and the activation mechanism is analyzed by combining the adsorption calculations between PMS and C-CND in different electrostatic potential regions. The results provide a valuable reference for the efficient photocatalytic activation of PMS by carbon self-doped g-C3N4.