title: Hydrogen Surface Reactions and Adsorption Studied on Y2O3, YSZ, and ZrO2.
abstract: The surface reactivity of Y2O3, YSZ, and ZrO2polycrystalline powder samples toward H2has been comparatively studied by a pool of complementary experimental techniques, comprising volumetric methods (temperature-programmed volumetric adsorption/oxidation and thermal desorption spectrometry), spectroscopic techniques (in situ electric impedance and in situ Fourier-transform infrared spectroscopy), and eventually structural characterization methods (X-ray diffraction and scanning electron microscopy). Reduction has been observed on all three oxides to most likely follow a surface or near-surface-limited mechanism involving removal of surface OH-groups and associated formation of water without formation of a significant number of anionic oxygen vacancies. Partly reversible adsorption of H2was proven on the basis of molecular H2desorption. Dictated by the specific hydrophilicity of the oxide, readsorption of water eventually takes place. The inference of this surface-restricted mechanism is further corroborated by the fact that no bulk structural and/or morphological changes were observed upon reduction even at the highest reduction temperatures (1173 K). We anticipate relevant implications for the use of especially YSZ in fuel cell research, since in particular the chemical state and structure of the surface under typical reducing high-temperature conditions affects the operation of the entire cell.
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 52a, A-6020 Innsbruck, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kogler
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 52a, A-6020 Innsbruck, Austria.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Köck
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 52a, A-6020 Innsbruck, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bielz
authors.affiliation: Section of Histology and Embryology, Medical University Innsbruck , Müllerstrasse 59, A-6020 Innsbruck, Austria.
authors.forename: Kristian
authors.initials: K
authors.lastname: Pfaller
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 52a, A-6020 Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Klötzer
authors.affiliation: Institute of Mineralogy and Petrography, University of Innsbruck , Innrain 52d, A-6020 Innsbruck, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Schmidmair
authors.affiliation: Institute of Mineralogy and Petrography, University of Innsbruck , Innrain 52d, A-6020 Innsbruck, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Perfler
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 52a, A-6020 Innsbruck, Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Penner