Facile Synthesis Toward Surface Decorated Ir1Ox@Pd35 with Low Iridium Content for Highly Efficient and Durable Proton Exchange Membrane Water Electrolyzer

Abstract Herein, we introduce an iridium‐decorated palladium nanocluster (Ir 1 O x @Pd 35 ) synthesized via an epoxide‐assisted sol‐gel method. The nanocluster had a unique surface‐decorated structure, as confirmed by transmission electron microscopy (TEM) and synchrotron‐based X‐ray photoelectron spectroscopy (XPS). Structural characterization indicated that the Ir shell inhibited Pd growth by forming a porous surface‐decorated structure, contributing to enhanced activity. With low Ir loading (0.10 mg Ir cm −2 ), Ir 1 O x @Pd 35 exhibits superior oxygen evolution reaction activity and durability compared to commercial IrO 2 . Ir 1 O x @Pd 35 also exhibited high performance and durability in a proton exchange membrane water electrolyzer (PEMWE), including a 20‐fold increase in Ir utilization compared to IrO 2 ‐based systems. Featuring tailored structures and enhanced Ir utilization, Ir 1 O x @Pd 35 offers a sustainable path for PEMWEs.