This thesis considers the electrochemistry of platinum-iridium electrodes in both sulphate- and chloride-containing electrolytes at 20 - 25°C. Both wire electrodes of appropriate alloy compositions and titanium-substrate electrodes were employed. Polarization curves were obtained, and a technique for measuring the surface area of the electrodes was employed in order to determine the effect of potentiostatic electrolysis on the electrochemically active area. The wire alloy electrodes showed polarization behaviour in 1M NaCl; pH 2 identical to that of platinum electrodes, indicating that iridium is not effective in reducing the passivation of these electrodes even with up to 25% alloy content. The coated electrodes showed irreversible surface area losses in both sulphate and chloride electrolytes, with the latter producing significant reductions after very short polarization times. It is suggested that oxidation of the substrate leading to electrical isolation of coating plates is responsible for the area decay. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Graduation date: 1991

published_or_final_version / Chemistry / Master / Master of Philosophy

Includes bibliography / 1 v. (various pagings) : ill ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1985

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 57 p. : ill. Includes abstract. Includes bibliographical references (p. 55-57).

This dissertation describes photocoulometric and AC impedance studies of dye-modified electrodes. The photocoulometric technique allowed photoelectrochemical phenomena to be observed without mass transport effects. These measurements confirmed the photoconductive properties of monomeric silicon phthalocyanine dye. They also showed that the photo-assisted oxidation of hydroquinone to benzoquinone at n-tin oxide electrodes modified with this dye involved a cation dye intermediate with a lifetime of between 0.05 and 350 ns, with the rate limiting step being charge transport through the dye film or charge transfer across the interface between the dye and the substrate. AC impedance studies included Mott-Schottky measurements and faradaic impedance experiments on tin oxide and gold metallized plastic optically transparent electrodes. They also examined the substrates modified with monomeric silicon phthalocyanine and chloro-gallium phthalocyanine. The Mott-Schottky measurement procedure was free of systematic errors that affected other published work, and the results of these measurements were consistent with those found by independent methods. The faradaic impedance technique was applied to dye-modified electrodes for the first time. These studies found evidence for an adsorption or electrodeposition process in the oxidation of hydroquinone at these electrodes, and gave exchange current densities that were consistent with the values that were found by other methods.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.