The work presented in this thesis involved a study of the photocatalytic oxidation of atmospheric pollutants NOx and S02. Anatase titanium dioxide powder was used as a photocatalyst, and compared with nanostructured titanium dioxide. Two novel coating procedures, screen printed ceramics and spray coated aluminium, were investigated for photocatalytic application. In addition anatase samples containing CeO2 and Zr02 were characterised and investigated for photocatalytic potential. All the samples in this thesis were characterised using X-ray photoelectron spectroscopy (XPS) and time of flight mass spectrometry (TOF-SIMS), with Raman analysis used for crystal phase analysis. Specifically for the Ce02 and Zr02 coated powders, scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) and X-ray diffraction (XRD) were performed. Electrolysis in a fluorine electrolyte produced anodically grown amorphous titania nanotubes. Annealing of the amorphous nanotubes was conducted at 600°C to produce a reactive anatase layer. In addition an anatase nanotube powder was created by a hydrothermal process in NaOH. These samples were imaged and analysed using scanning electron microscopy (SEM), focused ion beam (FIB) and transmission electron microscopy (TEM). Laboratory tests were performed to study the effect of moisture and ultraviolet (UV) light on the oxidation of the pollutant gases when exposed to photo catalytic samples. The structured testing involved exposure to NOx, S02 and a combination thereof with controlled environmental parameters tor 72 hour periods. XPS, Raman spectroscopy and TOF-SIMS were used for surface analysis of the samples after exposure to the reactive gas compounds. An increase in surface oxidation of reactive gases was observed in the presence of UV light and moisture. The synergistic relationship between SO2 and NOx initially proposed by Alien et al was supported by these observations. The nano-patterned anatase samples, with increased surface area, adsorbed larger quantities of pollutant gas and showed the highest recorded levels of nitrate and sulphate formation. The novel coated substrates also exhibited a photocatalytic activity equal to that of commercial grade anatase powder.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:618308 |
| Date | January 2009 |
| Creators | Jones, Christopher |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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