Precise coordination and electronic structure regulates the high-selectivity oxidation pathways in peracetic acid...

Selective modulation between radical and non-radical pathways remains a central challenge in developing sustainable advanced oxidation processes (AOPs) for complex water treatment. Herein, we propose a grain-boundary (GB) engineering strategy to reconstruct the coordination geometry and electronic structure of CoMn₂O₄ spinel catalysts enabling precise peracetic acid (PAA) activation and rapid sulfamethoxazole (SMX) degradation (optimized kinetics up to 0.52 min^-1). Increasing density of GB by lowering the calcination temperature generates disordered, low-coordinated Co-O-Mn sites that facilitate PAA adsorption (Eads = -1.85 eV) and peroxide bond cleavage, driving a transition from non-radical (singlet oxygen (¹O₂), high-valent metal-oxo (HVMO) and electron transfer pathways (ETP)) to hybrid radical/non-radical (organic radicals (R-O•), superoxide radicals (•O₂^-) and ¹O₂) mechanisms. Thus, regulating the density of GB allows the system to remove diverse pollutants, demonstrating considerable potential for treating complex water matrices. Impressively, the system exhibited remarkable long-term activity and scalability in continuous-flow reactions. Furthermore, life cycle assessment confirms the favorable environmental significance and feasibility in practical application. This strategy establishes a clear structure-reactivity-selectivity relationship in spinel systems and provides a general pathway to design multifunctional catalysts for selective and efficient water decontamination.