▎ 摘　　要

The bimetallic nanoparticles of Ni and Fe co-modified reduced graphene oxide (rGO) aerogel were prepared by a fishnet-like one-step hydrothermal method, and the nitrogen atoms were successfully doped to the carbon layers with heat treatment of ammonia. By SEM and TEM, it could be observed that the rGO aerogel is a porous structure with particles of metal uniformly distributed on carbon sheets, and the sizes of nanoparticles were approximately 20-100 nm. The Raman results indicated that the GO was successfully reduced by ethylene glycol in the hydrothermal process. XPS results showed that nitrogen was introduced to rGO nanosheets, and Ni-Fe-NrGO possessed the higher contents of pyridinic N and graphitic N. XRD results suggested the Ni3Fe phase exists in the Ni-Fe-NrGO, which was consistent with EDX results. The electro-catalyzed oxygen reduction reaction (ORR) properties were evaluated by a rotating disk electrode (RDE). The Ni-Fe-NrGO sample showed synergistic effect with a relatively higher onset potential and diffusion-limiting current density of approximately 4.01 mA cm(-2), with an electron transfer number close to 4, and exhibited an excellent ORR performance compared with the commercial Pt/C electro-catalyst. Graphic abstract