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

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...

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Main Authors: Goodwin, Sean, Muhammad, Sayyar, Walsh, Darren
Format: Article
Published: Elsevier 2018
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Online Access:https://eprints.nottingham.ac.uk/47154/
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author Goodwin, Sean
Muhammad, Sayyar
Walsh, Darren
author_facet Goodwin, Sean
Muhammad, Sayyar
Walsh, Darren
author_sort Goodwin, Sean
building Nottingham Research Data Repository
collection Online Access
description 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.
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spelling nottingham-471542020-05-04T19:40:45Z https://eprints.nottingham.ac.uk/47154/ The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids Goodwin, Sean Muhammad, Sayyar Walsh, Darren 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. Elsevier 2018-06-15 Article PeerReviewed Goodwin, Sean, Muhammad, Sayyar and Walsh, Darren (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 . pp. 187-192. ISSN 1873-2569 Ionic liquid; Ultramicroelectrode; Scanning electrochemical microscopy; Hydrogen evolution reaction; Underpotential-deposited hydrogen; Formic acid https://www.sciencedirect.com/science/article/pii/S1572665717307221?via%3Dihub doi:10.1016/j.jelechem.2017.10.021 doi:10.1016/j.jelechem.2017.10.021
spellingShingle Ionic liquid; Ultramicroelectrode; Scanning electrochemical microscopy; Hydrogen evolution reaction; Underpotential-deposited hydrogen; Formic acid
Goodwin, Sean
Muhammad, Sayyar
Walsh, Darren
The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title_full The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title_fullStr The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title_full_unstemmed The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title_short The contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
title_sort contrasting effects of diethylmethylamine during reduction of protons and oxidation of formic acid in diethylmethylammonium-based protic ionic liquids
topic Ionic liquid; Ultramicroelectrode; Scanning electrochemical microscopy; Hydrogen evolution reaction; Underpotential-deposited hydrogen; Formic acid
url https://eprints.nottingham.ac.uk/47154/
https://eprints.nottingham.ac.uk/47154/
https://eprints.nottingham.ac.uk/47154/