Enhancing Oxygen Reduction Reaction Performance Through Abundant Single Fe Atoms for Advanced Zinc–Air Batteries

Iron- and nitrogen-codoped carbon (Fe–N–C) catalysts with Fe–N4 active sites offer a promising alternative to noble metal-based materials for the oxygen reduction reaction (ORR), which is essential for energy storage and conversion in applications such as fuel cells and metal–air batteries. This study presents a straightforward and scalable method to synthesize an efficient ORR electrocatalyst that consists of nitrogen-doped carbon and a high density of atomically dispersed single iron atoms, created through the pyrolysis of Fe-zeolitic imidazolate framework (Fe-ZIF-8) precursors. The Fe-ZIF-8 framework effectively restricts the migration and agglomeration of iron species, resulting in obtained Fe–N–C with conductive, mesoporous carbon structures and abundant Fe–N4 sites. This structure provides excellent electrocatalytic activity for the ORR, demonstrated by a positive onset potential of 0.985 V vs RHE and a half-wave potential of 0.905 V vs the reversible hydrogen electrode (RHE) in alkaline media, outperforming commercial Pt/C. Additionally, when used as the cathode in a zinc–air battery, the Fe–N–C catalyst delivers high maximum power densities of 170.1 mW cm–2, showcasing its potential for practical energy storage applications.