Graphene-encapsulated cobalt nanoparticles embedded in porous nitrogen-doped graphitic carbon nanosheets as efficient electrocatalysts for oxygen reduction reaction

Transition metal and nitrogen (N) doped carbon materials are regarded as promising alternatives to expensive Pt-based catalysts for oxygen reduction reaction (ORR), thanks to their natural abundance, good stability and high energy conversion efficiency. Herein, a facile efficient pyrolysis approach was developed to prepare graphene-encapsulated Co nanoparticles (NPs) embedded in porous nitrogen-doped graphitic carbon nanosheets (Co@G/N-GCNs), in which g-C3N4 served as C and N sources, and cobalt phthalocyanine (CoPc) as the Co- and N-sources. The as-obtained catalyst exhibited exceptional ORR activity (E1/2 = 0.86 V vs. RHE), good durability (12 mV negative shift of E1/2 after 2000 cycles), and strong methanol resistance, surpassing those of commercial Pt/C catalyst in alkaline conditions. The pyrolysis temperature and entrapped contents of metal NPs had critical impacts on the ORR features. This work offers a feasible strategy for designing low-cost non-noble-metal catalysts for energy storage and conversion.