Bimetallic cobalt molybdenum carbide-cobalt composites as superior bifunctional oxygen electrocatalysts for Zn-air batteries

Designing composite material that contains high-active oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) species is an effective strategy for synthesizing bifunctional electrocatalysts for Zn-air batteries. In this work, we first reported the preparation of the Co6Mo6C2-Co@NC nanorod composite by using the Mo-polydopamine@ZIF-67 composite as the precursor. Because of the highly active Co6Mo6C2 for OER and the high-active Co for ORR, the Co6Mo6C2-Co@NC exhibits superior OER activity, with a low overpotential of 268 mV at 10 mA cm(-2), and high ORR performance. When used as bifunctional electrocatalysts for the Zn-air battery, the battery exhibits a high open-circuit voltage of 1.38 V and a specific capacity of 760 mA/h/g, as well as very high stability of up to 300 h with no obvious increase in charge-discharge voltage gap. (C) 2020 Elsevier Ltd. All rights reserved.