Abstract
We report a novel carbon nanotube (CNT) synthesis method by chemical vapor deposition (CVD) using catalysts obtained from carbon rich fly ash. In this approach two fly ash samples (S1 and S2) were treated by heating at 750 degrees C, and then analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). EDS results show that the treated fly ash contains the main components needed in the catalysis of CNTs growth such as Fe, Ni, Al and Si in their oxide forms. Iron levels are found to be higher in S1 than those in S2, while S2 contains an elevated amount of Ni. The as-grown CNTs on S1 and S2 were analyzed by SEM, transmission electron microscope (TEM) and Raman spectroscopy. The nanotubes grown on S1 have diameters in the range of 30-50 nm and lengths in the order of a few micrometers, while those grown on S2 have smaller diameters. These CNTs have around 12 walls as revealed by TEM, while Raman spectrum shows a good degree of wall graphitization (I-G/I-D = 1.35). These results suggest that this approach is quite suitable to obtain low cost catalysts for producing CNTs on a large-scale.