Conjugated Polymer Modifying TiO 2 Performance for Visible-Light Photodegradation of Organics.

Up to now, the use of TiO 2 has been considered a promising advanced technology for organic pollutants removal from air or water, since it has high biological and chemical stability, high photoactivity, low toxicity, and low-cost production. However, there are issues to be addressed in enhancing TiO 2 performance, and one of the current key issues is redesigning UV-active photocatalysts and making them active in the visible region of the electromagnetic spectrum. This way, solar light absorption will be insured, and thus, a more efficient photocatalyst could be obtained. For this reason, conjugated polymers and their derivatives are considered to act as photosensitizers, being able to shift the TiO 2 activity from the UV to the visible region. Therefore, this study focuses on the synthesis of TiO 2 /conjugated polymer systems, which was accomplished by the deposition of poly-3,4-ethylene-dioxy-thiophene (PEDOT [-C 6 H 4 O 2 S-] n ), a low-band semiconductor with an excellent stability due to its extending π-conjugated electron system, on titania nanoarchitecture. First of all, a TiO 2 nanoarchitecture was synthesized by an ultrasound-assisted sol-gel method. Then, TiO 2 /PEDOT systems were obtained and characterized by using different techniques such as X-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, UV-Vis diffuse reflectance, and N 2 sorption measurements. The synthesized composites confirmed their mesoporosity and lower band gap values compared to bare titania, which clearly shows the ability to work as photocatalysts under visible-light activity. Further, we demonstrated that an organic pollutant, Congo Red dye, used as a model molecule could be photodegraded with the synthesized TiO 2 /PEDOT systems, with efficiencies of up to 95% in the case of T conv PEDOT under UV light and up to 99% for T conv PEDOT under visible-light irradiation, accomplishing in this way a successful synthesis of visible-light-activated titania photocatalyst.