The University of Southampton
University of Southampton Institutional Repository

Transient studies of oxygen reduction at microelectrodes

Transient studies of oxygen reduction at microelectrodes
Transient studies of oxygen reduction at microelectrodes
Our group has previously reported the successful development of a steady state microelectrode sensor for the determination of dissolved oxygen concentrations in sea water. The work presented here underpins the development of a fast oxygen sensor for oceanographic applications; the overall aim is to determine the best conditions to measure dissolved oxygen concentrations with microdiscs on a time scale ranging from sub milliseconds to seconds. Previous studies with rotating disc and microelectrodes have shown how the apparent number of electrons, napp, varies between 4 and 2 as the steady mass transfer coefficient increases. The present study also aims to provide insight into the oxygen reduction reaction (ORR) and in particular to probe whether and how napp, depends on the time scale of the reaction. This thesis will describe the results of transient amperometric experiments recorded with microdisc electrodes. The experiments were carried out with different size Pt microdisc electrodes, using fast scan cyclic voltammetry, chronoamperometry and sampled current voltammetry. Model experiments were first conducted with ferrocene, FeCp2, in acetonitrile to validate the experimental approach. Subsequent model experiments were conducted with hexaammineruthenium (III) chloride, Ru(NH3)6Cl3, in aqueous chloride solutions. The ORR was also probed in aqueous chloride solutions. Experiments were also systematically conducted in absence of redox couple to investigate the role of background processes in determining the overall amperometric response over the different time scales considered. Where possible, fast scan voltammograms, chronoamperograms and sampled current voltammograms were compared to theoretical expressions or simulations. The work will also describe attempts to develop a potentiostatic conditioning waveform capable of pre treating the microdisc electrode in order to produce reliable oxygen reduction chronoamperograms. Various coatings were used for simultaneous determination of dopamine and oxygen species for biological application. The conditioning waveform at bare electrode was found to give more reproducible ORR amperometric response than the coatings alone.
Al-Shandoudi, Laila
a54d5139-85a7-4d2d-99f8-1020b52c435c
Al-Shandoudi, Laila
a54d5139-85a7-4d2d-99f8-1020b52c435c
Denuault, Guy
5c76e69f-e04e-4be5-83c5-e729887ffd4e

Al-Shandoudi, Laila (2015) Transient studies of oxygen reduction at microelectrodes. University of Southampton, Chemistry, Doctoral Thesis, 206pp.

Record type: Thesis (Doctoral)

Abstract

Our group has previously reported the successful development of a steady state microelectrode sensor for the determination of dissolved oxygen concentrations in sea water. The work presented here underpins the development of a fast oxygen sensor for oceanographic applications; the overall aim is to determine the best conditions to measure dissolved oxygen concentrations with microdiscs on a time scale ranging from sub milliseconds to seconds. Previous studies with rotating disc and microelectrodes have shown how the apparent number of electrons, napp, varies between 4 and 2 as the steady mass transfer coefficient increases. The present study also aims to provide insight into the oxygen reduction reaction (ORR) and in particular to probe whether and how napp, depends on the time scale of the reaction. This thesis will describe the results of transient amperometric experiments recorded with microdisc electrodes. The experiments were carried out with different size Pt microdisc electrodes, using fast scan cyclic voltammetry, chronoamperometry and sampled current voltammetry. Model experiments were first conducted with ferrocene, FeCp2, in acetonitrile to validate the experimental approach. Subsequent model experiments were conducted with hexaammineruthenium (III) chloride, Ru(NH3)6Cl3, in aqueous chloride solutions. The ORR was also probed in aqueous chloride solutions. Experiments were also systematically conducted in absence of redox couple to investigate the role of background processes in determining the overall amperometric response over the different time scales considered. Where possible, fast scan voltammograms, chronoamperograms and sampled current voltammograms were compared to theoretical expressions or simulations. The work will also describe attempts to develop a potentiostatic conditioning waveform capable of pre treating the microdisc electrode in order to produce reliable oxygen reduction chronoamperograms. Various coatings were used for simultaneous determination of dopamine and oxygen species for biological application. The conditioning waveform at bare electrode was found to give more reproducible ORR amperometric response than the coatings alone.

Text
Final corrected thesis Laila mirorred margain.pdf - Other
Available under License University of Southampton Thesis Licence.
Download (6MB)

More information

Published date: 25 June 2015
Organisations: University of Southampton, Chemistry

Identifiers

Local EPrints ID: 380893
URI: https://eprints.soton.ac.uk/id/eprint/380893
PURE UUID: 8200ac4d-48e6-4108-ae8d-febcb814f39a
ORCID for Guy Denuault: ORCID iD orcid.org/0000-0002-8630-9492

Catalogue record

Date deposited: 22 Sep 2015 12:43
Last modified: 26 Jul 2018 04:01

Export record

Contributors

Author: Laila Al-Shandoudi
Thesis advisor: Guy Denuault ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×