The mechanism of the sudden termination of carbon nanotube supergrowth

The effect of growth conditions and catalyst lifetime on the supergrowth of carbon nanotubes (CNTs) through a water assisted chemical vapor deposition has been investigated. The reasons behind the observed sudden termination of the CNT growth were explored. A proper amount of water was found to improve the activity of the catalyst and enhance the growth rate of CNTs. However, the introduction of water did not extend the catalyst lifetime leading to unavoidable termination of the CNT growth. Further experiments demonstrated that in addition to catalyzing the CNT growth, catalyst particles can also decompose/etch the C sp2/sp3 bonds including those in the CNTs. The existing termination mechanism for the CNT growth fails to explain this. We therefore propose a model based on the catalyst phase transformation using the Johnson–Mehl–Avrami–Kolmogorov theory to predict the growth rate and termination of the CNT growth.

Conditions and role of water in synthesis of Carbon Nanotubes were fully inspected. A new model was built to explain the mechanism of termination of Carbon Nanotubes..Figure optionsDownload as PowerPoint slideResearch highlights
► Conducted water assisted carbon nanotube supergrowth in hot-filament CVD system.
► Found experiment evidences of termination of growth of carbon nanotubes based on catalyst phase transformation.
► Constructed a model based on JMAK theory to predict the catalyst life and its effect on the synthesis of carbon nanotubes.