Bamboo-like nanotubes

The conversion of acetylene on an iron catalyst on Si02-support is a typical example. In this process, acetylene is thermally decomposed by leading it over a bed of catalyst within a quartz tube heated at about 700 °C (500-1000 °C, generally). Apart from the desired MWNT, there are also larger, fibrous structures and layers of amorphous graphene observed. These tend to coat the catalyst particles. The bamboo-like nanotubes (Section 3.3.4) usually obtained from this method are often covered with amorphous carbon too and, in parts, they are considerably curved. In addition to these bent species, there is also a spiral or helical structure... 

Figure 3.28 Mechanism of formation of bamboo-like nanotubes (a) ( Elsevier 2000) and HRTEM-image of such nanotubes (b) ( Elsevier 2002).

Heng, L.Y., Chou, A., Yu, )., Chen, Y, and Gooding, J.J. (2005) Demonstrating the advantages of using bamboo-like nanotubes for electrochemical biosensor applications compared to single walled carbon nanotubes. Electrochem. Commun., 7 (12), 1457-1462. 

Motivated by the possible catalyst interference in the electrochemical response of the nanotubes, Jones et al. studied the response of HOPG electrodes modified by catalyst-free CNTs. At least relative to the ferri/ ferrocyanide system, the study revealed that the electrodes were reversible and the peak current obtained was proportional to the amount of tubes. According to the authors, this response demonstrates the noninterference of the catalyst in the response of the nanotube probe (Ai p 60 mV) and the contribution of the amount of CNTs to the peak current of the electrode. The authors also observed that the same electrode modified with Bamboo like nanotubes features 66 mV peak separation. 

Because of the speeial atomie arrangement of the earbon atoms in a carbon nanotube, substitutional impurities are inhibited by the small size of the carbon atoms. Furthermore, the serew axis disloeation, the most eommon defeet found in bulk graphite, is inhibited by the monolayer strueture of the Cfj() nanotube. For these reasons, we expeet relatively few substitutional or struetural impurities in single-wall earbon nanotubes. Multi-wall carbon nanotubes frequently show bamboo-like defects associated with the termination of inner shells, and pentagon-heptagon (5 - 7) defects are also found frequently [7]. 

The carbon phase of obtained metal-carbon nanocomposites was shown to contain different types of nanostructured carbon particles in parallel with main graphite-like structures. Bamboo-like carbon nanotubes (CNT) with 14-30 nm in their outer diameter were observed in structured carbon material when GdCl3 was used as a component of composite-precursor (Fig. 4). In this case IR radiation intensity provides the heating of sample to 910 and 1000°C. 

Fig. 12 HREM image of Mo,. rWA.S3 nanotubes showing a rectangular tip in (a) and (b) bamboo-like slacking. The layer separation in the walls is -0.62 nm. (Reproduced with permission from ref. 40).

Figure 13.10 (a) Schematic depiction of a multiwaiied carbon nanotube (MWNT) as formed by a series of coaxial rolled-up graphene layers (b) TEM image of multiwaU coaxial nanotubes reported by lijimain 1991 (3). (c) Bamboo-like multiwaiied carbon nanotube. (Reproduced with permission from C. J. Lee et al., Chem. Phys. Lett. 2000, 323, 560.)... 

Fig. 9 TEM image of nanoporous carbonaceous nanotubes prepared using PS- -P2VP with a bamboo-like structure. Inset Hexagonal arrays of pores on the tube wall. Reproduced from [90]. (2006) American Chemical Society...

Eguilaz, M., Ferreyra, N.E, and Rivas, G.A. (2014) Dispersions of hollow and bamboo-like multi-walled carbon nanotubes in polyethyleneimine critical analysis of the preparation conditions and applications for electrochemical sensing. Electroanalysis, 26 (11), 2434- 2444. 

Cui, H., Zhou, O., Zhu, W. and Stoner, B. R., Deposition of aligned bamboo-like carbon nanotubes via microwave plasma enhanced chemical vapor deposition . Journal of Applied Physics, 2000,88, 6072-6074. 

Besides conventional nanotubes, other nanostructured anodic Ti02 was also reported. Ti02 nanowires (Fig. 5) were developed under specific anodization condition [38], Like bamboo splitting, the nanowires originated from the vertical splitting of nanotubes, which was caused by the electric field induced longitudinal flow of ions. A small addition of water is essential for the formation of nanowires and the amount of water required decreases with increasing applied potential. 

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