Johnston Matthew, Lee Jae-Joon, Chottiner Gary S, Miller Barry, Tsuda Tetsuya, Hussey Charles L, Scherson Daniel A
Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Phys Chem B. 2005 Jun 9;109(22):11296-300. doi: 10.1021/jp051243m.
The voltammetric characteristics of polycrystalline Au and W electrodes cleaned (thermal annealing at 1100 K) and characterized (Auger electron spectroscopy) in ultrahigh vacuum (UHV) have been examined in ultrapure AlCl(3)/1-ethyl-3-methylimidazolium chloride (EtMeImCl) melts in UHV. These experiments were performed using a custom-designed transfer system that allows for the all-Al electrochemical cell to be filled with EtMeImCl in an auxiliary UHV chamber and later transferred under UHV to the main UHV chamber that houses the Auger electron spectrometer. The results obtained for the underpotential (UPD) and bulk deposition of Al on Au were found to be very similar to those reported in the literature for measurements carried out under 1 atm of an inert gas in a glovebox. For the far more reactive W surfaces, voltammetric features ascribed to the stripping of underpotential-deposited Al could be observed following a single scan from 1.0 V vs Al(3+)/Al to a potential negative enough for bulk deposition of Al to ensue. This behavior is unlike that reported in the literature for experiments performed in a glovebox, which required either extensive potential cycling in the Al bulk deposition and stripping region or excursions to potentials positive enough for chlorine evolution to ensue for Al UPD features to be clearly discerned. These observations open new prospects for fundamental electrochemical studies of well-characterized, highly reactive metals, including single crystals, in a variety of low vapor pressure ionic liquids.
在超高真空（UHV）环境下，对经过清洁（在1100 K进行热退火）并表征（俄歇电子能谱）的多晶金电极和钨电极在超纯AlCl₃/1-乙基-3-甲基咪唑鎓氯化物（EtMeImCl）熔体中的伏安特性进行了研究。这些实验使用了定制设计的转移系统，该系统允许在辅助超高真空腔室中将全铝电化学池充满EtMeImCl，随后在超高真空条件下转移至容纳俄歇电子能谱仪的主超高真空腔室。结果发现，铝在金上的欠电位沉积（UPD）和本体沉积情况与文献中报道的在手套箱中1个大气压惰性气体下进行测量的结果非常相似。对于活性高得多的钨表面，在从相对于Al³⁺/Al为1.0 V单次扫描至足以引发铝本体沉积的负电位后，可以观察到归因于欠电位沉积铝脱附的伏安特征。这种行为与文献中报道的在手套箱中进行的实验不同，在手套箱实验中，要么在铝本体沉积和脱附区域进行大量的电位循环，要么将电位升高到足以引发析氯的程度，才能清晰辨别铝的欠电位沉积特征。这些观察结果为在各种低蒸气压离子液体中对包括单晶在内的经过充分表征的高活性金属进行基础电化学研究开辟了新前景。
