Facile Synthesis of Pt-Polypyrrole Modified Hollow TiO2 Composites and Their Photocatalytic Application

Well-designed Pt-polypyrrole modified hollow TiO2 (HPPT) spheres were successfully synthesized as promising visible light responsive photocatalysts. Pt and polypyrrole (PPy) were deposited onto hollow TiO2 (HT) by a simple one-step oxidation-reduction reaction. The developed one-step direct synthesis of Pt and polypyrrole can be used to design other functional materials. The properties of the photocatalyst were characterized by a series of combined techniques. The results confirmed the hollow structure and the successful deposition of Pt and PPy on HT, and indicated that the band gap of HPPT was narrower than that of HT. The adsorption properties and photocatalytic kinetics of HPPT under visible light were studied in detail for different Pt/Ti and pyrrole/Ti mass ratios using the degradation of methylene blue (MB). The amount of MB adsorption was proved to be negatively correlated to the PPy content in the photocatalyst, which implied the existence of an optimal PPy amount giving the best photocatalytic effect. HPPT with 1.0 wt% Pt/Ti and 1.0 wt% pyrrole/Ti exhibited the best photocatalytic activity. A reasonable pollutant removal reaction mechanism by the HPPT photocatalyst was also derived by detecting hydroxyl radicals (center dot OH) and superoxide radicals (O-center dot(2)-)