▎ 摘 要
Development of efficient electrocatalysts for the oxygen reduction reaction (ORR) is vitally important for the commercialization of metal-air batteries. In this work, we demonstrate a novel graphene coated/Co9S8 nanoparticles-embedded nitrogen doped porous carbon dodecahedron hybrid (Co9S8/NPCP@rGO) prepared by the pyrolysis and sulphuration of precursors composing of graphene oxide and zeolitic imidazolate-frameworks (ZIP). The Co9S8/NPCP@rGO hybrid is used as a highly efficient nonprecious metal electrocatalyst for oxygen reduction and exhibits more positive onset potential and half-wave potential, higher limiting current density, lower Tafel slope, and better durability and methanol tolerance in alkaline media in comparison to the commercial 20 wt.% Pt/C catalyst. The greatly improved electrocatalytic performance of Co9S8/NPCP@rGO can be attributed to the unique structure with Co9S8 nanoparticles dispersed uniformly inside nitrogen doped porous carbon matrix, and the synergistic effect between Co9S8/NPCP polyhedral hybrid and rGO. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.