The influence of water content in a proton-conducting ionic liquid on the double layer properties of the Pt/PIL interface

Wippermann, Klaus; Giffin, Jürgen; Kuhri, Susanne; Lehnert, Werner; Korte, Carsten

doi:10.1039/c7cp04003b

Cited by 28 publications

(40 citation statements)

References 87 publications

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“…Furthermore, the addition of water decreases the density of both ILs. These results are comparable with other bibliographic references [5][6][7]. In the case of speed of sound ( Figure 2), similar behaviors have been observed; that is, a decrease of this parameter with the temperature for all of the studied fluids, which is in good agreement with other previous works [1] Using Equation 2, the thermal expansion coefficient has been calculated and represented in and also decreases linearly with temperature.…”

Section: Resultssupporting

confidence: 91%

Thermophysical Characterization of Two DyethylMethylAmmonium Ionic Liquids

Parajó

Villanueva

Fernández-Míguez

et al. 2018

22nd International Electronic Conference on Synthetic Organic Chemistry

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Density (ρ), speed of sound (U), and the derived magnitudes of two diethylmethylammoniumionic liquids (ILs) against temperature have been studied in this work. The chosen ILs were diethylmethylammonium trifluoromethanesulfonate [C2C2C1N][OTf] and diethylmethylammonium methanesulfonate [C2C2C1N][MeSO3]. In order to analyze the influence of water content, saturated and dried samples of these ILs were studied. The ILs were dried using a vacuum pump, and the saturation level (28% and 6% in weight for [C2C2C1N][MeSO3] and [C2C2C1N][OTf], respectively) was achieved by keeping the ILs in an open bottle at ambient temperature. Direct measurements of density and speed of sound were taken with an Anton Paar DSA 5000. Linear equations were used to express the correlation of both properties with temperature, and the thermal expansion coefficient, αp, and the adiabatic bulk modulus constant, KS, have been also obtained. Additionally, results were compared with previous literature data in order to have a deeper understanding of the liquid properties and detect possible anomalous behaviors. The effect of water content is different on both properties. Thus, the density of the samples slightly increases when water is removed, whereas the opposite behavior was found with regard to the speed of sound, which decreased when the water content was completely removed.

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Section: Resultssupporting

confidence: 91%

Thermophysical Characterization of Two DyethylMethylAmmonium Ionic Liquids

Parajó

Villanueva

Fernández-Míguez

et al. 2018

22nd International Electronic Conference on Synthetic Organic Chemistry

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“…[2-Sema][TfO] was prepared by slowly adding trifluoromethanesulfonic acid (reagent grade, 98%, Sigma Aldrich) to 2-methylaminoethansulfonic acid (N-methyltaurine, 99%, Sigma Life Science). A more detailed description of the preparation process can be found elsewhere [9]. Coulometric Karl-Fischer titration (852 Titrando/Metrohm company) yielded a water concentration of 0.6 wt.%.…”

Section: Ionic Liquid Preparationmentioning

confidence: 99%

PBI‐type Polymers and Acidic Proton Conducting Ionic Liquids – Conductivity and Molecular Interactions

Lin

Korte

2020

Fuel Cells

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Proton conducting ionic liquids (PILs) are discussed as new electrolytes for the use as non‐aqueous electrolytes at operation temperatures above 100 °C. During fuel cell operation the presence of significant amounts of residual water is unavoidable. The highly Brønsted‐acidic PIL 2‐Sulfoethylmethylammonum triflate [2‐Sema][TfO] is able to perform fast proton exchange processes with H2O, resulting from 1H‐NMR and pulsed field gradient (PFG)/diffusion ordered spectroscopy (DOSY) self‐diffusion measurements. Proton conduction takes place by a vehicle mechanism via PIL cations or H3O+, but also by a cooperative mechanism involving both species. Thus, highly Brønsted‐acidic PILs are promising candidates for the use as non‐aqueous electrolytes. To use [2‐Sema][TfO] as electrolyte in a proton electrolyte fuel cell (PEFC) it has to be immobilized in a host polymer. There is a (slow) uptake of the PIL by polybenzimidazole (PBI) up to a weight increase of ∼130%, due to a swelling process. A protonation of the basic imidazole moieties takes place. NMR analysis was applied to elucidate the molecular interactions between PBI, PIL, and residual water. Proton exchange, respectively an interaction between the polar groups and water can be observed in spectra, indicating a network of H‐bonds in doped PBI. Therefore, highly acidic PILs are promising candidates for the use as non‐aqueous electrolytes.

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“…A more detailed description of the preparation process can be found elsewhere. 48 Coulometric Karl-Fischer titration (852 Titrando / Metrohm company) yielded a water content of 6400 ppm (0.64 wt%).…”

Section: Electrolytes: [2-sema][tfo] [Dema][tfo] and Binary Mixturesmentioning

confidence: 99%

In Situ Determination of the Water Content of Ionic Liquids

Wippermann

Giffin

Korte

2018

J. Electrochem. Soc.

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This study examines the applicability of electrochemical methods to the in situ determination of the water content in proton-conducting ionic liquids (PILs). Two proton-conducting ionic liquids with different acidities and hygroscopicities of the cations, sulfoethylmethylammonium trifluoromethanesulfonate, [2-Sema][TfO] and N,N-diethylmethylammonium trifluoromethanesulfonate, [Dema][TfO], were used. At first, PIL water electrolytes with known water concentrations ([2-Sema][TfO]: 0.64-6.1 wt%, [Dema][TfO]: 0.18-99.5 wt%) were prepared. Then, the influence of the water content on the electrochemical properties, namely the electrical conductivity, charge of hydrogen oxidation, charge of Pt oxide reduction and onset potential of Pt oxidation, were investigated. The four parameters were plotted as a function of the water concentration and fitted by exponential, linear or asymptotic functions. These fits serve as calibration curves that can be used to determine the actual water concentration by measuring one or more of the four parameters investigated. It was found that the measurement of specific ion conductivity is a fast and simple method across a wide range of water concentrations. The evaluation of the Pt oxide reduction charge from cyclic voltammograms is more time-consuming, but provides higher accuracy at low water concentrations, although the accuracy also depends on the nature of the ionic liquid.

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The influence of water content in a proton-conducting ionic liquid on the double layer properties of the Pt/PIL interface

Cited by 28 publications

References 87 publications

Thermophysical Characterization of Two DyethylMethylAmmonium Ionic Liquids

Thermophysical Characterization of Two DyethylMethylAmmonium Ionic Liquids

PBI‐type Polymers and Acidic Proton Conducting Ionic Liquids – Conductivity and Molecular Interactions

In Situ Determination of the Water Content of Ionic Liquids

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