NaCl Modification: A Novel Strategy for Boosting Oxygen Evolution Activity of Ir Catalysts in Proton Exchange Membrane Water Electrolysis

Abstract The development of high‐performance, low‐content Ir catalysts is essential for enhancing the cost efficiency of anode catalysts and accelerating the widespread adoption of proton exchange membrane water electrolysis (PEMWE) for sustainable hydrogen production. Existing strategies, such as reducing catalyst particle size and alloying with non‐precious metals, have shown limited success in surpassing the intrinsic activity of commercial IrO ₂ catalysts. This study presents a novel synthesis strategy for IrO _x catalyst using NaCl as a structure modifier, delivering a catalyst (IrO _x _NaCl) that achieves an impressive current density of 2.48 A cm ⁻² at 1.9 V, outperforming commercial IrO ₂ (2.35 A cm ⁻² ), even under low Ir catalyst loading in single‐cell PEMWE test. Ex situ and in situ spectroscopic analyses suggested that NaCl incorporation effectively modulates the oxidation states and coordination structure of IrO _x , leading to enhanced activity, improved stability, and greater cost efficiency. These findings offer a transformative pathway for designing advanced Ir‐based catalysts for PEMWE applications.