Short-Range-Engineered Nd-Doped IrOx Enables Oxide Path Mechanism for High-Performance PEM Water Electrolysis.

Proton-exchange-membrane water electrolysis (PEMWE) demands high-performance anodes with minimal iridium content, yet conventional Ir-based catalysts suffer from an inherent activity-stability trade-off. We address this challenge by designing neodymium-doped amorphous IrOx catalysts (Nd-IrOx) that enable precise control over short-range structure to activate the oxide path mechanism (OPM). Incorporating Nd3+ into an amorphous IrOx matrix dominated by edge-sharing IrO6 octahedra optimizes the prerequisites for the OPM: lattice distortion tailors Ir-Ir distances to enable direct *O-O* coupling, while electronic modulation stabilizes OH ligands within the local coordination environment, facilitating *O formation. The optimized Nd-IrOx catalyst delivers an ultralow acidic OER overpotential of 254 mV at 10 mA cm-2 with 520 h of stability. Remarkably, PEMWE employing an ultralow Ir-loading anode (0.5 mgIr cm-2) achieves a DOE-relevant current density (4 A cm-2 at 1.9 V) and remarkable 1000-h stability at 1 A cm-2. This work pioneers short-range engineering in Ir-based oxides, offering fundamental insights for catalyst design and OER pathway control toward efficient hydrogen production.