Methane/nitrogen plasma-assisted synthesis of graphene and carbon nanotubes

Abstract

Abstract An experimental and numerical study of plasma-assisted synthesis of graphene and carbon nanotubes is presented. Experiments were carried out using methane/nitrogen plasma generated by a DC plasma torch with pressure variation in the 100–710 Torr range. The synthesis products were studied by synchronous thermal analysis and scanning electron microscopy. The results of these experiments are shown in thermogravimetry graphs and snapshots of the synthesized structure morphology. It is shown that structures in the form of graphene ‘flakes’ are thermally stable. Carbon nanotubes synthesized at different pressures show different morphologies. Using express gravimetric analysis, the maximum nitrogen content in nanostructures was determined to be 8 at.%. Spectral investigation of a jet of nitrogen plasma with the addition of methane and pure nitrogen under atmospheric pressure was performed. The results of the emission spectra analysis agree with the gas phase composition obtained by kinetic modelling. It is shown that the conversion products consist of the following components: H, H 2 , C 2 , CN, HCN, C 2 H 2 , C 4 H 4 , and C 6 H 6 , the ratio of which varies with decreasing temperature. Our calculations show that the gas phase composition remains practically unchanged at different pressures.