Axial N Ligand‐Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single‐Atoms Nanozymes

Learning and studying the structure–activity relationship in the bio‐enzymes is conducive to the design of nanozymes for energy and environmental application. Herein, Fe single‐atom nanozymes (Fe‐SANs) with Fe–N(5) site, inspired by the structure of cytochromes P450 (CYPs), are developed and characterized. Similar to the CYPs, the hyperoxide can activate the Fe(III) center of Fe‐SANs to generate Fe(IV)=O intermediately, which can transfer oxygen to the substrate with ultrafast speed. Particularly, using the peroxymonosulfate (PMS)‐activated Fe‐SANs to oxidize sulfamethoxazole, a typical antibiotic contaminant, as the model hyperoxides activation reaction, the excellent activity within 284 min(−1) g(−1) ((catalyst)) mmol(−1) ((PMS)) oxidation rate and 91.6% selectivity to the Fe(IV)=O intermediate oxidation are demonstrated. More importantly, instead of promoting PMS adsorption, the axial N ligand modulates the electron structure of FeN(5) SANs for the lower reaction energy barrier and promotes electron transfer to PMS to produce Fe(IV)=O intermediate with high selectivity. The highlight of the axial N coordination in the nanozymes in this work provides deep insight to guide the design and development of nanozymes nearly to the bio‐enzyme with excellent activity and selectivity.