Supercapacitance of bamboo-type anodic titania nanotube arrays

Highly oriented titania nanotube arrays are formed by self-organizing anodization of Ti foil in organic electrolytes in the presence of fluoride ions. The effects of tube length and the tube wall stratified layer on the electrochemical capacitance of these bamboo-type nanotubes are investigated. Field emission scanning electron microscopy (FESEM) is used to characterize the surface morphology, while cyclic voltammetry is used to investigate the pseudocapacitive properties of these nanostructured electrodes. The bamboo-type titania nanotube array with a higher aspect ratio shows a higher specific capacitance value of 52 μF cm− 2 in 1 M Na2SO4 with excellent reversibility characteristics. The introduction of surface defects by annealing in NH3 increased the specific capacitance value to 118 μF cm− 2. This simple and cost-saving binder-free electrode is considered a promising candidate for supercapacitor applications.