Characterization of adsorption sites on IrO2via temperature programmed O2 desorption simulations

Abstract

This study presents simulations of temperature-programmed desorption (TPD) profiles using desorption energy data from density functional theory (DFT) calculations. We apply this method to investigate the desorption of oxygen (O₂) from IrO₂(110) to gain insight into the kinetics of oxygen coupling and desorption, important elementary steps in the oxygen evolution reaction (OER). Initially, we confirm the thermodynamically stable adsorption site for oxygen in the pristine IrO₂(110) as Ir_CUS, even with a high oxygen coverage. We successfully simulate TPD for O₂ desorption, achieving good agreement with experimental TPD data for different initial oxygen exposures when including more than one adsorption site. We identify a new adsorption site, related to the formation of steps on IrO₂(110)(Ir_CUS-step-0.5), that is essential for reproducing the experimental TPD. Our findings suggest that the observed TPD peaks are the result of different adsorption sites on the surface, rather than solely a lateral interactions effect. This work provides insight into the behavior of oxygen adsorption on IrO₂, with implications for understanding surface reactivity and catalytic processes involving this material.