Wafer-Scale Manufacturing of Ultrathin Nanoporous Transition Metal Dichalcogenide Membranes Using Chemical Etching for Water Purification and Other Applications

这项先进的制造拨款支持用于高效净水的新型超薄薄膜的研究。为了提高水过滤和水处理的精度，本工作主要集中在大面积制造超薄过渡金属二卤化物膜。该项目通过了解水分子和离子在这些改进的膜中原子尺度上的运动机制，创造了新的基础知识。减少膜厚度的一个重要动机是它导致了水通量的增加。这种薄膜是通过在薄膜上化学气相沉积过渡金属二卤化物，然后在酸中进行化学腐蚀使其成为纳米孔而制成的。除了水净化，这项工作预计还将影响其他使用膜的应用，如气体和生物分子过滤。该项目利用教育和推广方面的研究成果。与广泛的纳米材料社区和薄膜工业的接触包括共享制造工艺数据。教育部分为处于固态物理、材料科学和高分辨率显微镜十字路口的所有级别的学生提供创新的多学科学习机会。这笔助学金支持先进的二维(2D)纳米材料的制造，以创造新型厘米尺度的膜，其中单层由坚固的几层膜支撑。二维纳米材料，如过渡金属二卤化物，已经显示出许多潜在的应用前景，从电子设备的无缺陷材料到用于膜分离技术的缺陷工程材料，如水淡化和气体分离。目前的2D纳米孔膜的制备往往在控制方面受到限制，或者依赖于离子和电子束的照射，这是缓慢和昂贵的。这项工作使用简单的化学蚀刻，使用工业湿法蚀刻剂在膜上打孔，从而实现可控的膜孔隙率和经济的制造。这项研究回答了与最先进的聚合物膜相比，离子流作为膜性能、厚度、孔径和密度的函数对高效海水淡化的基本性质的关键科学问题。该研究方法包括化学气相沉积生长高达4英寸晶片尺寸的单原子和少原子厚度的2D纳米材料，优化2D纳米材料转移到孔上以制备2D纳米材料膜，然后进行湿法刻蚀和传输研究，以了解基本的成孔和离子传输机制。这项研究涉及优化超薄膜的制造，在保持膜完整性的同时最大限度地增加水流。这项工作进一步发展了通过卷到卷纳米多孔膜的制造来扩大规模的仪器。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This advanced manufacturing grant supports research in novel ultrathin membranes for efficient water purification. This work focuses on large-area manufacturing of ultra-thin transition metal dichalcogenide membranes to improve the precision of water filtration and treatment. This project creates new fundamental knowledge through the understanding of the mechanisms of water molecule and ion motion at atomic scales in these improved membranes. An important motivation for decreasing the membrane thickness is that it leads to increased water fluxes. The membranes are made by chemical vapor deposition of transition metal dichalcogenides on foils, followed by chemical etching in acids to make them nanoporous. Besides water purification, this work is anticipated to impact other applications where membranes are used such as gas and biomolecule filtration. This project leverages research outcomes for education and outreach. Outreach to the broad nanomaterials community and to membrane industry involves sharing of manufacturing processing data. The educational component provides innovative multidisciplinary learning opportunities for students at all levels at the crossroads of solid-state physics, materials science and high-resolution microscopy. Student outreach includes presentations to high school students and participation in STEM activities.This grant supports advanced manufacturing of two-dimensional (2D) nanomaterials towards creating novel cm-scale membranes, in which monolayers are supported by robust few-layer membranes. Two-dimensional nanomaterials, such as, transition metal dichalcogenides, have demonstrated potential for many applications from defect-free materials for electronics to defect-engineered materials for membrane separation technologies like water desalination and gas separation. Current fabrication of 2D nanoporous membranes is often limited in terms of control or rely on the use of ion and electron beam irradiation, which is slow and costly. This work uses simple chemical etching to make holes in membranes using an industrial wet etchant, leading to controllable membrane porosity and economic manufacturing. This research answers key scientific questions about fundamental properties of ion flow as a function of membrane properties, thickness, pore size and density towards efficient water desalination in comparison with state-of-the-art polymer membranes. The research approach encompasses chemical vapor deposition growth of single- and few-atom thick 2D nanomaterials up to 4-inch wafer-scales, the optimization of 2D nanomaterials transfer on to apertures to make 2D nanomaterial membranes, followed by wet etching and transport studies to understand fundamental pore-forming and ion transport mechanisms. The research involves optimizing the manufacture of ultrathin membranes and maximizing water flow while retaining membrane integrity. This work further develops the instrumentation towards scale-up via roll-to-roll nanomanufacturing of the nanoporous membranes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.