▎ 摘　　要

To balance the anchoring sites and conductivity of the catalyst supports is a dilemma in electrocatalytic oxygen reduction reaction (ORR). Nitrogen-doped mesoporous graphene (N-MG) with large surface area, high porosity, and superior intrinsic conductivity has been developed to address this issue. Using N-MG as the backbone, a hybrid catalyst of Co3O4 nanocrystals embedded on N-MG (Co3O4/N-MG) was prepared for the electrocatalytic ORR in alkaline media. The Co3O4/N-MG showed high catalytic activity for the four-electron ORR, giving a more positive onset potential (0.93 V vs RHE) and a higher current density. The unique property of N-MG and the synergetic effect of Co3O4 and N-MG are prominent for ORR. With improved electrocatalytic activity and durability, the Co3O4/N-MG can be an efficient nonprecious metal catalyst and potentially used to substitute the platinum-based cathode catalysts in fuel cells and metal-air batteries.