Electric Double Layer of Au(100)/Imidazolium-Based Ionic Liquids Interface: Effect of Cation Size

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• 作者：Yuzhuan Su ; Jiawei Yan ; Miangang Li ; Meng Zhang ; Bingwei Mao
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：January 10, 2013
• 年：2013
• 卷：117
• 期：1
• 页码：205-212
• 全文大小：449K
• 年卷期：v.117,no.1(January 10, 2013)
• ISSN：1932-7455

文摘

We have carried out differential capacitance measurements and in-situ scanning tunneling microscope (STM) characterizations to investigate the effect of the length of alkyl side chains on an electric double layer of Au(100)/imidazolium-based ionic liquids interface. In ionic liquids consisting of BMI⁺ cation (1-butyl-3-methylimidazolium), differential capacitance curves present an obvious bell-shaped feature. In ionic liquids with PMI⁺ (1-methyl-3-propylimidazolium) or OMI⁺ (1-methyl-3-octylimidazolium) cations, the rising of capacitance from about 鈭?.5 V disturbs the bell-shaped feature. In-situ STM characterizations reveal the generality of surface etching and micelle-like adsorption of imidazolium cations on Au(100) at potential around the peaks of the bell-shaped feature, demonstrating that the potential of zero charge (PZC) should locate at the potential close to the peaks. Because of the longer side chain length and stronger interaction with Au(100) substrate, an extra capacitance peak appears at the potential as negative as 鈭?.65 V in OMIPF₆ and a corresponding order鈥揹isorder transformation of OMI⁺ cation adlayer is revealed by STM, indicating a correlation between differential capacitance curve and STM.