Ag改性TiO_2/SnO_2纳米薄膜及光催化降解甲基橙的性能

Silver modification of TiO_2/SnO_2 thin films and their photocatalytic activity for methyl orange

以光还原沉积法对TiO2/SnO2薄膜进行Ag改性,制备Ag-TiO2/SnO2纳米薄膜,讨论紫外光照时间、光照强度、AgNO3浓度等工艺条件对光催化活性的影响。用XRD和SEM对薄膜的结构、表面形貌和化学组成进行表征,以甲基橙为模拟污染物对光催化性能进行测定。结果表明:在最佳条件下制备的Ag-TiO2/SnO2薄膜,Ag担载量为0.51%(摩尔分数),Ag簇直径在30～90nm之间;薄膜具有较高的光催化活性,对甲基橙的降解率是修饰前TiO2/SnO2薄膜的2.02倍,是相同质量TiO2/ITO薄膜的3.30倍;催化活性的提高,源于反应机理的改变;薄膜中Ag-TiO2异质结的引入,一方面进一步促使光生电荷的分离,另一方面加速了氧气与激发电子的还原反应。

Silver-modified TiO2/SnO2 thin films （Ag-TiO2/SnO2 thin films） were prepared by photodeposition method. The effects of preparation conditions on the photocatalytic activity of Ag-TiO2/SnO2 thin films were discussed. The surface morphology, chemical composition and structure of the film were characterized by SEM and XRD, and its photocatalytic property were evaluated with methyl orange as model compound. The results show that the optimum content of Ag on the film surface is 0.51% （mole fraction）, and the diameters of Ag particles are about 30-90 nm. The Ag-TiO2/SnO2 film is photocatalytically more active than TiO2/SnO2 and TiO2/ITO. The photocatalytic degradation rate of Ag-TiO2/SnO2 film is 2.02 times as thatof the TiO2/SnO2 film, and 3.30 times as that of the TiO2/ITO film. The increasing photocatalytie activity is mainly duo to the change of reaction mechanism. The heterojunction of Ag-TiO2 in Ag-TiO2/SnO2 film efficiently promotes the separation of charges, and accelerates the reaction of excited electrons with oxygen in photocatalytic degradation for methyl orange.