Bridged peracetic acid adsorption at a Co-O_v-Ce defect interface redirects activation toward singlet-oxygen-dominated water purification

Peracetic acid (PAA)-based advanced oxidation processes are attractive for water purification because of their environmental compatibility and facile activation. However, poorly controlled interfacial adsorption and O-O activation can promote indiscriminate radical release, decoupling PAA consumption from selective contaminant oxidation. Here, we constructed a Co-O_v-Ce defect interface that induced bridged PAA adsorption and redirected activation toward a surface-mediated, ¹O₂-dominated pathway. The resulting system exhibited a k_obs of 0.322 min^-1, 5.6 times that of Co-CeO₂/PAA, and increased PAA productivity to 208.1 mg Naproxen(NPX) mmol^-1 PAA, representing a 35.8% improvement. The defect interface enabled Co and vacancy-associated Ce to cooperatively anchor the two peroxide oxygens, promoting charge redistribution across the O-O unit and stabilizing oxygenated intermediates at the surface. Consequently, the reaction shifted from one-end radical release toward a lower-energy interfacial oxygen-rearrangement sequence through *O/*OOH/*O₂, thereby suppressing radical escape and favoring ¹O₂ formation. The catalyst maintained 94.9-99.6% NPX removal in tap, lake, and seawater and sustained 95-98% removal during 1200 min continuous operation. These findings establish defect-coupled adsorption geometry as a strategy for controlling oxidant fate and enabling selective, resource-efficient PAA-based water purification.