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Molecular orientation and reactions probed via SERS

Molecular orientation and reactions probed via SERS
Molecular orientation and reactions probed via SERS
Surface enhanced Raman spectroscopy (SERS) can be combined with electrochemical techniques (EC-SERS) to allow the in situ analysis of electrode surfaces, including understanding the fundamental interactions between the electrode and adsorbed molecules, and identifying the intermediates, products and mechanisms of electrochemical reactions. In this work, the potential dependent orientation of ortho-, meta- and para- nitrile substituted benzenethiol self assembled monolayers (SAMs) has been investigated on Au sphere segment void (SSV) substrates by analysis of the in plane and out of plane SERS vibrational band intensities, peak positions and the selection rules. The electroreduction of p-nitrothiophenol (PNTP) and electrooxidation of p-aminothiophenol (PATP) SAMs have also been probed. By using density functional theory (DFT) calculated Raman spectra evidence of new intermediate species has been discovered for both reactions, including a different oxidation mechanism for PATP in acidic and alkaline media. Furthermore, the adsorption and orientation of thioamide terminated molecular wires, an interesting new species for molecular electronics, has been investigated by examining both the absence of expected vibrations and the most intense SERS bands. Finally, further understanding of glycerol electrooxidation has important applications in direct liquid fuel cells (DLFCs), but has a complex reaction mechanism with many intermediates. By careful analysis of the peak pattern of in situ SERS spectra, intermediate species have been identified and the reaction mechanism uncovered.
University of Southampton
Keeler, Alexander, John
a09b190d-f7be-4879-938d-05bea9799287
Keeler, Alexander, John
a09b190d-f7be-4879-938d-05bea9799287
Russell, Andrea
b6b7c748-efc1-4d5d-8a7a-8e4b69396169

Keeler, Alexander, John (2019) Molecular orientation and reactions probed via SERS. University of Southampton, Doctoral Thesis, 187pp.

Record type: Thesis (Doctoral)

Abstract

Surface enhanced Raman spectroscopy (SERS) can be combined with electrochemical techniques (EC-SERS) to allow the in situ analysis of electrode surfaces, including understanding the fundamental interactions between the electrode and adsorbed molecules, and identifying the intermediates, products and mechanisms of electrochemical reactions. In this work, the potential dependent orientation of ortho-, meta- and para- nitrile substituted benzenethiol self assembled monolayers (SAMs) has been investigated on Au sphere segment void (SSV) substrates by analysis of the in plane and out of plane SERS vibrational band intensities, peak positions and the selection rules. The electroreduction of p-nitrothiophenol (PNTP) and electrooxidation of p-aminothiophenol (PATP) SAMs have also been probed. By using density functional theory (DFT) calculated Raman spectra evidence of new intermediate species has been discovered for both reactions, including a different oxidation mechanism for PATP in acidic and alkaline media. Furthermore, the adsorption and orientation of thioamide terminated molecular wires, an interesting new species for molecular electronics, has been investigated by examining both the absence of expected vibrations and the most intense SERS bands. Finally, further understanding of glycerol electrooxidation has important applications in direct liquid fuel cells (DLFCs), but has a complex reaction mechanism with many intermediates. By careful analysis of the peak pattern of in situ SERS spectra, intermediate species have been identified and the reaction mechanism uncovered.

Text
Keeler Final Thesis for Award - Version of Record
Restricted to Repository staff only until 30 June 2022.
Available under License University of Southampton Thesis Licence.

More information

Published date: April 2019

Identifiers

Local EPrints ID: 433182
URI: http://eprints.soton.ac.uk/id/eprint/433182
PURE UUID: 3929745e-7f78-4aaa-8638-c809f94020e7
ORCID for Andrea Russell: ORCID iD orcid.org/0000-0002-8382-6443

Catalogue record

Date deposited: 09 Aug 2019 16:30
Last modified: 10 Aug 2019 00:37

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Contributors

Author: Alexander, John Keeler
Thesis advisor: Andrea Russell ORCID iD

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