Structural Dynamics of Surface Reactions: Oxidation and Heterogeneous Catalysis
Judith C. Yang
Department of Chemical and Petroleum Engineering, Department of Physics
University of Pittsburgh
Transmission electron microscopy (TEM) has proven to be a powerful tool to measure composition, chemistry and internal structure at the nanoscale and below. Recent and rapid developments of in situ TEM has confirmed it to be a transformative tool to gain unique dynamic processing/structure/property relationships of nanomaterials. Of particular interest are the structural changes occurring under “real” environmental conditions observable by environmental TEM (ETEM). ETEM allows for dynamic studies for fundamental, atomic-level understanding of surface chemical reactions, such as oxidation and heterogeneous catalysis.
For example, using an ultra-high vacuum ETEM, Dr. Yang’s group demonstrated that the transient oxidation stage of Cu and its alloys bear a striking resemblance to heteroepitaxy, where the initial stages of growth are dominated by oxygen surface diffusion. The second part of this seminar will concentrate on heterogeneous catalysis, which depends sensitively on the nano-sized 3-dimensional structural habits of nanoparticles (NPs) and their physicochemical structural sensitivity to the environment. Dr. Yang’s focus is on the development of integrated characterization and modeling tools and their applications appropriate for carrying out detailed studies on metallic NPs, as their structures behave differently than atoms or bulk material. For example, Pt NPs may be both ordered and disordered, depending on its size, support and adsorbates. A statistical description of nanoparticles is more appropriate in understanding structure/property of nanoparticles and their surface reactions.
Professor Judith C Yang received her PhD in Physics from Cornell University in 1993. She then joined the Max-Planck-Institute of Metallforschung, Stuttgart, Germany as a NSF Postdoctoral Fellow. In 1995, she returned to the US as a Postdoc and visiting lecturer to the Materials Research Laboratory at the University of Illinois at Urbana-Champaign. In 1999, she joined the faculty at the University of Pittsburgh. She is the 2002 recipient of the NSF career award, 2004 B.P. America Faculty fellowship, and the 2005 Chancellor’s Distinguished Research Award. Dr. Yang is the Nickolas A. DeCecco Professor in Chemical and Petroleum Engineering. Her research areas include oxidation, heterogeneous catalysis, nano-materials, gas-surface reactions, and transmission electron microscopy, especially in situ.