QENS Study of Diffusive and Localized Cation Motions of Pyridinium-Based Ionic Liquids

Embs, Jan Peter; Burankova, Tatsiana; Reichert, Elena; Fossog, Verlaine; Hempelmann, Rolf

doi:10.7566/jpsjs.82sa.sa003

Cited by 12 publications

(20 citation statements)

References 13 publications

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“…It is particularly suitable to obtain information about the geometrical and dynamical features of diffusion processes in hydrogenated systems. Some recent QENS studies on pyridinium based ionic liquids have revealed two independent relaxation processes in the system 38,39 . Similarly, different mobilities of different molecules in glyceline DES (glycerol+choline chloride) was also observed using QENS experiments 40 .…”

Section: Introductionmentioning

confidence: 99%

Transport Mechanism of Acetamide in Deep Eutectic Solvents

et al. 2020

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Over the last couple of decades, deep eutectic solvents (DESs) have emerged as novel alternatives to ionic liquids that are extensively used in synthesis of innovative materials, metal processing, catalysis, etc. However, their usage is limited, primarily because of the large viscosity and poor conductivity. Therefore, an understanding of the molecular origin of these properties is essential to improve their industrial applicability. Here, we present the report of the nanoscopic diffusion mechanism of acetamide in a DES synthesized with lithium perchlorate as studied using neutron scattering and molecular dynamics (MD) simulation techniques. Although, the acetamide based DES (ADES) has remarkably lower freezing point compared to pure acetamide, the molecular mobility is found to be enormously restricted in the former. MD simulation indicates a diffusion model with two distinct processes, corresponding to, long range jump diffusion and localised diffusion within a restricted volume. This model is validated by analysis of neutron scattering data in both molten acetamide and ADES. The long range diffusion process of acetamide is slower by a factor of three in ADES in comparison with molten acetamide. MD simulation reveals that the long range diffusion in ADES is restricted mainly due to the formation of hydrogen bond mediated complexes between the ionic species of the salt and acetamide molecules. Hence, the origin of higher viscosity observed in ADES can be attributed to the complexation. The complex formation also explains the inhibition of the crystallisation process while cooling and thereby results in depression of the freezing point of ADES.

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Section: Introductionmentioning

confidence: 99%

Transport Mechanism of Acetamide in Deep Eutectic Solvents

et al. 2020

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“…Consequently, also the associated activation energies underlie such an averaging. While the translational diffusion of the ionic liquid in the pores of MoC-15 has an activation energy similar to the bulk value of 12.3-14.8 kJ/mol [37,38,40,41], the one for BC-6-no is higher, whereas it is smaller for BC-6. It is imaginable that the interaction with the pore wall and structural changes of the ionic liquid that are provoked by the respective pore morphology lead to an alteration of the ionic liquid's dynamics and the related activation energies.…”

Section: B Full Quasielastic Spectramentioning

confidence: 85%

“…Subsequently the nanopores of the carbide-derived carbons are filled with the room-temperature ionic liquid 1-Nbutylpyridinium bis-[(trifluoromethyl)sulfonyl]imide, in the following shortly denoted as [BuPy][Tf 2 N] and whose bulk molecular dynamics have been already extensively studied [37][38][39][40][41]. The structure formulas of the cation and anion are depicted in Fig.…”

Section: Sample Preparation and Characterizationmentioning

confidence: 99%

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Ionic liquid dynamics in nanoporous carbon: A pore-size- and temperature-dependent neutron spectroscopy study on supercapacitor materials

Busch

Hofmann

Frick

et al. 2020

Phys. Rev. Materials

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The influence of spatial confinement on the thermally excited stochastic cation dynamics of the roomtemperature ionic liquid 1-N-butylpyridinium bis-[(trifluoromethyl)sulfonyl]imide ([BuPy][Tf 2 N]) inside porous carbide-derived carbons with various pore sizes in the sub-to a few nanometer range is investigated by quasielastic neutron spectroscopy. Using the potential of fixed window scans, i.e., scanning a sample parameter, while observing solely one specific energy transfer value, an overview of the dynamic landscape within a wide temperature range is obtained. It is shown that already these data provide a quite comprehensive understanding of the confinement-induced alteration of the molecular mobility in comparison to the bulk. A complementary, more detailed analysis of full energy transfer spectra at selected temperatures reveals two translational diffusive processes on different time scales. Both are considerably slower than in the bulk liquid and show a decrease of the respective self-diffusion coefficients with decreasing nanopore size. Different thermal activation energies for molecular self-diffusion in nanoporous carbons with similar pore size indicate the importance of pore morphology on the molecular mobility, beyond the pure degree of confinement. In spite of the dynamic slowing down we can show that the temperature range of the liquid state upon nanoconfinement is remarkably extended to much lower temperatures, which is beneficial for potential technical applications of such systems.

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“…Subsequently the nanopores of the carbide-derived carbons are filled with a room-temperature ionic liquid 1-Nbutylpyridinium bis-((trifluoromethyl)sulfonyl)imide, in the following shortly denoted as [BuPy][Tf 2 N] and whose bulk molecular dynamics have been already extensively studied. [37][38][39][40][41] The structure formulas of the cation and anion are depicted in Fig. 2.…”

Section: Sample Preparation and Characterisationmentioning

confidence: 99%

Ionic liquid dynamics in nanoporous carbon: A pore-size- and temperature-dependent neutron spectroscopy study on supercapacitor materials

Busch,

Hofmann,

Frick

et al. 2020

Preprint

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The influence of spatial confinement on the thermally excited stochastic cation dynamics of the room-temperature ionic liquid 1-N-butylpyridinium bis-((trifluoromethyl)sulfonyl)imide ([BuPy][Tf2N]) inside porous carbide-derived carbons with various pore sizes in the sub-to a few nanometer range are investigated by quasi-elastic neutron spectroscopy. Using the potential of fixed window scans, i.e. scanning a sample parameter, while observing solely one specific energy transfer value, an overview of the dynamic landscape within a wide temperature range is obtained. It is shown that already these data provide a quite comprehensive understanding of the confinementinduced alteration of the molecular mobility in comparison to the bulk. A complementary, more detailed analysis of full energy transfer spectra at selected temperatures reveals two translational diffusive processes on different time scales. Both are considerably slower than in the bulk liquid and show a decrease of the respective self-diffusion coefficients with decreasing nanopore size. Different thermal activation energies for molecular self-diffusion in nanoporous carbons with similar pore size indicate the importance of pore morphology on the molecular mobility, beyond the pure degree of confinement. In spite of the dynamic slowing down we can show that the temperature range of the liquid state upon nanoconfinement is remarkably extended to much lower temperatures, which is beneficial for potential technical applications of such systems.

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QENS Study of Diffusive and Localized Cation Motions of Pyridinium-Based Ionic Liquids

Abstract: We have investigated stochastic motions of the cations of the pyridinium based ILs

Cited by 12 publications

References 13 publications

Transport Mechanism of Acetamide in Deep Eutectic Solvents

Transport Mechanism of Acetamide in Deep Eutectic Solvents

Ionic liquid dynamics in nanoporous carbon: A pore-size- and temperature-dependent neutron spectroscopy study on supercapacitor materials

Ionic liquid dynamics in nanoporous carbon: A pore-size- and temperature-dependent neutron spectroscopy study on supercapacitor materials

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