Oxidative polymerization of pyrrole photocatalyzed by TiO2 nanoparticles and interactions in the composites

Oxidative polymerization of pyrrole is initiated by photoexcited TiO2 nanoparticles. Pyrrole oligomers rend polypyrrole (PPy) are continuously produced with reaction time. The conversion of pyrrole monomer changes as a function of the concentration of TiO2 nanoparticles. It is found that PPy in the composite has the conjugated structure and is partially oxidized with a formation of positively charged N+. Results from X-ray photoelectron spectroscopy and Raman analysis consistently indicate that a strong interaction is esiablished between the TiO2 and PPy. According to the results of UV-vis spectroscopy, a mechanism of photocatalytic oxidation is proposed for this polymerization. The interaction between TiO2 and PPy is found to arise from the photocatalytic reaction and discussed in terms of photoinduced Ti3+. (C) 2008 Wiley Periodicals, Inc.