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Diethylmethylammonium trifluoromethanesulfonate protic ionic liquid electrolytes for water electrolysis

Lookup NU author(s): Dr Ravikumar Ravikumar, Emeritus Professor Keith Scott, Professor Mohamed MamloukORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


© 2019Protic ionic liquids (PILs) are promising electrolytes for electrochemical devices, owing to their wide electrochemical stability, good ionic conductivity, low vapour pressure and good thermal stability. In this study, we demonstrate that [Dema-H]+[TfO]- can be used as an electrolyte for intermediate temperature water electrolysis. The cyclic voltammograms of [Dema-H]+[TfO]- on Pt show a potential window of 2.5 V which is beyond water decomposition potential of 1.23 V. Two hydrogen evolution reactions are observed on Pt electrode in both “as prepared” [Dema-H]+[TfO]- and 10% [Dema-H]+[TfO]- in water. The first HER involving H3O+ had a peak potential at −0.255 V (vs SHE with limiting current density of 0.016 mA/cm2 assigned to Pt low surface coverage/adsorption of H+/H3O+. The second HER involving [Dema-H]+ had an on-set at −0.475 V vs SHE and did not show limiting current up to 0.1 mA cm−2 (−0.8 V vs. SHE). Second observed HER is believed to be due to reduction of two [Dema-H]+ to produce H2 and diethyl methyl amine [Dema]. The latter is reoxidised at anode to reproduce [Dema-H]+. In-situ mass spectrometric analysis confirmed H2/O2 evolution at both potentials. The oxygen evolution reaction (OER) on IrO2 in 10% [Dema-H]+[TfO]- also shows two onset potentials.

Publication metadata

Author(s): Thimmappa R, Walsh D, Scott K, Mamlouk M

Publication type: Article

Publication status: Published

Journal: Journal of Power Sources

Year: 2020

Volume: 449

Print publication date: 15/02/2020

Online publication date: 19/12/2019

Acceptance date: 10/12/2019

Date deposited: 21/02/2020

ISSN (print): 0378-7753

ISSN (electronic): 1873-2755

Publisher: Elsevier BV


DOI: 10.1016/j.jpowsour.2019.227602


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