Synthesis of highly aligned carbon nanotubes by one-step liquid-phase process: Effects of carbon sources on morphology of carbon nanotubes

This paper describes a unique and innovative synthesis technique for carbon nanotubes (CNTs) by a one-step liquid-phase process under ambient pressure. Vertically aligned multi-walled CNT arrays with a maximum height of 100 mu m are prepared on stainless steel substrates, which are submerged and electrically heated in straight-chain primary alcohols with n(C) = 1-4 (n(C): number of C atoms in the molecule) containing an appropriate amount of cobalt-based organometallic complex as a catalyst precursor. Structural isomers of butanol were also used for the synthesis to examine the effects of structural factors on the morphology of the deposited products. Notably, 2-methyl-2-propanol, which is a tertiary alcohol, produced only a small amount of low-crystallinity carbonaceous deposits, whereas vertically aligned CNTs were grown from the other isomers of butanol. These results suggest that the presence or absence of beta-hydrogen in the molecular structure is a key factor for understanding the dissociation behavior of the carbon source molecules on the catalyst. (C) 2017 The Japan Society of Applied Physics