title: Water-Gas Shift and Methane Reactivity on Reducible Perovskite-Type Oxides.
abstract: Comparative (electro)catalytic, structural, and spectroscopic studies in hydrogen electro-oxidation, the (inverse) water-gas shift reaction, and methane conversion on two representative mixed ionic-electronic conducting perovskite-type materials La0.6Sr0.4FeO3-δ(LSF) and SrTi0.7Fe0.3O3-δ(STF) were performed with the aim of eventually correlating (electro)catalytic activity and associated structural changes and to highlight intrinsic reactivity characteristics as a function of the reduction state. Starting from a strongly prereduced (vacancy-rich) initial state, only (inverse) water-gas shift activity has been observed on both materials beyond ca. 450 °C but no catalytic methane reforming or methane decomposition reactivity up to 600 °C. In contrast, when starting from the fully oxidized state, total methane oxidation to CO2was observed on both materials. The catalytic performance of both perovskite-type oxides is thus strongly dependent on the degree/depth of reduction, on the associated reactivity of the remaining lattice oxygen, and on the reduction-induced oxygen vacancies. The latter are clearly more reactive toward water on LSF, and this higher reactivity is linked to the superior electrocatalytic performance of LSF in hydrogen oxidation. Combined electron microscopy, X-ray diffraction, and Raman measurements in turn also revealed altered surface and bulk structures and reactivities.
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Austria.
authors.forename: Ramona
authors.initials: R
authors.lastname: Thalinger
authors.affiliation: Institute of Materials Chemistry, Vienna University of Technology , Getreidemarkt 9/BC/01 A-1060 Vienna, Austria.
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Opitz
authors.affiliation: Institute of Materials Chemistry, Vienna University of Technology , Getreidemarkt 9/BC/01 A-1060 Vienna, Austria.
authors.forename: Sandra
authors.initials: S
authors.lastname: Kogler
authors.affiliation: Ernst Ruska Zentrum und Peter Grünberg Institut, Forschungszentrum Jülich GmbH , 52425 Jülich, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Heggen
authors.affiliation: International Iberian Nanotechnology Laboratory, Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal.
authors.forename: Daniel
authors.initials: D
authors.lastname: Stroppa
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: Ralf
authors.initials: R
authors.lastname: Tappert
authors.affiliation: Institute of Materials Chemistry, Vienna University of Technology , Getreidemarkt 9/BC/01 A-1060 Vienna, Austria.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fleig
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Klötzer
authors.affiliation: Institute of Physical Chemistry, University of Innsbruck , Innrain 80-82, A-6020 Innsbruck, Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Penner