Redirecting ROS oxidation to targeted interfacial electron transfer via Fe atom-cluster tandem for reactant-tailored Fenton-like processes

Asymmetric Fe atom-cluster tandem sites were rationally engineered in N − C substrates by precisely manipulating metal dispersion states. This design achieves unprecedented Fenton-like activity, with turnover frequencies 3–66 times higher than those of conventional single-atom catalysts. Beyond inter-site electronic modulation, the stereochemical complementarity between the asymmetric peroxymonosulfate (PMS) molecule and the tandem sites unlocks distinctive geometric synergy. This synergy induces a bidentate coordination mode (Fe−O−O−Fe) that elongates the O−O bond to 1.65 Å, synergistically facilitating deep PMS activation. Theoretical calculations and in situ spectroscopic characterizations validated that this configuration bypasses homolytic O−O cleavage, instead generating surface-activated PMS* species that mediate fast interfacial electron transfer rather than inefficient homogeneous aqueous oxidation. Frontier orbital theory demonstrates that such reactant-tailored interfacial process significantly narrows the molecular orbital gap (Δ E MO = 1.47 eV), facilitating targeted organic removal and accelerating key oxidation kinetics. The intensified inter-site interactions confer exceptional resistance to demetalation, enabling long-term stability (>100 h) for device-level water purification. This work redefines cooperative catalysis principles in multi-center catalysts and opens avenues for precise Fenton-like chemistry in advanced water treatment.