Photodegradation of Congo Red catalyzed by nanosized TiO2

The effects of various physical properties (particle size, shape, surface area, crystal structure, and phase composition) on the photocatalytic performance of nanosized TiO2 were studied through the photodegradation of Congo Red. Kinetic results showed that anatase TiO2 was a superior photocatalyst to rutile TiO2 due to the inherent difference in the two crystal structures. Anatase TiO2 nanorods with predominantly (101) surface exhibited low activity because the non-dissociative adsorption of H2O to this surface retarded the generation of OH. radicals required for facile photocatalytic oxidation. It was found for the first time that the shape of TiO2 nanocrystals significantly affected their photocatalytic activities. The previously reported anatase-rutile synergetic effect in commercialized mixed-phase TiO2 (Degussa P25) was not observed in this study, perhaps, due to poor contact between the two phases and the extremely small sizes, as well as the not-optimized phase compositions in the current work. (c) 2005 Elsevier B.V. All rights reserved.