Solar photocatalysts from Gd–La codoped TiO₂ nanoparticles

Gd–La codoped TiO₂ nanoparticles with diameter of 10 nm were successfully synthesized via a sol–gel method. The photocatalytic activity of the Gd–La codoped TiO₂ nanoparticles evaluated by photodegrading methyl orange has been significantly enhanced compared to that of undoped or Gd or La monodoped TiO₂. Ti⁴⁺ may substitute for La³⁺ and Gd³⁺ in the lattices of rare earth oxides to create abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron–hole pairs and methyl orange photodegradation. The formation of an excitation energy level below the conduction band of TiO₂ from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd–La codoped TiO₂, resulting in versatile solar photocatalysts. The results suggest that Gd–La codoped TiO₂ nanoparticles are promising for future solar photocatalysts.