Abstract
Well-ordered nanoporous alumina templates were fabricated by two-step anodization method by applying a constant voltage of40 V in oxalic acid solution or of 25 V in sulfuric acid solution. The cylindrical pore diameter and pore density of the templatesutilized for the carbon nanotube (CNT) growth were 86 ± 5 nm and 1.2· 1010 cm. 2 in oxalic acid solution and 53 ± 1 nm and3.1· 1010 cm. 2 in sulfuric acid solution, respectively. The CNTs with uniform diameter of 50 ± 10 nm (oxalic acid) and44 ± 2 nm (sulfuric acid) were grown on the porous alumina template as electrode materials for the electrochemical double layercapacitor (EDLC). The EDLC characteristics were examined by measuring the capacitances from cyclic voltammograms and thechargedischarge curves. The specic capacitances of the CNT electrodes are 30 ± 1 F/g (U = 50 ± 10 nm) and 121 ± 5 F/g(U = 4 ± 2 nm). The high specic capacitance of the CNT electrode was achieved by using nanoporous alumina templates withthe high pore density and the small and uniform pore diameter.