Accelerated sulfate radical generation from peroxymonosulfate by ZIF-67-derived Co3O4 encapsulated in g-C3N4: A gift from in situ growth

Metal-organic frameworks (MOFs)-derived catalysts have attracted growing attention for wastewater decontamination. However, the design of effective catalysts for the generation of on-demand reactive oxidative species (ROS) from peroxymonosulfate (PMS) remains challenging. Herein, we prepared hollow Co3O4 confined in g-C3N4 (CN) through in situ growth of ZIF-67 (Co3O4@CN). Characterizations revealed that this unique route endowed mesoporous Co3O4@CN with good hydrophilicity, thus promoting its adsorption capacity towards both pollutants and PMS. Furthermore, Co3O4@CN demonstrated high activity for fast ciprofloxacin (CIP) degradation. The heterojunction between Co3O4 and defective CN, and the abundant active sites (Co2+) formed during in situ growth remarkably facilitated SO4•− generation as the dominant species for CIP oxidation. Two possible pathways for CIP mineralization were proposed. Theoretical and experimental investigation indicated that the toxicity of the intermediates could be attenuated by deep mineralization. This work provides profound insights into engineered MOFs-derived catalysts for fast wastewater mineralization.