Correlating atomic-scale structural and compositional details of Ca-doped LaCoO3 perovskite nanoparticles with activity and stability towards the oxygen evolution reaction

Developing efficient oxygen evolution reaction (OER) electrocatalysts requires a thorough understanding of structure-activity-stability relationships, ideally at the atomic scale. Herein, we employed atom probe tomography and transmission electron microscopy to reveal compositional and structural changes on LaCoO3 3 and Ca- doped LaCoO3 3 surfaces during OER. We reveal that the topmost surfaces of pristine perovskite are terminated by the A-site element (La). After OER, amorphous La(OH)3 3 is formed on the surfaces of LaCoO3, 3 , which leads to significant activity deterioration. For Ca-doped LaCoO3, 3 , enhanced intercalation and penetration of hydroxide ions, along with the appearance of Co 3 +/4 + redox couple, are observed, contributing to its enhanced OER activity and stability. Our study demonstrates how atomic-scale compositional and structural details of electrocatalyst surfaces deepen our understanding of their activity and stability.