Geometry-Controlled Cooperativity at Binuclear Fe2-N6 Sites Enables Selective FeIV═OGeneration for Durable Fenton-Like Oxidation.

Abstract

Single atom catalysts (SACs) are emerging as a promising platform for Fenton-like water purification; however, their practical deployment is often constrained by the trade-off between high intrinsic activity and long-term stability. Here, we construct an N-bridged binuclear architecture that pairs isolated Fe-N4 sites into a precisely defined Fe2─N6 configuration on N-doped carbon (Fe2─N6/NC). This Fe─N─Fe architecture induces charge delocalization and regional polarization, strengthening interfacial electronic coupling and enabling cooperative dual-site adsorption of peroxymonosulfate (PMS). As a result, PMS activation becomes thermodynamically favored and proceeds selectively via a high-valent FeIV═O pathway, fundamentally distinct from the singlet-oxygen-dominated regime of conventional single-atom sites (Fe─N4). The FeIV═O species generated over the proximity dual site simultaneously accelerate pollutant degradation while suppressing demetalation, thereby securing both catalytic activity and operational durability. In the continuous-flow reactor, Fe2─N6/NC maintains stable performance over 14 days of operation. Life cycle assessment and real-world hospital wastewater treatment further demonstrate concurrent organic removal, reduced toxicity, and lower environmental impact. This work proposes binuclear site engineering as a general strategy to overcome the catalytic activity-stability dilemma in SAC-based Fenton-like systems, advancing their translation toward scalable, sustainable systems for real-world water purification.