ADSORPTION OF H2O ON METAL-OXIDES - A PERIODIC AB-INITIO INVESTIGATION

We present ab-initio periodic Hartree-Fock calculations of water molec ules on TiO2 and MgO. On MgO, H2O does not dissociate and is adsorbed parallel to the surface. The main interaction concerns the Mg from the surface and the p pair of the water. At saturation, adsorbate-adsorba te interactions favor the formation of an ice monolayer. On TiO2 the w ater molecule is strongly adsorbed, dissociating to generate surface h ydroxyl groups. The reactivities of the two surfaces are compared and explained in terms of hard and soft acid and base theory. (C) 1998 Els evier Science B.V. All rights reserved.