The surface energy and band structure of γ-WO3 thin films

By means of ab initio calculations we demonstrate sizable anisotropy in surface energy of the γ-WO3 (001), (010) and (100) surfaces. The (001) surface has the smallest surface energy followed by the (010) and (100) surfaces. Their surface band structures are characterized by dispersion of bands near the gap region and by band-gap values similar to the ones of the bulk. The role of surface atoms in stabilizing the band gap is revealed. Variations in the position of the Fermi level are traced with respect to the different surface reconstruction

A molecular mechanism for the water-hydroxyl balance during wetting of TiO2

We show that the formation of the wetting layer and the experimentally observed continuous shift of the H2O-OH balance towards molecular water at increasing coverage on a TiO2(110) surface can be rationalized on a molecular level. The mechanism is based on the initial formation of stable hydroxyl pairs, a repulsive interaction between these pairs and an attractive interaction with respect to water molecules. The experimental data are obtained by synchrotron radiation photoelectron spectroscopy and interpreted with the aid of density functional theory calculations and Monte Carlo simulations