3C03
カーボンナノチューブからグラフェンナノリボンへ
Transforming Carbon Nanotubes into Graphene Nanoribbons
1

崔 大憲、1 北浦 良、1 宮田 耕充、2 東 康男、2 真島 豊、1 篠原 久典
Daeheon Choi1, Ryo Kitaura 1, Yasumitsu Miyata1, Azuma Yasuo2, Yutaka Majima2,and Hisanori Shinohara*1
1名古屋大学理学研究科、2 東京工業大学応用セラミックス研究所
1

2

Graduate School of Science, Nagoya University,
Materials and Structures Laboratory, Tokyo Institute of Technology
464-8602 名古屋市千種区不老町、noris@nagoya-u.jp

Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan, noris@nagoya-u.ac.jp
Abstract
We have fabricated flattened carbon nanotubes, Graphene nanoribbon (GNR), using solution-phaseextraction of inner tubes from large-diameter multi-wall CNTs (MWNTs). Arc-grown MWNTs werefirst oxidized in air at 700℃ to remove impurities and etch the surface of MWNTs. The extraction ofinner tubes was carried out by vigorous dispersion of MWNTS in H2O with 1% sodium cholate
hydrate (SC). After ultracentrifugation, the obtained supernatant solution contains many flattened
CNTs, and we found that approximately 80% of MWCNTs provide flattened CNTs of high qualityand purity.

1. IntroductionThe graphene nanoribbon(GNR) is one of the most promising candidates for the fabrication ofnano-electronic devices such as thin-film transistors of very high-mobility [1,2]. Lithographic andchemical methods have been used to produce GNRs from few layers graphene and unzipping ofcarbon nanotubes(CNTs). However, only few amounts of GNRs have so far been produced by using
previous methods which entail structure defects on GNRs. Here, we report a novel high-yield
fabrication method of another type of GNRs: fully flattened CNTs [2,3] using solution-phaseextraction of inner tubes from large-diameter multi-wall CNTs (MWNTs).

2. Results and Discussion

Our previous study [4] shows that inner CNTs can be efficiently extracted from double-wall CNTsby vigorous sonication with water containing surfactants. Here, we have applied this method to extract
1-3 layers CNTs of large diameter from arc-grown MWNTs for the fabrication of fully flattened
CNTs due to its high purity and crystallinity. Solution-phase process was carried out according to thepreviously reported procedures [2,4]. The obtained solution contains many GNRs, and we found thatapproximately 80% of MWCNTs provide GNRs of high quality and purity.
Figure 1 shows typical low-magnification TEM images of fully flattened CNTs extracted, whichclearly show GNR structure with a ribbon width of typically 40nm. The magnified image shows across sectional view of a triple layer barbell-like structure, indicating that CNTs are flattened to form
GNRs. To the best of our knowledge, this is obviously the first TEM image that clearly shows
cross-section of flattened CNTs (GNR). Figure 1 (c) is a typical AFM image and height distribution ofGNR corresponding to 4 layer GNRs.

3. Summary
We have succeeded to fabricate GNRs using solution-phase extraction of inner tubes fromlarge-diameter MWNTs. The obtained solution contains many GNRs with approximately 80% yield.
Investigation of FET characteristics and detailed structural characterization using TEM are currently
underway.
4. References[1] T. Shimizu et.al., Nature Nanotech. 6 45-50 (2011)[2] D.H.Choi et al., Sci. Rep. 3, 1617 (2013).
[3] N. Chopra et al. Nature. 377, 135 (1995).
[4] Y. Miyata et.al., ACSNano. 4 5807 (2010)

Figure 1. TEM images of flattened CNTs: GNRs

Figure 2. AFM image of flattened CNTs