Atomically dispersed iron catalyst supported on nitrogen doped biomass aerogels for high-performance rechargeable zinc-air batteries

Atomic dispersed metal-nitrogen-carbon (M-N-C) catalysts have shown great promise as efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in metal-air batteries. In this work, we report the scalable synthesis of atomically dispersed iron single-atom catalysts supported on nitrogen-doped biomass-derived carbon aerogels (Fe-N-C) via direct high-temperature gas transport based on iron foil. The optimal Fe-N-C catalyst prepared at 1000 °C with 0.67 wt% Fe loading exhibits outstanding ORR activity with a half-wave potential of 0.84 V, along with robust OER performance reaching 10 mA/cm 2 at 250 mV overpotential. The catalyst also demonstrates remarkable stability over 5000 cycles. Owing to the excellent ORR and OER activity and stability, an aqueous rechargeable zinc-air battery fabricated with Fe-N-C as the bifunctional air cathode delivers a high open circuit voltage of 1.49 V, peak power density of 125.4 mW/cm 2 , and exceptional cycling stability over 147 h. The biomass-derived porous carbon structure, nitrogen doping, and isolated Fe single atoms act synergistically to optimize oxygen reaction kinetics, active site density, and stability. Our work provides a scalable strategy to produce high-performance M-N-C catalysts for commercially viable metal-air batteries.