Mesoporous Al₂O₃-supported CoMoO₄ boosts peroxymonosulfate activation via Co³⁺/Co²⁺-Mo⁶⁺/Mo⁴⁺ redox cycles for...

The efficient utilization of active sites in heterogeneous catalysts remains a critical yet often overlooked challenge in peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for antibiotic degradation. Herein, we report a mesoporous Al₂O₃-supported CoMoO₄ composite (CoMoO₄/Al₂O₃) synthesized via an in-situ hydrothermal method. The incorporation of Al₂O₃ as a structural scaffold dramatically increases the specific surface area by 8.86 times compared to pristine CoMoO₄, substantially exposing accessible active sites, as evidenced by an 8.8-fold increase in turnover frequency. After reaching adsorption equilibrium, the CoMoO₄/Al₂O₃-PMS system further degrades 96.3% of the remaining oxytetracycline (OTC) within 60 min. Comprehensive quenching experiments and electron spin resonance (EPR) spectroscopy analysis demonstrate that superoxide radicals (•O₂^-) and singlet oxygen (¹O₂) are the predominant reactive oxygen species, with ¹O₂ playing the leading role. Mechanistic studies demonstrate a synergistic redox cycle between Co³⁺/Co²⁺ and Mo⁶⁺/Mo⁴⁺, where the Co-driven PMS activation is coupled with Mo-facilitated •O₂^- conversion ¹to generate abundant ¹O₂. Furthermore, the system exhibits robust reusability, high tolerance to coexisting anions and natural organic matter, and consistent performance across different water matrices. Three plausible degradation pathways of OTC are proposed on the basis of intermediates identified by liquid chromatography-mass spectrometry (LC-MS) analysis, involving demethylation, dehydroxylation, and ring-opening reactions. This work highlights a promising strategy to enhance active site utilization via porous support engineering, demonstrating improved degradation efficiency and mechanistic understanding for antibiotic removal from water.