Characterization and photocatalytic activity of Ni-doped TiO ₂ nano photocatalysts prepared by low temperature combustion synthesis

Ni-doped TiO ₂ photocatalysts were prepared by low temperature combustion synthesis and some properties, such as optical absorption, crystal type, grain size distribution and chemistry transformation during temperature rising were characterized by UV-Vis DRS, X-ray diffraction (XRD), laser light dispersion grain size measurement machine and TG-DSC respectively. The photocatalytic activities of the prepared photocatalysts under visible light irradiation were evaluated by monitoring the degradation of methylene blue dye, a probe pollutant. The results indicate that the Ni-doped TiO ₂ photocatalysts prepared by low temperature combustion synthesis shift the optical absorption threshold to visible light, the band gap of 0.4 Ni-TiO ₂ (atomic ratio) is 2.3 eV, which corresponds to a 564nm threshold in the visible light range. The crystal type of photocatalyst is anatase TiO ₂ and the content of NiTiO ₃ rise with the increase of Ni dopant. The grain size of photocatalyst distributes from 50 to 150nm, which account for 96.9% of entire quantity. During temperature rising, the TiO ₂ phase in photocatalyst transforms from amorphous structure to anatase and NiTiO ₃ crystallites appear at 445.2°C. After 150 min visible light irradiation, 93.9% of methylene blue dye are degraded over 0.4 Ni-TiO ₂ photocatalyst. The photocatalytic activity of Ni doped TiO ₂ is higher than that of P25 under identical conditions.