PNNL

Abstract

Many TiO2 applications (e.g., in heterogeneous catalysis) involve contact with ambient atmosphere and/or water. The resulting hydroxylation can significantly alter its surface properties. While behavior of single, isolated OH species on the model metal oxide surface of rutile TiO2(110) is relatively well understood, much less is known regarding highly-hydroxylated surfaces and/or whether TiO2(110) could be fully-hydroxylated under ultra-high vacuum conditions. Here we report in-situ formation of a well-ordered, fully-hydroxylated TiO2(110)-(1 ? 1) surface using an enhanced photochemical approach, key parts of which are pre-dosing of water and multi-step dissociative adsorption and subsequent photolysis of the carboxylic (trimethyl acetic) acid. Combining scanning tunneling microscopy, ultra-violet photoelectron spectroscopy and density functional theory results, we show that the attained “super OH” surface is also fully-reduced, as a result of the photochemical trapping of electrons at the OH groups.