PPy film/TiO2 nanotubes composite with enhanced supercapacitive properties

Abstract

In this paper, a film-on-tube PPy/TiO₂ composite composed of polypyrrole (PPy) and well-aligned TiO₂ nanotube array is reported. Pyrrole is polymerized on the top of TiO₂ nanotubes by a two-step anodic oxidation. The morphology and microstructure of these composites are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) and infrared spectroscopy (FT-IR). The electrochemical performance of the PPy/TiO₂ composite is determined by cyclic voltammetry and charge–discharge measurement. It indicates that these film-on-tube composites take advantage of the high electrochemical activity of TiO₂ and polypyrrole, the high electronic conductivity of PPy, and the large specific surface area of ordered TiO₂ nanotubes. These merits together with the elegant synergy between TiO₂ and PPy lead to a good specific capacitance of 459 F g⁻¹ at a current density of 5 A g⁻¹ and excellent cycling stability with capacitance retention of 92.6% after 1000 charge–discharge cycles. The high capacitance as well as excellent cycling stability makes this film-on-tube composite promising as an anode material for supercapacitors.