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 CoNx on N-doped porous carbon (Mn-CoNx/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-CoNx/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-CoNx/N-PC electrocatalyst shows a high power density (145 mW·cm−2) and good cycle performance.