FAST BREAKING PAPERS - 2008

Why do you think your paper is highly cited?

This paper reports on the first growth of ultralong (4.7 mm) double wall carbon nanotube (DWCNT) arrays. The longest CNT array reported previously was 2.5 mm long.

Long CNT arrays have several advantages over shorter ones in many applications. For example, longer CNTs, if spinnable, can produce stronger CNT fibers. We found that DWCNTs grown using our method are more conducive to spinning. In fact, we have been able to spin CNT fibers from arrays as long as 1.5 mm. The CNT fibers spun from such long arrays not only have a much higher specific strength, but also much better conductivity than those spun from shorter arrays by other groups. Indeed, growing longer CNT arrays has been a hot topic and many additional papers on this subject have been published since the publication of our paper in 2006.

Does it describe a new discovery, methodology, or synthesis of knowledge?

This paper reported on a systematic study of the fast growth of clean, long DWCNTs. We used a unique technique, ion-beam assisted deposition, to deposit the buffer layer and catalyst film. We also used a very low hydrogen concentration in the synthesis of the CNTs, which makes the process safer and cheaper. The very fast growth also makes the synthesis conducive to large-scale production.

Would you summarize the significance of your paper in layman's terms?

We've developed a technology that can grow long DWCNTs at a very fast rate. The nanotube arrays are like a nanotube forest, in which individual nanotubes stand upright on a substrate. Such long nanotube arrays have numerous quite advanced applications such as ultrahigh strength fibers (yarns) for aerospace structure and supercapacitors for energy storage.

How did you become involved in this research, and were there any problems along the way?

As team leader at the Los Alamos National Lab during this effort to grow long carbon nanotube arrays for spinning strong nanotube fibers, I’d like to primarily attribute this important technological breakthrough to Dr. Qingwen Li, who was a former team member and is now affiliated with the Suzhou Institute of Nanotech and Nanobionics of the Chinese Academy of Sciences. Dr. Li was instrumental in developing this technology. Our main challenges were to optimize the catalyst deposition and, for safety reasons, to use less hydrogen than other research groups.

Where do you see your research leading in the future?

The growth of long spinnable arrays has already led to the production of nanotube fibers that are much stronger per weight than any current engineering material or fiber. We expect to grow even longer spinnable nanotube arrays for spinning stronger nanotube fibers (yarns).

Do you foresee any social or political implications for your research?

This technology will have a significant positive impact on society. First, long nanotube arrays produces ultrastrong fibers that will significantly improve or revolutionize tens of thousands of products including golf clubs (sports equipment), armor, and aerospace structures (aircraft, satellites, launch vehicles) by making them stronger, lighter, safer, and more energy efficient.

In fact, a commercial US company, CNT Technologies Inc., in Seattle, Washington, is currently commercializing this technology. Additionally, long-length DWCNTs can also be used to make a variety of products including transparent conducting films, solar cells, and supercapacitors for energy harvesting and storage, all of which can help solve the global energy issue.

Yuntian T. Zhu, Ph.D.
Associate Professor
Department of Materials Science & Engineering
North Carolina State University
Raleigh, NC, USA

Qingwen Li, Ph.D.
Professor
Suzhou Institute of Nanotech and Nanobionics
Chinese Academy of Science
Suzhou, PRC

Keywords: ultralong carbon nanotube arrays, fiber spinning, double wall carbon nanotube arrays, dwcnt, dwcnts, cnt arrays, cnt fibers, nanotube arrays, spinnable nanotube arrays, nanotube fibers