苹果酸辅助水热合成WO3及WO3-CuCrO2的光催化性能

Synthesis of WO3 by the Hydrothermal Method with Malic Acid and Photocatalytic Performance of WO3-CuCrO2

摘要:

以钨酸钠和钨酸铵为原料，硝酸为酸化剂，在苹果酸的辅助作用下，水热法合成了WO3，并对样品进行了XRD，SEM，及Raman分析。结果发现，苹果酸的加入，反应温度的升高及反应时间的延长都会促进单斜相WO3的形成。探讨了苹果酸辅助下，水热反应过程中，WO3的转化机制。测试了不同条件下制得WO3与CuCrO2复合后所得复合催化剂的光催化产氢活性。结果发现，水热反应时的钨源类型、苹果酸加入量、反应温度及反应时间对WO3的性能均有影响，而水热反应所得WO3样品，经热处理后再与CuCrO2复合，所得WO3-CuCrO2的活性较不经热处理制得对应样品的活性有大幅提高，结果显示，焙烧使WO3的结晶完整性得到了改善。300 W氙灯照射下，WO3-CuCrO2光催化分解纯水1 h可以产氢8 μmol以上，高于课题组前期制得催化剂的活性。

Abstract:

The WO3 was synthesized by the hydrothermal method using sodium tungstate and ammonium tungstate as raw materials, nitric acid as acid source, and malic acid as surfactant. The samples were characterized analysis by XRD, SEM, and Raman. The experimental results indicated that the addition of malic acid was efficient for the synthesis of monoclinic WO3. A high hydrothermal temperature and a long hy-drothermal time were favorable for the formation of monoclinic WO3. The formation mechanism of monoclinic WO3 in the malic acid-assisted hydrothermal process was also given and discussed. Further-more, we investigated the activity of the synthesized tungsten trioxides composite with CuCrO2 in the photocatalytic water splitting. The reaction results indicated that the activity of WO3 was affected by the type of tungsten source, the amount of added malic acid, the hydrothermal temperature, and the hydrothermal time. A preheat-treatment of WO3 before mixing with CuCrO2 was found to significantly promote the photocatalytic activity of the WO3-CuCrO2 compound. The characterization results suggested that the crystallinity of WO3 was improved by the heat-treatment. In this paper, The WO3 composited with CuCrO2 have the activity of photocatalytic decomposition of pure water for produce hydrogen, and more than 8 μmol H2 was produced under the irradiation of a 300 W xenon lamp for 1 h. It is higher than the activity of the catalyst prepared in the early stage of the research group.