Production and State‐of‐the‐Art Characterization of Aligned Nanotubes with Homogeneous BC_xN (1 ≤ x ≤ 5) Compositions

Abstract

methanol produced from the hydrolysis of the TMOS was slowly removed using a diaphragm vacuum pump (DIVAC 1.2 L) connected to a rotary evaporator at ambient temperature to avoid the destruction of the liquid-crystalline order [20,22]. Within about 5 min, the resulting viscous liquid changed to a translucent, gel-like substance and acquired the desired shape and size of the reaction vessel (Fig. 1). The translucent glassy monoliths were collected and dried at 40 C for 16 h. The surfactant and the incorporated alkanes were removed by calcination at 450 C (3 h under nitrogen and then 14 h under oxygen).XRD patterns were measured using a MXP 18 diffractometer (Mac Science Co. Ltd.) with Cu Ka radiation. The N 2 isothermal data were collected with a Shimadzu ASAP 2020 surface area analyzer. All samples were outgassed at 300 C for 8 h before the N 2 adsorption analyses. The TEM micrographs were obtained with a JEOL JEM-2000 FXII Apparatus operating at an acceleration voltage of 200 kV. SEM micrographs were also obtained with a Hitachi S-800 SEM operated at 7 kV.

TOWARDS THE SINGLE-WALLED B- AND/OR N-DOPED CARBON NANOTUBES

“…In earlier studies via the post-synthetic substitution route, Golberg et al and Terrones et al have ever successfully obtained B x C y N z -MWNTs with the homogenous compositions. 65,66 More recently, a latest achievement in synthesizing the ternary homogenous B x C y N z nanotubes was reported by Kim et al 67 By employing a high-temperature (1200 • C) thermal CVD growth process, these authors have produced the homogenously-doped B 0.45 C 0.1 N 0.45 bamboolike MWNTs. A detailed XPS characterization of the B 0.45 C 0.1 N 0.45 -MWNTs showed the presence of a significant amount of B-C and C-N bonding states, as well as the existence of a pyridine-like C-N structure.…”

“…Nevertheless, one must be aware that the spatial resolution of the energy filtered images (by Omega filter TEM instrument) was estimated to be ∼ 0.5 nm; thus the possible existence of sub-nanometer (dimensions below 0.5 nm) fragments made of the pure BN and pure C phases could not be entirely ruled out. 65,66,68 At present, solving this problem is beyond the spatial resolution capabilities of state-of-the-art instruments. Complementary evidences for elucidating the ternary-bonding nature of B x C y N z -SWNTs also come from the XPS characterization.…”

Funcionalização de nanotubos de Carbono

“…Os exemplos mais típicos desse tipo de funcionalização são os nanotubos de carbono dopados com N 70 , B [71][72][73] , ou ambos 74,75 . Esses sistemas dopados são interessantes, pois aumentam significativamente a reatividade dos nanotubos.…”

Cables of BN-insulated B–C–N nanotubes

“…It is noteworthy that the present mixed B-C-N rather than pure C or CN x shells 19-26 were verified using high-resolution electron energy loss spectroscopy. 27 Figure 3͑a͒ is a LEEPS image of a representative rope composed of BN-shielded B-C-N NTs. The rope stretches into the microgrid hole.…”