Confined coordination to construct lignin‐based Fe single atoms and CoFe clusters for accelerated oxygen reduction

Abstract

To advance zinc‐air batteries (ZABs), it is crucial to engineer cost‐effective, highly efficient, and durable transition metal‐based catalysts for the oxygen reduction reaction (ORR). In this study, a lignin‐based coordination framework is established through solvent‐induced assembly. Leveraging the confinement effects of this structure, the catalysts containing high‐density Fe single atoms and CoFe nanoalloy clusters (CoFe/FeSA‐NC) are successfully constructed. In situ characterizations and theoretical calculations demonstrate that the CoFe nanoalloy clusters change the rate‐determining step (RDS) from *OH generation to *OOH formation, thereby substantially lowering the reaction energy barrier. The strong coordination between metal and lignin promotes charge transfer, forming a highly active FeSA‐NC interface that enhances the ORR activity and stability. 0.5‐CoFe/FeSA‐NC exhibits a half‐wave potential of 0.873 V. Additionally, the constructed ZABs achieve a maximum power density of 186.6 mW cm ⁻² with stability exceeding 550 h, significantly surpassing that of the commercial Pt/C catalyst (99.7 mW cm ⁻² ).