Enhanced photocatalytic performance of poly(3,4-ethylenedioxythiophene)-coated TiO2 nanotube electrodes

This study presents the design of a mixed organic–inorganic system to be utilized in solar-light chemical energy conversion applications, where the visible-light absorption properties of the conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), are combined with the enhanced charge transport properties of TiO2 nanotubes, thus creating an efficient photoelectrode. A dispersion of PEDOT doped with p-toluenesulfonate (tosylate) ions was synthesized using a simple solution-casting polymerization process, which was then spin-coated onto an ordered array of anodically fabricated TiO2 nanotubes to be used for solar energy conversion. Electron microscopy observation confirmed the presence of PEDOT in the hybrid (PEDOT–TiO2) and Fourier transform infrared spectroscopy verified the vibrational modes of the polymerized PEDOT. The ultraviolet-visible diffuse reflectance data indicated a change in the absorption edge of the pure TiO2 nanotubes to longer wavelengths after PEDOT coating. The developed photo-electrodes exhibited a significant increase in photocurrent response and lower charge transfer resistance with respect to the pure TiO2 nanotubes, as verified by electrochemical impedance spectroscopy.