A theoretical analysis of adsorption and dissociation of CH3OH on the stoichiometric SnO2(110) surface

A theoretical analysis based on the Hartree-Fock pseutdopotential method and a density-functional theory calculation using a hybrid combination of general gradient approximation with pseudopotential procedure has been carried out to study the adsorption and dissociation of methanol on the stoichiometric SnO2(110) surface. The dependence of the results upon model system and computing method is discussed. An optimization procedure of adsorbate and substrate atom positions on a six-layer slab model has been selected to characterize the corresponding geometric parameters, adsorption energy and charge-transfer processes related with the molecularly adsorbed CH3OH and dissociative channels to yield methoxy or methyl fragments. In the high-coverage limit (theta = 1), we find that dissociation of the methanol molecule via the heterolylic cleavage of the C-O bond is favoured. At lower coverage (theta = 1/2), this channel and the molecularly adsorbed methanol present similar adsorption energies. (C) 1999 Elsevier Science B.V. All rights reserved.