Synergistic coupling of Mo₂N and Fe single atoms in hollow carbon enables robust bifunctional catalysis in zinc–air battery applications

Single-atom (SA) catalysts based on Fe-group elements are highly effective for the oxygen reduction reaction (ORR) in rechargeable zinc–air batteries (ZABs), yet their oxygen evolution reaction (OER) performance remains a critical bottleneck for practical applications. Here, we report a bifunctional electrocatalyst comprising ultrafine Mo₂N nanoparticles encapsulated within Fe SA-anchored N-doped hollow carbon heterostructures (Mo₂N@Fe–N–HC). The synergistic interaction between Mo₂N and densely distributed Fe SAs, combined with a hierarchical porous architecture, enhances reaction kinetics, optimizes ORR/OER intermediate adsorption energies, and improves mass transport. Mo₂N@Fe–N–HC outperforms commercial Pt/C and RuO₂ benchmarks, exhibiting exceptional bifunctional activity. ZABs incorporating Mo₂N@Fe–N–HC demonstrate high discharge power density and remarkable durability, with aqueous ZAB operating stably for over 650 h and solid-state ZAB for 130 h at −15 °C. This work offers a robust strategy for designing advanced electrocatalysts, advancing the efficiency and longevity of ZABs for practical energy storage solutions.