Department of Chemical Engineering, Stanford University , 443 Via Ortega, Stanford, California 94305, United States.
SUNCAT Center for Catalysis and Interface Science, SLAC National Accelerator Laboratory , 2675 Sand Hill Road, Menlo Park, California 94025, United States.
Langmuir. 2017 Sep 19;33(37):9464-9471. doi: 10.1021/acs.langmuir.7b01170. Epub 2017 Jul 10.
We have studied the influence of low concentrations (0.1 M) of the ionic liquid 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) on suppressing the hydrogen evolution reaction (HER) using polycrystalline Ag, Cu, and Fe electrodes in aqueous acidic and basic media. HER suppression is generally desired when aiming to catalyze other reactions of interests, e.g., CO electro-reduction. Cyclic voltammetry and chronoamperometry measurements were performed at potentials between -0.2 and -0.8 V versus the reversible hydrogen electrode (RHE) to investigate HER activity in a simulated CO electrolysis environment without the CO. In an acidic electrolyte, a decrease in HER activity was observed for all three electrodes with the largest effect being that of Fe, where the HER activity was suppressed by 75% at -0.5 V versus RHE. In contrast to the effect of [EMIM]Cl in an acidic electrolyte, no HER suppression was observed in basic media. Using H nuclear magnetic resonance spectroscopy on the electrolyte before and after electrolysis, it was determined that [EMIM]Cl breaks down at both the working and counter electrodes under reaction conditions under both acidic and basic conditions. These results underscore the challenges in employing ionic liquids for electrochemical reactions such as CO reduction.
我们研究了低浓度（0.1 M）的离子液体 1-乙基-3-甲基咪唑氯化物([EMIM]Cl)对多晶 Ag、Cu 和 Fe 电极在酸性和碱性水溶液中抑制析氢反应(HER)的影响。当旨在催化其他感兴趣的反应时，通常需要抑制 HER，例如 CO 的电还原。在相对于可逆氢电极（RHE）的-0.2 至-0.8 V 的电位下进行循环伏安法和计时电流法测量，以在没有 CO 的情况下研究模拟 CO 电解环境中的 HER 活性。在酸性电解质中，所有三种电极的 HER 活性均降低，其中 Fe 的影响最大，在相对于 RHE 的-0.5 V 时，HER 活性被抑制了 75%。与酸性电解质中[EMIM]Cl 的作用相反，在碱性介质中未观察到 HER 抑制。通过对电解前后电解质进行 H 核磁共振波谱分析，确定[EMIM]Cl 在酸性和碱性条件下的工作电极和对电极在反应条件下均发生分解。这些结果突出了在 CO 还原等电化学反应中使用离子液体所面临的挑战。
