Fabrication and electrical double-layer capacitance performance of interconnected and independent titania nanotube array

The interconnected and independent titania nanotube array (TiO2 NTA) grown on titanium metal foil with tunable nanotube diameter and length is fabricated by ultrasonic bath-assisted anodisation process. The electrical double-layer capacitance is highly dependent on the nanotube microstructure, crystal phase and working electrolyte. Anatase TiO2 NTA shows cyclic voltammetry-based current response and capacitance in H2SO4 rather than NaOH electrolyte, which is due to higher electrical conductivity and more effective proton diffusion rather than hydroxyl ion diffusion. Interconnected and independent TiO2 NTA with a diameter of 60, 120, 200nm and a length of 0.62, 1.69, 1.28μm exhibits galvanostatic charge-discharge based capacitance of 0.76, 1.88 and 2.63 mF cm−2 at 0.1mA cm−2 in 1.0M H2SO4 electrolyte. The superior capacitance performance of independent TiO2 NTA is ascribed to more effective ion diffusion in the enlarged independent nanotube channels. TiO2 NTA with a tunable microstructure is accordingly suitable for supercapacitor electrode substrate application. © 2020 Informa UK Limited, trading as Taylor & Francis Group.