In this branch, the oxidation of carbon monoxide is investigated using transition-metal catalytic surfaces. The study of CO oxidation reaction is of practical importance for the control of the environmental pollution that results from combustion processes. In
general, the catalytic activity for the CO oxidation over transition metal surfaces is determined by the propensity of the metal surface to dissociate oxygen molecules and counter balanced by the bond strength of the active oxygen species on the metal
surface. We analyze the adsorption of O and CO on transition metal surfaces such as Ir(100) using the electronic structure interpretations to provide a deep understanding of the site preference for different coverages. The pathway and transition state are then determined using constrained minimization and nudge elastic band methods. The key event of such reactions is the movement of both CO and O to a site with less stability. The energy barrier is then determined, which is the energy needed for the diffusion of the species to activated sites and weakening for species bonds with metal surface.