盐酸溶液处理钒酸铋增强可见光催化活性及其机理

采用盐酸水溶液处理BiVO₄ 的方法获得增强的光催化活性. 在0.1 mol·L^-1 酸溶液中浸渍反应6 h,BiVO₄ 的可见光催化降解苯酚的活性提高了3.5 倍. 采用X 射线衍射(XRD), 扫描电镜(TEM)和漫反射光谱(DRS)等表征手段研究处理后样品的晶相组成和表面形貌, 结合不同酸和氯化物处理的对照实验, 结果表明,在H⁺和Cl^-的协同作用下, BiVO₄表面部分溶出并以BiOCl 沉积, 形成了表面具有凹陷沟壑的BiVO₄颗粒与片状结构BiOCl 的复合物. 采用悬浮液光电压法测定BiOCl 平带电位, 通过BiVO₄和BiOCl 的能带分析及其混合颗粒的光催化活性测试, 确证二者间不存在颗粒间电子转移效应. 增强的光催化活性主要归因于BiVO₄表面形成了有助于光生电荷迁移的凹凸不平结构. 这种表面处理方法有望成为一种增强半导体化合物光催化活性的有效途径.

Enhanced Visible Light Activity of BiVO4 by Treating in HCl Aqueous Solution and Its Mechanism

Enhanced photocatalytic activity of BiVO₄ has been achieved by immersing in HCl aqueous solution. After treated for 6 h in 0.1 mol·L^-1 HCl solution, the visible light activity of BiVO₄ for phenol degradation increased by 3.5 times. X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS) were carried out to analyze the crystal components and surface morphology of the treated samples. Comparison of samples treated in different acids and chlorides indicated that with the appropriate concentrations of H⁺ and Cl^- ions, BiVO₄ partially dissolved, was deposited as BiOCl, and finally a composite of flaked BiOCl and micro-particles of BiVO₄ with pits formed over the surface. The flatband potential of BiOCl was measured by a slurry method. According to the results of energy band analyses and photocatalytic activity tests of mixed BiVO₄ and BiOCl particles, there is no interparticle electron transfer effect between them. Therefore, the mechanism of the enhanced photocatalytic performance of the treated BiVO₄ can be attributed to the unevenness of the surface, which can facilitate photogenerated charge separation. This type of surface treatment method could be developed into an effective method for preparing photocatalysts with enhanced photocatalytic performance.