Further Investigation Of Preparation Of Carbon Nanotube Arrays By Chemical Vapor Deposition And Their Foundational Research Of Application

In this paper, carbon nanotube arrays (CNTAs) were prepared by chemical vapordeposition (CVD). The scanning electron microscope, transmission electronmicroscope, Raman spectrometer, X-ray diffraction and thermal analysis were used tocharacterize the products of reaction in order to investigate the repetitiveness andreproducibility of the preparation of CNTAs and the effect of diameter sizes of quartztube reactor. The effects of the reaction temperature and the solvents on themorphology, quality and yield of the raw CNTAs were also investigated. The growthmechanism of CNTAs was discussed. The suspensions of CNTAs in the differentsolvents or solutions were collocated by ultrasonication. The dispersive results ofCNTAs and the stabilities of suspensions were investigated. The changes of theelectrical conductivity of the suspensions with the increase of temperature weremeasured.The experimental results show that the repetitiveness of the preparation of CNTAsis comparatively good, and the reproducibility is acceptable. The effect of diametersizes of quartz tube reactor on the quality and morphology of the CNTAs is notremarkable, but the percent yield of the CNTAs is increased markedly when thequartz tube reactor with smaller diameter is used. The reaction temperature has animportant effect on the percent yield, morphology and quality of the raw CNTAs. Theyield of the raw CNTAs of good quality reaches a maximum of~7.0wt.%at850℃.The effect of reaction temperature depends on both the ratios of the active carbonspecies (A) to the active Fe catalyst species (C)(I=A:C) and the other carbon species(B)(II=A:B). The effect of solvents on the morphology and quality of the CNTAs isobvious, i.e., the quality of the raw CNTAs obtained from solvent1and solvent3respectively is good, and that obtained from solvent2is not good, but there are noCNTAs obtained from solvent4. The effect of the solvents is closely related to theirformation enthalpy and the C C bond energy, but there is no significant correlationwith their boiling point. The factors that drive/keep the growth of CNTAs continuesmay be the unsaturated bonds at the top ends of MWCNTs, enough amounts of activecarbon atoms, and the microelectric and micromagnetic interactions among them,which lead to that the active carbon atoms self-assemble to form MWCNTs. The experimental results of the stabilities and electrical conductivity measurementof suspensions indicate that the dispersion of CNTAs in distilled water is very poor,but good in ethanol, and the stabilities of the corresponding suspensions are also good.Especially the suspension collocated with the CNTAs mass percentage0.125%inethanol and the ultrasonication time4h has the best dispersive result and stability, andits electrical conductivity remarkably increases with the increase of temperature.The results of this study have very important practical and some academic meaningto expand the scale of the preparation of CNTAs and to promote the study ofapplication of CNTAs, especially in the field of electrically conductive solution andother related ones.