A General Synthetic Platform for Defect-Mediated Surface Functionalization of 2D Transition Metal Dichalcogenides

About This Grant

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Christina W. Li of Purdue University will study the defect chemistry of two-dimensional transition metal chalcogenide (TMD) materials. TMDs are unique materials because they can exist stably as a single layer of atoms, which is the thinnest possible form of matter. They can exhibit a broad range of electronic properties depending on the composition and phase of the TMD and can consequently serve as electronic conductors, semiconductors, light absorbers, or catalysts. In addition, the ultra-thin nature of these materials makes their properties highly sensitive to defects on the surface. Under this award, Professor Li’s team will develop strategies to create defects on TMD surfaces in a controlled fashion and to utilize the defects for subsequent functionalization of TMDs to modulate their properties. Understanding the surface chemistry of these ultra-thin materials will guide the development of more efficient electronic and catalytic materials and will have important broader impacts on next-generation semiconductor and energy storage devices. In addition, the team will develop educational demonstrations based on these concepts targeted at K-12 students across Indiana, showcasing energy storage devices and batteries. Under this award, Professor Li's team will study defect-mediated surface functionalization of two-dimensional transition metal dichalcogenide materials. The first goal will be to develop chemical activation strategies to controllably generate specific defect types on the surface of TMDs by utilizing chemical reagents that have strongly nucleophilic, reducing, or basic properties. The characterization methods necessary to study defect density and structure will be developed simultaneously, focusing on reactive titration methods, electronic and vibrational spectroscopy, and high-resolution scanning transmission electron microscopy. Each defect type can subsequently be functionalized with a specific dopant class. In this study, the team will focus on the interaction between chalcogenide vacancies and anionic metal chalcogenide complexes to generate bilayer or multilayer heterostructures. The catalytic and electronic properties of functionalized TMDs will be studied to understand how defect and dopant structure influence TMD band structure and surface chemistry. Finally, the generality of the defect generation and characterization methods will be assessed for a wide range of TMD compositions. 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.