Highly durable iron single-atom catalysts for low-temperature zinc-air batteries by electronic regulation of adjacent iron nanoclusters

Durability of carbon-supported Fe single-atom catalysts has remained a critical issue for metal-air batteries. Herein, Fe single atoms with adjacent Fe nanoclusters supported on nitrogen-doped carbon aerogels (NCA/Fe_SA+NC) are prepared via a facile two-step pyrolysis procedure using biomass hydrogels as the precursor and template. The Fe atomic centers are found to exhibit an increased 3d electron density and decreased magnetic moment by the nanoclusters. This markedly enhances the oxygen reduction reaction activity and anti-oxidation stability of the FeN₄ sites, as compared to the nanocluster-free counterparts. With NCA/Fe_SA+NC as the cathode catalysts, a flexible zinc-air battery delivers a remarkable performance even at −40 °C, with an open circuit voltage as high as 1.47 V, power density 49 mW cm⁻², and excellent durability after 2300 continuous recharging/charging cycles. The performance is even higher at ambient temperature. These results highlight the significance of electronic manipulation in enhancing the durability of single atom catalysts.