State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, 100871, China.
College of Energy, Xiamen University, Xiamen, Fujian, 361005, China.
Small. 2022 Aug;18(34):e2203396. doi: 10.1002/smll.202203396. Epub 2022 Jul 30.
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.
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，特别是对于类似离子的高效分离。在这里，报道了一种在人工纳米结构中实现碱金属离子高选择性的新策略。通过施加压力和/或电场，结合分子动力学（MD）模拟和实验来研究单价阳离子通过氧化石墨烯（GO）纳米狭缝的传输。结果发现，在压力驱动下的离子传输选择性与电场驱动下的选择性相反。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输运模式，即压力下水化壳驱动离子，而电场下拉曳离子。因此，当选择的离子保持运动而其他离子被固定时，可以通过调节两种驱动力引起的净迁移率来有效地分离具有不同水化强度的离子。并且证实了纳米限域可以提高分离效率。这一发现为在无需精心设计仿生纳米结构的情况下分离类似离子开辟了新途径。
