Investigation Of Preparation Of Aligned Carbon Nanotubes By Catalyzed Decomposition Of Cyclohexane

Due to their unique physical, chemical, mechanical and electronic properties, aligned carbon nanotubes (ACNTs) have the attractive applications in some areas, such as field display devices, nano-electronic devices, hydrogen storage, composite materials, and chemical sensors, etc. However, the study on the applications of ACNTs is restricted large, owing to the low yield and high cost of ACNTs.In this paper, the ACNTs was synthesized by chemical vapor deposition (CVD) method. The scanning electron microscope (SEM) was used to investigate the effects of carbon source, reactor temperature, and screen mesh size on the morphology of the products obtained from the CVD reactions.The experimental results indicate that at the reaction temperature of 850℃, the morphology of ACNTs synthesized by catalyzed decomposition of cyclohexane shows more regular arrangement, lower impurity content and well-aligned direction, the uniform thickness-about 180μm, and the raw yield of the ACNTs reaches to nearly 7% for the first time. At the reaction temperature of 750℃, the thickness of the ACNTs is about 60μm, and the raw yield is merely 1.4%, further more, the horizontal-aligned product may be obtained. There was almost no product deposited at the reaction temperature of 700℃. The mesh size of the screens wrapped over the quartz sheets has some influences on the morphology of the products, namely when the sheet was wrapped with 200 mesh screen, the thickness of the ACNTs product on it was about 160μm, and the density of the surface was lower, the lengthways sections of ACNTs was better-aligned and more clean, compared with those grown on the sheet wrapped with 10 mesh screen or nothing. But the thickness of the ACNTs in the later two cases is larger, i.e., about 180μm. There are by-products on the surface of ACNTs, if the sheet is unwrapped with the screen.The HRTEM characterization results show that outer and inner diameters of CNTs in the ACNTs synthesized by catalyzed decomposition of cyclohexane under the reaction temperature of 850℃are about 20~100nm and 10nm, respectively. It was also observed that transition metal catalyst existed inside the hollow space of CNTs.The above results have some important practical significance in promoting the applications of ACNTs, especially the research of CNTs-FED.