Transport Properties, Local Coordination, and Thermal Stability of the Water/Diethylmethylammonium Methanesulfonate Binary System

Abstract

Ammonium based protic ionic liquids are highlighted for their great potential to sustain proton transport in proton exchange membrane (PEM) fuel cells. Yet, there remain questions concerning the effect of water produced by the fuel cell at the cathode side on the performance of the ionic liquid. In this contribution we report the effect of water on the transport properties and the local coordination in the binary system of the protic ionic liquid diethylmethylammonium methanesulfonate ([DEMA][OMs]) and water, employing 1H NMR, Raman, and infrared spectroscopy. We observe that the self‐diffusion of cations and anions increases with the water content and that cations and anions diffuse at the same rate at all concentrations investigated. 1H NMR and vibrational spectroscopy, on the other hand, indicate that added water interacts primarily with the anion and slightly affects the ionicity of the ionic liquid. In addition, by investigating the thermal stability of the binary system we find that although [DEMA][OMs] displays a continuous loss of water upon increasing temperature a fraction of water molecules can be retained even above 120 °C, and that the complete loss of water is immediately followed by decomposition, which is observed to occur at about 185 °C.

Achieving enhanced ionic mobility in nanoporous silica by controlled surface interactions

“…In this respect, we have recently reported a thermal decomposition for pure DEMAOMs where dehydration precedes the back transfer of the protons from DEMA + to OMs À with the consequent evaporation of neutral amine species. 36 As shown in Fig. 5b, the conductivity in functionalized silica deviates from the expected VFT behavior above B85 1C (or below 1000/T = 2.8), which is also the temperature for a first mass loss phenomenon detected by TGA for the corresponding gel ( Fig.…”

“…S2, ESI †). 36 This observation suggests that for the specific need of hightemperature applications, e.g. in next-generation fuel cells operating above 120 1C, a protic ionic liquid more thermally stable than DEMAOMs should be selected.…”

The peculiar effect of water on ionic liquids and deep eutectic solvents

“…From these observations, they concluded that when x water o 0.8, there is no major modification of the structure and the ionic association occurs despite of the strong decrease of the viscosity occurs. Yaghini et al 259 studied how the added water affects the transport properties, the local coordination, and the thermal behaviour of [DEMA][MeSO 3 ] by NMR, Raman and infrared spectroscopy. The results show that water interacts primarily with the anion and slightly affects the ionicity of IL.…”

Physicochemical study of diethylmethylammonium methanesulfonate under anhydrous conditions

“…reported that the added water increased the self-diffusion of cations and anions and interacted primarily with the anion and slightly affected the ionicity of [DEMA][OMs]. 16 (2) The applications of [DEMA][OMs]. 17−19 For instance, Atilhan et al showed that [DEMA][OMs] is suitable for pressure driven CO2 capture processes that might lead to reduction in solvent regeneration cost.…”