Embedded Ir─Ru Single‐Atom Alloy with Self‐Limiting Motifs for Sustainable Proton Exchange Membrane Water Electrolysis

Abstract Designing acid‐stable anodic electrocatalysts with low noble‐metal loading is essential for the industrial‐scale application of proton exchange membrane water electrolysis (PEMWE). However, existing catalyst systems struggle to fully utilize the intrinsic properties of active sites. Here, a precisely engineered nanocatalyst is unveiled through a hierarchical atomic assembly strategy for synthesis, featuring an ultralow‐content Ir─Ru single‐atom alloy integrated into robust titanium dioxide nanowires (Ir 1 Ru/TiO 2 ). This lattice‐embedded structure induces the support to reduce the dissolution and excessive oxidation of Ru/Ir sites through strong interfacial coupling, significantly enhancing the corrosion resistance of catalysts. Moreover, atomically dispersed Ir induces the formation of uniquely shortened Ru─O ligand bonds, serving as stable self‐limiting motifs, in contrast to the conventional formation of amorphous oxide layers. The Ir 1 Ru/TiO 2 catalyst showcases an initial mass activity of 1971.5 A , enabling stable operation at 10 mA cm −2 for over 3200 h and at the rated current density of 2 A cm −2 for 2000 h in PEMWE.