Adsorption of H₂O on the V₂O₅(010) surface studied by periodic density functional calculations

We have investigated the molecular and dissociative adsorption of a water molecule on the V₂O₅(010) surface by means of periodic boundary models and density functional approach. It has been observed that molecular adsorption of water on the V₂O₃(010) surface occurs favorably, whereas the dissociation hardly occurs on the stoichiometric surface due to the significant Coulombic repulsion of the lattice oxygens around the exposed vanadium center to the approaching oxygen of the hydroxyl species. For molecular adsorption at the surface oxygen sites, it has been confirmed that hydrogen bonding plays a crucial role, and the adsorption abilities of the surface oxygens correlate with the electron-donating ability from the surface oxygen sites to the water molecules, and with the ratio of the accumulated charge on the adsorption site and the adsorbed water species. As for molecularly adsorbed water species at the exposed vanadium site, the coordination interaction and hydrogen bonding are the important contributions. For both the molecular and dissociative adsorption, it has been elucidated that the vanadyl oxygen plays the most important role among the three surface oxygens and acts as the most favorable adsorption site.