Photodegradation of dye pollutants on one-dimensional TiO 2 nanoparticles under UV and visible irradiation

Abstract

Titanium dioxides (TiO 2) nanoparticles with one-dimensional (1D) geometry, nanorods and nanostripes, were used as photocatalysts to photodegrade Rhodamine B (RhB) under ultraviolet (UV) and visible irradiation. The nanorods catalyst exhibited very interesting photocatalytic properties: under the UV irradiation its catalytic activity was slightly below that of the well-known TiO 2 catalyst P25, while under visible light it exhibited a better activity than P25. This fact indicates that the nanorods have a superior ability to utilize less energetic but more abundant visible light. Moreover, the 1D TiO 2 nanoparticles can be readily separated from aqueous suspensions by sedimentation after the reaction. With these advantages the 1D TiO 2 catalysts have a great potential for environmental applications. Various analytical techniques were employed to characterize TiO 2 catalysts and monitor the photocatalytic reaction. It was found that the catalytic performance of the catalysts is greatly dependent on their structures: The superior activity of P25 (consists of anatase and rutile nanocrystals) under UV light results probably from the interfacial interaction between anatase and rutile nanocrystals in this solid, which do not exist in the nanorods (only anatase). The titanate nanostripes (titanate) can absorb UV photons with shorter wavelength only.