模拟太阳光下稀土Gd掺杂TiO2纳米晶的光催化性能研究

以甲基橙的光催化降解为探针反应,采用氙灯模拟自然条件下的太阳光,评价了通过酸催化的溶胶-凝胶法制备的稀土Gd掺杂改性TiO₂纳米晶的光催化活性及对甲基橙水溶液TOC的去除效果.运用XRD和UV-Vis DRS表征技术考察了Gd掺杂对纳米TiO₂的微晶尺寸、晶体结构与光学性能的影响.结果表明,Gd掺杂可以抑制TiO₂由锐钛矿相向金红石相的转变,阻碍TiO₂晶粒增长,使TiO₂的光吸收带边发生蓝移且有利于对可见光的吸收,从而使Gd掺杂TiO₂在模拟太阳光下光催化降解甲基橙的能力得到明显提高,但样品对甲基橙水溶液TOC的去除效果要滞后于其对色度的去除.

Study on the Photocatalytic Activity of Rare Earth Gd-doped TiO_2 Nanocrystallites under Simulated Sunlight

Gd-doped TiO2 nanocrystallite photocatalysts were prepared by an acid-catalyzed sol-gel method. The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities and the TOC removal effect of methyl orange irradiated with a xenon lamp. The prepared samples were characterized by means of the techniques such as XRD, and UV-Vis DRS. The effects of Gd doping on the crystallite sizes, crystal pattern, and optical property of the catalysts were investigated. The results showed that the Gd doping can hinder the transformation from anatase to rutile, decrease the crystallite size of the samples, cause blue-shift of the onset of the absorption spectrum, and enhance the visible light absorption ability of TiO2, which were responsible for the remarkable increase in photocatalytic decomposition of methyl orange on Gd-doped TiO2 under simulated sunlight. However, the TOC removal rate was inferior to the apparent decomposition rate of methyl orange on Gd-doped TiO2.