This thesis focuses on the synthesis, characterization and performance towards CO2 electroreduction of mono and bi-metallic particles based on p-block metals. With an industrial perspective in mind... Show moreThis thesis focuses on the synthesis, characterization and performance towards CO2 electroreduction of mono and bi-metallic particles based on p-block metals. With an industrial perspective in mind, we try to synthesize particulate, high surface area materials with clean, scalable synthesis methods where possible and test their performance in H-Cell and gas diffusion electrode flow cell configurations. With a combination of characterization techniques, we find possible explanations for the catalytic behaviors. Show less
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... Show moreIn 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. Show less
Catalysis is the working horse of the chemical industry. In many cases, it is a poorly understood process taking place at the surfaces of nanoparticles under relatively harsh conditions, such as... Show moreCatalysis is the working horse of the chemical industry. In many cases, it is a poorly understood process taking place at the surfaces of nanoparticles under relatively harsh conditions, such as high pressures and high temperatures. This thesis focuses on new approaches to acquire atomic-scale information on catalytic processes on metal nanoparticles in high-pressure, high-temperature conditions. This thesis starts with a comprehensive approach to the development of novel instruments and methods for in-situ experiments on model catalysts under working conditions. We introduce the ReactorAFM, the world’s first high-pressure, high-temperature non-contact Atomic Force Microscope, and two software packages for data analysis. Next, we have applied several in-situ measurement techniques to study catalytic model systems at atmospheric pressures and elevated temperatures. We describe a study of the interaction of gas mixtures of nitric oxide and hydrogen on the Pt(110) surface, using surface X-ray diffraction. In the next chapter, we used similar mixtures but with a Pt nanoparticle model catalyst in a high-pressure reaction cell in a transmission electron microscope. Lastly, we have applied four in-situ techniques, including our new ReactorAFM, to investigate the role of thin oxide shells in spontaneous reaction oscillations on Pd nanoparticles during the catalytic oxidation of carbon monoxide Show less
