Adsorption and Surface Chemistry Studies on Strontium Titanate(001) Single Crystals: (I) Methyl Radicals, (II) Ammonia and Pyridine, (III) Vanadyl Tri-isopropoxide

The use of surface science techniques to examine model catalytic systems has been well documented. For example, work conducted on supported vanadia catalysts has shown relationships between the vanadia loading, as well as the support material, and the observed reactivity for the oxidative dehydrogenation of alkanes to their respective alkenes. To help further the knowledge of catalytic systems, SrTiO3 (001) single crystals and their interaction with various reagents were examined as SrTiO3 is the quintessential model system for materials in the perovskite class.;In this work, four reagents were examined on SrTiO3 (001) single crystals: methyl radicals, ammonia, pyridine, and vanadyl tri-isopropoxide. To gain a further understanding of the results seen from the single crystals: SrTiO3 powders were examined for the ammonia and pyridine cases and an alumina film on a silicon substrate grown using atomic layer deposition was utilized for the work on vanadyl tri-isopropoxide. The results show that: (i) the SrTiO3 (001) surface was not active for the adsorption of methyl radicals agreeing with density functional theory calculations, (ii) only after the introduction of defects is the adsorption of ammonia observed on SrTiO3 (001), and (iii) that vanadyl tri-isopropoxide undergoes a ligandexchange reaction with the SrTiO3 (001) surface where only one of three ligands reacts which greatly affects the nature of the supported vanadia species.