Liquid-phase synthesis of vertically aligned carbon nanotubes and related nanomaterials on preheated alloy substrates

Carbon nanotubes (CNTs) and related nanocarbons were selectively synthesized on commercially available alloy substrates by a simple liquid-phase technique. Fe-and Ni-rich stainless-steel (JIS SUS316L and Inconel (R) 600, respectively) and Ni-Cu alloy (Monel (R) 400) substrates were used for the synthesis, and each substrate was preheated in air to promote the self-formation of catalyst nanolayers on the surface. The substrates were resistance heated in ethanol without any addition of catalysts to grow CNTs. The yield of the CNTs effectively increased when the preheating process was employed. Highly aligned CNT arrays grew on the SUS316L substrate, while non-aligned CNTs and distinctive twisted fibers were observed on the other substrates. An Fe oxide layer was selectively formed on the preheated SUS316L substrate promoting the growth of the CNT arrays. Characterizations including cyclic voltammetry for the arrays revealed that the CNTs possess a comparatively defect-rich surface, which is a desirable characteristic for its application such as electrode materials for capacitors. (C) 2018 The Japan Society of Applied Physics