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Title: Oxygen sensing and oxide formation : optimisation and novel X-ray studies
Author: Leach, Andrew Stephen
ISNI:       0000 0004 7967 1340
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2019
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Platinum remains vital for the use of electrochemical devices, therefore, understanding of the reactions which occur at the platinum-solution interface is paramount in continuing to improve gas sensors, as well as fuel cells and electrolysers. The following body of work uses a number of electrochemical techniques and X-ray spectroscopies to investigate the surface processes of platinum in acidic media. The pH range over which the electrochemical behaviour can be accurately modelled by the Nernst equation, has been extended into highly acidic solutions by employing the Hammett acidity function (H0) in place of pH when working below pH 1. Sulfuric acid and perchloric acid have been investigated. Both the hydrogen region and oxide formation region have been studied, and the comparison between these two potential regions by cyclic voltammetry has produced a method for electrolyte concentration measurements. A variety of X-ray spectroscopies have been used to provide additional understanding of the oxide formation process on platinum. Conventional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) have presented a baseline for High Energy Resolution Fluorescence Detection (HERFD)-XANES, which offers higher spectral resolution, and Energy Dispersive EXAFS (EDE), which can measure on much smaller time scales. The surface oxidation and reduction of platinum nanoparticles will be discussed. Additionally, a statistically designed set of experiments have been presented, investigating five parameters in an industrial gas sensor electrode manufacturing process. Both sensor output measurements and lab based techniques were employed to characterise the electrodes. It was shown that the electrode loading could be reduced without affecting the sensors initial performance, so cheaper electrodes can be used.
Supervisor: Russell, Andrea Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available