Synthesis of carbon nanofiber monoliths by chemical vapor deposition

Carbon nanofiber (CNF) monoliths with excellent properties were prepared by catalytic chemical vapor deposition, using ethylene (C₂H₄) and a non-supported Cu-Ni alloy as carbon source and catalyst, respectively. The structure, mechanical properties, and specific surface area of the CNF monoliths were characterized for various preparation conditions. The formation of CNF monoliths mainly depended on the Cu/Ni ratio, growth temperature and time. A CNF monolith synthesized at 580℃ for 3 h from a Cu-Ni catalyst with a Cu/Ni mass ratio of 0.25 exhibited a bulk density of 0.28 g/cm³, a compressive elastic modulus of 1.7 kPa, and a specific surface area of 117 m²/g. SEM images of the CNF monoliths in the initial growth stage further indicated that they were composed of thick octopus-like nanofibers and thin nanofibers that were interwoven with each other to form a three dimensional CNF network and finally the CNF monolith.