Enhanced photocatalytic activity for the degradation of rhodamine B by TiO2 modified with Gd2O3 calcined at high temperature

Abstract

TiO2 modified with Gd2O3 (Gd/TiO2) nanoparticles were prepared by an impregnation method using TiO2-500°C support (anantase phase) or TiO2-650°C support (mixed phases of anatase and rutile), respectively. The surface and bulk crystalline phases of Gd/TiO2 have been characterized by UV Raman spectroscopy and XRD. Besides, the morphology, particle size, and the optical properties of Gd/TiO2 have been studied by TEM, BET, and UV–visible diffuse reflectance spectra. It is interesting to note that the surface crystalline phase (surface anatase phase or surface mixed phases) of TiO2 which has been impregnated with Gd2O3 can be stabilized after calcination at 800°C. This work provides a promising method for controlling the surface phase, crystallinity, and particle size of TiO2 at high temperatures. Moreover, photocatalytic activity of Gd/TiO2 has been evaluated by degradation of rhodamine B and 4-chlorophenol in aqueous solution under UV irradiation. It is found that Gd/TiO2 exhibits good photocatalytic activity compared to pure TiO2. The higher photocatalytic activity of Gd/TiO2 is mainly attributed to an increase in the anatase crystallinity, an increase in photoinduced charge separation, which induced by surface phase junction, and to an increase in the extent of its optical absorption spectrum, as compared to TiO2.