Impeding Thermal Atomization Enables Synthesizing Fe ₂ N Cluster Liganded Single Fe‐Atom Catalyst for Highly Efficient Oxygen Reduction Reaction

Abstract

Abstract Anchoring a ligand, such as a functional group or a cluster, on the active metal center is an effective strategy for regulating the electronic structure of single‐atom catalysts (SACs). Herein, we present a nitridation‐induced‐clustering strategy to produce not only SAC Fe‐N 4 in N‐doped carbon nanorods, but also Fe 2 N cluster as a ligand anchored on the active Fe site (Fe 2 N nc /Fe 1 ‐N‐C). Unlike the conventional iron atomization process, the reactive nitridation process can generate thermodynamically stable Fe 2 N intermediates by nitriding the initially formed iron oxide, thereby impeding subsequent thermal atomization to fabricate Fe 2 N nc /Fe 1 ‐N‐C catalysts. Compared to the conventional SAC Fe 1 ‐N‐C with Fe‐N 4 active sites, the Fe 2 N nc /Fe 1 ‐N‐C nanorods are more active for oxygen reduction reaction (ORR), yielding a record high half‐wave potential of 0.957 V versus RHE in alkaline condition. The Fe 2 N nc /Fe 1 ‐N‐C nanorods can be utilized as air‐cathode catalysts for Zn‐air batteries with a charge‐discharge gap of only ∼0.658 V and outstanding cyclability up to 1000 h. Theoretical calculations show that the Fe 2 N nc ligands indeed modified the electronic structures of Fe‐N 4 sites, leading to a lower adsorption energy for the ORR intermediate OH* and facilitating the desorption of OH* and thus higher activity for ORR.