Carbon-nanotube cotton for large-scale fibers

A new form of carbon nanotube (CNT) material, CNT cotton, made of ultralong individual CNTs for large-scale fibers were analyzed. Catalytic chemical vapor deposition was used to synthesize the CNT cotton. The catalyst precursor solution was prepared by dissolving CoCl₃ and FeCl₃ in ethanol to reach a concentration of 0.05M Co + 0.05M Fe. This solution was then applied to one edge of a Si substrate that had a 0.1μm thick SiO₂ layer on its surface. The Si substrate on which the catalyst was applied after removing the topmost CNT cotton was examined under SEM to understand the growth mechanism. The CNT cotton was spun into fibers using a spinning set-up built in-house. The CNTs did not show any fracture during tensile test, suggesting that the strength of CNT fibers can be further increased by optimizing the structural arrangements of CNTs in the fiber. Results show that this form of CNT material has great potential for large-scale fiber production.