Electron transfer chemistry of octadecylamine-functionalized single-walled carbon nanotubes

Single-walled carbon nanotubes were chemically functionalized by virtue of the interactions between the nanotube-bound carboxylic moieties and octadecylamine ligands. The electronic conductivity properties of the resulting nanotubes were probed voltammetrically. Two approaches were employed. The first entailed the fabrication of a nanotube monolayer at the air|water interface and the conductivity was measured in situ with a vertically aligned interdigitated arrays (IDAs) electrode. The overall current profiles are analogous to those of a Coulomb blockade and the conducting current pathways are found to be one-dimensional within the two-dimensional arrays of nanotubes. The second technique was taking advantage of the dispersibility of the nanotubes in a solution where conventional electrochemical methods were used. From these measurements, the nanotube bandgap energy could also be estimated, which was quite comparable to that determined by spectroscopic measurements.