CAREER: Synthesis of Novel Two-Dimensional Materials from Metastable Layered Materials

非技术描述：原子和少数原子薄的二维（2D）材料由于其独特的性质和形态而处于纳米材料研究的前沿。它们通常是由剥离层状材料产生的，这些材料通过弱键和力（如范德华力）结合在一起。控制二维材料的组成可以调整其性质，从而调整其在电化学储能等应用中的性能。本项目的目标是利用块状层状陶瓷材料的亚稳性来合成具有独特成分的新型二维材料和异质结构，并研究它们作为电化学储能电极材料的行为。在这个项目中生产的新型二维材料的重要性超越了电化学储能，扩展到许多其他领域，包括电子、复合材料、电磁干扰屏蔽、催化等。研究目标与教育计划相结合，服务于不同层次（博士，本科生，K-12）的广泛学生，通过实践学习方法教育和培训下一代材料科学家和工程师，加强材料科学和工程教育，使科学和工程劳动力多样化。技术细节：通过将不同性质的二维材料堆叠成vdW异质结构，可以实现不同寻常的性能和现象。在这种异质结构中，理解和设计固体/固体界面是具有挑战性的。另一种在二维材料属性空间中填补这一空白领域的方法是剥离新的块状层状材料以产生新的二维材料。大多数已知的热力学稳定的vdW键合层状材料已经被剥离成二维材料。因此，需要新的方法来合成新的可剥离的块状层状材料。在这个项目中，利用拓扑化学反应将强结合的陶瓷材料转化为亚稳可剥落的vdW层状材料。为了实现这个项目的目标，有三个具体的目标。第一个目的是了解亚稳vdW层状材料的形成反应机理。二是了解这些亚稳vdW层状材料的剥落机理。第三部分关注二维材料的异质结构，旨在揭示二维异质结构之间的界面在电化学储能中的作用。除了开发一系列新的二维材料外，该项目的理解和知识还可以应用于其他成分和结构材料空间。这个项目的部分教育计划包括在材料科学与工程本科课程中加入一个新的服务学习部分。本科生开发新的动手材料活动，以参与和教育中学生材料科学与工程。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Atomically -and few atomically- thin two-dimensional (2D) materials are at the forefront of nanomaterials research due to their unique properties and morphology compared to their bulk counterparts. They are usually produced by exfoliating layered materials that are held together with weak bonds and forces (such as van der Waal (vdW) forces). Controlling the 2D materials composition tunes their properties and therefore their performance in applications such as electrochemical energy storage. The goal of this project is to exploit metastability in bulk layered ceramic materials to synthesize novel 2D materials and heterostructures with unique compositions and study their behavior as electrode materials for electrochemical energy storage. The importance of the new 2D materials that are produced in this project extends beyond electrochemical energy storage to many other fields including electronics, composites, electromagnetic interference shielding, catalysis, etc. The research goal is integrated with an educational plan that serves a broad spectrum of students at different levels (doctoral, undergraduate, K-12) to strengthen the materials science and engineering education and diversify the science and engineering workforce by educating and training the next generation of materials scientists and engineers through hands-on learning approach.TECHNICAL DETAILS: Unusual properties and phenomena can be realized by stacking 2D materials of different properties into vdW heterostructures. In such heterostructures, understanding and engineering the solid/solid interface is challenging. Another approach to populate this unoccupied territory in the 2D materials properties space, is to exfoliate new bulk layered materials to produce novel 2D materials. Most of the known thermodynamically stable vdW bonded layered materials have been exfoliated already into the 2D materials. Therefore, novel approaches are necessary to synthesize new bulk layered materials that can be exfoliated. In this project, topochemical reactions are utilized to render strongly bonded ceramic materials into metastable exfoliateable vdW layered materials. To achieve the goal of this project, three specific aims are pursued. The first aim is to develop understanding for the formation reaction mechanism of metastable vdW layered materials. The second is to understand the exfoliation mechanism of these metastable vdW layered materials. The third focuses on heterostructures of 2D materials with aim to unveil the role of interfaces between 2D heterostructures in electrochemical energy storage. In addition to developing a novel family of 2D materials, the understanding and knowledge in this project can be employed to other compositional and structural materials spaces. Part of the educational plan in this project involves integrating a new service-learning section into the Materials Science and Engineering undergraduate course. Undergraduate students develop new hands-on materials activities to engage and educate middle school students in materials science and engineering.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.