Nitrogen Vacancy-Modulated Peroxymonosulfate Nonradical Activation for Organic Contaminant Removal via High-Valent Cobalt-Oxo Species

Rapid generation of high-valent cobalt-oxo species (Co(IV)═O) for the removal of organic contaminants has been challenging because of the low conversion efficiency of Co(III)/Co(II) and the high activation energy barrier of the Co(II)-oxidant complex. Herein, we introduced nitrogen (N) vacancies into graphite carbon nitride imbedded with cobalt carbonate (CCH/CN–Vn) in a peroxymonosulfate (PMS)/visible light system to break the limitations of a conventional two-electron transfer path. These N vacancies enhanced the electron distribution of the Co 3d orbital and lowered the energy barrier to cleave the O–O bond of PMS in the Co(II)-PMS complex, achieving the modulation of major active species from 1O2 to Co(IV)═O. The developed synergistic system that exhibited adsorption and oxidation showed remarkable selectivity and contaminant removal performance in inorganic (Cl–, NO3–, HCO3–, and HPO4–) organic (HA) and even practical aqueous matrices (tap water and secondary effluent). This study provides a novel mechanistic perspective to modulate the nonradical path for refractory contaminant treatment via defect engineering.