Short-Range-Engineered Nd-Doped IrO_x 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 IrO_x catalysts (Nd-IrO_x) that enable precise control over short-range structure to activate the oxide path mechanism (OPM). Incorporating Nd³⁺ into an amorphous IrO_x 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-IrO_x 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 mg_Ir 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.