Observations of novel carbon nanotubes with multiple hollow cores

Usually carbon nanotubes (CNTs) containing only one hollow core are obtained from the catalytic decomposition of hydrocarbons when hydrocarbon gases flow straight into the reaction tube. However, unusual carbon nanotubes with multiple hollow cores were observed when the gas-feed method was changed in an attempt to increase CNT production yield using a floating catalyst method. The fraction of multicored carbon nanotubes can be as high as 60%. The formation of such an unusual structure is ascribed to the introduction of pentagon and heptagon defects to the CNTs in the growth process, owing to the change of gas-feed method. This finding enriches the family of CNTs and could be helpful in understanding the CNT formation mechanism.