Visible and near-infrared light-driven photocatalytic activity of erbium-doped CaTiO3 system

Abstract Erbium-doped CaTiO 3 system has been prepared by a microwave-assisted hydrothermal method. The as-obtained photocatalysts were characterized by several techniques such as X-ray powder diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area. From the structural characterization, it can be demonstrated that the presence of Er 3+ ions would cause an increase of the cell volume of the CaTiO 3 crystalline phase. The photocatalytic behavior of the samples was evaluated by means of the degradation of methylene blue under UV–vis–NIR irradiation. The results showed that the presence of Er 3+ ions induces a significant increase of the photocatalytic activity of the system providing higher degradation rates (4.54 × 10 −5  s −1 ) with respect to pristine CaTiO 3 (1.86 × 10 −5  s −1 ). However after a heat treatment at 850 °C, the photocatalytic efficiency of the system increased dramatically until values of 11.9 × 10 −5  s −1 . From experiments carried out under vis–NIR irradiation, it was possible to obtain experimental evidence of the presence of up-conversion process from Er 3+ ions.