Synthesis of aligned few-walled carbon nanotubes on conductive substrates

We report a robust synthesis of densely aligned few-walled carbon nanotubes on industrially useful conductive substrates such as carbon fibers and carbon papers. This was achieved by water-assisted chemical vapor deposition using an Al/Fe bimetallic catalyst and a thin epoxy-based polymer layer beneath the catalyst. The carbon nanotubes had a mean diameter of 6 nm, mainly double walls, and lengths up to a couple of millimeters. Raman spectroscopy showed high G-band/D-band intensity ratio (>5) indicating high quality of the nanotubes. They were tightly bound and electrically connected to the substrates, as confirmed by ultrasonication test and enhanced cyclic voltammetry signals, respectively. High quality carbon nanotubes synthesized on conductive substrates may find applications in fuel cells, lithium-ion batteries, and field emitters.