Comparison of Synthesis and Purification of Carbon Nanotubes by Thermal Chemical Vapor Deposition on the Nickel-Based Catalysts: NiSio sub(2) and 304-Type Stainless Steel

In this study by Thermal Chemical Vapor Deposition (TCVD) method, the synthesis of carbon nanotubes (CNTs) and temperature affects on the grown CNTs on the NiSio sub(2) catalyst and 304-type stainless steel was investigated. The purification of the grown CNTs on the 304-type stainless steel was also investigated in this study. The synthesis and purification of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), termogravimetric analysis (TGA) and Raman spectroscopy. Our obtained result by SEM and TEM shows that densities of CNTs growth on the 304-type stainless steel are more than the CNTs growth on the NiSio sub(2) catalyst and both of them have a bamboo structure. The synthesis of CNTs in the range 750 to 850 degree C are also investigated in this study. Optimum temperature for synthesis of CNTs on the NiSio sub(2) catalyst is about 825 degree C and for the 304-type stainless steel is about 750 degree C. The purification process includes oxidation in the range 450 to 750 degree C, washing with 5 mol hydrochloric acids, disperse with ultrasonic and filtration. Our obtained result by TGA indicates that the CNTs burn in 600 degree C. A comparison of the Raman spectroscopy before and after of purification shows that the D-band shape is less than the G-band that due to the samples purified. Hence, the reported 304-type stainless steel provides a good sample for synthesis of CNTs by TCVD method.