Enhanced electrochemical performance of TiO2 nanotube array electrodes by controlling the introduction of substoichiometric titanium oxides

Although anodized titania nanotubes (TNTs) possess unique advantages as an electrode material, the poor electrical conductivity limits their practical application. We herein report a facile route to enhance electrical conductivity and improve electrochemical behavior by controlling the introduction of substoichiometric titanium oxides (TinO2n-1), which can facilitate charge propagation in TNTs and improve kinetics of ions and electron transport in the electrode. Specific capacitance is as high as 3.77 mF cm−2, which is about 47 times higher than that of the untreated samples (0.08 mF cm−2). Galvanostatic charge-discharge results show TNT arrays-based electrode stable capacitance behavior with excellent capacitance retention even after 1000 continuous charge-discharge cycles at a current density of 50 μA cm−2 in Li2SO4 electrolyte. The ease of synthesis and the superior electrochemical performance suggest a promising application for the TNT arrays-based material in energy storage field.