Integrating NiCo Alloys with Their Oxides as Efficient Bifunctional Cathode Catalysts for Rechargeable Zinc-Air Batteries

The lack of high-efficient, low-cost, and durable bifunctional electrocatalysts that act simultaneously for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is currently one of the major obstacles to commercializing the electrical rechargeability of zinc-air batteries. A nanocomposite CoO-NiO-NiCo bifunctional electrocatalyst supported by nitrogen-doped multiwall carbon nanotubes (NCNT/CoO-NiO-NiCo) exhibits excellent activity and stability for the ORR/OER in alkaline media. More importantly, real air cathodes made from the bifunctional NCNT/CoO-NiO-NiCo catalysts further demonstrated superior performance to state-of-the-art Pt/C or Pt/C+IrO₂ catalysts in primary and rechargeable zinc-air batteries. A NiCo alloy-based bifunctional electrocatalyst (NCNT/CoO-NiO-NiCo) exhibits excellent activity and stability in alkaline solutions for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). When integrated into air cathodes of primary and rechargeable zinc-air batteries, the performance of NCNT/CoO-NiO-NiCo is superior or comparable to Pt/C or (Pt/C+IrO₂)-based air cathodes.