Morphology and CO Oxidation Reactions on Anion Doped CeOXFY/Rh(111) and CeOX/Rh(111) Inverse Catalysts
Doping cerium oxide with additives is a common procedure that improves stability of cerium oxide-based catalysts. We prepared fluorine-doped cerium oxide samples in the form of inverse catalysts on Rh(111) and compared their electronic, chemical, and morphological properties with fluorine-free CeOX samples. By means of X-ray photoelectron spectroscopy (XPS), we followed the formation of oxygen vacancies and the depletion of fluorine after exposure of CeOXFY to CO and O2 gases at elevated temperatures. According to Ce 3d XPS spectra, the ability to create oxygen vacancies is not altered by fluorine atoms. Our results from low energy electron diffraction (LEED) and atomic force microscopy (AFM) show that fluorine affects mainly the morphology of the layers. Unlike the CeO2 layers, fluorine-doped samples form 3D islands, which are partially rotated with respect to Rh [11̅0] direction due to stretching of the lattice constant caused by cerium oxide reduction. The possibility for creation stable Ce3+ sites without reducing the oxygen storage capacity makes anion doping a perspective tool for defect engineering in cerium oxide-based catalysts.
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- Miroslav Kettner, Tomáš Duchoň, Matthew J. Wolf, Jolla Kullgren, Sanjaya D. Senanayake, Kersti Hermansson, Kateřina Veltruská, Václav Nehasil. Anion-mediated electronic effects in reducible oxides: Tuning the valence band of ceria via fluorine doping. The Journal of Chemical Physics 2019, 151 (4) https://doi.org/10.1063/1.5109955