Photodegradation of Congo Red catalyzed by nanosized TiO 2

Abstract

The effects of various physical properties (particle size, shape, surface area, crystal structure, and phase composition) on the photocatalytic performance of nanosized TiO 2 were studied through the photodegradation of Congo Red. Kinetic results showed that anatase TiO 2 was a superior photocatalyst to rutile TiO 2 due to the inherent difference in the two crystal structures. Anatase TiO 2 nanorods with predominantly (1 0 1) surface exhibited low activity because the non-dissociative adsorption of H 2O 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 TiO 2 nanocrystals significantly affected their photocatalytic activities. The previously reported anatase–rutile synergetic effect in commercialized mixed-phase TiO 2 (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.