Doping Nitrogen into Q‑Graphene by Plasma Treatment toward Peroxidase Mimics with Enhanced Catalysis

A facile and efficient plasma treatment strategy has been applied for the first time to dope heteroatom nitrogen (N) into Q-graphene (QG) under ambient temperature toward a carbon-based green nanozyme. It was discovered that the resulting N doped QG (N-QG) nanozyme can present the greatly enhanced catalysis activity, which is nearly 5-fold higher than that of pristine QG, as comparably revealed by the kinetic studies. Herein, the plasma treatment-assisted N doping could improve the conductivity (hydrophilicity) and create the surface defects of QG so as to promote the electron transferring toward the enhanced catalytic activities of N-QG. Furthermore, the catalase, superoxide dismutase, and oxidase-like catalysis activities of N-QG were explored, indicating the N doping could endow the obtained nanozyme with a high specificity of peroxidase-like catalysis. The application feasibility of the developed N-QG nanozyme was demonstrated subsequently by the catalysis-based colorimetric assays for H2O2 in milk samples, with the linear range from 2.00 to 1500 μM. Importantly, such a plasma-assisted heteroatom doping route may open a door toward the large-scale applications for the rational designs of various enzyme mimics with improved catalysis performances.