Photocatalytic degradation of methyl orange in water by samarium-doped TiO₂

A series of Sm-doped TiO₂ nanoparticles were prepared by the sol-gel method and characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), and ultraviolet-visible diffuse reflectance spectra (DRS). Their photacatalytic activities were studied by photodegradation methyl orange in water under UV and simulant solar light irradiation, respectively. The results showed that Sm doping led to the crystal expansion and matrices distortion. Sm doping restrained a crystal size increase, which was beneficial for transportation and exchanges of organic and productions; furthermore, redounds to photogenerated carriers shifting to the surface of photocatalyst and preventing the recombination of the carriers, and then improving the photocatalytic activity. Appropriate concentration Sm doping induced the absorption profile red-shift of TiO₂, which made Sm-doped TiO ₂ possess high catalyst activity under simulant solar light irradiation whose major emission was the focus on the visible light region. Sm doping was an effective means to improve the photocatalystic activity of TiO₂ for degradation methyl orange in water whether under UV or solar light irradiation.