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A diethyl methyl ammonium triflate based protic ionic liquid polymer membrane for intermediate temperature water electrolysis

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

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Abstract

Diethylmethylammonium trifluoromethanesulfonate [Dema][TfO], a protic ionic liquid, was used as an electrolyte for an intermediate temperature water electrolyser. In this study we fabricated polymer electrolyte membrane based on PTFE pore filled membrane impregnated with [Dema][TfO]. The activation energy obtained for an ionic conductivity was 8.12 kJ mol^-1. Hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) were studied in the solid-state cell with an in-situ RHE reference electrode, using Pt/C cathode and IrO₂ anode respectively. The HER was observed at two different potentials, one at a peak potential of -0.47 V vs RHE with a limiting current density of -9.7 mA/cm², assigned to reduction of hydronium ion. The second HER was observed at -0.63 V vs. RHE, assigned to the [Dema-H]⁺ cation reduction. Similarly, two oxidation peaks were assigned to OER one at 1.47 V and the second at 1.72 V vs RHE. The full cell water electrolyser achieved a current density of 70 mA/cm² at 2.2 V with 50% RH at 100 ^oC. The stability of [Dema-H]⁺[TfO]^- was studied with in-situ mass spectrometry which showed the loss of DEMA at > -0.8 V vs RHE while [TfO]^- anion was stable up to 2.5 V vs RHE.

Publication metadata

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

Publication type: Article

Publication status: Published

Journal: International Journal of Hydrogen Energy

Year: 2020

Volume: 45

Issue: 53

Pages: 28303-28312

Print publication date: 30/10/2020

Online publication date: 21/08/2020

Acceptance date: 02/08/2020

Date deposited: 07/08/2020

ISSN (print): 0360-3199

Publisher: Elsevier BV

URL: https://doi.org/10.1016/j.ijhydene.2020.08.016

DOI: 10.1016/j.ijhydene.2020.08.016

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