Origins of the peroxidase mimicking activities of graphene oxide from first principles

Graphene-based nanomaterials, including graphene oxide (GO) and reduced graphene oxide (rGO), play key roles in the nanozyme field. GO and rGO carrying various oxygen-containing functional groups, including epoxy, hydroxyl, ether, endoperoxide, carbonyl, carboxyl, and ester, have been reported to display peroxidase mimicking activities. However, the active center and the underlying mechanism responsible for its peroxidase mimicking activities still remain unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H 2 O 2 as the model reaction, we investigate the possible catalytic mechanisms using DFT calculations. The results indicate that the carbonyl groups are the active centers. The activation of the C&z.dbd;O bond is the key step in the catalytic cycle. The results will help realize the rational design of carbon-based nanozymes. The carbonyl groups are the active centers responsible for the peroxidase-mimicking activities of graphene oxides.