关键词: chemical vapour deposition , carbon nanotubes , NiO/γ-Al2O3 catalyst , reduction temperature , chemical vapour deposition, carbon nanotubes, NiO/γ-Al2O3 catalyst, reduction temperature

Abstract: The synthesis of carbon nanotubes (CNTs) via chemical vapour deposition of methane on NiO/γ-Al2O3 catalyst has been investigated. The reduction behavior of NiO/γ-Al2O3 with methane was studied by using thermogravimetric (TG) analysis and X-ray diffraction techniques. It was found that the reduction of NiO supported on γ-Al2O3 to Ni0 with methane was completed at the temperature range of 710−770 °C. The catalytic activity of NiO/γ-Al2O3 for CNTs synthesis by in situ chemical vapour deposition of methane during the reduction was also investigated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe and analyze the structural variation of CNTs produced at different reduction temperatures. The results indicated that the reduction temperature exhibits significant influence on the morphology and the yield of CNTs. The CNTs with diameters about 20 nm were obtained at the reduction temperature of 750 °C, but a high temperature led to increase in diameter and decrease in yield of CNTs.