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Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons


Graphene, or single-layered graphite, with its high crystallinity and interesting semimetal electronic properties, has emerged as an exciting two-dimensional material showing great promise for the fabrication of nanoscale devices1,2,3. Thin, elongated strips of graphene that possess straight edges, termed graphene ribbons, gradually transform from semiconductors to semimetals as their width increases4,5,6,7, and represent a particularly versatile variety of graphene. Several lithographic7,8, chemical9,10,11 and synthetic12 procedures are known to produce microscopic samples of graphene nanoribbons, and one chemical vapour deposition process13 has successfully produced macroscopic quantities of nanoribbons at 950 °C. Here we describe a simple solution-based oxidative process for producing a nearly 100% yield of nanoribbon structures by lengthwise cutting and unravelling of multiwalled carbon nanotube (MWCNT) side walls. Although oxidative shortening of MWCNTs has previously been achieved14, lengthwise cutting is hitherto unreported. Ribbon structures with high water solubility are obtained. Subsequent chemical reduction of the nanoribbons from MWCNTs results in restoration of electrical conductivity. These early results affording nanoribbons could eventually lead to applications in fields of electronics and composite materials where bulk quantities of nanoribbons are required15,16,17.

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Figure 1: Nanoribbon formation and imaging.
Figure 2: Stepwise opening of MWCNTs to form nanoribbons.
Figure 3: Characterization of the oxidized and reduced nanoribbons derived from MWCNTs.
Figure 4: Device fabrication and electrical properties of graphene nanoribbons on SiO 2 –Si.


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The authors thank P. M. Ajayan, W. Guo, J. Duque, Z. Sun, and Z. Jin for technical assistance and discussions. Mitsui & Co. generously donated the MWCNTs. The work was funded by the US Defense Advanced Research Projects Agency, the US Federal Aviation Administration, Department of Energy (DE-FC-36-05GO15073) and Wright Patterson Air Force Laboratory through the US Air Force Office of Scientific Research.

Author Contributions D.V.K. discovered the unzipping reaction and made most of the analysed ribbons. A.L.H. obtained and analysed most of the analysis data including the TEM, AFM, ultraviolet, XPS, TGA, Raman and infrared data; she also made some of the ribbons and wrote the majority of the manuscript. A.S. fabricated and tested the electronic devices. J.R.L performed some of the spectral analysis including the X-ray diffraction. A.D. prepared and studied the nanoribbons on silicon surfaces for electrical analysis. B.K.P. performed some of the AFM analyses. J.M.T. oversaw and directed all aspects of the syntheses, data analysis and manuscript correction and finalization.

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Correspondence to James M. Tour.

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Kosynkin, D., Higginbotham, A., Sinitskii, A. et al. Longitudinal unzipping of carbon nanotubes to form graphene nanoribbons. Nature 458, 872–876 (2009).

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