Enhancing\nOxygen Reduction Reaction Performance Through\nAbundant Single Fe Atoms for Advanced Zinc–Air Batteries

Iron-\nand nitrogen-codoped carbon (Fe–N–C) catalysts\nwith Fe–N<sub>4</sub> active sites offer a promising alternative\nto noble metal-based materials for the oxygen reduction reaction (ORR),\nwhich is essential for energy storage and conversion in applications\nsuch as fuel cells and metal–air batteries. This study presents\na straightforward and scalable method to synthesize an efficient ORR\nelectrocatalyst that consists of nitrogen-doped carbon and a high\ndensity of atomically dispersed single iron atoms, created through\nthe pyrolysis of Fe-zeolitic imidazolate framework (Fe-ZIF-8) precursors.\nThe Fe-ZIF-8 framework effectively restricts the migration and agglomeration\nof iron species, resulting in obtained Fe–N–C with conductive,\nmesoporous carbon structures and abundant Fe–N<sub>4</sub> sites.\nThis structure provides excellent electrocatalytic activity for the\nORR, demonstrated by a positive onset potential of 0.985 V vs RHE\nand a half-wave potential of 0.905 V vs the reversible hydrogen electrode\n(RHE) in alkaline media, outperforming commercial Pt/C. Additionally,\nwhen used as the cathode in a zinc–air battery, the Fe–N–C\ncatalyst delivers high maximum power densities of 170.1 mW cm<sup>–2</sup>, showcasing its potential for practical energy storage\napplications.