High-performance zinc–air batteries enabled by hybridizing atomically dispersed FeN2 with Co3O4 nanoparticles

Abstract

The development of rechargeable Zn–air batteries is greatly limited by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here we rationally design a high-performance ORR/OER hybrid catalyst by hybridizing a hierarchically porous atomically dispersed FeN₂ catalyst with uniform Co₃O₄ nanoparticles. Such a catalyst exhibits superior bifunctional activity towards the ORR and OER with a half-wave potential of 0.886 V (vs. the reversible hydrogen electrode, RHE) and an overpotential of 0.227 V at 10 mA cm⁻² in 0.1 M KOH compared to those of Pt/C and RuO₂/C benchmark catalysts. The resulting Zn–air batteries can deliver an ultrahigh peak power density of 236 mW cm⁻² and a long discharge–charge cycle of over 165 h at 5 mA cm⁻². The density functional theory calculations reveal that the FeN₂ active sites significantly improve the ORR and OER catalytic activities simultaneously. The results indicate that the hybrid catalyst can effectively enhance the performance of zinc–air batteries toward practical application.