Understanding Strain Effects on IrO₂ for Oxygen Evolution Electrocatalysis

Understanding how strain influences the electronic and geometric properties of surface active sites and the activity and stability of the iridium oxide-catalyzed oxygen evolution reaction (OER) has significant scientific and technological implications for designing next-generation electrocatalysts. In this study, we use density functional theory (DFT) calculations to systematically investigate the effect of compressive and tensile biaxial surface strains on the OER activity and stability of the IrO2(110), IrO2(100), and IrO2(101) surfaces. Our results reveal significant changes in the adsorption free energies of the OER intermediates due to strain, which in turn influences the OER activity. Furthermore, we evaluate how the electronic structure of IrO2 surface atoms varies with strain, leading to a fundamental theoretical understanding of strain effects. Our theoretical analysis further accounts for the effects of strain in the presence of a nearby surface Ir vacancy and high surface oxygen coverage, representing realistic surfaces under OER conditions. This work expands the current understanding of strain-assisted activity and stability enhancements in OER catalysts, paving the way for the development of strain-engineered electrocatalysts.