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.