Activation of peroxymonosulfate for enhanced antibiotic removal using OVs-Co₃O₄/Fe₂O₃: Synergistic modulation of...

To broaden the applicability of permonosulfate-based advanced oxidation processes (PMS-AOPs) for promising new pollutants removal, challenges such as limited active site exposure and rate-limiting steps in metal redox cycling should be well addressed. In this work, oxygen vacancies (OVs)-rich Co₃O₄/Fe₂O₃ (1:1) with heterostructures was designed to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. It was found that the heterostructured Co₃O₄/Fe₂O₃ (1:1) achieved a TC degradation efficiency of 99.9 % (k_TC = 0.1883 min^-1) and a PMS decomposition rate of 79.2 % (k_PMS = 0.0728 min^-1), respectively. Quenching experiments, EPR analyses, and probe experiments all indicated that SO₄^•- was the dominant reactive oxide species (ROS). Besides, formation of the both heterostructures and OVs enhanced the electron transfer properties of 7OVs-Co₃O₄/Fe₂O₃ (1:1) with PMS, facilitating the cleavage of the O-O bond in HSO₅^-. Notably, density functional theory (DFT) calculations revealed that OVs serve as the primary active sites, preferentially interacting with O_I (H-O_I-O_II-SO₃^-) to generate SO₄^•-. Moreover, the engineered heterostructures and OVs synergistically optimized the electronic configuration of Co(II) and Fe(III) sites, resulting in a remarkably low reaction energy barrier (ΔE₃ = 0.42 eV). Together with the construction of heterostructures and the formation of OVs, the current work presents a strategy for optimizing heterogeneous Fenton-like catalytic oxidation pathways.