Co@C,MnO-NAC via selective wrapping for effective oxygen electrocatalysis in rechargeable Zn–air batteries

Abstract

Exploring low-cost and active reversible oxygen electrocatalysts is desirable for efficient rechargeable Zn–air batteries. Herein, an efficient catalyst was prepared via in situ immobilizing Co and MnO hetero-nanoparticles onto N-doped hierarchical activated carbon (abbreviated as Co@C,MnO-NAC) using broussonetia papyrifera as the carbon source. The different redox properties of Co and Mn induced the selective wrapping of carbon shells on nanoparticles. The Co@C,MnO-NAC composite via selective wrapping possesses relatively independent oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) active centers and displays outstanding electrocatalytic activity for the synergistic effect between MnO, Co@C and NAC. It presents excellent ORR and OER catalytic performance with a small overpotential gap (E_OER − E_ORR = 0.72 V). An aqueous zinc–air battery based on Co@C,MnO-NAC exhibits an open-circuit voltage of 1.46 V and long-term stability of 110 cycles. This work provides a selective wrapping strategy for designing efficient metallic compound-activated carbon-based electrocatalysts to apply in energy conversion facilities.