Dissertation
Microscopy and Spectroscopy on Model Catalysts in Gas Environments
In surface science there is great effort to move from studying simple, flat model surfaces in vacuum to investigating more complex model catalysts in gas environments (in situ). This thesis gives three examples of such studies using microscopy and spectroscopy.
- Author
- Wenzel, S.
- Date
- 16 September 2021
- Links
- Thesis in Leiden Repository
In surface science there is great effort to move from studying simple, flat model surfaces in vacuum to investigating more complex model catalysts in gas environments (in situ). This thesis gives three examples of such studies using microscopy and spectroscopy. Exposure of ZnO(10-10) to moderate pressures of water in an in situ scanning tunneling microscope reveals that the surface roughens. The flat ZnO(10-10) is thus only conditionally suited as a model catalyst for reactions involving water.In the same microscope, surface gold oxide formation is observed on TiO2/Au(111) during CO oxidation at 1 bar pressure. Comparisons to the Au(111) surface suggest that the titania does not supply atomic oxygen to the Au(111) substrate as part of the reaction mechanism of the CO oxidation.Co(0001) is investigated as a model catalyst for Fischer-Tropsch synthesis, the reaction of CO and H2 to form hydrocarbons. In this thesis the oxidation behavior of the cobalt and the adsorption of carbon species during the reaction are investigated using near-ambient pressure X-ray photoelectron spectroscopy.Generally, this thesis exemplifies the significant influence that small concentrations of contaminants in gases and materials can have on the structure and behavior of surfaces in in situ studies.