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Modification of Ti02 surfaces to investigate catalytic properties

Williams, Oscar; (2021) Modification of Ti02 surfaces to investigate catalytic properties. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

This body of work investigates titanium dioxide model catalysts with an increasing complexity of design, using scanning probe microscopy to gain fundamental insight into surfaces relevant to clean energy applications. The simplest surface studied here constitutes an anatase TiO2(101) single crystal, which has been observed both at room temperature and at 78 K. Specifics of subsurface defect sites, and how gold single atoms interact with these sites, were determined. The subsurface sites prove significant in determining the position of the atoms, and scanning tunnelling spectroscopy is used to uncover an electronic state that forms in the band gap of the titania upon the deposition of gold atoms. The absorption, kinetics and photooxidation of benzoic acid is investigated on the rutile TiO2(110) surface at room temperature, as a model dye molecule. The added complexity of an ordered benzoate monolayer on the surface allows the importance of intermolecular forces and surface functional groups to be understood as a influencing factor behind reaction mechanisms and photodynamics. A surprising level of photoactivity is seen across a wide range of photon energies, and this is attributed to benzoate-induced electronic states that align with the titania band gap. The most complex system studied in this thesis introduces gold nanoparticles as an additional probe molecule to the benzoate / rutile TiO2(110) surface. This serves to shed further light on the integral role of surface hydroxyl groups in determining the photoreaction pathway for the benzoate molecules. Unique anisotropic effects in the photodynamics of the surface are observed in the presence of gold, and this is considered in the context of the previous findings.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Modification of Ti02 surfaces to investigate catalytic properties
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10126804
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