Adsorption of water on (0 0 1) surface of SrTiO3 and SrZrO3 cubic perovskites: Hybrid HF-DFT LCAO calculations

Hybrid HF-DFT LCAO simulations of (0 0 1) surface properties and water adsorption on cubic SrZrO3 and SrTiO3 perovskites are performed using a single slab model framework. Three slab models with the different surface termination including 6–11 atomic planes were used for calculations. The effect of the symmetry reduction and the role of an extra atomic layer basis set have been considered for the bare surface slabs. The optimized structures and water adsorption energies have been calculated for the various types of surface coverage. It is shown that the formation of H-bonds between the water hydrogens and surface oxygens, as well as between the water molecules themselves, controls the structure of the water adsorption layers on the perovskite surfaces. Obtained results indicate that the dissociative type of water adsorption is the energetically more favourable for SrO-terminated zirconate surface than for similar titanate surface giving evidence to the more basic nature of oxygen atoms on SrO-terminated SrZrO3 surface.