The parameters that are involved on the process of CNT fabrication play an important role in the final characteristics of these carbon nano-structures. Despite the fact that 4 main parameters were fixed, the changes in the investigated parameters were enough to vary significantly the carbon nanostructure morphologies, making possible finding a pattern that leaves a guide to produce either Ni core–shell nanoparticles or MWCNT. The temperature fine adjust is an interesting topic on the control of the fabrication process of carbon nanostructures and presents a very important way to finally reach the possibility of mass production of these structures. Here we demonstrate an effective way to obtaina high efficient fabrication of CNT and Ni core–shell nanoparticles by tuning the temperatures with the Ni catalyst thickness.
In the studied range it is evident that higher temperature promotes the core–shell configuration and for decreasing temperatures the formation of CNT is enhanced. The thickness of the Ni layer is an important parameter to take into account too. Even though carbon deposition was found for all thicknesses, it is clear to conclude that samples with 2 nm of Ni layer presented better results in the deposition of MWCNT, but a high rate of damage on the carbon shells on the core–shell nanoparticles; the reason couldbe the velocity of the process, as at higher temperature, the carbon diffusion on the metal catalyst is faster, thus, if the velocity is high (900 °C) and the superficial area low(2 nm) the process.