Electroless plated gold as a support for carbon nanotube electrodes

Abstract

A monolayer of -NH2 terminated 3-aminopropyltriethoxysilane (APS) was self-assembled onto a p-type silicon (1 0 0) substrate. This amine terminated silane monolayer provided an electrostatic point of attachment for citrate stabilised gold colloid nanoparticles, which act as 'seed' particles for the electroless deposition of gold, creating an electrolessly deposited gold layer on silicon. A -NH2 terminated cysteamine monolayer was then deposited onto the gold layer and carbon nanotubes, with high carboxylic acid functionality, were immobilised via a condensation reaction. A redox active molecule ferrocenemethanol was then chemically attached to the immobilised carbon nanotubes. These nanostructures were used as working electrodes in cyclic voltammetry to observe the oxidation and reduction of ferrocene. Important electrochemical parameters such as electrode kinetics, electron transfer rate and surface concentration of the redox active molecules were obtained, providing information on the ability of electroless plated gold surfaces to act as supports for carbon nanotube-based electrodes. This information has also provided insights into the behaviour of vertically aligned carbon nanotubes immobilised on nanoscale gold wires, which have been previously fabricated using atomic force microscopy. © 2008 Elsevier Ltd. All rights reserved.