Unsynchronized diameter changes of double-wall carbon nanotubes during chemical vapour deposition growth

Novel structural changes of double-wall carbon nanotubes (DWNTs) triggered by sudden swings of reaction condition have been elucidated. A quick temperature decrease or increase would lead to a decrease or increase, respectively, in the CH(4) decomposition rate and to reformation of catalyst metal particles. In particular, unsynchronized diameter changes of the inner and the outer tubes are observed in the DWNTs prepared by CoMo/MgO catalysts. We have found that the difference of the growth surroundings for the inner and outer tubes of DWNTs can consistently explain the observed unsynchronized diameter changes.