• • The Fe/FeIr-NC catalyst achieves an ORR half-wave potential of 0.91 V and an OER overpotential of 250 mV at 10 mA cm−2, yielding a bifunctional gap (ΔE) of 0.57 V—the lowest reported for single- and dual-atom catalysts, directly addressing the activity trade-off that limits conventional bifunctional electrocatalysts.
• • In a flexible fiber zinc-air battery, the catalyst delivers a peak power density of 3920 W kg−1, a 1.4-fold increase in energy efficiency, and a 2.6-fold extension in cycle life compared to the commercial Pt/C + IrO2 benchmark, demonstrating practical viability for wearable power sources.
• • The spatial decoupling of Fe single atoms (ORR) and Fe–Ir dual-atom pairs (OER) enables independent optimization of each reaction, overcoming the thermodynamic scaling relationship that typically compromises bifunctional performance.
• • The catalyst is synthesized on a nitrogen-doped carbon matrix, providing a scalable platform for atomically dispersed metal catalysts, with potential for extension to other metal combinations and applications beyond zinc-air batteries.