Biological ion channels exhibit excellent ion selectivity, but it has been challenging to design their artificial counterparts, especially for highly efficient separation of similar ions. Here, a new strategy to achieve high selectivity between alkali metal ions with artificial nanostructures is reported. Molecular dynamics (MD) simulations and experiments are combined to study the transportation of monovalent cations through graphene oxide (GO) nanoslits by applying pressure or/and electric fields. It is found that the ionic transport selectivity under the pressure driving reverses compared with that under the electric field driving. Moreover, MD simulations show that different monovalent cations can be separated with unprecedentedly high selectivity by applying opposite-oriented pressure and electric fields. This highly efficient separation originates from two distinctive ionic transporting modes, that is, hydration shells drive ions under pressure, but drag ions under the electric field. Hence, ions with different hydration strengths can be efficiently separated by tuning the net mobility induced by the two types of driving forces when the selected ions are kept moving while the other ones are immobilized. And nanoconfinement is confirmed to enhance the separation efficacy. This discovery paves a new avenue for separating similar ions without elaborately designing biomimetic nanostructures.

中文翻译：

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通过应用反向压力和电场高效分离一价阳离子的新策略

生物离子通道表现出优异的离子选择性，但设计其人工对应物一直具有挑战性，特别是对于相似离子的高效分离。在这里，报道了一种在具有人工纳米结构的碱金属离子之间实现高选择性的新策略。结合分子动力学 (MD) 模拟和实验，通过施加压力或/和电场来研究单价阳离子通过氧化石墨烯 (GO) 纳米狭缝的传输。发现压力驱动下的离子传输选择性与电场驱动下的离子传输选择性相反。此外，MD 模拟表明，通过施加相反方向的压力和电场，可以以前所未有的高选择性分离不同的单价阳离子。这种高效分离源于两种独特的离子传输模式，即水合壳在压力下驱动离子，但在电场下拖动离子。因此，当所选离子保持移动而其他离子固定时，通过调整由两种驱动力引起的净迁移率，可以有效地分离具有不同水合强度的离子。并且证实纳米限制可以提高分离效率。这一发现为在不精心设计仿生纳米结构的情况下分离相似离子铺平了新的途径。当所选离子保持移动而其他离子固定时，通过调整两种驱动力引起的净迁移率，可以有效分离具有不同水合强度的离子。并且证实纳米限制可以提高分离效率。这一发现为在不精心设计仿生纳米结构的情况下分离相似离子铺平了新的途径。当所选离子保持移动而其他离子固定时，通过调整两种驱动力引起的净迁移率，可以有效分离具有不同水合强度的离子。并且证实纳米限制可以提高分离效率。这一发现为在不精心设计仿生纳米结构的情况下分离相似离子铺平了新的途径。