dc.contributor.advisor |
Söhnel, T |
en |
dc.contributor.advisor |
Idriss, H |
en |
dc.contributor.advisor |
Metson, J |
en |
dc.contributor.author |
McGill, Philip |
en |
dc.date.accessioned |
2013-01-23T00:44:14Z |
en |
dc.date.issued |
2013 |
en |
dc.identifier.uri |
http://hdl.handle.net/2292/19935 |
en |
dc.description.abstract |
The study of adsorbates over well defined surfaces is important to a wide variety of fields ranging from industrial catalysis to the origin of life. This thesis presents a series of theoretical studies on the adsorption of model molecules over several surfaces of rutile TiO₂ and ruthenium. Evidence of formaldehyde polymerisation on adsorption led to an additional examination of its gas-phase polymerisation. The Lewis acidity of the proposed '(0 0 1)-brookite-like' model of the rutile TiO₂ (0 1 1) surface was probed by a study of ammonia adsorption and compared with the bulk-terminated model. While both surfaces show a strong preference for molecular adsorption, the (0 0 1)-brookite-like model has a weaker adsorption energy, disagreeing with experiment. Adsorption studies of formaldehyde, formic acid and formamide were carried out over the (1 1 0) surface of rutile TiO₂: Monomeric formaldehyde binds weakly through its carbonyl O to a surface cation. A strong dimerisation configuration was found, where formaldehyde dimers bridge between a surface cation and surface anion. Formic acid studies focused on its diffusion. It was shown that rather than the sliding diffusion suggested by prior studies, surface formates have a strong energetic preference toward walking diffusion. The findings suggest a way to control the rate of surface diffusion. Monomeric formamide adsorption was found to mirror formic acid, favouring the dissociation of a proton to surface oxygen. Formamide adsorption over the (0 0 0 1) surface of ruthenium with 2x1 oxygen overlayer was also investigated. Formamide adsorption energies were found to be far smaller than experimental values using DFT with a PBE functional, but could be improved relative to experiment using an empirical dispersion correction. Experimentally observed higher temperature adsorption modes were shown to relate to the generation of disorder in the oxygen overlayer. The equilibrium and kinetic barriers to gas-phase formaldehyde polymerisation were investigated. Brønsted acid initiated formaldehyde polymerisation proceeds by a neutral species, resulting from the addition of the acid across the C=O bond. Reaction energy barriers are considerably reduced by the simultaneous reaction of several monomers. Some initiation and growth is thermodynamically plausible in the gas-phase, but kinetically limited. |
en |
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
PhD Thesis - University of Auckland |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. |
en |
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.title |
Theoretical Studies of Model Molecule Adsorption to the Surfaces of Titania and Ruthenium |
en |
dc.type |
Thesis |
en |
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Doctoral |
en |
thesis.degree.name |
PhD |
en |
dc.rights.holder |
Copyright: The Author |
en |
pubs.elements-id |
372189 |
en |
pubs.record-created-at-source-date |
2013-01-23 |
en |
dc.identifier.wikidata |
Q112903703 |
|