Strontium Leaching Precedes SrIrO3 Dissolution by a Wide Potential Gap During Electrochemical Water Oxidation

Mechanistic studies of oxide electrocatalysts for heterogeneous water oxidation have been primarily focused on understanding the origins of activity, with fewer studies studying fundamental properties influencing stability. The main challenge is directly observing and quantifying local structural instability under operating conditions. In this work, we study the degradation pathways of SrIrO3, a highly active electrocatalyst, during the oxygen evolution reaction (OER). This material serves as a model system for degradation studies of perovskite AMO3 oxides, exhibiting both A-cation leaching and transition metal (M) dissolution. Using operando electrochemical atomic force microscopy (EC-AFM), we track the potential-dependent Sr leaching and perovskite dissolution at the nanometer scale. We observe Sr leaching preceding perovskite dissolution by up to 0.8 V with a Sr leaching rate controlled by electrolyte composition. Ultimately, our study demonstrates the overall stability of perovskite oxides during electrocatalysis can be substantially improved by suppressing A-site leaching.