采用微弧氧化工艺分别在钨酸盐和磷酸盐电解液中制备了WO_3/TiO_2复合薄膜和单一的TiO_2膜(P-TiO_2),利用X射线衍射、扫描电子显微镜、紫外-可见光谱和荧光光谱对这两种膜层的结构及光物理特性进行了表征.结果表明,P-TiO_2膜由锐钛矿与金红石混合相组成,而WO_3/TiO_2膜中除锐钛矿与金红石混合相外,还含有W0O相.两种膜层表面粗糙多孔,WO_3/TiO_2膜的孔洞数量更多,分布更均匀.WO_3/TiO_2膜的光吸收范围较P-TiO_2膜略宽,但后者在紫外光区的光吸收性能更好.WO_3O/TiO_2膜的荧光发光强度比P-TiO_2的小,光生电子-空穴之间的分离效果好.与P-TiO_2膜相比,WO_3/TiO_2膜的表面酸度高,吸附有机物和羟基的能力更强.紫外光下照射2 h,WO_3/TiO_2能够降解85%罗丹明,而P-TiO_2膜只能降解23%.WO_3/Ti0_2膜的高光催化活性源于它较高的比表面积、较优的电子.空穴分离效果和较高的表面酸度.
A WO_3/TiO_2 composite film and a pure TiO_2 film were prepared by microarc oxidation in tungsten electrolyte and phosphate elec-trolyte, respectively. The structure and photophysical properties of the two films were characterized by X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy, and photoluminescence. The results showed that the two films consisted of a mixture of anatase and mtile,but the ratio of anatase to rutile was different. In addition, WO_3 was present in the WO_3/TiO_2 composite film. The two films had porous structure, but more pores distributed homegeneously on the WO_3/TiO_2 composite film surface than on the Tie_2 film. The WO_3/TiO_2 compos-ite film showed wider absorption rang while the TiO_2 film presented better optical absorption in the UV region. The photoluminescence in-tensity of the WO_3/TiO_2 composite film was lower than that of the TiO_2 film, which meant that the recombination of photo-generated elec- trons and holes in the former was less than that in the later. Compared to the TiO_2 film, the WO3/TiO2 composite film had higher surface acidity, which increased the adsorption of organics and OH groups on the film surface. More than 85% of rhodanmine was removed by the WO_3/TiO_2 composite film, whereas only 23% of rhodamine was removed by the TiO_2 film for 2 h. The higher photocatalytic removal ratio of the WO_3/TiO_2 composite film was ascribed to the larger specific surface area, better separation between electrons and holes, and higher sur-face acidity.
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