A synchrotron study of the deposition of vanadia on TiO2(110)

The electronic structure of vanadia supported on TiO2(110) was investigated by means of low energy electron diffraction, Auger electron spectroscopy, X-ray photoelectron spectroscopy, work-function and near edge X-ray absorption fine structure spectroscopy (NEXAFS) measurements. Vanadia films in the submonolayer-to-multilayer coverage regime were deposited at 300 K by evaporation of metallic vanadium in an oxygen ambient. The vanadia films appear to grow in a two-dimensional fashion, without any long-range order, probably via a simultaneously multilayer growth mode. The photoemission data suggest the formation of a vanadium oxide with partially filled d-orbitals. The position and the line-shape of the vanadium L- and oxygen K-edges determined by NEXAFS indicate V2O3 formation; the titaniuim L-edge indicates only a weak electronic interaction of V2O3 with the surface of TiO2. V2O3 on TiO2 is stable up to a temperature of 1100 K, above this temperature the data indicate the formation of a ternary oxide at the interface and the simultaneous agglomeration of V2O3. (C) 1999 Elsevier Science B.V. All rights reserved.