Preparation and photocatalysis of TiO2 nanoparticles co-doped with nitrogen and lanthanum

Nanoparticles of TiO₂ powder co-doped with La and N were prepared using a coprecipitation method followed by being two hours calcinated at a temperature ranging from 500 to 600°C in NH₃/Ar atmosphere. Uniformly co-doped TiO₂ nanocrystalline was 5–15 nm with surface area 65–125 m²/g. Optical absorption along with the microstructural investigation for monodoped and co-doped catalyst provided that a part of O vacancy of Ti₅O₉ was occupied by N, which is responsible for the band-gap narrowing of TiO₂, while La³⁺ doping prevents the aggregation of powder in process of nitrification. Superior catalytic activity was observed in the co-doped TiO₂ under visible light (350 < < 450 nm). 20 mg/l methyl orange solution could be docomposed completely within 1 h using the 0.5 at.% La³⁺ doped TiO₂ calcinated in NH₃ for 2 h.