Carbon materials, such as graphite and conducting diamond, are highly popular for analytical and electrochemical applications, and fundamental knowledge of heterogeneous electron transfer is required to understand and optimise applications. In this thesis, the relationship between the structure of HOPG (Highly Oriented Pyrolytic Graphite) and its electrochemical behaviour has been thoroughly studied from the macroscale to the nanoscale. With the use of data collected from a wide range of techniques, spanning voltammetry, electrochemical imaging and high resolution microscopy, on 5 different grades of basal plane HOPG whose surfaces vary in defect density, the contribution of edge plane vs. basal plane on the electrochemical activity of HOPG has been re-examined. The significant body of work presented herein shows, without doubt, that the basal plane of HOPG is a very active electrode for Ru(NH)6 3+/2+; Fe(CN)6 4-/3-; the oxidation of the neurotransmitter, dopamine (DA), and quinones in aqueous solution. This overturns a well-established (textbook) model that the basal surface is inert, which researchers have assumed for two decades, with implications that carry over to related sp2 carbon materials, such as graphene and carbon nanotubes. A second aspect has considered polycrystalline boron-doped diamond (pBDD) to study neurotransmitters, such as DA and serotonin (5-HT). The electrode surface was found to be resistive towards permanent surface blocking during the electrochemical oxidation of these neurotransmitters. The properties of the film formed by 5-HT oxidative products, was thoroughly investigated using voltammetry and high resolution microscopy. It is shown, for the first time, that electro-oxidation of 5-HT results in an electrically insulating, but charged and porous film, but procedures are demonstrated that allow the pBDD to be renewed in-situ for precise electroanalysis.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582267 |
| Date | January 2012 |
| Creators | Patel, Anisha N. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/56386/ |
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