以硝酸铅和钛酸丁酯[Ti(OBt)4]为前驱体,用溶胶-凝胶法在活性炭表面制成了Pb掺杂TiO2薄膜.并用X射线衍射(XRD)、紫外可见光谱(UV-VIS)、透射电镜(TEM)对制得的Pb掺杂TiO2薄膜进行了表征.分别用甲基橙水溶液的光催化脱色反应、有机磷农药一氧化乐果(omethoate)水溶液的光催化降解反应评价了不同Pb掺杂TiO2薄膜的光催化活性.结果表明,薄膜为金红石和锐钛矿的混合晶相.相对于未掺杂的TiO2薄膜,由于金红石含量的增加,不同Pb掺杂TiO2薄膜的吸收带发生了微小的红移.Pb掺杂使薄膜的光催化活性明显提高,当Pb/TiO2质量分数为1.7％时,薄膜显示出最高的光催化活性. TiO2薄膜中的Pb可能以Pb(Ⅳ)和Pb(Ⅱ)两种形态存在,在紫外光的辐射下,Pb(Ⅳ)和Pb(Ⅱ)可能通过浅势俘获TiO2的光生电子和空穴而发生相互转化,减少了光生电子和空穴的简单复合,从而提高了薄膜的光催化活性.
Pb-doped TiO2 thin films were prepared on the surface of active carbon via a sol-gel
dip-coating method by using PbNO3 and Ti(OBt)4 as precursors. The as-prepared thin films were characterized by UV-VIS spectrophotometry,
transmission electron microscopy (TEM) and X-ray diffraction (XRD). Photocatalytic activities of the thin films were evaluated by photocatalytic
decoloration of methyl orange aqueous solution and photocatalytic degradation of omethoate aqueous solution, respectively. The results show that the rutile
phase is precipitated ad well as anatase phase. With an increase in the Pb amount in the films, the rutile content increases. Therefore, the band edges of
the various Pb-doped TiO2 thin films exhibit slightly red shift compared with un-doped TiO2 thin film. Photocatalytic activities
of the thin films are obviously enhanced due to Pb-doping. The thin film shows the highest photocatalytic activity when the Pb/TiO2 mass ratio
=1.7%. This is probably ascribed to the fact that Pb(Ⅱ) and Pb(Ⅳ) in the Pb-doped TiO2 thin films can transform each other via low-potential-
capturing the photo-generated holes and electrons of TiO2 under UV illumination. Thus, the recombination of photo-generated electrons and holes is
reduced, and the photocatalytic activity of thin film is enhanced.
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