Enhancement of TiO2 Photocatalyst Using Rare Earth Oxide (La2O3) via a Simple Preparation Method for Degradation of Methylene Blue under Visible Light

Abstract

The modification of TiO₂ using rare earth oxide (La₂O₃) to increase the photodegradation activity of TiO₂ under visible light has been conducted. The goal of this research is to identify the influence of La₂O₃ on the TiO₂ to the photocatalytic activity of TiO₂. The mixed oxide of TiO₂/La₂O₃ was prepared using the precipitation method. The as-prepared catalyst was then calcined at 923 K. The photocatalyst was characterized using SRUV, XRD, FTIR, and SEM-EDX. The results showed that the photocatalyst activity of TiO₂/La₂O₃-923 under visible light in the degradation of methylene blue was higher than pristine TiO₂. The decrease in bandgap energy of TiO₂/La₂O₃-923 from 3.2 eV to 3.01 eV was not the main factor in the increase of photocatalytic activity of TiO₂/La₂O₃-923. The optimum condition of photodegradation of MB was obtained when the ratio of TiO₂/La₂O₃ was 5, the concentration of MB was 10 ppm, the reaction time was 300 min, and the mass of the photocatalyst was 0.25 g. The reusability of TiO₂/La₂O₃-923 was stable up to 3 sequent runs with the MB photodegradation of more than 90%. The mechanistic study of the mixed oxide TiO₂/La₂O₃ showed that the hydroxyl radical played an important role in its high photocatalytic.

Keywords: TiO₂-La₂O₃, photocatalyst, visible light, methylene blue