Long‐Range Atomic Periodicity Unlocks Durable Water Electrolysis

The development of efficient and stable oxygen evolution reaction (OER) electrocatalysts is essential for proton exchange membrane water electrolyzers (PEMWEs). Although iridium (Ir)‐based catalysts balance activity and stability, their widespread adoption is hindered by persistent iridium leaching and oxidative dissolution, resulting in structural degradation. Here, we present a long‐range atomic ordered iridium–vanadium (Ir–V) intermetallic with strong heteroatomic bonds that significantly suppresses iridium dissolution and maintains structural integrity during acidic OER. Both theoretical and experimental analyses confirm that exceptional stability originates from the highly ordered atomic grid structure, in which a density of strong heteroatomic bonding effectively stabilizes iridium sites against oxidation and leaching. The optimized Ir–V intermetallic with a low Ir loading of 0.11 mg Ir cm −2 delivers a current density of 3.0 A cm −2 at 1.844 V in PEMWE and demonstrates operational stability over 2500 h under dynamic current densities alternating between 1.0 and 2.0 A cm −2 , highlighting great potential for sustainable green hydrogen production.