▎ 摘　　要

The catalysts for oxygen reduction reaction (ORR) have been the research hot-pot of electrochemical energy, especially the graphene-based non-precious metal catalysts. Generally, the properties of graphene for ORR are affected by their specific surface areas, doping atoms, morphology, and so on. In this study, nitrogen-doped mesoporous graphene spheres (NGS) have been synthesized through a simple and efficient spray drying approach. It was discovered that SiO2 played a key role in the ORR catalytic property of NGS. The addition of SiO2 could promote the formation of spherical structure of graphene oxide, so that the material could wrap the nitrogen source in and reduce the nitrogen loss in the process of heat treatment, which would increase the nitrogen content. Simultaneously, the mesoporous structure with high specific surface area can be obtained by removing SiO2 with HF, which can increase the contact area between catalyst and reactant, improve the efficiency of mass transfer, and further improve the ORR catalytic performance of NGS. Compared with commercial Pt/C, NGS demonstrates higher electrocatalytic activity and exhibits good durability.