Electrochemically Synthesized Fe–Mn Mesh Catalysts for Catalytic Ozonation Degradation of Phenol

Supported catalysts for liquid-phase catalytic ozonation often suffer from active-species detachment under ozone-bubble shear and continuous-flow operation, limiting long-term stability and causing persistent metal leaching. Herein, Mn-doped iron-mesh catalysts (x-FMM, x = 0.04, 0.08, 0.12) were synthesized via a modified cyclic chronopotentiometry method, and their catalytic performance and ozone-activation behavior in the ozonation of phenol were systematically investigated. XRD, SEM, and BET analyses revealed that Mn incorporation reduced the Fe2O3 crystallite size and produced a denser, more uniform granular morphology, thereby increasing the density of accessible surface hydroxyl active sites. Quasi in situ XPS, DMPO spin-trapping EPR, before/after-reaction ATR-FTIR, ozone-decomposition, and radical-quenching experiments jointly support a radical-mediated pathway in which hydroxyl/water-related surface species participate in ozone activation and HO· generation, while Fe–Mn electronic interaction is consistent with facilitated Fe2+ regeneration and sustained catalytic turnover. Under optimized electrodeposition conditions, 0.08FMM achieved 87.8% phenol removal and 60.5% TOC removal after 30 min at 25 °C. During a 20 h continuous-flow test, phenol removal decreased to ~82% within the initial 2 h and then remained near 79–80%, while Fe and Mn leaching decreased to ~4–5 and ~1–2 µg L−1, respectively, by 20 h. The electrochemical approach therefore provides a direct anchoring route for structured heterogeneous catalytic ozonation without high-temperature calcination, with moderate activity retention and low metal leaching under extended operation.