Electrical conductivity of carbon nanotubes grown inside a mesoporous anodic aluminium oxide membrane

Well-aligned, open-ended carbon nanotubes (CNTs), free of catalyst and other carbon products, were synthesized inside the pores of an anodic aluminium oxide (AO) template without using any metallic catalyst. The CNTs and the CNT/AO composites were characterized by scanning and transmission electron microscopy, thermogravimetric analysis, Raman spectroscopy and X-ray diffraction. Particular care was devoted to the reactor design, synthesis conditions, the catalytic role of the templating alumina surface and the preservation of the alumina structure. The transport properties (sorption, diffusion and permeability) to water vapor were evaluated for both the alumina template and the CNT/AO composite membrane. The measured effective electrical volume conductivity of the CNT/AO composite was found ranging from a few up to 10 kS/m, in line with the recent literature. The estimated averaged values of the CNTs-wall conductivity was around 50 kS/m.