Exogenous-Oxidant-Free Degradation of Pharmaceutical Residues via Continuous ROS Generation Over Fe/Mn Nanozymes Featuring Mn(IV) = O and Oxygen Vacancies.

The sustainable elimination of pharmaceutical residues from wastewater remains a critical environmental challenge. Herein, we report an aluminum matrix composite-supported manganese ferrite (Almc-MFO) nanozyme that enables self-driven reactive oxygen species (ROS) evolution from dissolved oxygen (DO) to degrade ofloxacin (OFX) without any external oxidants or energy input. The anchored MFO structure promotes interfacial electron transfer and stabilizes abundant oxygen vacancies, which synergistically facilitate the formation of Mn(IV) = O. The catalyst exhibits remarkable oxidative activity across pH 3-6, achieving 64%-95% degradation of OFX (1-10 mg L- 1) within 30 min and sustaining a continuous H2O2 generation rate of 67.5 ± 4.0 µmol L- 1 h- 1. DFT calculations further confirm that the *OOH intermediate, formed from O2 on Mn sites, exhibits an H2O2-like O─O bond and low adsorption energy, prompting its desorption and selective conversion to H2O2. The Fe site exhibits a lower energy barrier in the rate-determining step of H2O2 dissociation into •OH and synergizes with the Mn site to achieve efficient H2O2 turnover. This study provides a new theoretical foundation for designing advanced oxidation systems capable of self-sustaining H2O2 supply without exogenous oxidants.