Anchored NiCoMnS4 nanoparticles on N-doped rGO: High-performance bifunctional electrocatalysts for rechargeable Zn-Air batteries

The vast commercialization of advanced energy storage/conversion technologies like rechargeable metal–air batteries and regenerative fuel cells is greatly tied to the development of efficient catalysts capable of proceeding the pertinent electrochemical processes like oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Hence, exploiting an ideal bifunctional catalyst, e.g. the one includes dual active sites for both reactions, is of high interest and importance. Herein, a novel nonprecious-metal bifunctional catalyst based on a quaternary mixed metal sulfide synergized with nitrogen-doped reduced graphene oxide (NiCoMnS4/N-rGO) is synthesized through a simple anion-exchange route. The unique composition and synergism arising from uniformly anchoring the metal sulfide nanoparticles on N-rGO endow the as-prepared catalyst with remarkable electrocatalytic activity and durability towards ORR and OER. Importantly, the excellent electrocatalytic performance of NiCoMnS4/N-rGO hybrid was demonstrated in rechargeable Zn-air batteries (ZABs) as a real application. Accordingly, rechargeable ZABs assembled by NiCoMnS4/N-rGO hybrid-based air cathodes exhibit high capacity, energy density and excellent rate capability as well as favorable cycling stability. The outstanding performance of this NiCoMnS4/N-rGO hybrid together with the simplicity of synthetic method, make this hybrid promising as a highly efficient air-cathode catalyst for energy-related applications including high-performance rechargeable ZABs.