In Situ Characterization of Dehydration during Ion Transport in Polymeric Nanochannels
In Situ Characterization of Dehydration during Ion Transport in Polymeric Nanochannels
复制标题
聚合物纳米通道中离子传输脱水的原位表征
DOI：
10.1021/jacs.1c05765
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发表时间：
2021-09-08
影响因子：
15
通讯作者：
Qu, Jiuhui
中科院分区：
文献类型：
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作者：
Lu, Chenghai;Hu, Chengzhi;Qu, Jiuhui
水合离子跨纳米通道的运输是生物系统和基于膜的应用的核心，但由于缺乏原位表征技术，在运输过程中对其水合结构知之甚少。在这里，我们报告实验解决离子脱水跨膜运输过程中使用修改后的原位液体ToF-SIMS结合MD模拟的机制推理。值得注意的是，完全脱水是不必要的运输发生在具有亚纳米孔的膜。部分脱落的水分子从离子溶剂化壳，观察到的平均水合数的减少，允许碱金属离子研究这里（锂，钠，钾）渗透膜的孔隙小于其溶剂化的大小。我们发现，离子一般不能容纳两个以上的水分子在这个空间有限的运输。在纳米孔大于溶剂化壳的大小，我们表明，离子迁移率支配离子水合数分布。粘性效应，如与膜内羧基的相互作用，优先阻碍单水合物和二水合物的运输。我们原位研究离子溶剂化的新技术代表了纳米流体领域的重大技术飞跃，并可能使离子分离，生物传感和电池应用取得重要进展。
The transport of hydrated ions across nanochannels is central to biological systems and membrane-based applications, yet little is known about their hydrated structure during transport due to the absence of in situ characterization techniques. Herein, we report experimentally resolved ion dehydration during transmembrane transport using modified in situ liquid ToF-SIMS in combination with MD simulations for a mechanistic reasoning. Notably, complete dehydration was not necessary for transport to occur across membranes with sub-nanometer pores. Partial shedding of water molecules from ion solvation shells, observed as a decrease in the average hydration number, allowed the alkali-metal ions studied here (lithium, sodium, and potassium) to permeate membranes with pores smaller than their solvated size. We find that ions generally cannot hold more than two water molecules during this sterically limited transport. In nanopores larger than the size of the solvation shell, we show that ionic mobility governs the ion hydration number distribution. Viscous effects, such as interactions with carboxyl groups inside the membrane, preferentially hinder the transport of the mono- and dihydrates. Our novel technique for studying ion solvation in situ represents a significant technological leap for the nanofluidics field and may enable important advances in ion separation, biosensing, and battery applications.