Oxygen-Vacancy-Driven Electron Transfer Enables Synergistic Peroxymonosulfate Activation on Co₃O₄ Hollow Nanocubes

Conventional Co₃O₄ catalysts are limited by sluggish electron transfer, dominant radical pathways that suffer from interference in complex water matrices; shifting toward non-radical pathways via oxygen-vacancy engineering and hollow nanocube (HNC) architecture offers a promising strategy that enhances selectivity, stability, and anti-interference capability. Therefore, oxygen-vacancy-engineered Co₃O₄ HNCs (V_o-Co₃O₄ HNCs) were designed via a ZIF-67-templated etching-oxidation-reduction route that couples structural precision with defect control. The optimized 38 %-V_o sample exhibits a rare balance between activity and stability, achieving 98.7 % tetracycline removal within 5 min and maintaining over 96 % efficiency from pH 3-11 and real-water matrices. Spectroscopic and electrochemical analyses reveal that moderate V_o enrichment tunes the Co²⁺/Co³⁺ valence equilibrium and accelerates charge transport, thereby promoting a synergistic radical (SO₄ ^•-, •OH, O₂ ^•-) and non-radical (¹O₂, electron-transfer) oxidation network. Predominant ¹O₂ and high-valent Co (IV) = O species endow the system with exceptional anti-interference capability, low charge-transfer resistance (3.26 Ω), and long-term stability with negligible Co leaching. This work reveals a clear defect-structure-activity correlation for PMS activation and demonstrates that coupling rational morphology with precise oxygen-vacancy modulation enables fast, selective, and recyclable degradation of emerging organic pollutants, providing a general blueprint for defect-orchestrated transition-metal-oxide catalysts in sustainable environmental remediation.