Single-Atom Nanozyme Based on Mn-Center with Enhanced Peroxidase-like Activity for Organic Dye Degradation

Compared with natural enzymes, nanozymes have advantages such as high stability, low cost, and a broad application prospect. However, due to the low catalytic activity of conventional nanozymes, synthesizing nanozymes with excellent enzyme-like activity will be long-term work. Herein, we synthesized single-atom nanozymes centered on Mn with N, P, and S doped (Mn-SAzyme) with enhanced peroxidase-like (POD-like) activity. We found that the presence of the Mn metal center significantly increased the POD-like activity of the nanozyme, exhibiting catalytic properties consistent with Michaelis-Menten kinetics. The POD-like activity was measured to be 17.48 U/mg, which was higher than that of the sample without the metal center. Using methylene blue (MB) as the organic dye model, the degradation efficiency of Mn-SAzyme could reach 90.1% within 300 min at pH 6.5, within the H2O2 concentration of 0.1 M and 25 mg/L of nanozyme dosage. Free radical quenching experiments and electron paramagnetic resonance tests showed that center dot O2- and center dot OH were the key to degrading organic dyes. This work aims to explore more methods for synthesizing highly active nanozymes and successfully applying the synthesized nanozymes to the degradation of organic dyes.