Unusually improved peracetic acid activation for ultrafast organic compound removal through redox-inert Mg incorporation into active Co3O4

Peracetic acid (PAA) is increasingly used in advanced oxidation processes (AOPs) for water purification, yet there remains a critical need for highly-efficient and low-cost activators. Here, we constructed abundant oxygen vacancies (OVs) into redox-active CoO by incorporating redox-inert Mg species (MgCoO), achieving ultrafast degradation of sulfamethoxazole (SMX) via PAA activation. The MgCoO/PAA system successfully degraded SMX within 3 min, with a removal rate 154.8 times higher than the CoO/PAA system, surpassing even previously reported single-atom catalysts. The primary active species identified was the acetylperoxyl radical (CHC(O)OO•), with Co-oxo acting as a secondary active species that produced O-labeled sulfone compounds. We proposed a novel mechanism involving redox-inert Mg species that simultaneously strengthened PAA adsorption and activation. The enriched surface hydroxyl groups after Mg incorporation elevated the affinity for PAA binding. Meanwhile, the reduced Co average valence state and enhanced electron transfer capability facilitated PAA activation. This study offers an in-depth knowledge of redox-inert alkaline earth metals in PAA-AOPs.