High-purity fibrous carbon deposit on the anode surface in hydrogen DC arc-discharge Original Research Article

A brittle porous deposit consisting of high-purity fibrous carbon products with a diameter of 25–100 nm was obtained on a heated anode surface in hydrogen DC arc-discharge. Hydrogen arc plasma was generated between a graphite cathode and a carbon/metal composite anode consisting of 1.0 at.% Fe, 0.6 at.% Co, 2.4 at.% Ni, and 0.4 at.% FeS. X-ray diffraction analysis revealed that the fibrous products had a turbostratic carbon structure, with an interlayer spacing of 0.346 nm. Elemental analysis showed that the fibrous products were composed of 98.4 mass% of carbon. Three types of nano-structured fibrous products were observed using transmission electron microscopy, (1) with a bamboo structure, (2) with a hollow core, and (3) without a hollow core. The formation of fibrous products was initiated by arc-generated metal particles with a diameter of 5–75 nm, then carbon for further growth was supplied by the decomposition of polycyclic aromatic hydrocarbons that were created by interactions between arc-generated carbon clusters and atomic hydrogen. The nano-structure of the fibrous products is thought to depend on the size and morphology of the catalytic metal particles. The synthesis conditions, microstructural characterization and the growth mechanism of the fibrous carbon products are reported.