Boosting peroxymonosulfate activation over cyanuric acid-modified Co3O4@Fe2O3 for tetracycline degradation: insights into catalytic performance, degradation mechanism, and routes

Photocatalytic technology combined with peroxomonosulfate (PMS) advanced oxidation shows significant potential for effectively treating various challenging pollutants. In recent years, vacancy engineering has received widespread attention due to its unique electronic structure and is also considered an effective way in enhancing catalytic performance. In this work, Co-Fe bimetallic oxide composite with oxygen vacancy (O_v)–rich structure (L-Co₃O₄@Fe₂O₃) was constructed using in situ growth and modified with cyanuric acid etching to enhance dual synergistic photocatalysis and PMS activation. The findings demonstrated that the L-Co₃O₄@Fe₂O₃/PMS/UV-LED system achieved a removal rate of 99.4% tetracycline (TC) within 30 min, surpassing that of Co₃O₄@Fe₂O₃/PMS/UV-LED system. The presence of PMS as a Lewis base was found to expedite charge separation kinetics, leading to the generation of SO₄^•− and ^•OH radicals and enabling direct TC oxidation by efficiently separated holes. In combination with DFT calculations, the polarization properties and electric field effects of TC molecule were predicted using HOMO, LUMO, and Fukui indices. Notably, 15 intermediates were identified within this system, facilitating the accurate deduction of TC degradation pathways. This research not only introduces a novel modification strategy for developing cost-effective and environmentally friendly catalysts featuring O_v but also enhances the understanding of persulfate activation mechanisms with metal-based materials.