The V2O5/TiO2 (anatase) model catalyst structure: XPD study and single scattering cluster simulations

The catalyst V2O5/TiO2 (anatase) is an important industrial catalyst for the partial oxidation of hydrocarbons. Its catalytic properties are probably related to a specific interface and surface overlayer structure. Model catalysts of V2O5/TiO2 were prepared by depositing thin V2O5 layers on anatase single-crystal minerals by means of d.c. reactive magnetron sputtering. Azimuthal x-ray photoelectron diffraction (XPD) measurements were performed, recording the Ti 2p3/2, O 1s and V 2p3/2 photoelectron peaks. All azimuthal scans displayed diffraction maxima along the major axes of TiO2, including the V 2p scan, which indicates epitaxy between substrate and sputtered layer. This paper presents single scattering calculations based on several literature models for the structure of vanadium oxide upon anatase. These models have been tested for the presence of intensity maxima along TiO2 major axes in their theoretical azimuthal Ti 2p, O 1s and V 2p intensity patterns. Comparison of simulations and experiment points to a flattened VO layer upon the anatase substrate as the better model.