| AVS 55th International Symposium & Exhibition | |
| Surface Science | Friday Sessions |
| Session SS+AS+NC-FrM |
| Session: | Environmental Surfaces and Water Interaction with Oxide Surfaces |
| Presenter: | A.E. Becerra-Toledo, Northwestern University |
| Authors: | A.E. Becerra-Toledo, Northwestern University L.D. Marks, Northwestern University |
| Correspondent: | Click to Email |
Strontium titanate, SrTiO3, has been studied extensively as a model perovskite system. Among other advances, its variety of cation oxidation states has provided critical insights into oxide surface reaction mechanisms. Understanding the reaction of ubiquitous water molecules with SrTiO3 surfaces is of great importance to environmental science and catalysis. Density functional theory (DFT) calculations were performed to study the adsorption of water molecules on two different SrTiO3 (001) surfaces. A repeated slab model was employed to study both a bulk-like TiO2 surface termination and a 2x1 surface reconstruction. While similar studies have been carried out in the past, our treatment using a full-electron potential and a linear augmented plane wave plus local orbital (LAPW+lo) basis more accurately models the spatial character of single-particle wavefunctions. Two different exchange-correlation functionals were employed: the PBE1 generalized gradient approximation (GGA) and the TPSS2 meta-GGA. On the TiO2-terminated surface, both molecular and dissociative adsorption of water were modeled. The results did not show a significant dependence on the choice of exchange-correlation functional. Most importantly, the adsorption energies for molecular and dissociative adsorption were more similar than has been previously reported,3 and therefore favor the coexistence of hydroxyl groups and molecular water on the surface. On the 2x1 surface reconstruction, which was solved by Erdman et al.4 and is typically formed under oxidizing conditions, dissociative adsorption was studied with several distinct stable structures considered. The most stable of these showed an adsorption energy (per H2O molecule) much larger than that observed for the bulk TiO2 termination. In all cases we observe the effect of hydrogen bonding between adsorbate and surface anions on the stabilization of the structures.
1 Perdew, J.P. et al. Phys.Rev.Lett. 77, 3865 (1996).
2 Tao, J. et al. Phys.Rev.Lett. 91, 146401 (2003).
3 Evarestov, R.A. et al. Surf.Sci. 601, 1844 (2007).
4 Erdman, N. et al. Nature 419, 55 (2002).