Axial Fluorine Coordinated Fe Single‐Atom Catalyst for Boosting Electro‐Fenton Treatment of Organic Pollutants

ABSTRACT Electro‐Fenton is promising for advanced wastewater treatment, but its performance is limited by sluggish O 2 ‐to‐ • OH conversion and inorganic anion interference. Here we report an axial fluorine‐coordinated iron single‐atom catalyst (FeN 4 F‐G) to enhance • OH production and inorganic anion tolerance in the electro‐Fenton reaction. X‐ray‐based synchrotron radiation techniques confirm the formation of the FeN 4 center with axial F coordination. The FeN 4 F‐G achieves a 2.0‐fold higher rate than FeN 4 ‐G for electro‐Fenton degradation of ciprofloxacin (−0.7 V vs Ag/AgCl). It not only maintains similar ciprofloxacin degradation efficiencies across a wide pH range (3–9), but also exhibits better inorganic anion (CO 3 2− , HCO 3 − , Cl − ) resistance and stability than FeN 4 ‐G. The enhanced performance of FeN 4 F‐G is attributed to its accelerated • OH production (main species for electro‐Fenton), facilitated active hydrogen supply, and anion repulsion after axial fluorine coordination. Density functional theory reveals that fluorine coordination modulates the electronic structure of Fe, lowering the energy barriers for O 2 ‐to‐ • OH conversion. The FeN 4 F‐G‐based electro‐Fenton is efficient for treating the secondary effluent of pharmaceutical wastewater with a COD removal efficiency of 76.2% (meeting the wastewater discharge standard) and energy consumption of 21.8 kWh kg COD −1 .