Heteroengineered Fe ₂ N/CrN <i> _x </i> with Accelerated Proton‐Coupled Electron Transfer for Efficient Oxygen Reduction in Aluminum‐Air Batteries

Abstract The sluggish kinetics of the oxygen reduction reaction (ORR) impede the widespread adoption of renewable energy technologies. Here, a heterostructured Fe 2 N/CrN x @NC catalyst is presented, where CrN x clusters promote H 2 O dissociation and, in concert with Fe 2 N nanoparticles, optimize oxygen intermediates adsorption within an N‐doped carbon matrix. The CrN x ‐induced synergy is further confirmed by in situ Raman and infrared spectroscopy, kinetic isotope effect measurements, and theoretical analyses, which collectively reveal that the elaborate Fe 2 N–CrN x interface is pivotal in accelerating proton‐coupled electron transfer for ORR. As a result, Fe 2 N/CrN x @NC achieves a half‐wave potential of 0.935 V in 0.1 m KOH, exceeding Pt/C. When deployed as the air cathode in aluminum‐air batteries, Fe 2 N/CrN x @NC enables a high discharge voltage at 100 mA cm −2 and an outstanding specific capacity of 2286 mA h g Al −1 . This heterostructure engineering strategy, cooperatively manipulating water dissociation and intermediate adsorption, provides a generalized design paradigm for efficient aluminum‐air battery cathodes.