Tuning reaction pathways of peroxymonosulfate-based advanced oxidation process via defect engineering

Peroxymonosulfate (PMS)-based advanced oxidation process (AOP) has attracted great attention as an effective technique for oxidatively decomposing organic pollutants. The PMS activation mechanisms, nevertheless, are still ambiguous in many cases, and, thus, controlling PMS activation pathways for efficient pollutant removal remains challenging. In this work, taking defective PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) as a model system, we demonstrate that oxygen vacancies (Vo••) strongly promote PMS-based AOP, and PMS activation pathways are effectively tuned. Excessive Vo••s are found to modify the surface charge distribution, change PMS adsorption configuration, and break the S–O bond of PMS. As a result, the radical process is promoted, and the predominant nonradical activation pathway shifts from an electron transfer process to singlet oxygen formation. Our mechanistic understanding can guide the rational design of catalysts for efficient water remediation.