An Advanced Nitrogen-Doped Graphene/Cobalt-Embedded Porous Carbon Polyhedron Hybrid for Efficient Catalysis of Oxygen Reduction and Water Splitting

A novel hybrid electrocatalyst consisting of nitrogen-doped graphene/cobalt-embedded porous carbon polyhedron (N/Co-doped PCP//NRGO) is prepared through simple pyrolysis of graphene oxide-supported cobalt-based zeolitic imidazolate-frameworks. Remarkable features of the porous carbon structure, N/Co-doping effect, introduction of NRGO, and good contact between N/Co-doped PCP and NRGO result in a high catalytic efficiency. The hybrid shows excellent electrocatalytic activities and kinetics for oxygen reduction reaction in basic media, which compares favorably with those of the Pt/C catalyst, together with superior durability, a four-electron pathway, and excellent methanol tolerance. The hybrid also exhibits superior performance for hydrogen evolution reaction, offering a low onset overpotential of 58 mV and a stable current density of 10 mA cm(-2) at 229 mV in acid media, as well as good catalytic performance for oxygen evolution reaction (a small overpotential of 1.66 V for 10 mA cm(-2) current density). The dual-active-site mechanism originating from synergic effects between N/Co-doped PCP and NRGO is responsible for the excellent performance of the hybrid. This development offers an attractive catalyst material for large-scale fuel cells and water splitting technologies.