Synthesis of high-quality multi-walled carbon nanotubes by arc discharge in nitrogen atmosphere

Carbon nanotubes (CNTs) are a significant candidate for future channel materials for high-performance electronic devices, and this has attracted the attention of many researchers. Due to the scattering of defects in carbon nanotubes, the migration of charge carriers is greatly reduced, and the synthesis of defect free carbon nanotubes is an urgent and important issue that needs to be addressed. In this study, high-purity graphite powder served as the carbon source, and iron served as the catalyst to synthesize defect free MWCNTs through direct-current arc discharge (AD) in a nitrogen atmosphere. The effects of different pressures and catalysts on the yield and morphology of CNTs were studied. As the nitrogen pressure inside the vacuum chamber increases, the MWCNTs become longer and more erect. Fe has a high defect repair efficiency, which promotes the synthesizing of lattice-perfect and defect-free MWCNTs. It is found that the MWCNTs mainly exist in the iron mesh near the cathode. Using iron as a catalyst, we synthesize very straight MWCNTs with clearer walls under nitrogen pressure of 60 kPa. The results show that the method is characterized by low cost, implementability, and the ability to synthesize high-quality, defect free MWCNT compared to the conventional AD method.