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Title: Aerosol assisted chemical vapour deposition of photo-catalytic composite and doped TiO2 thin films
Author: Chadwick, N. P.
ISNI:       0000 0004 8503 193X
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2015
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This thesis details the use of Aerosol Assisted Chemical Vapour Deposition (AACVD) to synthesise doped and composite titanium dioxide (TiO¬2) thin films for use in technological applications. These applications range from advanced transparent coatings for self-cleaning windows to materials for the irradiation induced remediation of compromised water sources. First, a TiO2/SnO2 composite, which had been synthesised and characterised previously, is investigated by combinatorial AACVD (C-AACVD) itself a novel form of AACVD which separates precursor streams until they are in the reactor. This achieved films which graduate from TiO2 to SnO2 allowing changes in physical and elemental structure to be easily related to variances in functional properties. Next a new form of AACVD is used for the first time to provide insight into the growth of the TiO2/SnO2 composite, which is not achieved using combinatorial methods. Time Resolved AACVD (TR-AACVD) allows the creation of thin films that vary as a function of time, rather than elemental concentration as in combinatorial AACVD (C-AACVD). Advantageously many films can be created in a single deposition, allowing a full deposition to investigate the full growth of a material of interest. Whilst nitrogen doped TiO2 is a well characterised material within the scientific literature, questions still remain as to the true physical reasons for its functional properties. In this work Transient Absorption Spectroscopy (TAS) is used in conjunction with X-ray Photoelectron Spectroscopy (XPS) and photo-activity measurements to chart how the material changes as a function of irradiation time, providing an idea of how nitrogen doped TiO2 would fair in an environmental setting outside the laboratory. Finally, capitalising on the production of nitrogen doped TiO2, nitrogen and niobium co-doped TiO2 is synthesised using combinatorial AACVD to create a film which graduates from N: TiO2 to Nb: TiO2 with co-doped states created in between. The incorporation of TCO and photo-catalytic properties in TiO2 is explored.
Supervisor: Carmalt, Claire J. ; Parkin, Ivan Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available