Presentation av mastersarbete i fysik. Titeln på examensarbetet är "Fabrication and Characterization of Au/TiO2 Catalysts for Low Temperature CO Oxidation".
Allan Olesen
CO oxidation is the reaction between carbon monoxide and oxygen forming carbon dioxide as described by 2CO + O2 → 2CO2. It is most notably used in the three way catalyst present in automobiles, reducing the exhaust of toxic CO gas. Gold (Au) being a noble metal is not expected to be a good catalyst but exhibits an unexpectedly high activity towards CO oxidation even at temperatures as low as -70◦C. It is however only highly active when dispersed as nanoparticles below 5 nm in diameter on certain supporting materials, such as TiO2. In this work, a method of fabricating such a catalyst relying on solid state dewetting was developed. We where able to demonstrate that highly active gold nanoparticles could be formed by annealing 5 ˚A thin films of Au deposited on ˜10 nm films of TiO2 formed by reactive sputtering onto fused silica. The influence of varying parameters such as annealing time and temperature where investigated using surface science techniques. The performance towards CO oxidation was evaluated by employing mass spectrometry in combination with a gas reactor to measure the production of CO2. To gain a better understanding of the morphology of the samples, Scanning electron microscopy (SEM) was used to measure the size and dispersion of gold particles. The surface chemistry was studied using X-ray photoelectron spectroscopy (XPS) examining the chemical bonding of Ti, O and Au.
Handledare: Chrstoph Langhammar
Examinator: Dag Hanstorp
Opponent: Aishwarya James
Tuesday 4th June at 14.00 in Nexus