GROWTH OF MULTI-WALLED CARBON NANOTUBES ALONG WITH GRAVITY BY SPRAY PYROLYSIS OF NATURAL PRECURSOR.

Carbon nanotubes are prepared along the gravity direction in a spray pyrolysis setup over the silica-supported Fe-Co-Ni catalyst. The silica-supported Fe-Co-Ni catalyst coated over the copper strip is inserted in such a way the coating surface faces downward so that carbon nanotubes can grow along the direction of gravity. Plant-based natural precursor, Pine oil, is used as a carbon source for the preparation of carbon nanotubes by spray pyrolysis method. The effect of precursor flow rate on yield, morphology and structural properties of carbon nanotubes prepared along gravity are discussed. At an optimum flow rate, carbon nanotubes are formed in good yield. The carbon nanotubes synthesized are characterized using appropriate techniques. The scanning electron microscope results show that the synthesized carbon nanotubes are long, straight and well graphitized multi-walled type. The carbon nanotubes diameters are around 50 nm and the average length 20µm. Raman spectroscopy studies revealed that carbon nanotubes are well graphitized multi-walled type with defect-free. A mechanism for the growth of carbon nanotubes along gravity is proposed. Spray pyrolysis of the natural precursor, Pine oil, along with gravity over inversely placed support catalyst material is a promising technique for the growth of long and narrow carbon nanotubes. [ABSTRACT FROM AUTHOR]