The h-BN surface effect on CO oxidation reaction catalyzed by supported gold atom

Abstract

The mechanism of CO oxidation by O2 on Au atoms supported on the pristine and defected hexagonal boron nitride (h-BN) surface has been studied theoretically using density functional theory. Two possible routes for catalytic oxidation are considered. The first route consists in a preliminary dissociation of the adsorbed O2 followed by consequential oxidation of a reactant molecule by atomic oxygen. Although the presence of h-BN surface can change the O2 dissociation barrier, it remains relatively high. The second route is a direct oxidation reaction between the activated molecular oxygen and the reactant. We have found two different pathways for CO oxidation: a two-step pathway where two CO2 molecules are formed independently, and a self-promotion pathway where oxidation of the first CO molecule is promoted by the second CO molecule. Interaction of Au with the defect-free and defected h-BN surface considerably affects the CO oxidation reaction pathways and barriers. Therefore, Au supported on the h-BN surface (pristine or defected) cannot be considered as pseudo-free atom and support effects have to be taken into account, even when the interaction of Au with the support is weak.