Nanostructured 2D-transition metal dichalcogenides

二维（2D）材料是那些像纸一样在一个平面上延伸，但只有一个分子层厚的材料。因此，基本上二维材料中的所有原子都位于表面，并与其环境相互作用。这种形成反应表面的能力使得二维材料在促进化学反应方面很有趣，比如那些由电或光驱动的化学反应，分别被称为电催化或光催化。在完美的二维材料中，单分子层表面缺乏断裂的键通常使它们具有相当的化学惰性。有用的化学功能产生于晶体缺陷，这些缺陷很难以可靠和可控的方式产生。在这个项目中，南佛罗里达大学的Matthias Batzill教授和他的团队正在设计具有原子尺度晶体修饰的二维材料。然后，研究人员将二维材料的结构和电子特性与其化学功能联系起来。他们的研究可能会为制造新的或改进的多组分二维电催化材料带来新的概念。这个项目的研究是跨学科的，教给学生化学概念，为他们在工业界或学术界的工作做好准备。此外，此计划亦加强国际合作，鼓励学生与海外合作院校交换学生，以获得国际研究经验。学生们将与中国电子科技大学以及分别在意大利和法国的eletra和Soleil同步加速器进行合作。在化学部大分子、超分子和纳米化学（MSN）项目的资助下，研究了多组分和纳米结构的过渡金属二硫族化合物（TMDCs），以确定在这些材料中产生催化活性位点的基本原理。采用分子束外延（MBE）技术合成了具有明确晶体修饰的模型体系。调节MBE中的生长条件可以控制边缘密度、成分和相边界，以及内在和外在缺陷。利用扫描隧道显微镜和光谱学对其结构、缺陷和界面进行了原子分辨率表征。光电发射提供了额外的洞察电子状态和能带排列，促进电荷转移过程。通过探针分子吸附和反应的真空表征，以及在实际反应条件下的光催化和电催化研究，将纳米结构TMDCs的结构和电子性质与化学性质联系起来。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。

Two-dimensional (2D) materials are those that extend in one plane like a piece of paper, but are only a single molecular layer thick. Thus, essentially all atoms in a 2D material are located at the surface and interact with their environment. This ability to form reactive surfaces makes 2D materials interesting for promoting chemical reactions, such as those driven by electricity or light, processes known as electro- or photocatalysis, respectively. In perfect 2D materials, the lack of broken bonds at the surface of the single molecular layers often makes them quite chemically inert. Useful chemical functionalities arise from crystal imperfections that are challenging to create in a reliable and controlled manner. In this project, Professor Matthias Batzill and his group at the University of South Florida are designing 2D materials with atomic-scale crystal modifications. The researchers then correlate the structural and electronic properties of the 2D materials with their chemical functionalities. Their research may lead to novel concepts for making novel or improved multicomponent 2D materials for electrocatalysis. The research in this project is strongly interdisciplinary and teaches students chemistry concepts that prepare them for jobs in industry or academia. Moreover, this project strengthens international collaborations and encourages students to gain international research experience by fostering student exchanges with collaborating institutions abroad. Students will collaborate with the University of Electronic Science and Technology of China (UESTC) as well as at Elettra and Soleil synchrotrons in Italy and France, respectively. With funding from the Macromolecular, Supramolecular and Nanochemistry (MSN) Program of the Chemistry Division, multi-component and nanostructured transition metal dichalcogenides (TMDCs) are investigated to determine fundamental principles for the creation of catalytically active sites in these materials. Molecular beam epitaxy (MBE) is employed to synthesize model systems with well-defined crystal modifications. Regulating growth conditions in MBE enables control over edge density, composition, and phase boundaries, as well as intrinsic and extrinsic defects. The structure, defects, and interfaces are characterized with atomic resolution by scanning tunneling microscopy and spectroscopy. Photoemission gives additional insight into electronic states and band alignments that promote charge transfer processes. These structural and electronic properties of nanostructured TMDCs are correlated to chemical properties by a combination of vacuum characterization of adsorption and reaction of probe molecules, as well as photocatalytic and electrocatalytic investigations under realistic reaction conditions.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.