Guide growth of carbon nanotube arrays using anodic porous alumina with Ni catalyst

The anodic porous alumina with a cell size of 25 to 40 run was prepared by applying a voltage of 20 V for 90 s in 20 wt % sulfuric acid at 15 degrees C. The nickel catalyst for the growth of carbon nanotubes (CNTs) was cathodically deposited at the bottom of the porous alumina at a constant current density of 10 mA/cm(2). Highly ordered CNT arrays with a diameter of 15 to 20 nm were linearly grown at 625 degrees C for 60 min along the inner wall of the porous alumina by ethanol CVD. On the other hand, the CNT arrays obtained using acetylene had twisted shapes and disordered carbon layers irrespective of the configuration of the porous alumina. This suggests that the alignment of CNTs depends on the crystallinity.