FeCo alloy nanoparticles embedded in N-doped carbon supported on highly defective ketjenblack as effective bifunctional electrocatalysts for rechargeable Zn-air batteries

The development of highly active non-precious metal-based electrocatalysts to accelerate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is an essential issue for practical application of metal-air batteries. Herein, hydrothermal and annealing processes are employed to prepare FeCo alloy nanoparticles in Ndoped carbon shells on a defect-rich carbon support (FeCoNC/D). The introduction of defect-rich carbon support combined with the strong coupling of distributed FeCo alloy and N-doped carbon shell efficiently enhances the electrocatalytic activity. The FeCoNC/D exhibits superior bifunctional electrocatalytic activity with a half-wave potential of 892 mV (vs. RHE) for the ORR and an overpotential of 362 mV to drive a current density of 10 mA cm-2 for the OER. Moreover, Zn-air secondary battery prepared with FeCoNC/D displays a higher specific capacity of 725 mA h gZn -1, a power density of 157 mW cm-2 at 245 mA cm-2, and long-term cycling stability compared to state-of-the-art Pt/C-RuO2.