Multiwall CVD Carbon Nanotubes as Insulated Nanowires

Carbon nanotubes grown from acetylene gas by chemical vapor deposition onto conducting substrates have been investigated as working electrodes for voltammetric studies. Both the bare carbon nanotubes as well as nanotubes decorated with electrochemically-deposited gold were investigated. The electrodes exhibit high specific capacitance and good electrode behavior for interfacial electron transfer. The nanotubes appear to have electrochemical properties that depend on the surface morphology; interfacial electron transfer occurs preferentially at the tube ends or edges, while double-layer capacitance reflects the higher surface area of the tube sidewalls. The nanotubes act as insulated wires. Cyclic voltammetry of the hexacyanoferrate (III/II) couple was used to estimate the relative electrochemical surface areas of the two regions.