Growth of polyaniline on TiO2 tetragonal prism arrays as electrode materials for supercapacitor

In this study, the method of hydrothermal synthesis is introduced to prepare the titanium dioxide (i.e.,TiO2) tetragonal prism array on the conducting plane of fluorine-doped tin oxide (i.e., FTO), and then the polyaniline (i.e., PANI) is coated on the surface of TiO2 array by normal chemical oxidation to form the PANI/TiO2 shell/core nanoarray. The array architecture of PANI/TiO2 composite is further confirmed by SEM, XPS, XRD, UV–vis and Raman spectroscopy. The regular array structure of PANI/TiO2 can reduce the resistance of ionic diffuse and charge transfer via optimizing the ionic diffusion to obtain a lower impedance and higher specific capacitance. Compared with the individual component (PANI or TiO2), the PANI/TiO2/FTO electrode possesses a higher specific capacitance as the supercapacitor electrode material. The maximum specific capacitances of 633 F/g at the rate of 10 mV/s and 781 F/g at the current density of 1 A/g are obtained in the PANI/TiO2/FTO electrode and it is superior or close to individual PANI or PANI-based materials. In addition, the TiO2 array can undertake some mechanical deformation in the redox process without destroying the electrode material to enhance the cyclic stability of PANI/TiO2/FTO electrode. The capacitance retention of PANI/TiO2/FTO electrode keeps 75% of its initial value which is higher than that of the PANI/FTO electrode (65%) after 2000 cycles. Therefore, such array architecture composite can be promisingly used as the electrode material for electrochemical capacitive energy storage.