Molecular Resolution Nanostructure and Dynamics of the Deep Eutectic Solvent-Graphite Interface as a Function of Potential

Justin S. Freeman, Mesfin Haile Mamme, Jon Ustarroz, Gregory G. Warr, Hua Li, Rob Atkin

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Interest in deep eutectic solvents (DESs), particularly for electrochemical applications, has boomed in the past decade because they are more versatile than conventional electrolyte solutions and are low cost, renewable, and non-toxic. The molecular scale lateral nanostructures as a function of potential at the solid-liquid interface-critical design parameters for the use of DESs as electrochemical solvents-are yet to be revealed. In this work, in situ amplitude modulated atomic force microscopy complemented by molecular dynamics simulations is used to probe the Stern and near-surface layers of the archetypal and by far most studied DES, 1:2 choline chloride:urea (reline), at the highly orientated pyrolytic graphite surface as a function of potential, to reveal highly ordered lateral nanostructures with unprecedented molecular resolution. This detail allows identification of choline, chloride, and urea in the Stern layer on graphite, and in some cases their orientations. Images obtained after the potential is switched from negative to positive show the dynamics of the Stern layer response, revealing that several minutes are required to reach equilibrium. These results provide valuable insight into the nanostructure and dynamics of DESs at the solid-liquid interface, with implications for the rational design of DESs for interfacial applications.

Original languageEnglish
Article number2204993
Number of pages14
JournalSmall
Volume19
Issue number12
Early online date10 Jan 2023
DOIs
Publication statusPublished - 22 Mar 2023

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