▎ 摘　　要

Three-dimensional nitrogen-doped graphene (3D-NG@SiO2) is prepared by pyrolyzing poly (o-phenylenediamine) (POPD) with high nitrogen content. POPD is prepared via an in situ chemical oxidation polymerization of o-phenylenediamine (OPD) in acetic acid with silica colloid as templates. The optimum parameter is OPD:SiO2 = 1:2, pyrolysis @ 900 degrees C. SEM and TEM images show the wrinkled and porous graphene structures. Raman spectra indicate that 3D-NG@SiO2 consists of 4-6 layers graphene. N-2 adsorption-desorption isotherms reveal that the pore size distributions mainly centralize at 5-10 nm. XRD illustrates the amorphous structure. XPS analysis shows that the nitrogen content is 3.6% and nitrogen mainly exists in the form of pyridinic nitrogen and pyrrolic nitrogen. The oxygen reduction reaction (ORR) performance investigated using a rotating disk electrode shows that the initial potential of 3D-NG@SiO2 is 0.08 V (vs. Hg/HgO). The electron transfer number is 3.92 @ -0.3 V (vs. Hg/HgO), indicating that 3D-NG@SiO2 mainly occurs via a four electron process. The oxygen reduction current density decreases by 21% after 60 h in the chronoamperometry test. The CVs manifests a current density loss of 0.16 mA cm(-2) after scanning for 5000 cycles. The high activity and durability indicate the promising potential of 3D-NG@SiO2 as ORR catalysts. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.