Ag3PO4/Bi2O3异质结光催化剂的制备及其光催化性能研究

Preparation and photocatalytic activity of heterojunction-structured photocatalysts Ag3PO4/Bi2O3

通过水热共沉淀法制备了Ag3PO4/Bi2O3异质结光催化剂,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线光电子能谱(XPS)和紫外-可见漫反射光谱(UV-Vis)等测试方法对制备的催化剂进行表征,并以罗丹明B(RhB)为目标污染物,研究了Ag3PO4/Bi2O3的可见光催化活性和稳定性.结果表明,Ag3PO4粒子均匀地沉积在Bi2O3表面,两者结合形成了异质结.Ag3PO4/Bi2O3异质结对RhB具有良好的可见光催化活性,60 min内可催化降解85%的RhB,在循环使用4次之后对RhB的降解率仍然高达80%左右.Ag3PO4/Bi2O3在可见光下催化降解RhB过程中的电荷转移和光催化增强机理是:Ag3PO4导带的光生电子转移到Bi2O3导带,光生空穴从Bi2O3价带转移到Ag3PO4价带上,有效地促进了光生电子-空穴对的分离,聚集在Ag3PO4价带上的空穴直接氧化RhB.

A heterojunction-structured photocatalyst Ag3PO4/Bi2O3 was successfully fabricated via a hydrothermal and co-precipitation method.The as-prepared catalysts were characterized by scanning electron microscopy,X-ray diffraction,energy dispersive X-ray spectroscopy and UV-Vis diffuse reflectance spectroscopy.The photocatalytic activity and stability of composite were evaluated by degradation of Rhodamine B(RhB)under visible light irradiation.The results showed that Ag3PO4 particles are uniformly deposited on the surface of Bi2O3 to form a heterogeneous structure.The Ag3PO4/Bi2O3 exhibits the high visible-light-driven activity,which can degrade about 85%RhB under visible-light irradiation within 60 min.Moreover,the stability of Ag3PO4/Bi2O3 is significantly improved.After Ag3PO4/Bi2O3 was recycled four times,the degradation rate of RhB was as high as about 80%.The charge transfer and photocatalytic enhancement mechanism of Ag3PO4/Bi2O3 is that the photo-generated electrons from the conduction band(CB)of Ag3PO4 could transfer to the conduction band of Bi2O3 while the holes could migrate from the valence band(VB)of Bi2O3 to the valence band of Ag3PO4.The separation of photo-generated electron-hole pairs is effectively promoted,and holes accumulated on the valence band of Ag3PO4 directly oxidize Rhodamine B.