Thermal treated three-dimensional N-doped graphene as efficient metal free-catalyst for oxygen reduction reaction

N-doped graphene has attracted a considerable interest in the development of a new promising metal-free catalyst for oxygen reduction reaction (ORR) to replace platinum-based catalysts. Herein we reported a facile fabrication of three-dimensional N-doped graphene (GC) using graphitic carbon nitride (g-C3N4) and graphene oxide (GO) as raw materials. Urea was used as a precursor of synthesizing g-C3N4 and N doping. Thermal treatment has been done at different temperatures. As a result, a large surface area with a unique porous structure were obtained for the sample GC-900. Our catalyst showed an outstanding catalytic activity with superb stability and methanol tolerance. The structural characterizations of different materials demonstrated that the combination of an optimal heating temperature, a high nitrogen N content and a porous structure was essential for high ORR electrocatalytic activities. •A facile fabrication of 3D N-Doped graphene with a porous structure.•The doping with nitrogen enhances the catalytic activity by introducing defects sites.•Pyridinic N and graphitic N are the actives center for the catalyst with a high ORR performance.•A large surface area favors efficient ion adsorption/desorption but it is not the key factor to enhance the catalytic activity.