EQCM Study of the [AuIIICl4]−−[AuICl2]−−Au(0) Redox System in 1-Ethyl-3-methylimidazolium Tetrafluoroborate Ro

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• 作者：Taku Oyama ; Shuichiro Yamaguchi ; Mohammad Rezaur Rahman ; Takeyoshi Okajima ; Takeo Ohsaka ; Noboru Oyama
• 刊名：Langmuir
• 出版年：2010
• 出版时间：June 1, 2010
• 年：2010
• 卷：26
• 期：11
• 页码：9069-9075
• 全文大小：878K
• 年卷期：v.26,no.11(June 1, 2010)
• ISSN：1520-5827

文摘

The electrochemical behavior of the [Au^IIICl₄]⁻−[Au^ICl₂]⁻−Au(0) redox system in room temperature ionic liquid (RTIL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF₄) has been investigated quantitatively using an in situ electrochemical quartz crystal microbalance (EQCM) technique based on a Pt film-coated quartz crystal electrode (Pt−QCE). A series of two-electron (2e) and one-electron (1e) reductions of the [Au^IIICl₄]⁻ to [Au^ICl₂]⁻ and [Au^ICl₂]⁻ to Au metal were recognized at the Pt surface. Besides, the disproportionation reaction of [Au^ICl₂]⁻ (i.e., the 2e-reduction product of [Au^IIICl₄]⁻) to [Au^IIICl₄]⁻ and Au metal was also observed. Electro-dissolution of the Au deposited on the Pt electrode through a 1e-oxidation reaction in the presence of chloride ions was also confirmed using the Pt−QCE based EQCM technique. A 2e-oxidation reaction of [Au^ICl₂]⁻ (i.e., the dissolved product) to [Au^IIICl₄]⁻ along with the oxidation of Cl⁻ ion on the Pt surface was also realized at high anodic potential. The results demonstrate that in situ EQCM technique is applicable and powerful in elucidating electrochemical surface phenomena accompanying a mass change in RTIL.