A Highly Efficient Visible-Light-Activated Photocatalyst Based on Bismuth- and Sulfur-Codoped TiO2

Titanium dioxide (TiO2) codoped with bismuth (Bi) and sulfur (S) elements was prepared by a simple sol−gel method using tetrabutyl titanate, bismuth nitrate pentahydrate, and thiourea as precursors. The codoped TiO2 calcined at 400 °C exhibits an intense absorption in the range of 500−800 nm. The absorption edge corresponds to a band gap of 2.0 eV. An indigo carmine solution of 20 mg/L was completely photodegraded in 40 min in the presence of such photocatalyst under visible light (λ > 410 nm). This highly active photocatalytic performance is associated with the existence of numerous oxygen vacancies, the acidic sites on the surface of TiO2, and the high specific surface area.