Water Reactions on Reconstructed Rutile TiO₂: A Density Functional Theory/Density Functional Tight Binding Approach

Far from being conclusively understood, the reactive interaction of water with rutile does still present a challenge to atomistic modeling techniques rooted in quantum mechanics. We show that static geometries of stoichiometric TiO₂/water interfaces can be described well by density functional tight binding. However, this method needs further improvements to reproduce the low dissociation propensity of H₂O after adsorption predicted by density functional theory (DFT). A reliable description of the surface reactivity of water is fundamental to investigate the nonstoichiometric reconstruction of the (001) facet rich in Ti interstitials. Calculations based on DFT predict the transition temperature for the onset of reconstruction in remarkable agreement with experiments and suggest that this surface, in contact with liquid water, can promote spontaneous H₂O splitting and formation of H₂ molecules.