Mechanistic studies of oxide electrocatalysts for heterogeneous water oxidation have been primarily focused on understanding the origins of activity. Despite encouraging progress, achieving long-term stability remains an important goal for their industrial implementation. In this work, we study the degradation pathways of a highly active SrIrO3 electrocatalyst during the oxygen evolution reaction (OER). SrIrO3 serves as a model system for perovskite AMO3 oxides as it can exhibit both A-cation leaching and transition metal (TM) oxide dissolution. Employing epitaxial SrIrO3 thin films, we explore the electrolyte- and potential-dependent leaching of Sr from the perovskite structure by following these processes through operando electrochemical atomic force microscopy (EC-AFM). Dissolution was imaged and quantified at the nanometer scale. We show that Sr leaching results in the in-situ formation of Sr1-xIrOy layer, with the leaching rate controlled via electrolyte composition. Crucially, Sr leaching occurs at a potential > 0.5V lower than that for transition metal oxide dissolution. Our study demonstrates that suppression of the A-site leaching is crucial for improving the overall stability of perovskite oxide during electrocatalysis.
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