Sustainable Low‐Valent Iridium Active Sites in Rhenium Doped Perovskite Iridates for Efficient Acidic Oxygen Evolution Reaction via Hybridized Reaction Pathways

Proton exchange membrane water electrolysis (PEMWE) is a promising route for sustainable hydrogen production, yet its adoption is limited by the scarcity and cost of Ir‐based oxygen evolution reaction (OER) catalysts. Here, we first report that a Re‐doped SrZr x Ir 1‐x O 3 (Re‐SZIO) perovskite iridate exhibits outstanding OER performance in acid media, combining a low overpotential (250 mV at 10 mA cm −2 ) and high Ir mass activity (> 1,300 A gIr −1 ) with robust durability. High‐valent Re doping stabilizes an active low‐valent Ir species in Re‐SZIO, suppresses overoxidation, and promotes sustainable formation of active sites. Combinational mechanistic studies using in situ spectroscopy and grand canonical density functional theory (GC‐DFT) with microkinetic modeling reveal that dynamic Re–Ir–O interactions open an additional oxide path mechanism (OPM) branch alongside the conventional adsorbate evolution mechanism (AEM), yielding a hybrid pathway in which the OPM contributes at low overpotentials while the AEM remains dominant at higher overpotentials. This work demonstrates a viable strategy for designing robust, efficient, and low‐Ir based OER catalysts via precise electronic modulation of both the reaction pathway and the framework stability.