Paper EN-TuP8
Optical and Photocatalytic Properties of Nanostructured Ce-TiO₂ Mixed Oxides

Tuesday, October 20, 2015, 6:30 pm, Room Hall 3

The use of nano-crystalline TiO₂ is a promising strategy for photocatalytic remediation of wastewater due to its broad ability to remove various pollutants in aqueous media. In order to use a major part of the spectral solar distribution it would be necessary to reduce the bandgap of TiO₂ based materials. In this study, a series of nanocrystalline CeO₂-TiO₂ powders were successfully synthesized by sol-gel at room temperature, employing titanium isopropoxide and cerium nitrate as precursors, with nominal 2, 5, 10, 20 and 50 % of CeO₂:TiO₂ molar ratio. The crystalline structure, surface morphology and optical properties of synthesized samples were characterized using powder XRD, TEM, SEM, XPS. The optical band gap was determined by DR-UV-Vis spectroscopy and the emission spectrum by photoluminescence spectroscopy. Photocatalytic activity was evaluated by the photodegradation of Orange II azo dye, employing two different sources of irradiation 365 and 425 nm. Structural characterization showed that the Ce-TiO₂ particles crystallized into the anatase phase. TEM micrographies shown clearly the formation of nanocrystals. The optical bandgap energy shows a red shift for all synthesized samples compared with pure TiO₂. The results shown that the incorporation of 5 % CeO₂ effectively improves the photocatalytic activity comnpared wit pure TiO₂ at UV; while Ce incorporation activates it for 425 nm excitation still the nominal 5% shows the best performance. The results are discussed in terms of the electronic structure modification by Ce incorporation in the TiO2 matrix.