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

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 configura-tion (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 center dot OH production. Moreover, the enriched pyridinic N serve as contaminant adsorption sites shortening center dot 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.