pH值对ZnWO_4粉体的微波水热法合成及光催化性能的影响

Effect of pH Value on Microwave-Hydrothermal Synthesis and Photocatalytic Properties of ZnWO_4 Powders

以Na2WO4.2H2O和Zn(NO3)2.6H2O为原料,采用微波水热法在不同pH值下200℃反应60 min制备出ZnWO4粉体。分析了pH值对合成样品的物相、形貌和比表面积的影响,并对不同pH值下合成粉体的光催化性能进行了研究。结果表明:pH值为5.0～7.5时适宜合成ZnWO4粉体,pH为5.0、6.0和7.5时分别合成了星状、颗粒状及纤维状ZnWO4粉体;制备出的ZnWO4粉体比表面积分别为15.79、28.12m2/g和54.27 m2/g;随着ZnWO4粉体比表面积的增加,ZnWO4粉体光催化性能随之提高,其中pH=7.5时合成的纤维状的ZnWO4粉体比表面积最大,在紫外光下,2h的光催化降解罗丹明B降解率达到了98.5%。

The powders of ZnWO4 were synthesized by a microwave-hydrothermal method with Na2WO4·2H2O and Zn（NO3）2·6H2O powders as raw materials at 200 ℃ for 60 min. The effect of pH value on the phase composition, morphology and specific surface area of the ZnWO4 powders synthesized were analyzed. The photocatalytic properties of the powders prepared at different pH values were investigated. The results indicated that the pH value of 5.0-7.5 could favor the synthesis of ZnWO4 powders. The ZnWO4 powders with various morphologies （i.e., star-like, sphere and fiber） and specific surface areas （Le., 15.79, 28.12 m^2/g and 54.27 m^2/g） were synthesized when pH was 5.0, 6.0, and 7.5, respectively. The photoeatalytic performance of ZnWO4 powders increased with the increase of specific surface area of the powders. The superior photocatalytic property was obtained in the ZnWO4 powder with the fiber morphology prepared at a pH value of 7.5, and the corresponding decolorizing rate was 98.5% under UV light irradiation for 2 h.