Optimizing the Electronic Structure of Iron Oxides via Nonmetallic Dopants for Enhanced Peroxidase Mimetic Catalysis.

Abstract

Efficiently enhancing the activity and selectivity of targeted nanozymes is a challenging task, primarily due to the inherent structural stability and heterogeneous atomic composition of traditional nanozymes. Herein, theoretical design is carried out to select Fe-based oxides (FO) nanozymes with high peroxidase (POD)-like activity by incorporating different nonmetallic atoms (N, P, S, and B). Among these dopants, B emerged as a superior candidate because it could effectively tune the adsorption energies of *OH intermediates and *H₂O₂, thereby endowing the nanozymes with superior POD-like performance. Leveraging this insight, Bdoped Fe-based oxides (FOB) is successfully synthesized, demonstrating remarkable POD-like activity and ultrafast reaction kinetics. Mechanistic investigations revealed that B doping enhances electron transfer and intermediate adsorption by increasing the electron density and reducing the coordination number of the Fe center, concomitantly lowering the energy barrier for hydroxyl radical (·OH) formation and the rate-determining step. As a proof of concept, a three-enzyme cascade colorimetric biosensor integrating acetylcholinesterase (AChE)-choline oxidase (ChOx)-POD is constructed to perform ultrasensitive and selective detection of AChE activity and inhibitors. This study establishes a novel framework for designing high enzyme-mimicking performance transition-metal oxide nanozymes with doping nonmetallic atoms, provoking an inspiration for the rational design of nanozymes by regulating the electronic and coordination environment.