TABLE 2.
Synthesis method | Carbon precursor | Catalyst | Energy source | CNFs Symmetry | CNTs |
---|---|---|---|---|---|
CVD/PECVD HipCO | Gas-phase precursors (methane, carbon monoxide, synthesis gas (H2/CO), ethyne, and ethane) | Fe, Co, Ni Cr, V, and Mo (alone or in combination, as powder or supported) | Heat/radio frequency, direct current glow discharge, inductively coupled plasma or microwave (500 to 1000 °C) | Platelet (iron powder) Tubular (iron supported on silica) Stacked-cup | Single wall/Multiwall |
Nanochannel templating | Gas-phase CCVD precursors (as above; discotic liquid crystals | CVD catalysts as above, or non-catalytic | Heat (from 300 to 1000 °C) | Platelet Carbon/carbon composite Nanoribbons | Multiwall |
Electric arc discharge | Graphite rod electrodes in inert gas (Ar or He) | Ni, Y | Electric discharge (2000 to 3000 °C) | Single wall (metal-doped electrodes)/Multi wall (pure graphite electrodes) | |
Laser ablation (vaporization) | Graphite in Ar flow | Co, Ni | High intensity laser (Nd:YAG) pulses in a high temperature atmosphere (1200 °C) | Single wall (metal-doped electrodes)/Multi wall (pure graphite electrodes |
PECVD, plasma-enhanced chemical vapor deposition; CCVD, catalytic chemical vapor deposition; Nd:YAG, neodumium-doped yttrium aluminum garnet