Asymmetric electronic coupling in Fe–Cu dual-atom sites enables accelerated oxygen electrocatalysis for high-performance Zn–air batteries

Abstract

Dual-atom catalysts (DACs) offer unique opportunities for advanced electrocatalysis by harnessing synergistic interactions between neighboring metal centers, yet precisely constructing heteronuclear dual sites with well-defined coordination environments remains challenging. Herein, we develop a coordination-environment engineering strategy to embed Fe–Cu dual-atom sites within porous N-doped carbon nanotubes (FeCu-NCNT). The reconstructed Fe–N₄ and Cu–N₄ motifs induce strong electronic coupling and asymmetric charge redistribution, thereby optimizing the adsorption and activation of oxygen intermediates. Consequently, FeCu-NCNT exhibits exceptional bifunctional electrocatalytic activity and durability toward both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media, surpassing commercial Pt/C and RuO₂ catalysts. Density functional theory (DFT) calculations reveal that the Fe–Cu dual sites modulate Fe–O binding at the potential-determining step, effectively reducing energy barriers and accelerating reaction kinetics. When employed as an air cathode in zinc–air batteries, FeCu-NCNT delivers high peak power densities of 168.7 mW cm⁻² in liquid-state and 135.1 mW cm⁻² in flexible solid-state configurations, along with excellent cycling stability. This work establishes a generalizable strategy for tailoring dual-site coordination and electronic structures to advance high-performance bifunctional catalysts for sustainable energy conversion and storage.