PNNL

Abstract

We have studied the electronic structure of oxidized and reduced CeO2 (111) surfaces using X-ray photoelectron spectroscopy (XPS). The 50 nm thick Co2(111) film was grown on a YSZ(111) substrate using oxygen plasma assisted molecular beam epitaxy (OPA-MBE). This film has been characterized using in-situ RHEED (reflection high energy electron diffraction) and ex-situ XRD (X-ray diffraction), HRTEM (high resolution transmission electron microscopy) and RBS (Rutherford backscattering spectroscopy). The lattice mismatch between CeO2(111) and YSZ(111) is less than 5% and yields a flat surface that is comprised of an equivalent number of Ce4? and O2? ions. Oxidation with O2 at 773 K under UHV conditions was sufficient to fully oxidize the CeO2(111). Surface reduction was carried out by annealing in UHV at 973 K.