| 研究実績の概要 |
Synthesis of single walled carbon nanotubes (SWNTs) with well-defined atom arrangements is widely recognized in the past decades as the largest challenge in SWNTs community, and has become the bottleneck for the application of SWNTs in many fields, e.g. in nano-electronics and solar cells. A lot of efforts have been made recently years in Selective growth of semiconducting or metallic SWNTs, as well as the chirality specific growth. In second year of this project, we achieved a selective synthesis of (12, 6) with enrichment of 50%-70% by chemical vapor deposition (CVD) using sputtered Co-W as catalyst. These SWNTs are grown more uniformly on the entire substrate and are synthesized at much milder conditions than previous reports.
Meanwhile, in-plane transmission electron microscope (TEM) study suggests an intermediate structure of Co6W6C, which is strongly associated with the selective growth. However, we found most of W atoms disappear after a 5 min CVD growth, implying that anchoring W may be important in this mysterious Co-W system.(Nanoscale, (2016), 8, 14523-14529.)
A more detailed exploration on the catalyst structure during growth reveals a time-dependent evolution of Co-W structure. One meta-stable Co structure, which does not exist in phase diagram, is clearly identified.
These progresses in controlled growth and new understanding on the growth mechanism will be help to advance the application of SWNTs.
Future work will be focused on how to increase the purity and yield of growth, and how to assemble these SWNTs in solar cells.
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