Smart van der Waals Sieves

我们的社会严重依赖于各种用于过滤、气体分离、海水淡化等的多孔材料。随着孔径变得更小和更好地定义，可以实现越来越高的选择性和性能特征。虽然沸石和金属有机骨架等功能多孔材料提供了固有的分子大小的孔，但它们很难集成到纳米级的检测和表征能力中。同时，用于制造集成半导体电路的现代微制造技术到目前为止还不能可靠地制造尺寸小到单个分子的孔。在这里，我提出了一种全新的自上而下的方法，通过按照设计序列组装范德华(VDW)晶体，可以在真正的原子尺度上纳米制造孔。这包括将层状大块晶体分解成单独的原子薄层，然后将这些层重新组装成人造异质结构。建议的智能VDW筛分装置将结合定义良好的纳米孔的分子分离功能和现代层析的检测功能。为了实现这种多功能的紧凑神奇筛，首先需要做大量的工作来获得限制在原子尺度狭缝中的各种感兴趣的分子的电学和光学特性，因为在强限制下的结构和输运特性预计将与整体的结构和输运特性截然不同。同时，我们将利用空间位阻和静电排斥相结合的方法开发高效的VDW狭缝分子筛分。在对分子尺度的结构特征和传输机制有了这样的基本了解后，我和我的团队将展示智能集成筛子(原子尺度的芯片实验室技术)，用于同时分离和检测各种分子。

Our society heavily relies on various porous materials, which are used for filtration, gas separation, desalination, etc. As pore sizes become smaller and better defined, increasingly enhanced selectivity and performance characteristics can be achieved. While functional porous materials such as zeolites and metal-organic frameworks offer intrinsic molecule-size pores, they are hard to be integrated for nanoscale detection and characterization capabilities. Meanwhile, modern microfabrication techniques used to make integrated semiconducting circuits, have so far been unable to reliably create pores with size down to that of individual molecules.Here I propose a radically new top-down approach that allows nanofabrication of pores at the true atomic scale by assembling van der Waals (vdW) crystals in designer sequences. This involves disassembly of layered bulk crystals into individual atomically thin layers, followed by reassembly of these layers into artificial heterostructures. The proposed smart vdW sieving devices would combine molecular separation functions of well-defined nanopores with detection functions of modern chromatography. The whole device can be reduced in size to that of a tiny microchip.To realize such multifunctional compact wonder sieves, extensive work is first required to obtain electrical and optical characteristics of various molecules of interest confined inside atomic-scale slits, because structural and transport characteristics under strong confinement are expected to differ drastically from those in the bulk. In parallel, we will develop efficient molecular sieving through these vdW slits using a combination of steric and electrostatic exclusion. With such fundamental understanding of structural characteristics and transport mechanisms at the molecular scale, my team and I will demonstrate smart integrated sieves (lab-on-a-chip technology at atomic-scale) for simultaneous separation and detection of various molecules.