MnS doping regulating Co active sites on fibrous cobalt nitride as bifunctional oxygen electrocatalyst for high-performance Zn-air battery

Aiming to achieve high-efficiency bifunctional catalysts, doping engineering is applied to construct bifunctional catalysts for oxygen electrodes in Zn-air batteries to strengthen the catalytic kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, MnS doped cobalt nitride catalyst (MnS/CoN _x) with divergent fiber morphology is prepared by low temperature nitriding for the self-assembling layered double hydroxides (LDH). The MnS/CoN _x shows excellent electrical conductivity and improved catalytic activity on ORR and OER with low overpotential of 290 mV at 10 mA cm ⁻² and a good half-wave potential of 0.80 V in ORR compared with CoNx and MnO/CoN _x. The contribution of the increased bifunctional catalytic performance is possible from the more active center Co ³⁺ and Mn ⁴⁺, and the elevated electron transport resulted from the opportune high conductive MnS doping. The MnS/CoN _x catalyst-driven Zn-air battery achieves a higher power density of 228 mW cm ⁻² and the excellent long-term stability of 500 h at 20 mA cm ⁻² far surpassing the commercial Pt/C+RuO ₂ catalyst.