Nitrogen-Doped Carbon Nanomaterials as Highly Active and Specific Peroxidase Mimics

Nanozymes, the enzyme-mimicking nanomaterials, have been developed to overcome the low stability and high cost of natural enzymes. Unlike highly active and specific enzymes, however, the catalytic activities of nanozymes are moderate and lack specificity. To address these issues, herein we demonstrated an effective and general strategy to specifically enhance the peroxidase-mimicking activities of carbon nanozymes. By doping heteroatom nitrogen (N) into reduced graphene oxide (rGO) and mesoporous carbon (MC), their peroxidase-mimicking activities were enhanced by over 100- and 60-fold, respectively. Moreover, N-doping did not significantly affect the oxidase-, superoxide dismutase (SOD)-, or catalase-mimicking activities of rGO and MC, demonstrating a specific enhancement of the peroxidase-mimicking activities. To understand the origin of the specific enhancement, we performed density functional theory calculations to examine the catalytic reaction mechanisms responsible for the peroxidase-, catalase-, oxidase-, and SOD-mimicking activities of N-doped rGO (N-rGO). We revealed that N-rGO selectively activated H2O2 rather than O2 and •O2– by forming and stabilizing radical oxygen species adjacent to the N sites of N-rGO. The radical oxygen species then oxidized peroxidase substrates, endowing N-rGO with peroxidase-mimicking activity. This study will aid in the rational design of highly active and specific peroxidase mimics and help elucidate the catalytic mechanisms of nanozymes