Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-5 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
Langmuir. 2010 Jun 1;26(11):9069-75. doi: 10.1021/la904483y.
The electrochemical behavior of the Au(III)Cl(4)-Au(I)Cl(2)-Au(0) redox system in room temperature ionic liquid (RTIL) of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF(4)) 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(III)Cl(4) to Au(I)Cl(2) and Au(I)Cl(2) to Au metal were recognized at the Pt surface. Besides, the disproportionation reaction of Au(I)Cl(2) (i.e., the 2e-reduction product of Au(III)Cl(4)) to Au(III)Cl(4) 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(I)Cl(2) (i.e., the dissolved product) to Au(III)Cl(4) 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.
在室温离子液体 1-乙基-3-甲基咪唑四氟硼酸盐（EMIBF4）中，通过基于 Pt 膜涂覆石英晶体电极（Pt-QCE）的原位电化学石英晶体微天平（EQCM）技术，定量研究了[Au（III）Cl4]（-）-[Au（I）Cl2]（-）-Au（0）氧化还原体系的电化学行为。在 Pt 表面上，识别了[Au（III）Cl4]（-）到[Au（I）Cl2]（-）和[Au（I）Cl2]（-）到 Au 金属的一系列两电子（2e）和单电子（1e）还原。此外，还观察到[Au（I）Cl2]（-）（即[Au（III）Cl4]（-）的 2e-还原产物）歧化反应为[Au（III）Cl4]（-）和 Au 金属。还通过基于 Pt-QCE 的 EQCM 技术，在存在氯离子的情况下，通过 1e 氧化反应，确认了 Au 在 Pt 电极上的电溶解。[Au（I）Cl2]（-）（即溶解产物）的 2e 氧化反应以及 Pt 表面上 Cl-离子的氧化反应也在高阳极电势下实现。结果表明，原位 EQCM 技术在阐明伴随 RTIL 中质量变化的电化学表面现象方面是适用且有效的。
