Probing the Active Nitrogen Species in Nitrogen-Doped Carbon Nanozymes for Enhanced Oxidase-Like Activity

Nitrogen doping emerges as a potent approach to enhance the oxidase-like activity of carbon nanozymes. However, the unclear knowledge of the active nitrogen species within nitrogen-doped carbon nanozymes hinders the advancement of high-performance carbon nanozymes. Herein, a group of nitrogen-doped carbon (N/C) nanozymes with controllable nitrogen dopants are successfully synthesized via a dicyandiamide-assisted pyrolysis method. The intrinsic connection between different nitrogen configurations (pyridinic N, pyrrolic N, and graphitic N) in N/C nanozymes and the oxidase-like performance are experimentally investigated. The results confirm pyridinic N is the active nitrogen species in N/C nanozymes for enhanced oxidase-like activity. Theoretical calculations further reveal the potential regulatory mechanism is pyridinic N can increase the local charge density of neighboring carbon atoms and accelerate the adsorption and activation of molecular oxygen. Notably, the optimized N/C nanozyme with the highest pyridinic N ratio presents impressive oxidase-like performance, surpassing most of the previously reported oxidase-like materials. Moreover, the optimized N/C nanozyme exhibits excellent antibacterial properties and can be easily incorporated into common medical and hygiene products to give them spontaneous antibacterial properties. The work will facilitate the rational design of carbon nanozymes with high-performance oxidase-like activity for applications in the antibacterial field.