Enhancement of the electrochemical capacitance of TiO2 nanotube arrays through controlled phase transformation of anatase to rutile

Here, we report the fabrication of self-organized titania (TiO 2 ) nanotube array supercapacitor electrodes through controlled phase transformation of TiO 2 , with aerial capacitances as high as 2.6 mF cm 2 , which far exceeds the values so far reported in the literature. The role of phase transformation in the electrochemical chargedischarge behaviour of nanocrystalline TiO 2 nanotubes is investigated and discussed in detail. The ease of synthesis and the exceptional electrochemical properties make these nanotube arrays an alternative candidate for use in energy storage devices. Annealing self-organized TiO 2 nanotubes under optimal conditions leads to achieve the highest reported capacitance values for an EDLC system.