| To study the reactivity of metal oxide single crystal surfaces, a new apparatus was designed, built and tested. It consists of three chambers: a spectroscopy chamber, a preparation chamber and a water cell. A sealing mechanism applying spring-loaded Teflon seals was incorporated between chambers so that each chamber can be isolated during sample preparation or characterization. The system is able to conduct photoelectron spectroscopy and temperature programmed reaction spectroscopy (TPRS) experiments.;Defects on a surface were believed to play important roles in surface reactions, and they may initiate unique reactions. The effect of defects, created by electron irradiation and Ar+ bombardment, on the decomposition of DCOOD was investigated by TPRS. The selectivity of the reaction for the production of CO, formaldehyde and D2 was increased significantly by the defects. An appreciable decrease in the temperature of CO formation on the defective surfaces produced by electron irradiation was observed, compared to the stoichiometric surface. Formation of formyl intermediates during DCOOD decomposition was proposed. The difference in the reactivity of the defects prepared by different methods was revealed and explained.;V2O5/TiO2 catalysts are used industrially for the partial oxidation of hydrocarbons and for the selective catalytic reduction of NO with NH3. However, the system is barely studied on well characterized single crystal surfaces due to lack of an effective preparation method. A V2O5/TiO2 (110) surface with various V2O5 coverages was successfully prepared for the first time by codosing VOCl3 and water vapor. The stability and electronic structure of the V2O5/TiO2 surface were studied by photoelectron spectroscopies. The reactivity of the V2O5/TiO2 surface was investigated by TPRS following adsorption of methanol, formic acid, formaldehyde, toluene, ethylene, propylene and butadiene. The reactivity was compared with those of TiO 2 (110), oxidized TiO2 (110) and reduced V2O 5/TiO2 (110) surfaces. Monolayer coverage of V2O 5 has the highest activity for methoxy dehydrogenation to formaldehyde. The V-O-Ti bond and the oxidation state of the vanadium cation were proposed to play an important role in the oxidation process. No significant effect of the deposited V2O5 on the reaction of other organic molecules, such as formic acid and toluene, was observed. |
