Ion Permeability and Selectivity in Composite Nanochannels: Engineering through the End Effects,The Journal of Physical Chemistry C

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Ion Permeability and Selectivity in Composite Nanochannels: Engineering through the End Effects
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2020-02-14 , DOI: 10.1021/acs.jpcc.9b11750
Ke Zhou ₁ , Zhiping Xu ₁

Affiliation

Ion transport through nanochannels allows ultrafast permeation and highly efficient separation, becoming promising for applications in water purification, mineral separation, and biological sensing. Spatial confinement down to the nanometer scale allows one to separate ions by their size, which, however, fails for ions with similar diameters of hydration. This selectivity can be boosted by enhancing the confinement to be comparable with or even lower than the size of hydrated ions, forcing the hydration shells to be distorted, even destroyed, or tuning the ion–wall interaction. We perform molecular simulations to explore ion transport processes across graphene nanochannels by exploring the end effects where both nanoconfinement and chemical functionalization are involved. We calculated the free-energy profiles that include the hopping barriers for dehydration/rehydration and adsorption/desorption of ions at the ends as well as the diffusivity of ions inside the nanochannel. A composite-channel model is then constructed for realistic membranes. The model and related parameters reported here allow us to quantitatively analyze the performance of nanochannel-embedded materials or devices, which conclude that, beyond subnanometer confinement that may be technically challenging for large-scale applications, edge engineering of the nanochannels by functional groups can significantly enhance the hopping-specific selectivity even if the diffusion-specific selectivity is gentle.

中文翻译：

复合纳米通道中的离子渗透性和选择性：通过末端效应进行工程设计

通过纳米通道的离子传输可以实现超快的渗透和高效的分离，在水净化，矿物分离和生物传感中的应用变得很有希望。缩小到纳米级的空间限制可以使离子按其大小进行分离，但是，对于具有相似水合直径的离子而言，这样做是不可行的。可以通过将限制提高到与水合离子的大小相当甚至更低的程度来提高选择性，从而迫使水合壳变形，甚至破坏或调整离子-壁相互作用。我们执行分子模拟，以探索涉及纳米约束和化学功能化的最终效应，从而探索跨石墨烯纳米通道的离子传输过程。我们计算了自由能分布图，其中包括末端离子的脱水/脱水和离子吸附/解吸的跳跃跃迁以及纳米通道内离子的扩散率。然后构建用于实际膜的复合通道模型。此处报告的模型和相关参数使我们能够定量分析纳米通道嵌入式材料或设备的性能，得出的结论是，除了亚纳米级的限制（对于大规模应用而言可能在技术上具有挑战性）之外，官能团对纳米通道的边缘工程处理可以显着提高即使特定于扩散的选择性温和，也可以提高特定于跳跃的选择性。然后构建用于实际膜的复合通道模型。此处报告的模型和相关参数使我们能够定量分析纳米通道嵌入式材料或设备的性能，得出的结论是，除了亚纳米级的限制（对于大规模应用而言可能在技术上具有挑战性）之外，官能团对纳米通道的边缘工程处理可以显着提高即使特定于扩散的选择性温和，也可以提高特定于跳跃的选择性。然后构建用于实际膜的复合通道模型。此处报道的模型和相关参数使我们能够定量分析纳米通道嵌入式材料或设备的性能，得出的结论是，除了亚纳米级的限制（对于大规模应用而言可能在技术上具有挑战性）之外，官能团对纳米通道的边缘工程处理可以显着提高即使特定于扩散的选择性温和，也可以提高特定于跳跃的选择性。

更新日期：2020-02-14

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