Role of oxygen vacancies and Sr sites in SrCo0.8Fe0.2O3 perovskite on efficient activation of peroxymonosulfate towards the degradation of aqueous organic pollutants

Metal-based perovskite oxides have contributed significantly to the advanced oxidation processes (AOPs) due to their diverse active sites and excellent compositional/structural flexibility. In this study, we specially designed a perovskite oxide with abundant oxygen vacancies, SrCo_0.8Fe_0.2O₃ (SCF), and firstly applied it as a catalyst in peroxymonosulfate (PMS) activation towards organic pollutants degradation. The result revealed that the prepared SCF catalyst exhibited excellent performance on organic compounds degradation. Besides, SCF showed much better activity than La_0.5Sr_0.5Co_0.8Fe_0.2O₃ (LSCF) in terms of reaction rate and stability for the degradation of the organic compounds. Based on the analysis of scanning electron microscope, transmission electron microscope, X-ray diffraction, N₂ adsorption–desorption, X-ray photoelectron spectroscopy and electron paramagnetic resonance, it was confirmed that the perovskite catalysts with high content of Sr doping at A-site could effectively create a defect-rich surface and optimize its physicochemical properties, which was responsible for the excellent heterogeneous catalytic activity of SCF. SCF can generate three highly active species: ¹O₂, SO^-₄· and ·OH in PMS activation, revealing the degradation process of organic compounds was a coupled multiple active species in both radical and nonradical pathway. Moreover, it was mainly in a radical pathway in the degradation through PMS activation on SCF and SO^-₄· radicals produced were the dominant species in SCF/PMS system. This study demonstrated that perovskite-type catalysts could enrich OVs efficiently by doping strategy and regulate the PMS activation towards sulfate radical-based AOPs.