Template synthesis of ultra-thin and short carbon nanotubes with two open ends

Anodic aluminium oxide (AAO) films containing small diameter channels with both ends open were prepared for use as a growth template for carbon nanotubes (CNTs). The smallest channel diameter was 7 nm and the smallest film thickness was 2 mu m. The CNTs produced from the AAO template by chemical vapor deposition of acetylene had controllable outer and inner diameters and length, and open ends. The pore texture, structure and crystallinity of the CNTs were characterized by electron microscopy, nitrogen gas adsorption-desorption, and thermogravimetric analysis. The inner diameters of the CNTs were adjustable by selecting AAO templates with specific channel diameters and/or tuning the duration of chemical vapor deposition. CNTs with an outer diameter, inner diameter and length of 7 nm, 4.5 nm and 2 mu m, respectively, were obtained, the narrowest and shortest ever reported for CNTs with two open ends. These thin, short, and open CNTs would render easy access, filling and transport of foreign matter into their one-dimensional cavity with prominent confinement effects