Growth and morphology of carbon nanostructures by microwave-assisted pyrolysis of methane

Both carbon nanospheres and CNTs with different morphologies were synthesized without any catalyst by microwave pyrolysis chemical vapor deposition using methane as carbon source and nitrogen as diluted gas. The morphology and structure of the products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy and Raman spectroscopy. The experimental results demonstrated that reaction temperature, gas ratio of methane to nitrogen and total gas flow rate strongly influenced the nature of various nanocarbon materials. Raman spectra indicated that the carbon nanospheres and CNTs possess relatively low degree of graphitization.