报告题目：Metal-Ligand Complexes for Singl-site Heterogeneous Catalysis
报告人：Prof. Steven L. Tait, Indiana University
A grand challenge in materials science is to predictively design building blocks for spontaneous self-assembly into functional structures. Our group uses scanning tunneling microscopy (STM) at the interface of precisely controlled solutions with graphite surfaces to examine dynamic molecular layers to advance understanding of molecular interactions and advanced materials design. Our group builds on this understanding of molecular interactions to construct metal-organic complexes at surfaces with the aim of addressing a key problem in heterogeneous catalysis: achieving high levels of selectivity with chemically uniform metal catalyst single-sites at surfaces. We have examined a variety of ligand-metal combinations to find system that achieve on-surface redox complexation to form stable and chemically active metal sites. We have also assembled quasi-square planar metal-organic complexes on high surface area powdered oxides through a modified wet-impregnation method. X-ray photoelectron spectroscopy measurements demonstrate loading of metal and ligand on the surface and synchrotron-based X-ray absorption spectroscopy measurements of the coordination shell of the metal centers demonstrates single site formation rather than nanoparticle assembly. These systems are shown to be active for the catalysis of hydrosilylation reactions at a level that is competitive with current homogeneous catalysts. In this talk, I will discuss the connections between our fundamental surface science studies and our examination of high surface area catalysts in flow reactors and discuss how these very different studies can inform each other and advance discovery of new catalysts.
Professor Steven Tait obtained a Bachelor of Science degree in Honors Physics and University Honors from Brigham Young University (Utah, U. S. A.) in 2000. He went on to graduate studies at the University of Washington, where his doctoral studies were co-supervised by Prof. Charlie Campbell in Chemistry and Prof. Sam Fain in Physics. During his graduate students, he received a fellowship to conduct research in the labs of Dr. Bruce Kay and Dr. Zdenek Dohnalek at Pacific Northwest National Laboratory in eastern Washington state. His doctoral work explored the desorption kinetics of small alkanes from solid surfaces, methane dissociation on Pd nanoparticles and the growth and sintering kinetics of Pd nanoparticles on aluminum oxide. He completed his PhD in 2005 and moved to Stuttgart, Germany for postdoctoral work with Prof. Dr. Klaus Kern at the Max Planck Institute for Solid State Research. There he studied the self-organization of supramolecular nanometer-scale structures at surfaces, especially systems formed by metal-organic coordination. Those studies were sponsored by fellowship awards from the Alexander von Humboldt Foundation and the Max Planck Society. In 2008, he moved to Indiana University to establish an independent research group in surface science. Prof. Tait is Professor of Chemistry and Adjunct Professor of Physics. His research group is supported by grants from the U.S. Department of Energy and National Science Foundation. He teaches courses in general chemistry, physical chemistry, and surface chemistry. For the past three years, he has been the director of graduate admissions for the Indiana University Chemistry Ph.D. program. Prof. Tait serves on several regional and national committees, including the executive committee of the American Chemical Society Division of Colloid and Surface Chemistry. He serves on the editorial board for the journal Surface Science and is an editor of Surface Science Reports.
Prof. Tait's research group uses an interdisciplinary approach to discover new surface chemistry that will address global energy challenges. The Tait lab makes use of molecule designs to program specific architectures at surfaces. Chemical, electronic, and catalytic function is being developed by characterization of these surface materials and design feedback with collaborators. The surface structures form by efficient and spontaneous molecular self-assembly. Characterization tools allow for molecular resolution imaging with scanning probe microscopy and chemical characterization by photoelectron spectroscopy and vibrational spectroscopy. Current work involves the development of single-site transition metal centers at surfaces which are of interest for novel chemical and catalytic functionality. A second active project in the group deals with the growth of organic thin films that have crystalline ordering to achieve excellent electronic characteristics. Efficient patterning of solid surfaces with organic materials is a challenging research problem that has the potential to open up new opportunities and new technologies in many fields, including molecular electronics, organic photovoltaics, sensors, and catalysis.