Sm/N-codoped TiO2 preparation, characterization, and photocatalytic decolourization of Acid Orange 7 and Basic Blue 41 in sunlight

A Sm/N-codoped TiO2 photocatalyst was successfully prepared via a sol-gel method using ammonium hydroxide and samarium(III) acetylacetonate as nitrogen and samarium sources, respectively. The anatase phase of TiO2 was mainly observed in a Sm/N-codoped product calcined at 500 degrees C as indicated by the X-ray diffraction pattern. The crystallite size of Sm/N-codoped TiO2 ranged from 6-10 nm with a surface area (S-BET) of 109-155 m(2)/g. Photoelectron spectroscopic results confirmed the incorporation of both Sm and N species into the TiO2 structure, which substantially lowered the band gap energy of TiO2. The photocatalyst activities were evaluated by the ability to decolourize solutions containing the organic azo dyes (i.e., AO7 and BB41) in sunlight. Sm/N-codoped TiO2 calcined at 500 degrees C shows higher decolourization of AO7 than any other doped TiO2 calcined at 500 degrees C, including undoped TiO2. Interestingly, Sm-doped TiO2 calcined at 400 degrees C could most efficiently decolourize AO7. For the decolourization of BB41 dye, N-doped TiO2 calcined at 500 degrees C showed the highest photocatalytic efficiency.