Manganese dioxide nanotube and nitrogen-doped carbon nanotube based composite bifunctional catalyst for rechargeable zinc-air battery

A composite bifunctional catalyst (MnO2–NCNT) was prepared from manganese dioxide (MnO2) nanotubes and nitrogen-doped carbon nanotubes (NCNT) for the purpose of oxygen reduction (ORR) and evolution (OER) catalysis in the rechargeable zinc-air battery. From the half cell test, the MnO2–NCNT composite illustrated excellent activities towards ORR and OER in alkaline conditions. Based on the battery test, the composite catalyst displayed outstanding discharge and charge performance while maintaining good stability. In both cases, the marked performance improvements from MnO2–NCNT compared favourably to the NCNT and MnO2, which are the constituents of the composite. In particular, MnO2–NCNT exhibited improved half wave potential by 220 mV compared to MnO2 and much superior OER stability compared to NCNT based on the rotating ring disk voltammetry results. According to battery test, MnO2–NCNT decrease the battery resistance by 34% and concurrently improved the durability, discharge and charge performance in comparison to the MnO2 nanotubes.

► MnO2–NCNT composite catalyst developed by simplistic procedure.
► Excellent bifunctional activity and stability demonstrated for alkaline conditions.
► Bifunctional activity results from the NCNT and MnO2 nanotube components.
► Battery cycling tests performed in zinc-air battery illustrate good rechargeability.
► MnO2–NCNT shows lower charge transfer resistance compared to unsupported MnO2 nanotube.