Synthesis of high purity single-walled carbon nanotubes from ethanol by catalytic gas flowCVD reactions

Abstract

Highly pure single-walled carbon nanotubes (SWNTs) with their contents>96% of the total products were achieved by chemical vapour deposition gas flow reactions usingethanol as the carbon source. The high purity SWNTs were formed under criticallycontrolled synthesis conditions and by applying a high hydrogen flow, under which thenon-catalytic condensation of carbon was completely suppressed. Purification of theproducts in acid at ambient conditions readily yielded over 99% pure SWNT products, asthe only impurities left in the products were iron particles of clean surface. Therefore, thepresent study demonstrates the full potential of the CVD gas flow reactions in continuousproduction of high quality SWNTs. Comparable syntheses were conducted usingother alcohols in place of ethanol and it was found that high alkyl alcohols likeisopropanol and hexanol produced more amorphous carbon while methanol produced nocarbon. The high yield growth of SWNTs was attributed greatly to the reactionchemistry of ethanol and the ‘right’ amount of hydrogen in the system, as discussed.