Effects of partial and total methane flows on the yield and structural characteristics of MWCNTs produced by CVD

Multi-walled carbon nanotubes (MWCNTs) were produced in a chemical vapor deposition (CVD) process employing methane and argon as hydrocarbon and carrier gas over supported sol–gel Co–Mo/MgO catalysts. A detailed study about the influence of the gas flow of both hydrocarbon and carrier gas on carbon yield, morphology, structure and graphitization degree is presented. Methane partial pressure, methane total flow rate, as well as the flow ratios of methane to argon and methane to hydrogen (reducing gas) were the parameters systematically varied. The results reveal that high MWCNT yields in the produced materials are strongly related to the methane partial pressure and the methane total flow, while a high degree of graphitization is more closely linked to the use of argon gas as inert atmosphere.