EDLC characteristics of CNTs grown on nanoporous alumina templates

Carbon nanotubes (CNTs) with uniform diameter were grown on the porous alumina templates. Well ordered nanoporous alumina templates for the growth of CNTs were fabricated by two-step anodization method in oxalic acid electrolyte. The diameter and length of pores of the porous alumina templates were ca. 90 nm and 2 μm, respectively, and the pore density was about ~10 10  pores/cm 2 . The barrier layer at the bottom of the cylindrical pore was thinned and dissolved away by the voltage drop treatment and the pore widening processes, sequentially. For EDLC applications, aluminium metal substrate below the porous alumina layer can work directly as the conductive electrode. The EDLC characteristics were examined by measuring the capacitances from both the charge–discharge curves and cyclic voltammograms. The specific capacitance of CNT electrodes was 49 ± 3 F/g. The CNTs grown uniformly on the well ordered nanoporous templates resulted in the enhanced specific capacitances.