Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are generally catalyzed by precious metals (Pt) and metal oxides (IrO₂) which still have many shortages including expensive price, poor selectivity and undesirable stability. In this work, we report a Mn⁰-doped CoN_x on N-doped porous carbon (Mn-CoN_x/N-PC) composite from carbonizing metal-organic framework (MOF) derivative as the dual-functional catalyst to boost both the ORR and OER performances. Owing to the strong coordination effect between nitrogen and metal elements, the introduction of N can obviously improve the content of Co-N-C active sites for ORR. Meanwhile, the Mn-doping significantly regulates the electronic structure of the Co element and increases the content of Co⁰ which provide efficient OER active sites. Mn-CoN_x/N-PC catalyst delivers super dual-functional activity with a half-wave potential of 0.85 V, better than the 20% Pt/C catalyst (0.82 V). When used in Zn-air batteries for testing, Mn-CoN_x/N-PC electrocatalyst shows a high power density (145 mW·cm⁻²) and good cycle performance.

It is of vital importance to design efficient and low-cost bifunctional catalysts for the electrochemical water splitting under alkaline and neutral pH conditions. In this work, we report an efficient and stable NiCo₂S₄/N, S co-doped reduced graphene oxide (NCS/NS-rGO) electrocatalyst for water splitting, in which NCS microspheres are composed of one-dimentional (1D) nanorods grown homogeneously on the surface of NS-rGOs). The synergetic effect, abundant active sites, and hybridization of NCS/NS-rGO endow their outstanding electrocatalytic performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both alkaline and neutral conditions. Furthermore, NCS/NS-rGO employed as both anode and cathode in a two-electrode alkaline and neutral system electrolyzers deliver 10 mA/cm² with the low cell voltage of 1.58 V in alkaline and 1.91 V in neutral condition. These results illustrate the rational design of carbon-supported nickel-cobalt based bifunctional materials for practical water splitting over a wide pH range.