复合催化剂AgI-Ag_3PO_4/TiO_2纳米带的制备及其光催化性能研究

Preparation and photocatalytic activity of AgI-Ag_3PO_4/TiO_2 composite catalyst nanobelts

通过化学沉淀法在TiO_2纳米带上首先制备了Ag_3PO_4/TiO_2,然后利用离子交换法成功将AgI负载到Ag_3PO_4上,制备了具有优异催化活性的复合催化剂AgI-Ag_3PO_4/TiO_2。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线衍射仪(XRD)、X-射线光电子能谱(XPS)等分析方法对复合催化剂的形貌、晶型结构、元素组成等进行了表征,结果表明:TiO_2纳米带形貌规整,宽度在50~400 nm之间,AgI-Ag_3PO_4纳米颗粒均匀地负载于TiO_2纳米带表面;TiO_2纳米带晶型为典型锐钛矿相,AgI为六方晶相的β-AgI,Ag_3PO_4为立方晶相;AgI-Ag_3PO_4/TiO_2中Ag元素以+1价态存在于催化剂中,没有Ag单质析出,表明复合催化剂结构稳定。以罗丹明B作为复合光催化剂的模型反应物,评估了不同批次、AgI/Ag_3PO_4不同比例催化剂的光催化性能,结果显示:AgI-Ag_3PO_4/TiO_2系列催化剂的催化活性均高于单独的TiO_2、Ag_3PO_4和AgI;当AgI与Ag_3PO_4物质的量比为3∶5时,AgI-Ag_3PO_4/TiO_2具有最高的光催化效率,该催化剂在30 min后对罗丹明B的降解率可达到98.7%,并且在多次重复实验后仍然保持较高的催化活性。

A novel AgI-Ag3PO4/TiO2 photocatalyst having excellent catalytic activity,has been successfully prepared by coprecipitation and ion exchange methods. The structure and optical properties of the AgI-Ag3PO4/TiO2 material were characterized by scanning electron microscopy(SEM）,transmission electron microscopy(TEM）,Xray diffraction(XRD） and X-ray photoelectron spectroscopy(XPS）. The SEM and TEM results show that the material contains uniform TiO2 nanobelts with a width range from 50 to 400 nm. Moreover,AgI and Ag3PO4 are well distributed on the surface of the TiO2 nanobelts. XRD patterns indicate the preservation of the anatase characteristics of the titania support,together with the presence of hexagonal β-AgI crystals and cubic Ag3PO4 crystals. XPS results show no peak which can be attributed to Ag0,further confirming that the structure is stable. The photocatalytic efficiencies of as-prepared nanocomposites were evaluated using the degradation of Rhodamine B(Rh B） as a probe reaction. The results showed that the AgI-Ag3PO4/TiO2 heterostructure exhibit significantly better visible light photocatalytic activity than TiO2,Ag3PO4,or AgI. AgI-Ag3PO4/TiO2 showed the highest photocatalytic efficiency when the molar ratio of AgI to Ag3PO4 was 3 ∶ 5. The degradation ratio of Rh B catalyzed by AgI-Ag3PO4/TiO2 reached 98. 7% after 30 min of visible light irradiation,and the catalyst maintained high activity after repeated reuse.