Facile synthesis of carbon coated cobalt-cobalt molybdenum carbide as advanced bifunctional oxygen electrocatalyst for rechargeable Zn-air battery

•Co-Co6Mo6C2 @NC nano polyhedron was synthesized using ZIF-67 as a precursor.•The Co6Mo6C2 can significantly improve the OER catalytic activity of the catalyst.•The Co-Co6Mo6C2 @NC-5 exhibits a low OER overpotential of 270 mV at 10 mA cm−2.•The Co-Co6Mo6C2 @NC-5 exhibits a high ORR half-wave potential of 0.80 V.•The Co-Co6Mo6C2 @NC can be used as a bifunctional electrocatalyst for Zn-air battery. A high effective bifunctional electrocatalyst was developed for rechargeable Zn-air batteries by rational integrating high active Co sites for ORR and Co6Mo6C2 specie for OER. [Display omitted] To facilitate the development of rechargeable metal-air batteries, the exploration of high effective bifunctional electrocatalysts is essential. In this work, we report a facile strategy to synthesize N doped carbon (NC) encapsulated Co-Co6Mo6C2 (Co-Co6Mo6C2@NC) nano polyhedron using ZIF-67 as a precursor and investigated its catalytic performance for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The introduction of Co6Mo6C2 into Co@NC can significantly improve the OER catalytic activity of the catalyst, while the high ORR catalytic activity of the catalyst is maintained. Specifically, Co-Co6Mo6C2@NC-5 shows a decent half-wave potential of 0.80 V for ORR, and a very low overpotential of 270 mV at 10 mA cm−2 for OER, demonstrating its bifunctional activity. The rechargeable Zn-air battery assembled using Co-Co6Mo6C2@NC-5 exhibits a maximum power density of 90.75 mW cm−2 and a high specific capacity of 768 mA h g−1, as well as good durability of 50 h without attenuation in performance, highlighting its practical application.