Flower-like NiCo2O4–CN as efficient bifunctional electrocatalyst for Zn-Air battery

Bifunctional transition metal oxide based electrocatalysts play an important role in oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for rechargeable metal-air batteries. Herein, we synthesize a kind of three-dimensional (3D) flower-like composite catalyst with NiCo2O4 and N doped carbon (NC) derived from g-C3N4, under hydrothermal conditions. The best NiCo2O4–CN catalyst shows a hierarchical structure composed of interconnected nanosheets, and exhibits versatile bifunctional ORR/OER electroactivities with a half-wave potential of 0.81 V for ORR and an overpotential of 383 mV for OER under a current density of 10 mA cm−2. The zinc-air battery with the NiCo2O4–CN cathode demonstrates superior peak power density (149.6 mW cm−2), excellent capacity performance up to 738.7 mAh g−1 and considerable durability, showing the feasibility of NiCo2O4–CN in electrochemical energy devices. •3D Flower-like NiCo2O4–CN composite catalyst with rich pores was synthesized.•Hydrothermal temperature can affect the content of N doping over carbon.•The NiCo2O4–CN-180 catalyst showed superior bifunctional ORR/OER performance.•The impressive activity is attributed to the collective effects.