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Title: The synthesis of one-dimensional titanium oxide nanostructures
Author: Cottam, Ben Francis
ISNI:       0000 0001 3389 9495
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2008
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My work has been focussed on the synthesis of titanium oxide (Ti02) nanostructures. Commercially available Ti02 is widely used in applications such as self-cleaning surfaces, water purification devices and solar cells. However, a new generation of Ti02particles offers high crystallinity, monodispersity, and well defined . geometry. High aspect ratio particles are likely to offer advantages in terms of transport properties and accessibility to other phases. I have investigated three distinct strategies for the preparation of Ti02 nanorods. The first involves a hydrolysis of titanium tetraisopropoxide (TrIP), with oleic acid as a surfactant, which prodUces anatase Ti02nanorods of -3 nm diameter and -30 nm in length. This reaction was performed both on the bulk seale, with a standard flask and manifold set-up, and also in the highly controlled environment of microfluidic chips. The use of continuous-flow, microfluidic devices confers several advantages over conventional macroscale techniques, including high surface area-ta-volume ratios and reduced diffusional dimensions. Our studies show a roughly ten-fold increase in reaction rate when the hydrolysis is performed onchip, as opposed to in a flask. As an alternative, a non-hydrolytic synthesis of Ti02nanorods was performed, via the reaction of TrIP and TiCI 4 in the presence of oleic acid. The non-hydrolytic reaction provides scope for higher reaction temperatures, different surface functionalities, and different reaction rates. The anatase nanorods obtained were -S nm in diameter and -SO nm in length. The reaction conditions (time of reaction, temperature, mode of addition of TiCI4) were optimised for purity, crystallinity and monodispersity. The third synthetic technique relied on the conversion of aligned multi-walled carbon nanotubes (MWCNTs) into rutile Ti02nanorods. The MWCNTs were grown via a standard CVD process in which a -3% ferrocenein xylene solution is gradually pumped into a quartz tube at -760��?���°C. The MWCNTs were then reacted with a volatile titanium iodide, generated in situ, at high temperature (800 -1200 ��?���°C) and reduced . pressure, to produce titanium carbide (TiC) nanorods with similar dimensions. Oxidation of the TiC at 800��?���°C, converts it to rutile Ti02nanorods. The resulting nanostructures are -SO nm in diameter and up to -SOO /-1m in lellgth, and composed of pure, polycrystaJline rutile .The process preserves the unidirectional alignment of the original nanotubes, which may be useful for applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available