الفهرس 
Preparation of carbon nanotubes over mixed metal-oxide catalysts
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Abstract
Catalytic chemical vapor deposition (CCVD) is one of the most promising synthesis methods for economically producing large quantities of different nanocarbon structures. This study is focused on the synthesis of different morphological structures of carbon nanotubes via acetylene decomposition over the surface of quaternary-metallic catalyst (Fe-Ni-Co-Mo) supported on MgO (Fe-Ni-Co-Mo/MgO). In this study, different growth parameters, such as catalyst pretreatment atmosphere, carrier gas, carbon precursor, temperature, and reaction time were investigated to optimize the yield, quality, size, purity and graphitic crystallinity of the deposited carbon. The obtained samples were characterized by high resolution transmission electron microscopy (HR-TEM), thermogravimetric analysis (TGA), Raman spectroscopy, FTIR and X-ray diffraction. TEM images and Raman spectra of samples showed, depending on the conditions of deposit carbon, showed a successful synthesis of carbon nanobud, Onion-like (O-CNT) structure, a high-yield and quality bamboo-like multiwalled carbon nanotubes (b-CNT), hybrid graphene/carbon nanotubes (G/CNT) and multilayer graphene (MLG). TGA analysis showed no evidence of carbonaceous materials is formed during the synthesis process. The results found seem essential for realizing the role of different synthesis parameters on the yield, quality, and morphology of the synthesized product