Theoretical study on the reactivity of the surface of pure oxides: The Influence of the support and oxygen vacancies

► The presence of oxygen vacancies both on ceria and gallia surfaces becomes these surfaces more reactive. ► Supported films are very reactive to oxidize CO and CO2 molecules, and also to dissociate the H2 molecule. ► Thin films of Ga2O3 and ZnO grown onto ceria are higher suitable catalysts than the unsupported oxides. ► The higher interaction with the studied molecules is mainly the presence of reduced cations on the surface.