Oxygen vacancies-mediated the peracetic acid activation to selectively generate ¹O₂ for water decontamination

As a pre-oxidation unit, developing non-radical pathway-dominant advanced oxidation processes (AOPs) with remarkably-efficient oxidation, superior environmental robustness, and ecological safety is essential in actual water pollution control. Herein, using Co₃O₄ as an example, we present an oxygen vacancies (OVs)-mediated peracetic acid (PAA) activation process, thereby predominantly generating singlet oxygen (¹O₂) for degrading contaminants. In-situ monitoring of PAA activation by OVs-rich Co₃O₄ (Co₃O₄-OVs) reveals that surface oxygen-containing intermediates (e.g., *OH and *O) are the precursors of ¹O₂. Theoretical calculations show that the selective adsorption of terminal oxygen atoms (ATO) in PAA serves as an activity descriptor for ¹O₂ generation. OVs can induce electron redistribution, triggering the ATO-dominated PAA adsorption to form the Co₃O₄-OVs-PAA* complex, followed by O-O bond breakage to yield *OH. Concurrently, OVs modulate the Co d-band center, lowering the energy barrier for ¹O₂ formation. The system enables ultra-fast catalytic performance (k_obs = 1.17 min^-1) for degrading sulfamethoxazole, outperforming pristine Co₃O₄ by 11.64-fold. The high-selectivity towards non-radical pathway endows the Co₃O₄-OVs/PAA system with remarkable stability in complex environment backgrounds and continuous-flow microreactor. This work not only provides a broad perspective on the modulation of non-radical pathways via defect engineering, but also advances the development of PAA-based AOPs for water decontamination.