Boosting bifunctional oxygen electrocatalysis by integrating Fe–Nx moieties and FeNi nanoparticles for highly efficient and long-life rechargeable zinc–air batteries†

Realizing high-performance and long-life rechargeable zinc–air batteries (ZABs) requires developing efficient and robust bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as the low efficiency and short lifetime of bifunctional oxygen electrocatalysts greatly limit the practical application of rechargeable ZABs. Herein, based upon multi-component-dependent electrocatalytic activity and selectivity, we propose to synthesize a promising bifunctional oxygen electrocatalyst enriched with highly ORR-active atomically dispersed Fe–N_x sites and exceptionally efficient FeNi nanoparticles for the OER. Owing to this integration, the developed catalyst Ni₃@Fe-N-GNS exhibits a small potential gap for catalyzing both the ORR and OER, accordingly making it an ideal electrocatalyst for rechargeable Zn–air batteries. Impressively, when used as an air electrode, the corresponding ZAB exhibits a high peak power density of 171 mW cm⁻², a small charge–discharge voltage gap of 0.71 V at 5 mA cm⁻², and excellent charge–discharge cycling stability without much deviation after 180 h of a continuous run. The present work proposes a new avenue for the rational design of bifunctional electrocatalysts to make advances in electrochemical energy technologies.