Decorating Silver Nanoparticles onto Multiwall Carbon Nanotube Sheets

Carbon nanotube sheets have great potential for specific engineering applications owing to their unique, tunable properties such as conductivity. To date, most CNT sheet materials (e.g., buckypapers) are fabricated by using single wall carbon nanotubes (SWNTs). However, multi-wall carbon nanotubes (MWNTs) are much cheaper than SWNTs, and better suited to large scale industrial applications. One drawback of MWCNTs is that the conductivity of MWNTs is typically one or two orders lower than that of SWNTs. The simplest way to achieve low-resistance ohmic contacts to these structures is to coat metals onto the nanotube surface. The only approach so far then is to deposit metals through a chemical reaction on the inner or outer surfaces of the tubes. [1] There are many ingenious methods of depositing metal nanoparticles onto CNT substrates in the literature, each offering varying degrees of control of particle size and distribution along the CNT. [2] However, the metals in these cases were formed by post-reduction of metal compounds with no specificity to the nanotube surface. Alternatively, there is a general method in which the nanotube surface can be modified by oxidation in order to obtain a more controlled and specific nucleation of metals and metal compounds on the surface. Oxidized nanotubes were normally covered by carboxylic (-COOH), carbonyl (-C=O) and hydroxyl (-OH) groups, which all increase the chemical reactivity and specificity of the relatively inert carbon surface.