Solvothermal synthesis of carbon nitrogen nanotubes and nanofibers
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Solvothermal synthesis of carbon nitrogen nanotubes and nanofibers Tiancheng Mu Department of Chemistry, Renmin University of China, Beijing 100872, People’s Republic of China; and Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China
Jun Huang, Zhimin Liu, Zhonghao Li, and Buxing Hana) Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China (Received 27 August 2005; accepted 22 December 2005)
Carbon nitrogen nanotubes and nanofibers with controlled nitrogen concentration have been prepared by reaction of cyanuric chloride and hexachlorobenzene (HCB) with sodium metal at 250 °C in cyclohexane. Electron microscopy and spectroscopic analysis were used to characterize the products. The total yields of the tubes and fibers decrease as the ratio of cyanuric chloride to HCB increases, and nitrogen content in the products could be controlled by the ratio. The nanostructures depended strongly on the nitrogen content. Lower nitrogen content was favorable for producing linear products.
I. INTRODUCTION
Preparation of heteroatom-containing carbon nanotubes is a promising method to control the electronic properties of nanotubes.1,2 Nitrogen substitution in carbon nanotubes enhances electronic conducting behavior.3 The prediction that carbon nitrides are superhard and metallic has attracted considerable attention in the synthesis of carbon nitrogen nanotubes.3,4 So far, several groups have successfully synthesized carbon nitrogen nanotubes5–7 or nanofibers8–10 by pyrolysis of nitrogenrich organic precursors11–15 or chemical vapor deposition.4,8,16,17 Trasobares et al. presented a systematic study of the effect of different synthesis parameters on nitrogen incorporation into carbon nanotubes.18 Glerup et al. and Tang et al. synthesized nitrogen carbon nanotubular fibers with a high concentration of nitrogen (about 20 at.%).19,20 The structure of reported carbonnitrogen nanotubes are mainly bamboo-shaped,14 and some of them are in aligned structure. For example, wellaligned nitrogen-doped multiwall carbon nanotube arrays have been successfully produced by floating-catalyst chemical vapor deposition at low temperatures (600 °C).21 The solvothermal route has been used to synthesize various materials, such as nitrides, carbides, and
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2006.0209 1658
J. Mater. Res., Vol. 21, No. 7, Jul 2006
oxides.22–24 Carbon dioxide, water, ammonia, benzene, and cyclohexane in supercritical or near critical conditions were used as solvents in these processes. Qian reported that the solvents used in the reaction were important for the solvothermal assembling reactions.25 Wurtz-type reactions have also been used to prepare carbon materials.25–29 Qian’s group26 reported the synthesis of diamond powder from the reaction of carbon tetrachloride with sodium. They also fabricated multiwall carbon nanotubes by reduction o
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