21COE Programme: The Mechanical System Innovation Open Seminar 2007 will be held as
follows. Professor Yuan Chen is a young and energetic researcher in carbon nanotube
synthesis. His recent works of chirality-controlled growth of single-walled carbon nanotubes
attract attention in nanotube field. Do not miss this chance to hear his talk in Tokyo.
Participants from any departments or outside of The University of Tokyo are welcome.
| Speaker : |
Professor Yuan Chen (School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore) |
| Subject : |
Pressure-Induced Single-Walled Carbon Nanotube (n, m) Selectivity on Co-Mo Catalysts |
| Date : |
March 12, 2008 (Wednesday) 10:30-12:00 (Lecture Room 232 (2-301), Faculty of Engineering bldg.2, Hongo campus)
Map :http://www.u-tokyo.ac.jp/campusmap/cam01_04_03_e.html |
| Map : |
My work focuses on (n,m) selective growth and enrichment of single walled carbon nanotubes
(SWCNTs). In this study, SWCNTs were synthesized using four different carbon precursors including CO,
C2H5OH, CH3OH, and C2H2 on Co-Mo catalysts. Semiconducting (n,m) abundance was evaluated by a method
based on a single-particle tight-binding theoretical model taking into consideration the relative
photoluminescence and absorption quantum efficiency for specific (n,m) tubes. (n,m) abundance determined in
photoluminescence analysis was used to reconstruct the near-infrared Es11 absorption spectra. Carbon precursor
pressure was found to be the key factor to the chirality control in this study. Narrowly (n,m) distributed
SWCNTs can only be obtained under high-pressure CO or vacuumed C2H5OH and CH3-OH. The majority of
these nanotubes are predominately in the same higher chiral-angle region. The carbon precursor chemistry may
also play an important role to obtain narrowly (n,m) distributed SWCNTs. We further found the selective growth
of bulk SWCNT samples enriched with three different dominant chiralities including (6,5), (7,5), and (7,6)
through adjusting the pressure of carbon monoxide on Co-Mo catalysts from 2 to 18 bar. The abundance of each
(n,m) tube can be systematically altered by changing the carbon monoxide pressure. (n,m) selectivity on Co-Mo
catalysts shifts under different carbon precursors providing the route for (n,m) specific SWCNTs production.
|
| Reference |
J. Am. Chem. Soc. 2007, 129, 9014-9019
J. Phys. Chem. C, Vol. 111, No. 40, 2007 14612-14616 |
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