Co, N co-doped carbon nanosheets coupled with NiCo2O4 as an efficient bifunctional oxygen catalyst for Zn-air batteries

Developing of inexpensive and efficient bifunctional oxygen catalysts is important for the zinc-air batteries (ZABs). Here, a composite of Co, N co-doped carbon nanosheets coupled with NiCo 2 O 4 (NiCo 2 O 4 /CoNC-NS) is developed as oxygen catalyst, which has good bifunctional oxygen catalytic activity and durability. Specifically, the half-wave potential of oxygen reduction reactions (ORR) is 0.849 V, and the overpotential of oxygen evolution reactions (OER) is 1.582 V at a current density of 10 mA cm −2 . And the assembled liquid ZABs based on NiCo 2 O 4 /CoNC-NS exhibit high open circuit potential (OCP, 1.482 V), high peak power density (148.3 mW cm −2 ) and large specific capacity (699.9 mAh g −1 ) with long-term stability. Moreover, the further assembled solid ZABs can also provide high OCP (1.401 V), good power density (58.1 mW cm −2 ) and superior stability. This work would provide a good reference for the development of other advanced oxygen catalyst in future. • A good oxygen catalyst composing of CoNC-NS coupled with NiCo 2 O 4 is developed. • This NiCo 2 O 4 /CoNC-NS has good ORR/OER performance almost close to the benchmark of noble metal. • Both NiCo 2 O 4 /CoNC-NS-driven liquid and solid state ZABs exhibit good performance.