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Gating of Hydrophobic Nanopores with Large Anions.
ACS Nano ( IF 15.8 ) Pub Date : 2020-03-17 , DOI: 10.1021/acsnano.9b09777 Jake W Polster 1 , Elif Turker Acar 1, 2 , Fikret Aydin 3 , Cheng Zhan 3 , Tuan Anh Pham 3 , Zuzanna S Siwy 1
ACS Nano ( IF 15.8 ) Pub Date : 2020-03-17 , DOI: 10.1021/acsnano.9b09777 Jake W Polster 1 , Elif Turker Acar 1, 2 , Fikret Aydin 3 , Cheng Zhan 3 , Tuan Anh Pham 3 , Zuzanna S Siwy 1
Affiliation
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Understanding ion transport in nanoporous materials is critical to a wide variety of energy and environmental technologies, ranging from ion-selective membranes, drug delivery, and biosensing, to ion batteries and supercapacitors. While nanoscale transport is often described by continuum models that rely on a point charge description for ions and a homogeneous dielectric medium for the solvent, here, we show that transport of aqueous solutions at a hydrophobic interface can be highly dependent on the size and hydration strength of the solvated ions. Specifically, measurements of ion current through single silicon nitride nanopores that contain a hydrophobic-hydrophilic junction show that transport properties are dependent not only on applied voltage but also on the type of anion. We find that in Cl--containing solutions the nanopores only conducted ionic current above a negative voltage threshold. On the other hand, introduction of large polarizable anions, such as Br- and I-, facilitated the pore wetting, making the pore conductive at all examined voltages. Molecular dynamics simulations revealed that the large anions, Br- and I-, have a weaker solvation shell compared to that of Cl- and consequently were prone to migrate from the aqueous solution to the hydrophobic surface, leading to the anion accumulation responsible for pore wetting. The results are essential for designing nanoporous systems that are selective to ions of the same charge, for realization of ion-induced wetting in hydrophobic pores, as well as for a fundamental understanding on the role of ion hydration shell on the properties of solid/liquid interfaces.
中文翻译：
疏水性纳米孔与大阴离子的门控。
了解纳米多孔材料中的离子传输对各种能源和环境技术至关重要，从离子选择膜，药物输送和生物传感到离子电池和超级电容器，应运而生。虽然通常通过连续模型描述纳米级传输，该模型依赖于离子的点电荷描述和溶剂的均匀介电介质，但在这里，我们证明了疏水界面处水溶液的传输高度依赖于尺寸和水合强度溶剂化离子。具体地，对通过包含疏水-亲水结的单个氮化硅纳米孔的离子电流的测量表明，传输性质不仅取决于施加的电压，而且取决于阴离子的类型。我们发现在含氯溶液中，纳米孔仅传导高于负电压阈值的离子电流。另一方面，引入大的可极化阴离子（例如Br-和I-）有助于孔隙润湿，使孔隙在所有检查电压下均具有导电性。分子动力学模拟显示，与Cl-相比，大阴离子Br-和I-具有弱的溶剂化壳层，因此易于从水溶液迁移到疏水表面，从而导致负离子积累，从而导致孔润湿。这些结果对于设计对相同电荷的离子具有选择性的纳米孔系统，对于实现离子诱导的疏水性孔润湿至关重要，
更新日期：2020-03-17
中文翻译：
疏水性纳米孔与大阴离子的门控。
了解纳米多孔材料中的离子传输对各种能源和环境技术至关重要，从离子选择膜，药物输送和生物传感到离子电池和超级电容器，应运而生。虽然通常通过连续模型描述纳米级传输，该模型依赖于离子的点电荷描述和溶剂的均匀介电介质，但在这里，我们证明了疏水界面处水溶液的传输高度依赖于尺寸和水合强度溶剂化离子。具体地，对通过包含疏水-亲水结的单个氮化硅纳米孔的离子电流的测量表明，传输性质不仅取决于施加的电压，而且取决于阴离子的类型。我们发现在含氯溶液中，纳米孔仅传导高于负电压阈值的离子电流。另一方面，引入大的可极化阴离子（例如Br-和I-）有助于孔隙润湿，使孔隙在所有检查电压下均具有导电性。分子动力学模拟显示，与Cl-相比，大阴离子Br-和I-具有弱的溶剂化壳层，因此易于从水溶液迁移到疏水表面，从而导致负离子积累，从而导致孔润湿。这些结果对于设计对相同电荷的离子具有选择性的纳米孔系统，对于实现离子诱导的疏水性孔润湿至关重要，
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