Enhanced Photocatalytic Degradation of Azo Dye Using Rare-Earth Metal Doped TiO 2 Under Visible Light Irradiation

Lanthanum doped TiO₂ nanoparticles (La doped TiO₂) have been prepared by a sol-gel process using TiO(C₄H₉)₄ as raw material and are characterized using XRD, FT-IR, SEM-EDS, TEM and UV-DRS. The insertion of La ion in TiO2 lattice has been confirmed by SEM-EDS and XRD data. TEM studies have confirmed that La ions are uniformly doped over TiO₂ lattice. The band gap level of La doped TiO₂ is decreased to 2.92 eV with a red shift due to charge transfer reaction which is confirmed by UV-DRS. The photocatalytic activities of the synthesized nanoparticles are evaluated for the degradation of Congo red dye (20 ppm) in an aqueous solution with La doped TiO₂ (0.25 g) at pH= 6.3, under solar light irradiation. The photocatalytic results confirmed that the La doped TiO₂ show good photocatalytic activity and can be considered as a promising photocatalyst for the degradation of organic pollutants in water. Due to the stability of La doped TiO₂ nanoparticles, it could be reused for more than five cycles reaching 100% degradation efficiency.