Nanoscale Mapping of the Directional Flow Patterns at Liquid-Solid Interfaces
Nanoscale Mapping of the Directional Flow Patterns at Liquid-Solid Interfaces
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DOI：
10.1103/physrevapplied.13.064003
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发表时间：
2020-06-01
影响因子：
4.6
通讯作者：
Voitchovsky, Kislon
中科院分区：
文献类型：
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作者：
Piantanida, Luca;Payam, Amir F.;Voitchovsky, Kislon
液体分子和溶质沿着与固体的界面的纳米级行为控制许多过程，例如分子交换、润湿、电化学、纳米流体、生物分子功能和润滑。在实验上，有几种技术可以探索浸入固体表面附近液体的平衡分子排列，但量化这种界面液体自然采用的纳米级流动模式仍然是一个相当大的挑战。在这里，我们描述了一种基于原子力显微镜的方法，并能够量化的流动方向优先采用的液体沿着界面与纳米级精度。该方法，称为涡流耗散显微镜（VDM），使用高频定向振荡，以获得局部流动信息周围的每个位置的接口探测。VDM有效地导出了平行于固体的界面液体的纳米级流程图，并且可以在广泛的软界面和硬界面上操作。为了说明它的能力，我们量化了含有KCl或MgCl 2的水溶液的动力学，沿着相同的氧化石墨烯薄片的表面。我们发现，溶解的K+离子可以均匀地移动在所有方向沿着的接口，而Mg 2+离子倾向于移动注册表与底层晶格由于双折射效应。结果提供了原位纳米尺度的见解的氧化石墨烯膜的离子特定的筛分性能。
The nanoscale behavior of liquid molecules and solutes along the interface with solids controls many processes such as molecular exchanges, wetting, electrochemistry, nanofluidics, biomolecular function, and lubrication. Experimentally, several techniques can explore the equilibrium molecular arrangement of liquids near the surface of immersed solids but quantifying the nanoscale flow patterns naturally adopted by this interfacial liquid remains a considerable challenge. Here we describe an approach based on atomic force microscopy, and able to quantify the flow direction preferentially adopted by liquids along interfaces with nanoscale precision. The approach, called vortex dissipation microscopy (VDM), uses high-frequency directional oscillations to derive local flow information around each location of the interface probed. VDM effectively derives nanoscale flow charts of the interfacial liquid parallel to a solid and can operate over a broad range of soft and hard interfaces. To illustrate its capabilities, we quantify the dynamics of aqueous solutions containing KCl or MgCl2 along the surface of a same graphene oxide flake. We show that dissolved K+ ions can move evenly in all directions along the interface whereas Mg2+ ions tend to move in registry with the underlying lattice due to enthalpic effects. The results provide in situ nanoscale insights into the ion-specific sieving properties of graphene oxide membranes.