Photocatalytic activity of poly(3-hexylthiophene)/titanium dioxide composites for degrading methyl orange

Poly(3-hexylthiophene) (P3HT) was synthesized by chemical oxidative polymerization method using FeCl3 as an oxidant in CHCl3 and poly(3-hexylthiophene)/titanium dioxide (P3HT/TiO2) composites were prepared by a convenient polymer/inorganic blending technique. The resulting P3HT/TiO2 composites were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). The results indicated that P3HT/TiO2 composites were formed from poly(3-hexylthiophene) covered titanium dioxide. UV–vis DRS measurements showed that P3HT/TiO2 composites have a broad and strong absorption in visible range, indicating that the incorporation of P3HT onto the surface of TiO2 can extend the photoresponse range of TiO2. P3HT/TiO2 composites can adsorb methyl orange (MeO) to a certain extent. Both under UV and visible light irradiation, P3HT/TiO2 composites were more efficient in removing dye from solution than pure TiO2. Using P3HT/TiO2 composites as photocatalysts, the different degradation pathways of MeO were found under UV and visible light irradiation. The chromophoric groups of MeO molecules were dominantly cleaved under UV light irradiation, while under visible irradiation, the competitive photodegradation reactions between the formation of intermediates with chromophoric group and degradation of MeO occured in the photocatalysis system.