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Ion transfer electrodes based on carbon nanofibers embedded in silicate film modified with room temperature ionic liquid

Ewa A. Rozniecka 1Joanna Niedziolka-Jonsson 1Juliette Sirieix-Plenet 2Laurent Gaillon 2Maria A. Murphy 3Frank Marken 4Marcin Opallo 1

1. Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland
2. Universite Pierre et Marie Curie, Place Jussieu, Bat F Boite 39, Paris 75252, France
3. Loughborough University, Leicestershire, Loughborough 113TU, United Kingdom
4. University of Bath, Claverton Down, Bath 27AY, United Kingdom


Biphasic systems composed of room temperature ionic liquids (RTILs) being in direct contact with an aqueous phase received recently some attention. This is because of their ability to extract ions or neutral molecules from the aqueous phase and therefore their potential application in extraction or liquid-liquid separation [1,2].
Among other driving forces the ion transfer across RTIL - aqueous solution interface can be driven by electric charge generation within RTIL during the electrooxidation of redox probe dissolved in this phase [3]. If RTIL is very hydrophobic this electrochemical process generates anion transfer from aqueous phase to RTIL [3]. To realise such system in practise the development of electrode support exhibiting strong affinity towards RTIL and repelling properties towards the aqueous phase is desirable. This can be done by application of heterogeneous conducting material combining above properties. Recently we have shown that carbon - hydrophobic silica composite material can be used for this purpose [4]. Since this material cannot be employed for thin film preparation we propose to use for this purpose hydrophobic carbon nanofibers (CNF) - silica film deposited on the electrode surface [5].
In this work we have attempted to immobilize microphases or thin film of redox probe (tert-butylferrocene, tBuFc) solution in the hydrophobic ionic liquid (1-decyl-3-methyl-imida- zolium bis(trifluoromethyl-sulfonyl)imide, C10mimN(Tf)2) on CNF-silica film modified ITO electrode.
The electrochemical properties of these electrodes were investigated using cyclic voltammetry and differential pulse voltammetry in the aqueous solution of wide range of anions. The shape of the voltammogram and the current magnitude depends on the type of electrode surface and the form of the ionic liquid deposit. The anion effect on the ability of tBuFc molecules to be electrooxidized is observed. The presence of the hydrophobic CNF-silica film enhances the magnitude of the current.

[1] Ionic Liquids in Synthesis (eds. P. Wasserscheid, T. Welton) Wiley-VCH, Winheim 2003.
[2] Ionic Liquids, Industrial Applications (eds. R. D. Rodgers, K. R. Seddon) ACS Symp. Ser., 2002, 818.
[3] J. Niedziolka, E. Rozniecka, J. Stafiej, J. Sirieix-Plenet, L. Gaillon, D. di Caprio, M. Opallo, Chem. Comm., 23 (2005) 2954.
[4] E. Rozniecka, G. Shul, J. Sirieix-Plenet, L. Gaillon, M. Opallo, Electrochem. Comm., 7 (2005) 299.
[5] J. Niedziolka, M. A. Murphy, F. Marken, M. Opallo, 2005, submitted.


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Presentation: Short communication at SMCBS'2005 Workshop, by Ewa A. Rozniecka
See On-line Journal of SMCBS'2005 Workshop

Submitted: 2005-07-21 12:11
Revised:   2009-06-07 00:44