Anomalous Capacitance Maximum of the Glassy Carbon-Ionic Liquid Interface through Dilution with Organic Solvents

David J. Bozym, Betül Uralcan, David T. Limmer, Michael A. Pope, Nicholas J. Szamreta, Pablo G. Debenedetti, Ilhan A. Aksay

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

We use electrochemical impedance spectroscopy to measure the effect of diluting a hydrophobic room temperature ionic liquid with miscible organic solvents on the differential capacitance of the glassy carbon-electrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5-10 mol% (i.e., μ1 M). We provide evidence that mixtures with 1,2-dichloroethane, a low-dielectric constant solvent, yield the largest gains in capacitance near the open circuit potential when compared against two traditional solvents, acetonitrile and propylene carbonate. To provide a fundamental basis for these observations, we use a coarse-grained model to relate structural variations at the double layer to the occurrence of the maximum. Our results reveal the potential for the enhancement of double-layer capacitance through dilution.

Original languageEnglish (US)
Pages (from-to)2644-2648
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume6
Issue number13
DOIs
StatePublished - Jul 2 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

Keywords

  • Ising model
  • acetonitrile
  • capacitance
  • electrochemical impedance spectroscopy
  • glassy carbon
  • room temperature ionic liquid

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