Impact of the fabrication method on the physicochemical properties of carbon nanotube-based aerogels

Abstract

The preparation and characterization of porous multi-walled carbon nanotube-based aerogels is reported here. Aerogels with varying nanotube content (25–100 wt.%) were fabricated by a combination of flash freezing/lyophilization process, using poly(vinyl alcohol) as a structural binder. The resulting aerogels were characterized by SEM imaging and nitrogen porosimetry. The specific surface area as well as the thermal behavior of the carbon nanotube-based aerogels were highly dependent upon nanotube loading. At nanotube content of 50 wt%, thermal incandescence of the aerogel at temperatures below 200 °C was observed, due to molecular friction interactions between confined water vapors and the aerogel structure. These data were strongly supported by TGA and DSC measurements. Specific surface area was shown to be a critical parameter for the absorption capacity of pyrene-containing substances by the porous aerogels. Spectrophotometric measurements revealed that aerogels with nanotube content 100 wt% showed the highest absorption capacity of the polynuclear substance. Carbon nanotubes in the form of powder and aerogel were used as catalyst supports of CuO nanoparticles for CO oxidation at low temperature. Preliminary investigations indicated that CuO/CNT aerogel induced 100% CO conversion at about 250 °C, whereas the corresponding temperature for the CuO/CNT powder was about 330 °C.