溴化银/二氧化钛复合材料的可见光催化性能

Phototcatalytic activity of silver bromide/titanium dioxide composite under visible light irradiation

将硝酸银的乙醇溶液与溶胶凝胶TiO2混合得到前驱体,随后经共沉淀-煅烧制备得到AgBr/TiO2复合材料;采用扫描电镜、X射线衍射仪、X射线光电子能谱仪分析了复合材料的形貌、晶体结构、Ag元素的价态,采用紫外-可见漫反射光谱仪测定了其光吸收性能;进而以甲基橙(MO)的可见光降解为探针反应测定了AgBr/TiO2复合材料的可见光催化性能.结果表明,当前驱体在不同温度下煅烧后,无定形TiO2颗粒逐渐增大,并逐渐转变为锐钛矿结构;担载的AgBr可明显拓展TiO2的可见光吸收范围;Ag物种主要以Ag+形式存在.当煅烧温度为300℃时,复合材料的光催化活性最高,MO的降解率在60min内达到90%以上;随着煅烧温度的增加,催化活性逐渐降低.

The ethanol solution of silver nitrate was mixed with sol-gel TiO2 to obtain a precur- sor. As-obtained precursor was then co-precipitated and calcinated to yield AgBr/TiO2 compos- ite. The morphology, crystal structure, and silver valence of as-prepared AgBr/TiO2 compos- ite were analyzed by means of scanning electron microscopy, X-ray diffraction, and X-ray pho- toelectron spectroscopy, and its light-absorbing performance was examined by means of ultra- violet-visible light diffuse reflectance spectrometry. Furthermore, the catalytic activity of as- prepared AgBr/TiO2 composite was evaluated by monitoring the degradation of methyl orange （MO） under visible light irradiation. Results show that after the mixed precursor is calcinated at different temperatures, the size of amorphous TiO2 particles gradually increases, and the amorphous TiO2 is gradually transformed into anatase. Besides, incorporated AgBr is able to significantly expand the visible light absorption range of TiO2, and silver species mainly exists in the form of Ag＋. Particularly, AgBr/TiO2 composite obtained after calcination at 300 ℃ possesses the best photocatalytic activity and provides a degradation rate of above 90% for MO within 60 min. However, the photocatalytic activity of AgBr/TiO2 composite declines gradual- ly with rising temperature of calcination.