High‐Entropy Alloy Navigating the Activity‐Durability Trade‐Off in Low‐Iridium Oxygen Evolution Reaction Catalyst

ABSTRACT Switching the oxygen evolution reaction (OER) pathway on Ir‐based catalysts from the adsorbate evolution mechanism (AEM) to the lattice oxygen mechanism (LOM) is an effective strategy to improve the intrinsic activity, but it comes at the expense of structural stability. Herein, we designed an IrRuCoMnV high‐entropy alloy catalyst with an IrRu‐rich surface (HEA@IrRu) incorporating oxophilic transition metals (Mn, V). This catalyst not only catalyzes the OER via the LOM pathway with inherent high activity, but also exhibits greatly improved structural stability. Combined experimental and theoretical results reveal that the oxophilic metals can promptly replenish the oxygen vacancies, thereby inhibiting the accumulation of oxygen vacancies and ensuring the structural integrity. Proton exchange membrane water electrolysis integrated with this catalyst as the anode delivers a low cell voltage (1.76 V at 2.0 A cm −2 , 65°C) and excellent long‐term stability while reducing the Ir usage to 0.4 mg cm −2 . This work presents a new viable strategy to simultaneously improve the OER activity and durability of low‐Ir catalysts.