Effect of nanoscale curvature sign and bundle structure on supercritical H 2 and CH 4 adsorptivity of single wall carbon
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Effect of nanoscale curvature sign and bundle structure on supercritical H2 and CH4 adsorptivity of single wall carbon nanotube M. Yamamoto · T. Itoh · H. Sakamoto · T. Fujimori · K. Urita · Y. Hattori · T. Ohba · H. Kagita · H. Kanoh · S. Niimura · K. Hata · K. Takeuchi · M. Endo · F. Rodríguez-Reinoso · K. Kaneko
Received: 21 December 2010 / Accepted: 9 March 2011 / Published online: 23 March 2011 © Springer Science+Business Media, LLC 2011
Abstract The adsorptivities of supercritical CH4 and H2 of the external and internal tube walls of single wall carbon nanotube (SWCNT) were determined. The internal tube wall of the negative curvature showed the higher adsorptivities for supercritical CH4 and H2 than the external tube wall of the positive curvature due to their interaction potential difference. Fine SWCNT bundles were prepared by the capillary force-aided drying treatment using toluene or methanol in order to produce the interstitial pore spaces having the strongest interaction potential for CH4 or H2 ; the bundled SWCNT showed the highest adsorptivity for supercritical CH4 and H2 . It was clearly shown that these nanostruc-
M. Yamamoto · T. Ohba · H. Kagita · H. Kanoh Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan T. Itoh · H. Sakamoto · T. Fujimori · S. Niimura · K. Takeuchi · M. Endo · K. Kaneko () Research Center for Exotic Nanocarbons, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan e-mail: [email protected] K. Urita Department of Applied Chemistry, Nagasaki University, 1-14 Bunkyo, Nagasaki, 852-8521, Japan Y. Hattori Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, 386-8567, Japan K. Hata National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8561, Japan F. Rodríguez-Reinoso Departamento de Química Inorgánica, Universidad de Alicante, 03080, Alicante, Spain
tures of SWCNTs are crucial for supercritical gas adsorptivity. Keywords Carbon nanotube · Capillary force · Nanoscale curvature · Nanoporosity · Hydrogen adsorption · Methane adsorption
1 Introduction Single wall carbon nanotube consists of a rolled graphene (tube) and hemispherical caps at both ends (Iijima and Ichihashi 1993). Hence open single wall carbon nanotube has a cylindrical tube structure having external and internal tube walls of positive and negative nanoscale curvatures, respectively. The open single wall carbon nanotube has an extremely high geometrical surface area of 2630 m2 g−1 , because all component carbon atoms are exposed to the external and internal walls. The sign of the nanoscale curvature should be essentially influential to adsorption properties for gases, because the interaction potential energies of a molecule with the single wall carbon nanotube wall of the different curvature sign are different each other. In particular, such a curvature sign difference should give an intensive effect on supercritical gas adsorption. This is because the molecule-single wal
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