In-situ studies of electrode surfaces using synchrotron X-ray radiation
In-situ studies of electrode surfaces using synchrotron X-ray radiation
In-situ X-ray diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy were used to investigate three different electrode materials. In-situ studies were made possible by access to a synchrotron radiation source. The first study focused on (0.3 μm - 3.0 μm thick) lead dioxide deposits on platinum. The electrochemical behaviour of such coatings in 1 M sulphuric acid was investigated and in-situ XRD confirmed that such coatings could only be partially reduced to lead sulphate. The conditions for the re-oxidation of such films were examined and it was found that such deposits were reluctant to cycle. The phase transformation of α-lead dioxide to β-lead dioxide was monitored in-situ during potential cycling. The second study examined the structural changes occurring to a platinised platinum electrode in 1 M sulphuric acid using in-situ, potential modulated XRD. The potential was stepped between the double layer and either the oxide formation or the hydrogen adsorption regions. The differences between the XRD patterns collected at the two potentials were small but a detailed examination of the data and construction of difference XRD patterns led to the conclusion that there was a slight shift in the position of the XRD peaks when the electrode potential was changed. This corresponded to a change in the d-spacing between the platinum atoms: an increase in the d-spacing at potentials in the oxide region and a decrease at potentials corresponding to the weakly adsorbed hydrogen region. The magnitude of the shift was estimated to be less than 0.1%. The third study involved in-situ EXAFS measurements at the platinum L3 edge for a dispersed platinum on carbon electrode in 1 M sulphuric acid. Changes in the near edge (XANES) and EXAFS spectra at potentials in the double layer and oxide formation region were monitored. Analysis of the spectra revealed that the oxide formed had a short range structure similar to platinum (IV) oxide: this was supported by potential step measurements. The lack of the longer distance platinum-platinum correlations expected for the bulk platinum (IV) oxide indicated that the oxide was probably chemisorbed.
University of Southampton
1991
Herron, Maura Ethna
(1991)
In-situ studies of electrode surfaces using synchrotron X-ray radiation.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In-situ X-ray diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy were used to investigate three different electrode materials. In-situ studies were made possible by access to a synchrotron radiation source. The first study focused on (0.3 μm - 3.0 μm thick) lead dioxide deposits on platinum. The electrochemical behaviour of such coatings in 1 M sulphuric acid was investigated and in-situ XRD confirmed that such coatings could only be partially reduced to lead sulphate. The conditions for the re-oxidation of such films were examined and it was found that such deposits were reluctant to cycle. The phase transformation of α-lead dioxide to β-lead dioxide was monitored in-situ during potential cycling. The second study examined the structural changes occurring to a platinised platinum electrode in 1 M sulphuric acid using in-situ, potential modulated XRD. The potential was stepped between the double layer and either the oxide formation or the hydrogen adsorption regions. The differences between the XRD patterns collected at the two potentials were small but a detailed examination of the data and construction of difference XRD patterns led to the conclusion that there was a slight shift in the position of the XRD peaks when the electrode potential was changed. This corresponded to a change in the d-spacing between the platinum atoms: an increase in the d-spacing at potentials in the oxide region and a decrease at potentials corresponding to the weakly adsorbed hydrogen region. The magnitude of the shift was estimated to be less than 0.1%. The third study involved in-situ EXAFS measurements at the platinum L3 edge for a dispersed platinum on carbon electrode in 1 M sulphuric acid. Changes in the near edge (XANES) and EXAFS spectra at potentials in the double layer and oxide formation region were monitored. Analysis of the spectra revealed that the oxide formed had a short range structure similar to platinum (IV) oxide: this was supported by potential step measurements. The lack of the longer distance platinum-platinum correlations expected for the bulk platinum (IV) oxide indicated that the oxide was probably chemisorbed.
This record has no associated files available for download.
More information
Published date: 1991
Identifiers
Local EPrints ID: 460910
URI: http://eprints.soton.ac.uk/id/eprint/460910
PURE UUID: 560410d7-ccf3-4a0b-8940-ab7730027cdf
Catalogue record
Date deposited: 04 Jul 2022 18:32
Last modified: 04 Jul 2022 18:32
Export record
Contributors
Author:
Maura Ethna Herron
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