Deciphering Interfacial Electronic Interactions Between Iridium Oxide and Ni‐Based Supports for High‐Current‐Density Anion Exchange Membrane Water Electrolysis

ABSTRACT Enhancing the oxygen evolution reaction (OER) performance of Ir‐based catalysts while minimizing Ir usage is crucial for advancing anion exchange membrane water electrolyzers (AEMWEs). Herein, we present binder‐free iridium oxide (IrO ₂ )‐Ni‐based electrodes prepared via a liquid‐phase synthesis, which directly anchors an ultralow quantity of IrO ₂ nanoparticles onto versatile Ni‐based foams. This design enables systematic investigation of how Ni‐based support chemistry modulates interfacial electronic interactions and thereby dictates catalytic performance. Electrochemical measurements reveal that IrO ₂ on nickel phosphide (Ni ₂ P) exhibits the highest activity and durability, with a significantly low overpotential of 232 mV and stable operation over 400 h at 10 mA cm ⁻² . Spectroscopic and density functional theory (DFT) analyses reveal that strong interfacial charge transfer between IrO ₂ and Ni ₂ P enriches the electron density around Ir and downshifts the Ir d‐band center, thereby optimizing the adsorption energetics of OER intermediates and accelerating the reaction kinetics. The binder‐free configuration enhances mechanical integrity and mass transport, which enables high‐current‐density operation (3.1 A cm ⁻² at 2.0 V _cell ) under practical AEMWE conditions. Thus, the Ni‐based support material enables tuning of the interfacial electronic coupling and catalytic behavior of IrO ₂ , thereby supporting the development of binder‐free low Ir‐loaded electrodes for cost‐effective and durable AEMWEs.