Engineering oxygen vacancy-rich CoFe2O4@C core-shell microreactors via defect-morphology dual synergy for ultrafast peroxymonosulfate activation

This study innovatively employs a "dual-engineering synergy" strategy combining defect engineering and morphological engineering to construct oxygen vacancy (O V )-enriched CoFe 2 O 4 @C core-shell microreactors (O V -CFO@C) for efficient peroxymonosulfate (PMS) activation. The optimized O V -CFO@C-500 catalyst exhibits exceptional Fenton-like performance, degrading 97.65% of CIP in 12 min ( k obs = 0.2984 min -1 , 29.25 times that of PMS alone). Structural characterizations confirm successful O V introduction and core-shell architecture, where carbon cores prevent CoFe 2 O 4 agglomeration while enabling reactant enrichment. Theoretical calculations reveal that core-shell structure and Ov modulate d-band center positions and electron delocalization, synergistically enhancing PMS adsorption energy and electron transfer efficiency. Mechanistic studies identify cooperative radical pathways (•OH/SO 4 •− contribution: 54.1%) and non-radical electron transfer processes. Notably, the catalyst demonstrates strong recyclability (88.91% CIP removal after 5 cycles), broad pH tolerance (pH 3–9), low metal ion leaching (< 0.06 mg/L), and practical applicability in real water matrices. In continuous-flow degradation systems, 12 h operation achieved sustained removal rates of 96.8% for CIP and 55.2% for total organic carbon (TOC). This study provides new insights into defect-microstructure engineering for advanced oxidation process optimization. Defect-morphology dual engineering constructs O V -CoFe 2 O 4 @C core-shell microreactors with four merits: more exposed active sites, enhanced electron transfer, facilitated mass transfer and reaction kinetics, and suppressed metal leaching, achieving 97.65% CIP removal in 12 min ( k obs =0.2984 min -1 ). • Dual-engineering synergizes O V with core-shell microreactor to boost PMS activation. • Ov-mediated d-band modulation triggers electron redistribution of catalyst. • The carbon matrix suppresses CoFe 2 O 4 agglomeration and enriches reactants locally. • O V -CFO@C-500 with enhanced stability and promising practical applicability.