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Potential Dependence of Surfactant Adsorption at the Graphite Electrode / Deep Eutectic Solvent Interface
Katharina Häckl,
Hua Li,
Iain Aldous,
Terrence Tsui,
Werner Kunz,
Andrew P Abbott,
Gregory G. Warr,
Rob Atkin
The Journal of Physical Chemistry Letters
Swansea University Author: Iain Aldous
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DOI (Published version): 10.1021/acs.jpclett.9b01968
Abstract
Atomic force microscope (AFM) and cyclic voltammetry (CV) are used to probe how ionic surfactant adsorbed layer structure affects redox processes at deep eutectic solvent (DES)/graphite interfaces. Unlike its behaviour in water, sodium dodecyl sulphate (SDS) in DESs only adsorbs as a complete layer...
| Published in: | The Journal of Physical Chemistry Letters |
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| ISSN: | 1948-7185 1948-7185 |
| Published: |
2019
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa51509 |
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| Abstract: |
Atomic force microscope (AFM) and cyclic voltammetry (CV) are used to probe how ionic surfactant adsorbed layer structure affects redox processes at deep eutectic solvent (DES)/graphite interfaces. Unlike its behaviour in water, sodium dodecyl sulphate (SDS) in DESs only adsorbs as a complete layer of hemicylindrical hemimicelles far above its critical micelle concentration (CMC). Near the CMC it forms a tail-to-tail monolayer at OCP and positive potentials, and which desorbs at negative potentials. In contrast, cetyltrimethylammonium bromide (CTAB) adsorbs as hemimicelles at low concentrations, and remains adsorbed at both positive and negative potentials. The SDS horizontal monolayer has little overall effect on redox processes at the graphite interface, but hemimicelles form an effective and stable barrier. The stronger solvophobic interactions between the C16 versus C12 alkyl chains in the DES allow CTAB to self-assemble into a robust coating at low concentrations, and illustrate how the structure of the DES/electrode interface and electrochemical response can be engineered by controlling surfactant structure. |
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| College: |
Faculty of Science and Engineering |