Fabrication and electrochemical behavior of vertically-aligned carbon nanotube electrodes covalently attached to p-type silicon via a thioester linkage

Vertically-aligned single-walled carbon nanotubes (SWCNTs) (VACNTs) are becoming increasingly recognized due to their fast electron transfer rates. However, the chemistry available for further functionalizing these electrodes is limited. Here we describe a new approach to the fabrication of VACNTs. SWCNTs were covalently attached to a p-type silicon (100) (Si) wafer surface using a thioester linkage in which the nanotubes were firstly acid treated and then, in the presence of a hydroxylated Si wafer surface, reacted with phosphorus pentasulfide (a mild electrophilic catalyst). The novel nanostructure was characterized using atomic force microscopy (AFM) showing vertical alignment with FTIR spectroscopy indicating pendant thiocarboxylic acid groups for further reaction. In addition, electrochemical properties using cyclic voltammetry indicate that the electrodes have excellent electrochemical properties with an electron transfer rate of 2.98 × 10− 3 cm s− 1.