高活性钒酸铋的尿素沉淀法控制合成及其光催化活性增强机制研究

Controllable Synthesis of Highly Active BiVO_4 by Urea Co-precipitation and the Mechanism for Enhanced Photocatalytic Performance

通过普通尿素沉淀法、超声协助和水热尿素法合成出高结晶度的单斜晶白钨矿型的钒酸铋粉末。利用XRD、SEM、DRS等手段分别对合成材料的晶型、微观形貌及光物理性质等进行研究。结果表明3种方法均能得到结晶度较高的钒酸铋颗粒,但微观形貌上有较大差异。在可见光下对难生化降解的红色染料FN-3G的降解效果表明,所合成的三种BiVO4样品的光催化性能均较好,超声协助法和水热法合成的样品光催化活性增强的机制主要归因于结晶度的提高和比表面积的增大。结晶度的提高可降低电子和空穴复合几率,从而增强光电转换效率;而比表面积的增大主要提高了染料分子的吸附能力。

Monoclinic Scheelite BiVO4 photocatalysts with high crystallinity were synthesized by a homogeneous precipitation method under the assistance of heat, ultrasonic and hydrothermal treatments. The crystal structure, morphology and photophysical property were characterized by XRD, SEM, and DRS techniques, respectively. It demonstrated that BiVO4 with a high crystallinity can be synthesized by three different processes. However, a great difference can be observed on the micrographic morphology. The photocatalytic performance visible-light of these catalysts were evaluated by the decolorization of red dye FN-3G in aqueous solution under irradiation （λ〉420 nm）. All the three samples showed high activity for the dye decomposition.The improved photocatalytic activities of the samples synthesized by the assistance of ultrasonic and hydrothermal treatment are mainly ascribed to the high crystallinity and large surface area. The improvement in the crystallinity can reduce the probability of electron-hole recombination, so as to enhance the photo-to-current conversion efficiency, while the increases in the surface area mainly improve the adsorption capacity of dye molecules.