Differential Capacitance at Au(111) in 1-Alkyl-3-methylimidazolium Tetrafluoroborate Based Room-Temperature Ionic Liquids

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• 作者：Muhammad Tanzirul Alam ; Jahangir Masud ; Md. Mominul Islam ; Takeyoshi Okajima ; Takeo Ohsaka
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：October 13, 2011
• 年：2011
• 卷：115
• 期：40
• 页码：19797-19804
• 全文大小：997K
• 年卷期：v.115,no.40(October 13, 2011)
• ISSN：1932-7455

文摘

Interfacial structures at Au(111) electrode in N₂-saturated 1-alkyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquids (RTILs) have been studied by the measurements of differential capacitances and cyclic voltammograms. Capacitance鈥損otential (C鈥揈) curves are found to vary significantly with changing the direction of potential scan and temperature. C鈥揈 curves measured by sweeping the potential from negative to positive direction always have lower capacitance values compared to the curves measured by reversing the direction of potential scan, and this difference is larger for the RTIL with longer alkyl group. Special arrangement of the ions at the interface in response to the starting potential, constraint in orientation, and change in the ion electrode and ion鈥搃on interactions are presumed to be the causes for this variation. Temperature has a dramatic effect on the Au(111)|EMIBF₄ interface. Capacitance around the potential of zero charge decreases with increasing the temperature at the Au(111)|EMIBF₄ interface, whereas at the Au(111)|BMIBF₄ and Au(111)|OMIBF₄ interfaces, it increases, which is discussed on the basis of the effect of temperature on the so-called solidlike crystallinity of RTILs.