Event
MSE Seminar Series: Renu Sharma
Friday, November 6, 2009
1:00 p.m.
Room 2108, Chemical and Nuclear Engineering Bldg.
Joanne Kagle
(301) 405-5240
jkagle@umd.edu
Power of Dynamic Observations in Understanding the Role of Catalyst in the Synthesis of Carbon Nanotubes and Nanowires
Presented by Dr. Renu Sharma
Center for Nanoscale Science and Technology, National Institute of Science and Technology and
Center for Solid State Science, Arizona State University
Nanotubes and nanowires form a fundamental building block for nanotechnology. Interestingly catalysis plays an important role in the nucleation and growth of these 1-D nanostructures. Most of these structures are synthesized using chemical vapor deposition (CVD) process where catalyst activates the decomposition of the precursor molecule and/or acts nucleation site for the nanotubes or nanowire. Transmission electron microscopy (TEM) related techniques are often employed to evaluate the nature of the catalyst and reaction conditions on the structure and morphology of nanotubes and nanowires formed. However in order to elucidate the exact function and nature of the catalyst during nucleation and growth, we need to make dynamic observations under the reaction conditions. Fortunately, recent developments in the TEM instrumentation and technology have made it possible to observe gas-solid interactions under reaction conditions. Such instruments are now commercially available and are often referred as environmental scanning/transmission electron microscope or ESTEM. At Arizona State University, we have been using this technology to understand the nature and role of catalyst for the growth carbon nanotubes and Nanowires (e.g. Si, Ge and GaN). We have also taken advantage of the small probe size (~0.2 nm) of Tecnai F-20 FEG to selectively synthesize model catalysts, by electron beam induced decomposition of metal-organic precursor, for CNT growth. These experiments have provided invaluable insight of the nucleation and growth processed as well as for suitable reaction conditions for selective synthesis.
