Researchers at USC have solved a long-standing challenge with carbon nanotubes: how to actually build them with specific, predictable atomic structures. “We are now working on scale up the process,” Zhou said. “Our method can revolutionize the field and significantly push forward the real applications of nanotube in many fields.”
Until now, scientists were unable to “grow” carbon nanotubes with specific attributes — say metallic rather than semiconducting — instead getting mixed, random batches and then sorting them. The sorting process also shortened the nanotubes significantly, making the material less practical for many applications.
They have identified the mechanisms required for mass amplification of nanotubes.
The nanotubes are tubes of graphene, which is made from sheets of carbon atoms arranged in a hexagonal pattern. (Courtesy of Chongwu Zhou and Jia Liu) – See more at: http://news.usc.edu/#!/article/54500/usc-researchers-figure-out-how-to-grow-carbon-nanotubes/
ABSTRACT – Structurally uniform and chirality-pure single-wall carbon nanotubes are highly desired for both fundamental study and many of their technological applications, such as electronics, optoelectronics, and biomedical imaging. Considerable efforts have been invested in the synthesis of nanotubes with defined chiralities by tuning the growth recipes but the approach has only limited success. Recently, we have shown that chirality-pure short nanotubes can be used as seeds for vapor-phase epitaxial cloning growth, opening up a new route toward chirality-controlled carbon nanotube synthesis. Nevertheless, the yield of vapor-phase epitaxial growth is rather limited at the present stage, due in large part to the lack of mechanistic understanding of the process. Here we report chirality-dependent growth kinetics and termination mechanism for the vapor-phase epitaxial growth of seven single-chirality nanotubes of (9, 1), (6, 5), (8, 3), (7, 6), (10, 2), (6, 6), and (7, 7), covering near zigzag, medium chiral angle, and near armchair semiconductors, as well as armchair metallic nanotubes. Our results reveal that the growth rates of nanotubes increase with their chiral angles while the active lifetimes of the growth hold opposite trend. Consequently, the chirality distribution of a nanotube ensemble is jointly determined by both growth rates and lifetimes. These results correlate nanotube structures and properties with their growth behaviors and deepen our understanding of chirality-controlled growth of nanotubes.
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