Document Type

Theses, Ph.D


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Publication Details

Successfully submitted for the award of Doctor of Philosophy (Ph.D) to the Technological University Dublin, 2003.


In this work, two contrasting polymer-modified electrodes are investigated. Electroanalysis of lead in aqueous solutions was performed with an electrode coated with Nafion and the redox behaviour of the electronically conducting polymer, polypyrrole, was characterised. In the first study, a glassy carbon electrode coated with Nafion was used in the determination of lead through anodic stripping voltammetry (ASV). Initially the work consisted of optimising the preparation of the electrode and the experimental conditions resulting in a reproducible Nafion-modified electrode (NME) with a lifetime of several weeks. Two different stripping techniques were examined. High frequency square wave ASV was found to yield much better results then the slower Differential Pulse technique. Interference from other metal cations was examined and in most cases eliminated through changing the experimental parameters or addition of masking agents. When fully optimised a detection limit of ~1ppb was possible. The NME was used to detect the quantity of lead in a certified reference material and real samples. The second study involved the electrochemistry and in-situ UV-vis Raman and SERRS (surface enhance resonance Raman scattering) spectroelectrochemistry of polypyrrole (PPy) doped with dodecylbenzenesupphonate (DBS) on a Pt substrate (or Au in the case of SERRS). The electrosynthesis of PPy/DBS films was optimised and multiple cycle cyclic voltammetry was performed to determine the stability of the film. Films synthesised at lower potentials were found to be less prone to degradations due to their more compact nature. The concentrations of the dication, radical cation and neutral forms of the polymer were followed by observing intensity and wavenumber changes of the Raman bands and absorption in UV-vis spectra. In comparing the Raman spectroelectrochemical behaviour of PPY/DBS and PPy/Cio 4 films it was found that the radical cation yielded a much stronger contribution in the former. SERRS of PPy/DBS on roughened Au substrates was found to offer enhancements of up to 2 orders of magnitude compared to normal Raman at a Pt substrate


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