Axial coordination tuning Fe single-atom catalysts for boosting H2O2 activation

Abstract

Precisely regulating the coordination microenvironment of single-atom catalysts (SACs) to achieve enhanced reactivity is significant and desired but still in its infancy. Herein, a coordination-tuned and pyrolysis-free strategy is reported for the fabrication of a Fenton-like SAC containing the axial five-coordinated configuration (Fe–N5). The N species on the N-doped graphene act as anchoring points for iron phthalocyanine (a typical Fe–N4 complex) to obtain isolated Fe–N5 sites, which significantly modulates the electronic state of Fe atoms and lowers the H2O2 activation barrier for •OH production. Moreover, the enriched pyridinic N serve as contaminant adsorption sites shortening •OH diffusion distance, establishing a dual-site reaction mechanism with Fe–N5 sites. As such, the Fe–N5 catalyst exhibits exceptional Fenton activity towards catalytic oxidation of phenol (k = 0.180 min−1). Our work unravels the dependence of Fenton activity on the single-atom coordination environment and provides a platform for precise engineering of SACs.