The production of a homogeneous and well-attached layer of carbon nanofibers on metal foils

Abstract

Carbon nanofibers (CNFs) were deposited on metal foils including nickel (Ni), iron (Fe), cobalt (Co), stainless steel (Fe:Ni; 70:11wt.%) and mumetal (Ni:Fe; 77:14wt.%) by the decomposition of C2H4 at 600°C. The effect of pretreatment and the addition of H2 on the rate of carbon formation, as well the morphology and attachment of the resulting carbon layer were explored. Ni and mumetal show higher carbon deposition rates than the other metals, with stainless steel and Fe the least active. Pretreatment including an oxidation step normally leads to higher deposition rates, especially for Ni and mumetal. Enhanced formation of small Ni particles by in situ reduction of NiO, compared to formation using a Ni carbide, is probably responsible for higher carbon deposition rates after oxidation pretreatment. The addition of H2 during the CNF growth leads to higher carbon deposition rates, especially for oxidized Ni and mumetal, thus enhancing the effect of the reduction of NiO. The diameters of CNFs grown on metal alloys are generally larger compared to those grown on pure metals. Homogenously deposited and well-attached layers of nanotubes are formed when the carbon deposition rate is as low as 0.1–1mgcm−2h−1, as mainly occurs on stainless steel.