Manipulating the Second Coordination Shell of Single-Atom Fe for Enhanced Fenton Reaction

While current methods use oxidizable metals as electron donors to effectively reduce Fe³⁺, they suffer from the irreversible oxidation of these metals, ultimately compromising the catalyst's longevity. To address this challenge, we engineered the second coordination shell of a single-atom Fe center by doping boron (B) onto a graphene-based support (Fe₁/B-graphene) and utilized H₂O₂ as the electron source for efficient Fe²⁺ regeneration. Experimental results, supported by theoretical calculations, revealed that the Fe-O-B motif functions like a micro galvanic cell, with intermediary O atoms facilitating electron transfer between electrodes. Specifically, electrons consumed during H₂O₂ activation at Fe₁ sites (positive electrode) are replenished by electrons extracted from H₂O₂ at B atoms (negative electrode), where the activation energy for H₂O₂ oxidation is significantly lower than that at Fe₁ sites. This study offers inspirational insights into the design of Fenton catalysts through precise regulation of the second coordination shell, demonstrating the potential of tailoring the outer coordination environment of single-atom catalysts to enhance catalytic performance across various reactions.