Porous Co-N-C ORR catalysts of high performance synthesized with ZIF-67 templates

Oxygen reduction reaction (ORR) is a multiphase reaction, involving electron transfer and ion diffusion. A high-performance ORR catalyst must have high activity and good-pore characteristics. In this study, we developed a new strategy to synthesize porous Co-N-C catalysts based on zeolitic imidazolate frameworks (ZIF-67) as both templates and nitrogen sources. During high-temperature annealing treatment of ZIF-67/ZIF-8/graphene oxide, ZIF-8 and ZIF-67 were decomposed to Co-N-C and ZnO. Then ZnO was reduced to volatile zinc at 920 °C, resulting in porous Co-N-C catalysts. Those Co-N-C catalysts showed a high limit current density of 6.23 mA cm−2, which was higher than the Co-N-C arising from ZIF-67/graphene oxide and N-doped carbon from ZIF-8/graphene oxide. The improved performance can be ascribed to the presence of Co-N-C and high specific surface area in Co-N-C from ZIF-67/ZIF-8/graphene oxide. The presence route may provide a new insight for synthesis and application of zeolitic imidazolate frameworks in energy fields.