Office: Mellon Institute 543
Phone: (412) 268-9448
Fax: (412) 268-1061
EDUCATION AND PROFESSIONAL EXPERIENCE
- Assistant Professor of Chemistry, 2006–present.
- Research Associate, James Franck Institute at the University of Chicago, Illinois, 2003–2006.
- Ph.D. Chemistry, Northwestern University, Illinois, 2003.
- M.S. Catalysis, Chinese Academy of Sciences/Dalian Institute of Chemical Physics, China, 1998.
- B.S. Chemical Physics, University of Science and Technology of China (USTC), China, 1995.
Camille Dreyfus Teacher-Scholar Award (2011), International Precious Metals Institute (IPMI) Student Advisor Award (2011), The Collegiate Inventors Competition Award Winner, Materials Research Society (MRS) Graduate Student Gold Award, International Precious Metals Institute Gemini Graduate Student Award, American Chemical Society Cognis Fellowship, Northwestern University Materials Research Center Fellowship, Distinguished Graduate of the University of Science and Technology of China (USTC), The 7th Huaxing Award (USTC).
Our research focuses on fundamental science and engineering questions motivated by the creation of materials at the nanometer scale (1 nm=10-9 m). Our research themes include the synthesis, characterization, and applications of nanoparticles (typically 1-100 nm in size). We develop chemical methods for synthesizing new types of inorganic nanoclusters and nanocrystals, hybrid nano-architectures, and inorganic/polymer nanocomposites. Extensive characterizations of the physical and chemical properties of nanoparticles and self-assembled nanomaterials are carried out with microscopy and spectroscopy techniques, including electron microscopy, atomic force microscopy, steady-state and ultrafast spectroscopies. We develop applications of nanoparticles in areas of catalysis, optics, chemo- and bio-sensing, and photovoltaics, etc.
1. Nanocluster and Nanocrystal Chemistry
One of the central themes in nanoscience research is to synthesize high quality nanoparticles with precise control over particle size, shape, structure, and composition. For inorganic nanoparticles (e.g. metal and semiconductor), two regimes are of particular interest, that is, nanoclusters in a size range from subnanometer to ~2 nm and nanocrystals (typically 2-100 nm).
Nanoclusters are comprised of an exact number of atoms, from several to dozens. These tiny nanoclusters exhibit fundamentally interesting and important properties (e.g. structural and electronic) different than their larger counterparts—nanocrystals. Molecular chemistry allows the synthesis of organometallic compounds containing few metal atoms, but the metal is often in oxidized states. To make metal nanoclusters Mn (n=10–102) in zero valence state, materials chemistry approach is necessary. Our research goal is to develop new chemical methods to synthesize stable metal nanoclusters with precise control over size, structure, and composition. The unique electronic and surface properties of metal clusters make them very promising in developing a new generation of catalysts that have extraordinary activity and selectivity for a wide range of industrially important chemical processes.
Nanocrystals are typically composed of thousands of atoms and possess a crystalline core (> 2 nm). Controlled synthesis of high quality (e.g. monodisperse and uniform) nanocrystals has been a major research goal in nanoscience. Inorganic nanocrystals and organic nanoparticles are promising in constructing next generation electronic and optoelectronic materials and devices, sensors, and photovoltaic devices. We develop chemical methodologies for synthesizing anisotropic nanocrystals and complex nanocrystal structures as well as nanocrystal/polymer composites for optical and electronic applications. By varying the shape, structural complexity, and chemical composition of the subunits, one can tune the properties of nanomaterials to meet specific needs in practical applications.
2. Linear and Nonlinear Optics of Nanoparticles
Nano-optics, which primarily studies light interaction with nanoparticles, has become a fascinating subfield of nanoscience and nanotechnology. Nanocrystal-based materials have shown great promise in the development of novel electronic and optoelectronic components or devices, such as optical enhancing materials, sensors, and high-density recording. To realize these goals, it is of fundamental importance to obtain an in-depth understanding of the electronic and optical properties of isolated and assembled nanostructures, such as their charge carrier dynamics and photophysics. We employ steady-state and time-resolved ultrafast spectroscopy in combination with high resolution microscopy to reveal the structure-property relationship of nanomaterials. Understanding such a relationship of nanoparticles and tailoring their properties is a prerequisite to designing novel nanomaterials.
3. Nanoscale Structure and Dynamics of Living Cell Membranes
Our research extends to the interface of chemical biology and nanoscience. We are interested in developing high resolution, real time imaging techniques and using such techniques to investigate biological systems, e.g. living cell membranes. The nanoscale structure and dynamics of eukaryotic cell membranes are of particular importance in order to clarify many physiological activities such as ligand-receptor interactions, signal transduction, and exocytotic and endocytotic processes. However, current imaging techniques have limited spatial and temporal resolution when they come to studying a living, dynamic cell membrane. We are interested in using nanocrystals as probes to image the distribution and motion of biomolecules in living cell membranes at high-resolution. High-speed, high-resolution optical imaging techniques are particularly appealing because they can reveal the real-time, nanoscale structure and dynamics of important cell membrane components, such as lipid rafts and membrane proteins. These structures regulate a variety of cell behaviors involved in everyday cellular activity and in human diseases, including bacterial and viral infections, diabetes, Alzheimer’s disease and cancer.