Multi-walled carbon nanotube concentration

Fig. 14. High resolution TEM observations of three multi-wall carbon nanotubes with N concentric carbon nanotubes with various outer diameters do (a) N = 5, do = 6.7 nm, (b) N = 2, do = 5.5 nm, and (c) N = 7, do = 6.5 nm. The inner diameter of (c) is d = 2.3 nm. Each cylindrical shell is described by its own diameter and chiral angle [151].

Five years after the discovery of fullerenes, Iijima reported in 19911 a novel form of organized carbon which consists of hollow cylindrical structures, a few nanometers in diameter and some micrometers long. Although hollow carbon nanofibers had been prepared for several decades, their walls had never been resolved by High-Resolution Transmission Electron Microscopy (HRTEM). These HRTEM images allowed Iijima to conclude that the walls of the so-called multi-walled carbon nanotubes (MWCNTs) are made up of several concentric cylinders, each being formed by a graphene sheet rolled... 

Y. Li, H. Wang, X. Cao, M. Yuan, and M. Yang, A composite of polyelectrolyte-grafted multi-walled carbon nanotubes and in situ polymerized polyaniline for the detection of low concentration triethylamine vapor, Nanotechnol., 19, 015503 (2008). 

Carbon annealed nanodiscs/nanocones [7440-44-0], These are available as a black powder containing a mixture of 20% cones, 70% discs and 10% of carbon black impurities by weight. The carbon cones have a nearly perfect geometry. The five theoretically possible cones with apical angles of 19.2°, 38.9°, 60°, 84.6° and 112.9° are all present in the mixture with cone lengths of 0.3-0.8p, maximum base diameter of l-2p and wall thickness of 20-50 nanometers. The diameter and thickness of the discs are 0.88-3.5p and 20-50 nanometers respectively. A product of almost 100% carbon is obtained by annealing at 2500-2700° which increases the structural order and reduces the concentration of impurities particularly of metals (from eatalyst). They are similar to multi-walled carbon nanotubes (MWCNTs). 

A performant reagentless ECL system for H2O2 detection based on electrop-olymerized luminol on pre-treated screen-printed electrodes was developed [64]. An ECL biosensor based on carboxylic acid-functionaUzed multi-walled carbon nanotubes (CCX)H-F-MWNT) and Au nanoparticles [65] and immobilization in sol-gel hybrid material was fabricated for sensing the efficiency of ethanol. The intensity of ECL increased linearly with ethanol concentration from 2.5 x 10 5.0 X 10 M and detection limit was 1.0 x 10 M [66]. 

Multi-walled carbon nanotubes (MWCNTs) consist of several concentrically arranged SWCNTs as illustrated in Figure 5.1(c). The radial distance between neighboring shells is in the range of the plain distance of pyrolitic and turbostratic graphite, between 0.344 and 0.354 nm, respectively. The outer diameters are well above 1 nm and can reach values up to 100 nm. The aspect ratios can be as large as those of SWCNTs. The mechanical... 

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