Tuning Fe-P covalency via regenerative phosphorus vacancies for efficient aqueous cyclohexanone degradation

Phosphorus vacancies (P_v) have recently emerged as a powerful tool in defect engineering, yet their role in enhancing catalytic activity and stability remains underexplored. Here, we report a P_v-enriched FeP catalyst (P_v-FeP) synthesized through in-situ phosphidation of FeOOH followed by NaBH₄ etching. The introduction of P_v delicately remodeled the electronic structure of FeP by weakening Fe-P covalency and enhancing the oxidative resistance of Fe sites, suppressing surface reconstruction and deactivation. This dual effect enabled the catalyst to simultaneously achieve high activity and long-term stability. Density functional theory (DFT) calculations further verified that P_v construction shifts the Fe 3d-band center upward and markedly reduces the adsorption energy of PMS at the O-O moiety, thus facilitating effective O-O bond cleavage and boosting the generation of both radical (•OH) and non-radical (¹O₂) species. As a result, the catalyst achieved over 92 % degradation of cyclohexanone (CYC) within 30 min under optimal conditions (0.1 g/L catalyst, 1 mM PMS, and initial pH of 7). Moreover, the catalytic capability could be readily regenerated through reversible lattice oxygen incorporation and extraction, demonstrating impressive reusability. These findings provide new insights into the rational design of robust Fe-based catalysts and underscore the potential of Pᵥ engineering for the efficient degradation of refractory VOCs in aqueous environments.