低温燃烧合成纳米Ni掺杂TiO2光催化剂的表征及活性研究

采用低温燃烧合成法制备了Ni掺杂TiO₂光催化剂,通过紫外-可见漫反射光谱(UV-Vis DRS)、X射线粉末衍射(XRD)、激光散射、热重-差示扫描量热分析(TG-DSC)等方法对催化剂的光吸收特性、晶相组成、粒度分布、升温过程中化学变化等进行了表征,以亚甲基蓝为模型污染物考察了催化剂在可见光下的光催化活性.结果表明,相对P25而言,Ni掺杂TiO₂的光吸收带边红移,当Ni/Ti原子比为0.4时,催化剂的带隙宽度为2.3eV,对应的吸收带边为564nm;催化剂晶型以锐钛矿TiO₂为主,随Ni掺杂量增大,NiTiO₃比例升高;催化剂粒径主要分布在50～150nm之间,占总量的96.9%;升温过程中催化剂在445.2℃发生晶型转化,出现锐钛矿和NiTiO₃晶体.催化剂显示出较高的催化活性,在可见光作用150min后最高可使93.9%的亚甲基蓝分解,活性高于P25.

Characterization and Photocatalytic activities of Ni-doped TiO2 Prepared by Low Temperature Combustion Synthesis

Ni-doped TiO2 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 TiO2 photocatalysts prepared by low temperature combustion synthesis shift the optical absorption threshold to visible light, the band gap of 0.4 Ni-TiO2 (atomic ratio) is 2.3 eV, which corresponds to a 564 nm threshold in the visible light range. The crystal type of photocatalyst is anatase TiO2 and the content of NiTiO3 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 TiO2 phase in photocatalyst transforms from amorphous structure to anatase and NiTiO3 crystallites appear at 445.2 degrees C. After 150 min visible light irradiation, 93.9% of methylene blue dye are degraded over 0.4 Ni-TiO2 photocatalyst. The photocatalytic activity of Ni doped TiO2 is higher than that of P25 under identical conditions.