Abstract
While current methods use oxidizable metals as electron donors to effectively reduce Fe(3+), 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 (Fe(1)/B-graphene) and utilized H(2)O(2) as the electron source for efficient Fe(2+) 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 H(2)O(2) activation at Fe(1) sites (positive electrode) are replenished by electrons extracted from H(2)O(2) at B atoms (negative electrode), where the activation energy for H(2)O(2) oxidation is significantly lower than that at Fe(1) 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.