Structural Investigation of Catalytically Grown Carbon Nanotubes

Carbon nanotubes (CNTs) having diameters in the range of 30–50 nm and few micrometers in length were synthesized in one step through a chemical-reduction route under autogenous pressure of H2/CO2. The synthesized materials prepared under different experimental conditions were characterized using different techniques. Results showed that V2O5 used as a catalyst for the nucleation of CNTs become carburized to vanadium carbide (V8C7) and provides a site for growth of CNTs. At high temperature, carbide particles thus formed become encapsulated at the tip of nanotube followed by the growth of CNTs through the tip-growth mechanism. Thermogravimetric analysis results showed that the CNTs obtained after the longer reaction time are more stable at high temperatures. Raman analysis showed a well-ordered graphite structure.