Interface defect engineering of CeO2/Co3O4 to hinder ineffective consumption of oxidant in Fenton-like reaction for polymerization-deposition removal of phenols

To precisely engineer the polymerization-deposition (PD) route of Fenton-like reactions for efficient phenols decontamination, this study developed a CeO 2 /Co 3 O 4 composite featuring abundant interfacial asymmetric oxygen vacancies (As-OVs), addressing ambiguous structure-activity relationship and unclear catalytic mechanism in PD route regulation. The catalytic behavior, peroxymonosulfate (PMS) activation pathway, phenols transformation mechanism and continuous operation performance were systematically investigated via experiments, characterization and theoretical calculation. Compared with symmetric oxygen vacancies (S-OVs) in Co 3 O 4 alone, As-OVs altered phenols oxidation from mineralization to PD route by anchoring PMS via terminal oxygen atoms rather than peroxide bond, avoiding O-O bond cleavage along with radical pathway, thus suppressing oxidant waste and enabling 100 % ETP-triggered PD route. At ultra-low PMS/BPA ratio (1.14), 79.7 % TOC removal was achieved, reducing PMS consumption to 4 % vs. mineralization pathway and enabling long-term continuous practical wastewater treatment. Experimental and theoretical calculation revealed that the unique PMS adsorption configuration, greater electron rearrangement tendency and enhanced phenoxyl radical adhesion around As-OVs facilitate efficient coupling to form crosslinked products on the catalyst, ensuring excellent structural and catalytic stability of OVs-CeO 2 /Co 3 O 4 . These findings deepen understanding of metal oxide-guided PD route via interfacial defect engineering, contributing to cost-efficiency and advancing high-performance, sustainable wastewater decontamination technologies with long-term operation.