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Issue 41, 2010
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Charge transport and diffusion of ionic liquids in nanoporous silica membranes

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Abstract

Charge transport in 1-hexyl-3-methylimidazolium hexafluorophosphate ionic liquid in oxidized nanoporous silicon membranes is investigated in a wide frequency and temperature range by a combination of Broadband Dielectric Spectroscopy (BDS) and Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR). By applying the Einstein–Smoluchowski relations to the dielectric spectra, diffusion coefficient is obtained in quantitative agreement with independent PFG NMR measurements. More than 10-fold systematic decrease in the effective diffusion coefficient from the bulk value is observed in hydrophilic silica nanopores. A model assuming a reduced mobility at the pore–matrix interface is shown to provide a quantitative explanation for the remarkable decrease of effective transport quantities (such as diffusion coefficient, dc conductivity and consequently, the dielectric loss) of the ionic liquid in non-silanized membranes. This approach is supported by the observation that silanization of porous silica membranes results in a significant increase of the effective diffusion coefficient, which approaches the value for the bulk liquid.

Graphical abstract: Charge transport and diffusion of ionic liquids in nanoporous silica membranes

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Publication details

The article was received on 22 Mar 2010, accepted on 11 Aug 2010 and first published on 08 Sep 2010


Article type: Paper
DOI: 10.1039/C004546B
Citation: Phys. Chem. Chem. Phys., 2010,12, 13798-13803
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    Charge transport and diffusion of ionic liquids in nanoporous silica membranes

    C. Iacob, J. R. Sangoro, P. Papadopoulos, T. Schubert, S. Naumov, R. Valiullin, J. Kärger and F. Kremer, Phys. Chem. Chem. Phys., 2010, 12, 13798
    DOI: 10.1039/C004546B

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