Faculty Candidate TEM Joint Chemistry/Physics Seminar: Characterization and Manipulation of Functional Nanomaterials at the Atomic- and Nano-scale

Emerging nanomaterials that are zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) have attracted tremendous interest because of their unique physical and chemical properties that enable novel functionality. These unique properties and new functionality have led to numerous applications in fields such as catalysis, energy harvesting, and medicine. Importantly, the properties and functionality of emerging nanomaterials are dictated by the microscopic structure, such as local crystal symmetry, defects, dopants, grain boundaries, and interfaces. These structural elements can be controlled and engineered during materials synthesis and processing and manifest at different length scales, from sub-angstrom to micrometers. Therefore, it is crucial to understand the microstructure in functional nanomaterials at different length scales to establish the process-structure-property correlation. An ideal technique to achieve this goal is scanning/transmission electron microscopy (S/TEM), which can resolve features as small as atomic-scale bonding distortion, and as large as micrometer-sized single-crystalline domains. Moreover, by integrating various in-situ techniques into S/TEM, novel structural engineering/manipulation with simultaneous property study can be realized at different length scales for these functional nanomaterials. In my talk, I will first discuss the characterization and manipulation of the microstructure in CVD-grown few-layer molybdenum disulfide (a representative 2D material) at the atomic scale via ex-situ and in-situ STEM. Next, I will focus on an in-situ TEM study that uses a nanomanipulator to tailor the geometry of individual carbon nanotubes (representative 1D nanostructures). Such manipulation enables both fundamental mechanical property studies and the development of new nano-electromechanical actuators. At the end, I will provide an outlook on my proposed research plan to explore novel applications of functional nano-composite/heterostructure materials and to establish strong correlations among synthesis, structure, property and performance for these materials. A combination of synthesis, state-of