聚合物辅助溶剂热合成ZnO纳米材料及其对Cr(VI)的光降解研究

Solvothermal Synthesis of ZnO Nanomaterials Assisted by Polymer and Its Photodegradation of Cr(VI)

摘要: 通过简单的溶剂热法，在聚乙烯吡咯烷酮(PVP)辅助下，乙二醇(EG)作为溶剂制备了的ZnO微/纳米材料。本文探究了不同的反应参数(反应时间、PVP的用量)对产物尺寸、晶相和形貌等的影响，制备出的空心球状ZnO。产品通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)进行表征。SEM结果表明随反应时间延长，所得到空心球状ZnO微/纳米结构的空隙会增大。在反应体系中，PVP作为结构导向剂和分散剂，用量为0.08 g时，所得产物的分散效果最好。经过表征发现，ZnO空心球是一种介孔物质，BET比表面积为83.26 m²/g。同时，在使用紫外灯(250 W高压汞灯)的辐照下，通过冰醋酸调节溶液的pH值，检测了空心球状ZnO对K₂Cr₂O₇溶液的光降解活性，发现在pH = 5的条件下，空心球状ZnO表现出最佳的光催化降解性能。

Abstract: Employing ethylene glycol (EG) as the solvent, ZnO micro/nanostructures were prepared by a simple solvothermal method with the aid of polyvinylpyrrolidone (PVP). In this paper, the effects of different reaction parameters (reaction time, amount of PVP) on the size, crystal phase and morphology of the as-prepared hollow spherical ZnO were investigated. The products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The SEM results show that, with the prolonging of reaction time, the voids of the hollow spherical ZnO micro/nano- structures are increased. In the reaction system, PVP is used as a structure-directing agent and a dispersing agent. When the amount is 0.08 g, the obtained product has the best dispersion effect. It was found that the hollow sphere structure of ZnO is mesoporous with a BET specific surface area of 83.26 m²/g. At the same time, glacial acetic acid was used to change the pH value of K₂Cr₂O₇ solution. Under the irradiation of UV light (250 W high-pressure mercury lamp), hollow spherical ZnO showed excellent photocatalytic properties by the degradation of K₂Cr₂O₇ solution, as a result, pH = 5 is the best condition.