Activation of peroxymonosulfate for enhanced antibiotic removal using OVs-CoO/FeO: Synergistic modulation of heterostructure and oxygen vacancy.

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 CoO/FeO (1:1) with heterostructures was designed to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. It was found that the heterostructured CoO/FeO (1:1) achieved a TC degradation efficiency of 99.9 % (k = 0.1883 min) and a PMS decomposition rate of 79.2 % (k = 0.0728 min), respectively. Quenching experiments, EPR analyses, and probe experiments all indicated that SO was the dominant reactive oxide species (ROS). Besides, formation of the both heterostructures and OVs enhanced the electron transfer properties of 7OVs-CoO/FeO (1:1) with PMS, facilitating the cleavage of the O-O bond in HSO. Notably, density functional theory (DFT) calculations revealed that OVs serve as the primary active sites, preferentially interacting with O (H-O-O-SO) to generate SO. 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 (ΔE = 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.