Synthesis and Structural Peculiarities of the Exfoliated Graphite Modified by Carbon Nanostructures

Carbon-carbon composite materials consisting of exfoliated graphite (EG) support and carbon nanotubes grown on its surface have been synthesized by catalytic chemical deposition method. Acetylene-hydrogen-argon gas mixture at 600°C was used as source of carbon. Nickel and iron compounds were investigated as catalysts in this process. The most catalytically active EG support was obtained by impregnation of intercalated graphite with aqueous ferric chloride solution with subsequent drying and thermal expansion of graphite matrix at 900–1000°C. It was detected by XRD method formation of iron crystallites under reductive conditions at 600–900°C. The growing of carbon nanotubes results fist in substantial increase of surface area, from 30–35 m2/g for initial EG support to 110 m2/g at 35% mass content of the grown carbon. However sample with 85% content of deposited carbon has surface area only 42 m2/g. After purifying this sample from amorphous carbon surface area increases to 233 m2/g. If effective catalyst is used the EG support is convenient for carbon nanotubes growing due to very big pore volume.