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The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids

Goodwin, Sean; Muhammad, Sayyar; Tuan, Li-Ping; Walsh, Darren

Authors

Sean Goodwin

Sayyar Muhammad

Li-Ping Tuan

DARREN WALSH DARREN.WALSH@NOTTINGHAM.AC.UK
Professor of Chemistry



Abstract

Ionic liquids are formally defined as liquids that consist entirely of ions, and which are liquid below 100 C. As these liquids are being proposed for use in a range of electrochemical devices and applications, understanding the electrochemical behaviour of these is increasingly important. In this contribution, we describe the effects of parent amine molecules on electrocatalysis in the protic ionic liquids diethylmethylammonium trifluoromethanesulfonate and diethylmethylammonium heptafluorobutanoate. We first show that diethylmethylamine can adsorb onto Pt electrodes during electrocatalytic reduction of trifluoromethanesulfonic acid in diethylmethylammonium trifluoromethanesulfonate. In contrast, diethylmethylamine promotes the oxidation of formic acid in this ionic liquid, by deprotonating the acid to the active formate species. Therefore, the neutral base can either inhibit or enhance electrocatalysis in the liquid, depending on the reaction under consideration. We also show that the mechanism of formic-acid oxidation in diethylmethylammonium heptafluorobutanoate differs significantly from that observed when using diethylmethylammonium trifluoromethanesulfonate. This phenomenon is attributed to adsorption of poisoning spectator species onto the electrode surface, demonstrating that changes to the structure of ionic-liquid anions can have drastic effects on the electrochemistry of these liquids.

Citation

Goodwin, S., Muhammad, S., Tuan, L., & Walsh, D. (2018). The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids. Journal of Electroanalytical Chemistry, 819, https://doi.org/10.1016/j.jelechem.2017.10.021

Journal Article Type Article
Acceptance Date Oct 10, 2017
Online Publication Date Oct 13, 2017
Publication Date Jun 15, 2018
Deposit Date Mar 2, 2018
Publicly Available Date Oct 14, 2018
Journal Journal of Electroanalytical Chemistry
Print ISSN 1572-6657
Electronic ISSN 1873-2569
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 819
DOI https://doi.org/10.1016/j.jelechem.2017.10.021
Keywords Ionic liquid; Ultramicroelectrode; Scanning electrochemical microscopy; Hydrogen evolution reaction; Underpotential-deposited hydrogen; Formic acid
Public URL https://nottingham-repository.worktribe.com/output/938509
Publisher URL https://www.sciencedirect.com/science/article/pii/S1572665717307221?via%3Dihub

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