This award, a renewal of an earlier one, to Washington University by the Solid State Chemistry program in the Division of Materials Research is to develop an understanding of factors governing the synthesis of metal nanostructures so that one may predictably prepare them with well-controlled shapes, sizes, and compositions for integration into various technologies. The main focus of this work will be on the mechanistic studies of the generation and control of the twin defects in the nanostructures and hence a deeper understanding of the fundamental framework within which nanostructures of a certain shape can be fabricated. This is an important area and yet challenging issue in nanoscience and nanotechnology in that the materials properties and functionalities (e.g., photonics and catalysis) are sensitively dependent upon the surface morphologies. The current state of the art is more like art than science. The proposed work is anticipated to offer some fundamental insights to the mechanistic control and hence a rationale for materials design and preparation. Such a fundamental understanding is highly relevant to design such nanoparticles for applications in sensing, electronics, catalysis and medicine.
The project has links with many scientific disciplines that include solid state chemistry/physics, catalysis, and photonics, and has potential applications in medicine, environment, energy and other fields. The PI plans to continue to widely disseminate the results from his studies to the science community. This project, if successful, is expected to provide new advances in such areas as new class of nanomaterials for sensing, biomedical applications, and catalysis that will address issues related to national security, health, environment, and energy. In addition, the planned research is expected to enhance both graduate and undergraduate education through this multidisciplinary research and training.
During this 3-year project, we have developed a large number of methods for producing metal (e.g., silver, gold, palladium, and platinum) nanocrystals with well-defined and controllable shapes. More importantly, we have designed a range of mechanistic studies to understand why nanocrystals of a specific shape are formed under a specific set of experimental conditions. These results have enabled us to start building a scientific basis for producing metal nanocrystals with well-controlled shapes that are pivotal to a broad range of fundamental studies and niche applications: including, for example, understanding how the optical properties and catalytic activities of metal nanocrystals depend on the structures of atoms on the surface; development of more active electrocatalysts for energy-conversion devices such as fuel cells; achievement of sustainability by reducing our dependence on scarce and precious metals such as platinum; exploration of these nanocrystals as imaging contrast enhancement agents for cancer diagnosis and treatment. During this project, we have graduated five Ph.D. students (all of them have chosen their careers in science or engineering); we have supervised a total of 22 undergraduates and 2 high school students (three of the undergraduate students have already entered graduate programs in science and engineering); we have delivered a total of more than 60 department seminars or invited talks; we have published a total of >60 papers in peer-reviewed journals; the PI has created two new courses on the Washington University campus: Nanostructured Materials, and Physical Methods for Biomedical Students; and the PI has helped create a new undergraduate minor program on Nanotechnology on the Washington University campus.
