Highly Efficient and Selective Degradation of Electron-Rich Organic Pollutants in a Co-CN/Peroxymonosulfate System via the Synergistic Interaction of Regulating the Active Site and Producing Singlet Oxygen

Singlet oxygen (1O2) generation during peroxymonosulfate (PMS) activation is crucial for the selective removal of emerging electron-rich organic contaminants (EROCs) in complex water matrices. However, the efficient and selective production of 1O2 during PMS activation remains a significant challenge. Herein, an N-doped carbon material with a uniform dispersion of Co nanoparticles was synthesized for the effective generation of 1O2 and the selective removal of refractory EROCs. The precursor was deliberately designed by anchoring Co2+ with l-histidine to achieve strong binding of Co–NX sites and introducing sufficient N sources by doping with melamine to improve the electronic structure of adjacent carbon atoms and a uniform distribution of Co nanoparticles with reduced particle size. This material achieved efficient and selective removal of EROCs over a wide range of pH values. Multiple characterizations demonstrated that the active species during the reaction were 1O2, and electron transfer facilitated the degradation reactions, which contributed to the high reactivity and selectivity. Density functional theory calculations further confirmed that the presence of a Co–NX site is favorable for PMS activation to selectively produce 1O2. This study provides a new approach for developing materials to effectively generate 1O2 and selectively degrade EROCs.