Reduction of thin-film ceria on Pt(111) by supported Pd nanoparticles probed with resonant photoemission

SURFACE SCIENCE

卷:605

Article

Matharu, J.^1,2  Cabailh, G.^1,2  Lindsay, R.³  Pang, C. L.^1,2  Grinter, D. C.^1,2  Skala, T.⁴  Thornton, G.^1,2 

[1] UCL, London Ctr Nanotechnol, London WC1H 0AJ, England

[2] UCL, Dept Chem, London WC1H 0AJ, England

[3] Univ Manchester, Ctr Corros & Protect, Sch Mat, Manchester M13 9PL, Lancs, England

[4] Sincrotrone Trieste, I-34149 Basovizza Trieste, Italy

关键词: Ceria;    Thin film;    Resonant photoemission;    Palladium;    RESPES;    XPS;   

DOI  :  10.1016/j.susc.2011.03.005

来源: Elsevier

【 摘 要 】

Local defects present in CeO(2-x) films result in a mixture of Ce(3+) and Ce(4+) oxidation states. Previous studies of the Ce 3d region with XPS have shown that depositing metal nanoparticles on ceria films causes further reduction, with an increase in Ce(3+) concentration. Here, we compare the use of XPS and resonant photoemission spectroscopy (RESPES) to estimate the concentration of Ce(3+) and Ce(4+) in CeO(2-x) films grown on Pt (111), and the variation of this concentration as a function of Pd deposition. Due to the nature of the electronic structure of CeO(2-x), resonant peaks are observed for the 4d-4f transitions when the photon energy matches the resonant energy; (hv = 121.0 eV) for Ce(3+) and (hv = 124.5 eV) for Ce(4+). This results in two discrete resonant photoemission peaks in valence band spectra. The ratio of the difference of these peaks with off-resonance scans gives an indication of the relative contribution of Ce(3+). Results from RESPES indicate reduction of CeO(2-x) on deposition of Pd, confirming earlier findings from XPS studies. (C) 2011 Elsevier B.V. All rights reserved.

【 授权许可】

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