Mesoporous, nanocrystalline, metal oxide films exhibit a broad range of attributes attractive for technological applications, including high surface area, semiconducting behaviour, optical transparency in the visible region of the electromagnetic spectrum and excellent mechanical properties. They can be functionalised by the attachment of metal complexes and organic molecules to the metal oxide surface through ligating groups such as carboxylic acids. This thesis addresses the interaction of such functionalised metal oxide films with redox species and ions in solution for applications including dye-sensitised solar cells (DSSCs) and heterogeneous sensing and scavenging of pollutants. The first study reported in this thesis employs a thiourea based organic molecule to functionalise a mesoporous Ah03 film, and demonstrates that this functionalised film can be used as a heterogeneous colorimetric cyanide sensor in aqueous solution. This strategy is extended to a series of ruthenium based metal complexes which are employed to functionalise mesoporous Ti02 films. These functionalised films are shown to bind mercury ions, enabling them to function as selective mercury scavengers. This mercury binding is also shown to disrupt lateral cation percolation between adjacent dye molecules. Electrochemical studies are employed to analyse this cation percolation in detail for two different transition metal complexes, with the introduction of a secondary acceptor group shown to result in an order of magnitude increase in the kinetics of cation percolation. The cation percolation results are discussed in relation to their importance in dye-sensitized solar cells. The last two results' chapters of this thesis address the interaction of functionalised mesoporous metal oxide films and iodine in solution, and the importance of this interaction for the function of dye-sensitised solar cells. Based upon these studies, an enhancement of cell performance is expected through modification of dye structure and the electrolyte composition.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:590040 |
| Date | January 2012 |
| Creators | Li, Xiaoe |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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