Methanol-Selective Oxidation Pathways on Au Surfaces: A First-Principles Study

Abstract

With density functional theory, all elementary steps of methanol (CH3OH) dehydrogenation and oxidation on atomic-oxygen-covered or OH-covered Au (111) surfaces are systematically studied. Our results suggest that on low oxygen coverage Au (111) surface the production of CH2O and CO start from α-H elimination and β-H elimination, respectively. The selective oxidation pathway is controlled by thermodynamics of the first step rather than kinetics. The overall energy barrier to produce CO is 0.39 eV corresponding to gas-phase methanol, which indicates that the reaction can proceed at low temperature. On high oxygen coverage Au (111) surface, the elimination of α-H and one β-H can take place simultaneously to form CH2O for the cooperative interaction of two nearby atomic oxygen. The missing observation of CH2O may come from the fact that the newly formed CH2O is ready to react with surface atomic oxygen and hydroxyl to form CH2OO(H) rather than desorption from the surface. The rate-limiting step of the oxidati...