Influence of Water on the Electrified Ionic Liquid/Solid Interface: A Direct Observation of the Transition from a Multilayered Structure to a Double-Layer Structure
Influence of Water on the Electrified Ionic Liquid/Solid Interface: A Direct Observation of the Transition from a Multilayered Structure to a Double-Layer Structure
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DOI：
10.1021/acs.jpcc.6b02549
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发表时间：
2016-05-05
影响因子：
3.7
通讯作者：
Endres, Frank
中科院分区：
文献类型：
--
作者：
Cui, Tong;Lahiri, Abhishek;Endres, Frank
离子液体是用于能量储存装置如电池和电容器的潜在设计电解质，其中通过改变离子液体（IL）的阳离子和阴离子，可以调节固/液界面，从而影响电荷和质量传递过程。本文利用原位原子力显微镜（AFM）和光谱研究了水对离子液体1-乙基-3-甲基咪唑三氟甲基磺酸盐（[Tm]TfO）/Au（111）界面的影响。使用振动光谱，在20 - 30体积%的水的范围内可以观察到清晰的“IL中的水”到“水中的IL”的转变。高于30体积%的水的阳离子/阴离子的相互作用在离子液体中急剧减少，这是确定的光谱和界面研究，使用原位原子力显微镜。原位AFM结果进一步揭示了最内层（Stern）的结构取决于所施加的电极电位和加入的水的量。当水浓度从30体积%变化到50体积%时，在-1.0 V下发生从多层结构到经典双层结构的转变。此外，在电解液中加入水可以改变电沉积Zn的形貌，这对于Zn基电池具有一定的潜力。
Ionic liquids are potential designer electrolytes for energy storage devices such as batteries and capacitors wherein by changing the cation and anion of the ionic liquid (IL) the solid/liquid interface can be tuned, thereby influencing the charge and mass transfer processes. In this paper, we show the influence of water on the electrified ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([Emim]TfO)/Au(111) interface using in situ atomic force microscopy (AFM) and spectroscopy. A clear "water in IL" to "IL in water" transition could be observed in the range of 2030 vol % of water using vibrational spectroscopy. Above 30 vol % of water the cation anion interaction in the ionic liquid drastically reduced, which was ascertained by both spectroscopy and interfacial studies using in situ AFM. In situ AFM results further revealed that the structure of the innermost (Stern) layer depends both on the applied electrode potential and the amount of added water. A transition from a multilayered structure to a classical double-layered structure occurred at -1.0 V on changing the water concentration from 30 to SO vol %. Furthermore, the morphology of the electrodeposited Zn could be altered with addition of water to the electrolyte which has some potential for Zn-based batteries.