A “two-pronged” strategy: Boosting electrocatalytic oxygen reduction reaction property based on the Ni–MnO synergistic effect and high conductivity of rod-like Ni–MnO/N–C composites prepared via simple solution-free route

To develop a low-cost and high-efficient electrocatalyst as a substitution of Pt/C for oxygen reduction reaction (ORR) is of great significance. We propose simple “two-pronged” strategy to boost synchronously the electrocatalytic activity and stability via the combination of the active MnO and metallic Ni with the conductive N-doped carbon (N–C) materials. The synergistic effect of active species between MnO and metallic Ni enables Ni–MnO/N–C composites to motivate-boost catalytic activity, the N–C greatly enhances the conductivity and endows Ni–MnO/N–C composites with large surface area for ORR. To our satisfaction, the Ni–MnO/N–C composites exhibits robust electrocatalytic ORR activity with the limiting current density (J) of 6.39 mA cm−2, the half-wave potential (E1/2) of 0.81 V vs. RHE and an ideal four-electron transfer pathway, competing to the commercial Pt/C. Furthermore, the Ni–MnO/N–C composites as a cathode in assembled Zn-air battery shows the power density of 179 mW cm−2, delivers the specific capacity of 702 mA h g−1 at a discharge current density of 10 mA cm−2 while utilizing 84% of the theoretical capacity (~835 mA h g−1). This work highlights a new feasible strategy to explore an efficient electrocatalyst via synchronously heightening the catalytic activity and conductivity.