Patterned growth of vertically aligned carbon nanotubes on pre-patterned iron/silica substrates prepared by sol-gel and shadow masking

The sol-gel technique has been used to prepare film-like iron/silica substrates for the large-scale growth of highly aligned carbon nanotubes. Here, we show that by using transmission electron microscopy (TEM) grids as shadow masks, the sol-gel technique can be readily adapted to prepare patterned film-like iron/silica substrates, on which various kinds of micropatterns of vertically aligned carbon nanotubes can be fabricated. Not only were micropatterns composed of regularly arranged nanotube towers of (when viewed from the top) squares and hexagons obtained, but also patterns consisting of complex tube features (for example, hollow tube-like towers and nanotube networks) were fabricated via our approach. The synthesis of these morphologies can be readily controlled by using TEM grids with different openings and by tuning the parameters in preparing the patterned substrates. In comparison with other techniques that involve sophisticated lithography, our technique represents a simple and low-cost approach to the micropatterning of aligned carbon nanotubes.