A novel combination of simple foaming and freeze-drying processes for making carbon foam containing multiwalled carbon nanotubes

To fabricate carbon foam with high surface area and electrical conductivity, a novel combination of foaming followed by growth of multi-walled carbon nanotubes (MWCNTs) aerogel inside the porous body has been investigated. Open cell sucrose based carbon foam was prepared by thermo-foaming and dehydration at 250 °C. A well-dispersed 1.5 wt% MWCNTs aqueous solution in carboxyl methyl cellulose was vacuum impregnated into the porous body and lyophilized using a freeze-drying process. The resulting macro to mesoporous morphology was characterized by scanning electron microscopy and nitrogen porosimetry. Due to the lower thermal conductivity of hydrated carbon foam, the MWCNTs/carbon foam exhibited a random cellular-type morphology with crinkly and curvy sheets of nanotubes. The prepared MWCNTs/carbon foam displayed a very low density of 0.24 g cm^-3 and a fairly high compressive strength of 1.45 MPa. The electrical conductivity being 0.021 S cm^-1, improved eight orders of magnitude compared to that of the dehydrated carbon foam without MWCNTs. Surface area as high as 320 m² g^-1 with the pore size distribution centered at 25 and 150 nm and macro to meso porous morphology was achieved which can be considered for various energy storage and environmental applications.