Atomic-Scale Three-Dimensional Local Solvation Structures of Ionic Liquids.
Atomic-Scale Three-Dimensional Local Solvation Structures of Ionic Liquids.
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DOI：
10.1021/acs.jpclett.9b03874
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Kenichi Umeda;K. Kobayashi;T. Minato;Hirofumi Yamada
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文献类型：
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作者：
Kenichi Umeda;K. Kobayashi;T. Minato;Hirofumi Yamada
室温离子液体由于其各种优越的特性，是下一代电化学、催化和生物装置的有用介质。由于器件的性能通常由固-液界面上的溶剂化结构决定，因此它们的原子化图像是非常需要的。然而，目前还没有关于它们原子尺度的三维溶剂化结构的实验报道。在这里，我们使用最近建立的超低噪声三维调频原子力显微镜来描述离子液体的分子分布。为了系统地研究它们的物理性质，我们比较了质子态和非质子态的溶剂化结构。它们的水溶液分别表现出横向长周期和点状溶剂化结构。结合分子动力学模拟，我们揭示了这种差异源于氢键网络的存在或不存在。我们的方法也适用于非水的RTIL，并为未来开发离子液体的广泛应用铺平了道路。
Room-temperature ionic liquids are useful media for future-generation electrochemical, catalytic, and biological devices due to their various superior characteristics. Since the device performance is often dictated by the solvation structures at solid-liquid interfaces, their atomistic pictures are in great demand. However, there have been no experimental reports on their atomic-scale three-dimensional solvation structures. Here, we present the molecular distribution of ionic liquids using a recently established ultra-low noise three-dimensional frequency-modulation atomic force microscopy. To conduct a systematic investigation of their physical nature, we compare the solvation structures of protic and aprotic species. Their aqueous solutions exhibit laterally long-periodic and dot-like solvation structures, respectively. Combined with molecular dynamics simulations, we reveal that this difference originates from the presence or absence of the hydrogen bonding networks. Our methodology is also applicable to the nonaqueous RTILs and paves the way for a broad range of future applications exploiting ionic liquids.