Carbon nanotube growth on cobalt-sprayed substrates by thermal CVD

We present a very simple spray-coating method for depositing cobalt catalyst over quartz substrates that can be efficiently utilized in the production of carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD). Very uniform multi-walled carbon nanotubes (MWNTs) have been grown from cobalt catalyst over large surfaces by thermal CVD using mixtures of acetylene and ammonia. The effect of catalyst pretreatments and CNT growth temperature on the CNT diameter has been studied and discussed.