The interaction of Pt with CeO2 in Pt-doped cerium oxide layers deposited on a Si wafer at normal and grazing incidence, and on multiwall carbon nanotubes (MWCNTs), was investigated by using X-ray photoelectron spectroscopy (XPS). 30-nm-thick Pt-doped CeO2 layers were deposited by rf-magnetron sputtering of a composite CeO2 - Pt target. XPS showed formation of cerium oxide with completely ionized species Pt-2+,Pt-4+ embedded in the film.
The Pt2+/Pt4+ ratio depends on the deposition angle and increases in the case of the film deposition on the MWCNTs. This behavior was explained by the dependence of the polycrystalline film grain morphology on a deposition angle.