Large amounts of amorphous carbon nanotubes (ACNTs) were prepared with Co–Ni alloy powders as catalyst in hydrogen gas atmosphere by a modified arc discharging furnace which can control temperature during the electric arcing process. The experimental results indicate that the cooperative function of temperature and catalyst plays an important role in the soot production rate and the relative ACNT purity. When temperature increases from 25°C to 700°C, the soot production rate increases from around 1 g/h to 8 g/h, the best relative ACNT purity at 600°C can reach up to 99% compared to the room temperature sample. Without catalyst, only plate graphite is formed at 25°C and very few carbon nanotubes are found when temperature increases to 600°C. TEM, SEM, HRTEM and XRD analysis showed that the as-prepared carbon nanotubes are almost amorphous. The soot production rate is 8 g/h and diameter range of amorphous carbon nanotubes is about 7–20 nm, respectively. © 2005 Elsevier Ltd. All rights reserved.

The effect of oxygen on the growth of single-walled carbon nanotubes was studied with Ni–Co alloy powder as catalyst under helium atmosphere of 500 Torr by electric arc discharge. The oxygen included in nickel or (and) cobalt oxides was added in catalyst. The content of oxygen in atmosphere was controlled by changing vacuum degree inside furnace before inputting buffer gas. The examinations of TEM and Raman scattering showed that oxygen in metal oxide as catalyst promotes the nucleation of SWCNT by taking effect on the metal catalyst particles. However, O2 in atmosphere has the role of oxidizing amorphous particles along with nanotubes. When its molar proportion is higher than 0.22 ppm (Parts per million), the carbon nanotubes produced are oxidized and their purity decreases. The diameter of single-walled carbon nanotube obtained under different condition has a narrow distribution around 1.28 nm.

Single-walled carbon nanotubes (SWCNTs) were prepared by a modified arc discharging furnace using Fe-Ni-Mg powders as catalyst at 600◦C. The effects of catalyst composition and content on the production rate and purity of SWCNTs are investigated in this paper. When the Fe-Ni-Mg catalyst composition is 2 : 1 : 2 wt% and the catalyst content is 5 wt%, the experimental results indicate that the production of SWCNTs is 12 grams per hour, and the purity and diameter of SWCNTs are 70% and 1.22~1.38 nm, respectively. The results indicate that the cooperative function of catalyst composition and content plays an important role in the production of SWCNTs. The aim of this work is to control the production process of SWCNTs efficiently.