钒酸银改性二氧化钛制备及其可见光光催化性能研究

通过水热法将钒酸银掺杂负载到二氧化钛上,制备了一种新型改性二氧化钛复合光催化剂.利用扫描电镜、透射电镜、X射线衍射、X射线光电子能谱和紫外-可见光漫反射技术对催化剂进行了表征,以亚甲基蓝为目标降解物,考察了该催化剂在可见光下的光催化活性、稳定性等,探讨分析了反应机理.结果表明,可见光下该催化剂降解亚甲基蓝的反应过程符合一级反应动力学,其降解速率常数为0.009min-1,是二氧化钛P25的3倍,且3次回收利用后降解率仅下降4.8%,仍具有较高活性.钒酸银与二氧化钛形成耦合异质结,在可见光照射下,光生电子由钒酸银导带传到二氧化钛导带上,空穴则聚集在钒酸银价带上,产生的h+、·OH等是降解亚甲基蓝的主要物质,电子与受体的结合是反应的限速步骤.

Preparetion and photocatalytic properities of silver vanadate modified titania under visible light irradiation

A novel silver vanadate modified titania photocatalyst was prepared by one-pot hydrothermal method in this paper. The product was characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy analysis. Methelene blue(MB) was employed to investigate its photocatalytic activity and stability, and the mechanism of the degradation of MB was also discussed according to experimental results. The results demonstrated that the photocatalytic degradation of MB by silver vanadate modified titania was a first-order reaction, and the rate constant (0.009 min-1) was three times bigger than that of P25 under visible light irradiation. The enhancement of the photocatalytic activity might attribute to the formation of coupling heterojunction between silver vanadate and titanium, and the photo-generated electrons could spontaneously migrate from conduction band of silver vanadate to conduction band of titania while the hole left on the valence band of silver vanadate to generate hydroxyl radical. The oxidation of hole as well as hydroxyl radicals played a leading role in the action. The combination of electron and receptor was the limiting step. In addition, the hybrids showed strong stability and high activity in this study. The degradation rate decreased only 4.8% after repeated for three times.