An XPS study of the growth and electronic structure of vanadia films supported on CeO2(1 1 1)

The growth and electronic structure of vanadia films supported on CeO2(1 1 1) were investigated using X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) of O2. Vanadium atoms deposited on CeO2(1 1 1) reacted with lattice oxygen from the support to form an oxidized vanadia species that contained primarily V+3. Exposure of submonolayer and monolayer coverages of vanadia to 10−7 Torr of O2 at temperatures up to 550 K resulted in vanadia layers with a stoichiometry close to that of V2O3. Further oxidation of vanadia films formed in this manner occurred upon annealing in 10−3 Torr of O2 at 400 K. This oxidation treatment produced films that contained predominantly V+5. For multilayer vanadia coverages, similar oxidation treatments produced only V2O3. During TPD with oxygen-dosed V2O5 films supported on CeO2(1 1 1), O2 desorption was observed between 330 and 550 K.