Cobaltic Core-Carbon Shell Nanoparticles/N-Doped Graphene Composites as Efficient Electrocatalyst for Oxygen Reduction Reaction

The oxygen reduction reaction(ORR) catalysts of fuel cells with low cost, high electrocatalytic properties are desirable but challenging. Herein, an effective and facile route was developed to synthesize cobaltic core-carbon shell nanoparticles/N-Doped Graphene (CS−Co/NGs), which can serve as efficient electrocatalysts for ORR. The MOFs in the process acted as the carbon source and nitrogen source, and the polyethyleneimine (PEI) was employed as another special nitrogen source which can also avoid aggregation of the MOFs, then composited with graphene and carbonized at different temperatures under Ar atmosphere, all samples showed electrocatalytic activity for ORRs in alkaline media. CS−Co/NG-650 exhibited superior catalytic activity, the onset potential was −0.075 V and the half-wave potential was −0.150 V (vs. Ag/AgCl), even 15 mV surpassed than that of Pt/C (0.165 V), it also displayed excellent long-term durability and outstanding methanol tolerance. The superb catalytic performance was attributed to the generated mesoporous, the core-shell nanostructure derived from MOFs, the proper nitrogen source and the high conductivity of the graphene carbon matrix.