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以钨酸铵为钨源,硝酸为沉淀剂,首先通过沉淀法制备前驱体H_2WO_4,随后采用热分解H_2WO_4法合成六方及单斜晶相WO_3催化剂。利用X射线衍射(XRD)、拉曼光谱、差热-热重(TG-DTA)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)及紫外-可见漫反射光谱(UV-Vis DRS)对H_2WO_4向WO_3转变过程中结构、形貌、组成及光学性质的变化进行研究。结果表明,热处理后前驱体发生如下相变过程:H_2WO_4→六方相WO_3→六方/单斜相WO_3→单斜相WO_3。此外,以罗丹明B为模拟污染物,考察不同晶相WO_3的光催化活性,结果表明,六方相WO_3具有更高的光催化性能,单斜相WO_3的活性较低。
Ammonium tungstate was used as the tungsten source and nitric acid was used as the precipitating agent. The precursor H_2WO_4 was prepared by precipitation method and then the hexagonal and monoclinic WO_3 catalysts were synthesized by thermal decomposition of H_2WO_4. The microstructure and mechanical properties were characterized by X-ray diffraction, Raman spectroscopy, TG-DTA, SEM, XPS and UV-Vis DRS ) On the structure, morphology, composition and optical properties of the H_2WO_4 to WO_3 transformation process. The results show that the precursors undergo the following phase transformation after heat treatment: H_2WO_4 → hexagonal phase WO_3 → hexagonal / monoclinic phase WO_3 → monoclinic phase WO_3. In addition, rhodamine B was used as a simulated pollutant to investigate the photocatalytic activity of different crystal phases. The results showed that the hexagonal phase WO 3 has higher photocatalytic activity and the monoclinic phase WO 3 has lower activity.