Aggregation of Surfactants at Graphite (FINAL).docx (1.58 MB)
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Potential Dependence of Surfactant Adsorption at the Graphite Electrode/Deep Eutectic Solvent Interface

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journal contribution
posted on 26.02.2020, 16:31 by Katharina Haeckl, Hua Li, Iain M Aldous, Terrence Tsui, Werner Kunz, Andrew P Abbott, Gregory G Warr, Rob Atkin
Copyright © 2019 American Chemical Society. Atomic force microscopy and cyclic voltammetry are used to probe how ionic surfactant adsorbed layer structure affects redox processes at deep eutectic solvent (DES)/graphite interfaces. Unlike its behavior in water, sodium dodecyl sulfate (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 open-circuit potential (OCP) and positive potentials, and it 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.

History

Citation

Journal of Physical Chemistry Letters, 2019, 10, 18, 5331-5337

Author affiliation

Department of Chemistry

Version

AM (Accepted Manuscript)

Published in

Journal of Physical Chemistry Letters

Volume

10

Issue

18

Pagination

5331 - 5337 (13)

Publisher

American Chemical Society

issn

1948-7185

eissn

1948-7185

Acceptance date

20/08/2019

Copyright date

2019

Publisher version

https://pubs.acs.org/doi/full/10.1021/acs.jpclett.9b01968

Spatial coverage

United States

Language

English