A redox induced structural transformation for 2 monolayers of vanadia on α-TiO2(110) (rutile) was studied by in situ X-ray standing waves and ex situ X-ray photoelectron spectroscopy. The VOX film was grown by atomic layer deposition. Oxidation and reduction were carried out by annealing in O2 and H2, respectively. We found that an epitaxial rutile VO2 film was formed in the reduced phase with V 4+ cations in lateral alignment with Ti lattice positions. Oxidation was found to produce V5+ cations uncorrelated to the substrate lattice in the oxidized phase. The redox induced structural and oxidation state transformation proved reversible and involved the entire film; not just the surface layer. The current study suggests that the structural order needs to be considered in order to study the activity of supported vanadium oxide catalysts.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films