Explorations On Growth Mechanism And Controlled Synthesis Of Aligned Multi-Walled Carbon Nanotube Array

Control the growth orientation of carbon nanotubes, especially control thepreparation of various orderly array structured carbon nanotube films is a matter ofimportance to realize the practical application of carbon nanotubes. Also it is the mainchallenge for the realization of the actual application of carbon nanotubes. In thisdissertation, both chemical vapor deposition and plasma enhanced chemical vapordeposition were used to investigate the growth mechanism and controllable growth ofaligned carbon nanotube array films. The main results were as follows:By regulating hydrocarbon gas, rf power, the interelectrode distance and theapplied substrate negative bias, realized the control on plasma conditions andcontrollable growth of carbon nanotubes. Experimental results proved that the self biascan be used as a suitable parameter to diagnose plasma conditions and to control thegrowth of carbon nanotubes. It was also demonstrated that the self bias played a keyrole during carbon nanotube growth. And the self bias was found to have both goodimpact and destructive influence on carbon nanotube growth.We have developed a low-cost method to achieve controllable growth of carbonnanotubes. Using plasma enhanced chemical vapor deposition technique combiningwith two-dimensional colloidal crystal template technology, through controlling thegrowth time, the annealing time of two-dimensional colloidal crystal template and thediameter of polystyrene spheres, effectively realized well-control on the growth position,growth density and pattern. The relationship between the microstructure of catalyst filmand the morphologies of carbon nanotube arrays was also discussed.We have put forward a simple and convinient method to control the growth modeof carbon nanotubes. Carbon nanotubes were synthesized by plasma enhanced chemicaldeposition technique combined with two-dimensional colloidal crystal templatetechnology. It was shown that the growth mode can be switched from base-growthmode to tip-growth mode by insertion of plasma pre-treatment of catalyst before carbonnanotube growth. A layer of two-dimensional ordered porous membrane of Fe3C wasloaded by the carbon nanotube array grown with tip-growth mode. And this very uniquemorphology and structure demonstrated excellent hydrophobic property, ferromagneticbehavior and photocatalytic characteristics. The influence of partial pressure of hydrocarbon gas, temperature and partialpressure of water on the growth dynamics of carbon nanotube array was studied indetail. By water assisted chemical vapor deposition (WACVD) method, and throughorthogonal test,1mm thick aligned multi-walled carbon nanotube array film wasobtained with big inner diameter and uniform distribution of length and diameter. Whenthe aligned carbon nanotube array film was used as cathode materials of lithium ionbattery, it showed stable charge-discharge cycling stability.