Versatile Catalytic System for the Large-Scale and Controlled Synthesis of Single-Wall, Double-Wall, Multi-Wall, and Graphene Carbon Nanostructures

This work reports a low-cost production method of carbon nanotubes (CNTs) and few-layer graphene sheets in large quantities through radio-frequency catalytic chemical vapor deposition (RF-cCVD). As the reaction temperature was varied over a range of 700-1000 degrees C, different types of high-quality carbon nanostructures were synthesized on a single Fe-Co/MgO catalytic system, while utilizing acetylene as the hydrocarbon source. The reaction efficiencies were found to be dependent on the morphological properties of the corresponding nanostructures and varied significantly with the synthesis temperature. Highly crystalline multi-wall, double-wall, and single-wall CNTs were obtained when the temperature was in the range of 700-950 degrees C, whereas large quantities of few-layer graphene sheets (1-5 layers) were synthesized at 1000 degrees C. The carbon nanostructures were characterized via several analytical techniques, such as electronic microscopy, Raman spectroscopy, X-ray diffraction, etc. It was determined that the synthesis temperature had a strong influence, both on the catalyst system and on the type of the nanostructures synthesized. By utilizing the same catalytic system and varying only one reaction parameter, it may be possible to reduce the production cost of CNTs and graphene nanosheets significantly, so that they may be utilized in various advanced applications.