Effect of organic additives in catalyst preparation on the growth of single-wall carbonnanotubes prepared by catalyst-assisted chemical vapour deposition

Abstract

The effect of organic additives, including citric acid, PEG (2000) and PEG (200), on theyield and quality of single-wall carbon nanotubes (SWNTs) synthesized by a Fe–Mocatalyst dispersed on an alumina matrix prepared by the sol–gel process in assistedchemical vapour deposition (CVD) has been investigated by transmission electronmicroscopy (TEM), thermo-gravimetric analysis (TGA) and Raman spectroscopy. Differentmorphologies of catalyst including big flakes, spherical particles and porous supportingmaterials were obtained using citric acid, PEG (2000) and PEG (200) as dispersant,respectively. SWNT yields of 10 wt%, 16 wt% and 33 wt% were obtained using citric acid,PEG (2000) and PEG (200) as the dispersants, respectively, which implies thatthe PEG (200) is the most effective at improving the yield of SWNTs due tothe effect of additives on the specific surface area of the catalyst. The as-grownSWNTs are mostly in large bundles with diameters of 0.5–2 nm, but in somecases, isolated tubes with much larger diameters can also be found. Finally apreliminary explanation for the increased SWNT yield using PEG (200) is presented.