Carbon nitride with grafted molecular as electron acceptor and active site to achieve efficient photo-activated peroxymonosulfate for organic pollutants removal

The effective activation of peroxymonosulfate (PMS) by polymer carbon nitride (PCN) is hampered by the unpredictable movement and rapid recombination of photocarriers. In this study, niacin served as a beneficial modifier to help constructed the directional electron transfer pathway from the center to the edge in the synthesized PCN catalyst (UCNNA) for efficient PMS activation. The UCNNA/PMS/vis shows the highest kinetic constants (0.050 min⁻¹), which is 2.9-fold increase over the PCN/PMS/vis. The experiments and theoretical calculations indicated that niacin as electron acceptor group prevents the recombination of photocarriers in-plane. Simultaneously, niacin can serve as PMS adsorption site, further facilitating electron transfer and the ¹O₂ generation. Mass spectrometry analysis and Fukui index calculations confirm the priority of lateral chain oxidation (¹O₂ attack site) during atrazine degradation. These results provide new insights into rational design of metal-free catalysts/PMS/vis system, as well as providing guidance and theoretical support for atrazine degradation mechanisms.