CONICET | Buscador de Institutos y Recursos Humanos

Methanol adsorption on â-Ga2O3 surface has been studied by Fourier transform infrared spectroscopy (FTIR)and by means of density functional theory (DFT) cluster model calculations. Adsorption sites of tetrahedraland octahedral gallium ions with different numbers of oxygen vacancies have been compared. The electronicproperties of the adsorbed molecules have been monitored by computing adsorption energies, optimizedgeometry parameters, overlap populations, atomic charges, and vibrational frequencies. The gallia-methanolinteraction has different behaviors according to the local surface chemical composition. The calculationsshow that methanol can react in three different ways with the gallia surface giving rise to a nondissociativeadsorption, a dissociative adsorption, and an oxidative decomposition. The surface without oxygen vacanciesis very reactive and produces the methanol molecule decomposition. The molecule is nondissociatively adsorbedby means of a hydrogen bond between the alcoholic hydrogen atom and a surface oxygen atom and a bondbetween the alcoholic oxygen atom and a surface gallium atom. Two neighbor oxygen vacancies on tetrahedralgallium sites produce the dissociation of the methanol molecule and the formation of a bridge bond betweentwo surface gallium atoms and the methoxy group.