In situ spectroelectrochemical studies of potential driven changes in the structure of the electrical double layer at the ionic liquid|electrode interface

离子液体界面电双层结构变化的原位光谱电化学研究

• 批准号: 324675223
• 负责人: Privatdozentin Dr. Izabella Brand
• 金额: --
• 依托单位: Institut für Chemie (IfC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/324675223?language=en
• 关键词: situ; spectroelectrochemical; studies; potential; driven

The properties of room-temperature ionic liquids ((RTILs), a pure ionic solvent with potential window of 3-6 V) are very attractive for their applications as electrolytes in electrochemical systems, as solvents for studies of complex redox reactions or as supercapacitors. By contrast to conventional media in which molecules of a solvent and ions of a supporting electrolyte are in a direct contact with an electrode, in RTILs only ions are present on the electrode surface. It influences the macroscopic electrochemical properties and structure of the electrical double layer of RTILs comparing to solvents commonly used in electrochemistry. Despite the fact that little is known about the structure of the electrical double layer of RTILs at a sub-molecular level, in situ studies of the electrical double layer of RTILs are very rare. In this project the structure of the electrical double layer of RTILs will be studied using electrochemistry and polarization modulation infrared reflection-absorption spectroscopy (PM IRRAS) under electrochemical control. According to recent findings (Kirchner et al., Electrochim.Acta.,110,2013,762) the supramolecular structure of the electrical double layer of RTILs depends on the potential applied to the electrode and varies from multilayer to monolayer assemblies. In this project Langmuir-Blodgett (LB) films mimicking the composition and structure of the electrical double layer of RTILs will be prepared on the surface of Au and Pt electrodes. Electrochemical potential window of the film adsorption, potential of zero charge and surface charge as the function of the electrode potential will be studied in LB films in aqueous and RTIL solutions. PM IRRAS under electrochemical control will be used to study impact of the potential applied to the electrode on the structure and orientation of anions and cations at the model RTIL|electrode interface. Next, in situ PM IRRAS will be used to investigate potential-driven changes in the structure and orientation of ions in the electrical double layer of pure RTILs. A differentiation of the IR absorption signals from the RTIL ions present in the bulk liquid phase from the ions adsorbed on the electrode surface is the main challenge of this research project. It will be possible only for such settings of the spectroelectrochemical cell in which the intensity of the p-polarized light (brings information on the ions adsorbed in the electrode surface and in the environment of the sample (electrolyte)) and the intensity of the s-polarized light (brings information about the environment of the sample) are the same. This smart experimental approach ensures a successful realization of this project and enlarges the applicability of the PM IRRAS as structure and surface analyzing technique.

室温离子液体（（（rtils），一种纯离子溶剂为3-6 V）的性能对于它们作为电化学系统中的电解质的应用非常有吸引力，作为用于研究复杂的氧化还原反应或超级电容器的溶剂。与常规培养基相比，溶剂的分子和支撑电解质的离子与电极直接接触，在电极表面上只有离子。它影响了与电化学常用的溶剂相比，RTIL的宏观电化学特性和结构。尽管事实上，关于RITILS的电气双层的结构知之甚少，但对电气双层RTIL的原位研究非常罕见。在该项目中，将使用电化学和极化调制红外反射 - 吸收光谱（PM IRRAS）在电化学控制下研究RITIL的电气双层的结构。根据最近的发现（Kirchner等人，Electrochim.acta。，110,2013,762）RTIL的电气双层的超分子结构取决于应用于电极的电势，并且从多层层到单层组件有所不同。在这个项目中，Langmuir-Blodgett（LB）膜模仿了RITILS电气双层的组成和结构，将在AU和PT电极的表面上制备。在水溶液和RTIL溶液中的LB膜中，将研究膜吸附，零电荷和表面电荷的电势，零电荷和表面电荷的电势的电势窗。电化学控制下的PM IRRA将用于研究施加到电极对模型rtil |电极界面的阴离子和阳离子的结构和方向的电势的影响。接下来，原位PM IRRA将用于研究纯Rtils电气双层离子结构和方向的潜在驱动变化。 IR吸收信号与在电极表面吸附的离子中存在的IR吸收信号的分化是该研究项目的主要挑战。仅对于光谱电池的这种设置，其中P极光的强度（带来了吸附在电极表面和样品环境（电解质）环境（电解质））的离子的强度以及S偏振光的强度（带有样品环境的信息）是相同的。这种智能实验方法确保了该项目的成功实现，并扩大了PM Irras作为结构和表面分析技术的适用性。