Photoresponsive polypyrrole-TiO2 nanoparticles film fabricated by a novel surface initiated polymerization

A Photosensitized electrode was fabricated through a novel polymerization of pyrrole initiated by TiO2 nanoparticles under UV irradiation. Conjugated polypyrrole (PPy) continuously grows on the surface of the TiO2 film, resulting in fully covered film with the stably-bound PPy layer. The film structures were analysed using Raman and X-ray photoelectron spectroscopy (XPS). It was found that the film electrode exhibits improved photoresponse including the flat band potential, photocurrent and separation of charges. The lowest unoccupied molecular orbital (LUMO) level of the PPy is higher in energy than the LUMO of PPy in electrodeposited electrodes, providing a stronger driving force for the electron injection into the TiO2. (C) 2008 Elsevier Ltd. All rights reserved.