Efficient visible-light photocatalysts from Gd-La codoped TiO_2 nanotubes

摘要

Robust visible-light Gd-La codoped TiO_2 nanotubes were successfully synthesized via an ultrasonic hydrothermal method and the photocatalytic activities were evaluated by photodegrading Rhodamine B (RB). The calcined Gd-La codoped TiO_2 nanotubes have significantly enhanced photocatalytic activities than the uncalcined ones. The La~(3+) and Gd~(3+) in the lattices of rare earth oxides may be substituted by Ti~(4+), creating abundant oxygen vacancies and surface defects for electron trapping and dye adsorption, accelerating the separation of photogenerated electron-hole pairs and RB photodegradation. The formation of an excitation energy level below the conduction band of TiO_2 from the binding of electrons and oxygen vacancies decreases the excitation energy of Gd-La codoped TiO_2 nanotubes, resulting in robust photocatalysts. The results suggest that Gd-La codoped TiO_2 nanotubes calcined at 500 °C are very promising for enhancing the photocatalytic activity of photocatalysts in visible-light region.