Probing Voltage- and Electrolyte-Dependent Monolayer Dynamics with 2D-IR Spectroscopy

Abstract
Little is known about structural dynamics at electrode surfaces under applied potential. Here, we report 2D-IR spectra of a 4-mercaptobenzonitrile monolayer on a gold electrode, revealing chemical exchange between two subensembles on sub- to tens-of-picoseconds time scales. Dynamics are measured in 100 mM MgCl2, LiCl, and KCl at −200 and +300 mV vs Ag/AgCl. At +300 mV, all electrolytes exhibited ≥48 ps exchange, while at −200 mV, the slower exchange component ranged from ≥33 to ≥43 ps. The dynamics correlate with ion concentration, according to radial distribution functions calculated from molecular dynamics simulations, suggesting that local ion densities, regardless of valency or sign, slow dynamics. Results show solvation, electric double layer formation, and monolayer reorientation. This work reveals how electrolyte composition modulates molecular reorientation and hydrogen bonding at functionalized electrodes.
Description
This article was originally published in Journal of the American Chemical Society. The version of record is available at: DOI https://doi.org/10.1021/jacs.5c14718 © 2025 The Authors. Published by American Chemical Society This article is under embargo until October 24, 2026 This publication is licensed under CC-BY 4.0 . cc licence License Summary* You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below: cc licence Creative Commons (CC): This is a Creative Commons license. ny licence Attribution (BY): Credit must be given to the creator. View full license https://creativecommons.org/licenses/by/4.0/ This summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials.
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Citation
"Probing Voltage- and Electrolyte-Dependent Monolayer Dynamics with 2D-IR Spectroscopy Austin B. Gilbert, Wonjae Jeong, Kyle R. Billings, Aritri Biswas, Matthew J. Ryan, Kijeong Kwac, Minhaeng Cho, Alexei A. Kananenka, and Martin T. Zanni Journal of the American Chemical Society Article ASAP DOI:https://doi.org/10.1021/jacs.5c14718"