CPT

Calendar of Physics Talks Vienna

Tuning material properties: role of nanostructuring and metal/oxide interfaces on oxide reducibility
Speaker:Gianfranco Pacchioni (Dipartimento di Scienza dei Materiali, Universitá Milano-Bicocca, Milano/Italy)
Abstract:Oxide reducibility is an important property in catalysis by metal-oxides. Usually, oxides can be classified based on their bulk reducibility, i.e. the tendency to loose oxygen, generating excess electrons in the material. In this respect, SiO2, MgO, and ZrO2 are considered non-reducible oxides, while TiO2, CeO2, and Fe2O3 are typical reducible oxides. However, the reducibility of an oxide can be substantially modified, either by generating nanostructures (nanoparticles, nanowires, or nanofilms) or by creating an interface between the oxide and a metal. We will use ZrO2 as a prototype of non-reducible oxides, and we will show how the properties, and in particular the reducibility, of the material can be tuned by nanostructuring or by depositing metal particles on ZrO2 (classical heterogeneous catalysts) or, as an alternative, by growing ZrO2 films on metal surfaces (inverse catalysts). We
Date: Tue, 05.02.2019
Time: 09:30
Location:TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B
Contact:Univ.Prof. Dr. Ulrike Diebold

Cerium Oxide Surfaces: Defect Structure and Their Role as Support in Catalysis – A Theoretical Perspective
Speaker:M. Verónica Ganduglia-Pirovano (Instituto de Catálisis y Petroleoquímica, Madrid/Spain)
Abstract:Ceria (CeO2) is the most significant of the oxides of rare-earth metals in industrial catalysis. Deep understanding of the oxygen defect structure of ceria surfaces under reducing conditions is essential to tailor their functionality in catalytic applications. For the CeO2(111) surface, whether oxygen vacancies prefer the subsurface or the surface and if surface oxygen vacancies attract or repel, are still heavily debated. Also, a number of ordered phases have been observed upon reduction, namely, (√7 × √7) R19.1º, (√7 × 3) R19.1º, (3 × 3), (√3 × √3) R30º, and (4 × 4), but their structures have remained elusive. Here, supported by experimental and theoretical results, the current understanding of the structure of the CeO2-x (111) surface will be discussed [1-6]. Furthermore, the role of ceria as support in the catalytic activity of metal-ceria systems is not fully understood. Its non-inn
Date: Tue, 05.02.2019
Time: 10:30
Location:TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B
Contact:Univ.Prof. Dr. Ulrike Diebold