Ab initio study on the adsorption and dissociation process of methanol on a silver surface

Abstract

The geometries of methanol adsorbed on an oxygen-free silver surface, a promoted silver surface and an oxygen preadsorbed silver surface were optimized at the MP2 level and the energies were calculated at the MP4 level. Our calculations showed that weak physisorption of methanol occurs on the clean silver surface, but stable molecular chemisorption occurs in the other two cases. The adsorption and dissociation process of methanol was postulated to occur via two pathways, i.e. the Eley-Rideal mode and the Langmuir-Hinshelwood mode. The calculations also showed that the presence of atomic oxygen at a silver surface is essential for the cleavage of the OH bond in the methanol. The dissociation of methanol in the Langmuir-Hinshelwood mode has a small energy barrier but has no energy barrier in the Eley-Rideal mode.