Direct growth of multiwall carbon nanotube on metal catalyst by chemical vapor deposition: In situ nucleation

Carbon nanotubes (CNTs) are among the most promising materials for applications in future nanotechnology. The combination of excellent physical and mechanical properties beside chemical resistance seems very interesting for different industrial applications. However, the commercialization of nanotube-based nanocomposites has been hampered by their high cost and minuscule production. In the present study, we have tried to understand the fundamental aspects of multiwall carbon nanotubes (MWCNTs) direct growth on metal catalyst particles via thermal chemical vapor deposition (T.CVD) in the presence of zirconium hydride (ZrH2) and aluminum nanoparticles. The effects of different parameters such as gas flow rates, metal catalyst systems, and temperature on the quality and quantity of the obtained MWCNTs were investigated and some interesting results were obtained. It was found that at moderate temperatures, MWCNTs growth rate on iron-based (Fe) catalyst was much more than that on nickel (Ni) and cobalt (Co) particles. Transmission electron microscopy (TEM) results and TGA analysis revealed that metal nanoparticles as the nucleation sites come from the fragmentation of catalyst surfaces and the application of relatively small amounts of ZrH2 significantly enhances this mechanism. Besides, crystalline structure of MWCNTs was performed by Raman spectroscopy, X-ray diffraction (XRD) and selected area electron diffraction (SAED) technique. This method shows great promise for achieving the goal of mass-production due to its high quality and yield; simplicity, and ease of scale-up.