尿素量对CeO2粒子结构、形貌和光催化活性的影响

Effect of Urea Amount on Structure,Morphology and Photocatalytic Activity of CeO2 Particles

以尿素为沉淀剂,采用微波回流法制备了CeO2粒子。利用X射线衍射(XRD),扫描电子显微镜(SEM),孔隙比表面积(BET)以及荧光光谱(PL)等对样品的物理化学性能进行了表征。研究了不同尿素添加量对样品结构、形貌的影响,并通过降解苯酚溶液考察了所制备的CeO2粒子的光催化活性。结果表明,所制备的CeO2粒子形貌为规则的菱形,随尿素添加量的增加,CeO2粒子的尺寸先增大后减小且逐渐变得均匀。当硝酸铈与尿素物质的量比为1∶7时,所得CeO2-4样品的PL光谱强度最低,比表面积最大。在紫外光照射下,CeO2-4样品的光催化性能最好,这可以归结为其具有较高的比表面积以及有效的电子-空穴对的分离效率。因此,合适的尿素添加量有利于光催化活性的提高。

CeO2 particles were prepared by microwave reflux method using urea as precipitant.The physical and chemical properties of the samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),pore specific surface area(BET)and fluorescence spectrum(PL).The effects of urea contents on the structure,morphology and photocatalytic properties of the samples were studied.The photocatalytic activity of as-prepared nanoparticles was studied with phenol solution.The results show that the morphology of cerium dioxide particles is regular rhombus,and its size increases firstly,then decreases and gradually becomes uniform with the increase of urea addition.When the ratio of cerium nitrate to urea is 1∶7,the PL spectral intensity of the obtained CeO2-4 sample is the lowest and the specific surface area is the largest.CeO2-4 sample has the best photocatalytic performance with ultraviolet irradiation,which can be attributed to its high specific surface area and effective electron-hole pair separation efficiency.Therefore,the appropriate amount of urea is conducive to the improvement of photocatalytic activity.