Mn, N co-doped Co nanoparticles/porous carbon as air cathode for highly efficient rechargeable Zn-air batteries

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.