MnO2–TiO2/C nanocomposite arrays for high-performance supercapacitor electrodes

Abstract Coaxial TiO 2 and carbon nanotube arrays (TiO 2 /C NTAs) are prepared by hydrothermal treatment of anatase TiO 2 nanotube arrays (TiO 2 NTAs) in a glucose solution and carbonized under N 2 at 700 °C. The TiO 2 /C NTAs provide an extremely large, solvated, ion accessible surface area as well as a direct pathway for charge transport, thus yielding substantially improved areal capacitance of 26.1 mF/cm 2 at a current density of 0.1 mA/cm 2 that is 60 times larger than the capacitance of anatase TiO 2 NTAs under the same conditions. The TiO 2 /C NTAs provide a good support for depositing highly pseudocapacitive materials such as MnO 2 to form coaxial MnO 2 , C and TiO 2 nanotube arrays (MnO 2 –TiO 2 /C NTAs), producing better capacitive properties. The MnO 2 –TiO 2 /C electrode shows a high specific capacitance (580 F/g at a current density of 2.6 A/g), an excellent rate capability and a good cycling stability.