Synthesis of bamboo-shaped multiwalled carbon nanotubes using thermal chemical vapor deposition

The vertically aligned multiwalled carbon nanotubes (CNT) are synthesized in high density on a large area of cobalt deposited silicon oxide substrate, by thermal chemical vapor deposition using C2H2 gas, at 950°C. The diameter of CNTs is distributed in the range of 80–120 nm and the length is about 20 μm. High-resolution transmission electron microscopy analysis reveals that the multiwalled CNTs have the crystalline graphite sheets and the bamboo structure that the tube consists of hollow compartments separated with graphite layers. A possible growth mechanism is suggested to explain the structure of CNTs. The emission current density is 1.1 mA cm−2 at 4.5 V μm−1, showing the Fowler–Nordheim behavior.