Complex Iridium Oxides Converge In Structure And Reactivity During Acidic Oxygen Evolution Electrocatalysis

ABSTRACT Iridium‐containing complex oxides are attractive catalysts for the oxygen evolution reaction (OER) in acidic media, but the link between their structure and long‐term performance remains poorly defined. We synthesize a library of Ir‐containing double perovskites (’ with A = Sr, Ba, and B' = Fe, Co, In, Y, La, Ce, Pr, Nd, Tb) to systematically probe how composition influences restructuring dynamics and steady‐state OER activity. Using surface‐sensitive spectroscopy, electron microscopy, and rotating disk electrode measurements, we show that all compositions converge to a similar intrinsic activity for the OER after restructuring, but do so at different rates. The B'‐site cation dictates dissolution kinetics, with more oxophilic cations showing slower restructuring. These results reveal that while changing the composition of complex Ir oxides has little influence on the intrinsic OER activity of these materials, it has an important effect on dissolution rates and restructuring dynamics, offering a means to engineer catalyst durability under acidic OER conditions.