Catalytic dissociation of H 2O by SrTiO 3(100) step sites

Abstract

The adsorption of H 2O on fractured and planar surfaces of SrTiO 3(100) has been studied using photoemission spectroscopy. Valence region spectra evidence molecular adsorption on the planar surface and dissociative adsorption on the fractured surface. Features arising from surface Sr (Ti) atoms on the SrO (TiO 2) terraces of SrTiO 3(100) have been resolved in core-level photoemission spectra: the surface Sr 3d (Ti 3s) features lie to lower (higher) initial energy of the bulk-derived peaks by ca. 1.0 eV (1.7 eV). These results are consistent with the expected enhancement of covalent bonding in the TiO 2-terrace surface. From the valence and core level spectra we deduce that step-sites, which connect the two types of terrace, act as catalytic centres for H 2O dissociation.