Anomalous Capacitance Maximum of the Glassy Carbon鈥揑onic Liquid Interface through Dilution with Organic Solvents

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• 作者：David J. Bozym ; Bet眉l Uralcan ; David T. Limmer ; Michael A. Pope ; Nicholas J. Szamreta ; Pablo G. Debenedetti ; Ilhan A. Aksay
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：6
• 期：13
• 页码：2644-2648
• 全文大小：279K
• ISSN：1948-7185

文摘

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鈥揺lectrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5鈥?0 mol% (i.e., 鈭? 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.