Quantum molecular dynamics study of water on TiO2(110) surface

The adsorption of water on perfect TiO₂(110) surface is studied by quantum molecular dynamics simulation adopting a periodic model formed by five water molecules on a (5×1) surface unit cell of a five layer slab of TiO₂. The total simulation time is 3.2 ps. At about 1.3 ps, one water molecule dissociates with the help of other adsorbed waters and surface bridging oxygens. During the remaining 1.9 ps, the waters and OH groups vibrate, but no more dissociation or recombination is observed. By comparing recent experimental O1s photoemission (x-ray photoelectron spectroscopy) spectra of H₂O/TiO₂(110) to the computed spectrum of the adsorbate in the configurations supplied by the molecular dynamics simulation, the observed peaks can be attributed to different oxygen species. The proposed assignment of the main spectral features supports the occurrence of partial water dissociation (~20%) also on a perfect TiO₂ surface.