片状和球状纳米CeO_2的可控制备及其光催化性能

以乙二醇、水和丙酸为溶剂,使用无模板溶剂热法通过改变溶剂中乙二醇的体积比在180℃的条件下制备了前驱体,将前驱体在500℃的空气中焙烧2 h得到分散性较好的片状和球状纳米CeO_2。采用X射线衍射(XRD)、扫描电镜(FE-SEM)、紫外-可见漫反射光谱(UV-Vis DRS)对样品进行表征,以亚甲基蓝(MB)的光催化降解为目标反应评价其光催化活性。结果表明:焙烧后试样仍保持前驱体的片状或球状形貌,由纳米颗粒组装而成,片状纳米CeO_2直径为0.3~1μm,厚度为20~60 nm,球状纳米CeO_2径为120~200 nm;超细纳米结构使得CeO_2光学带隙能减小、光吸收阀值红移、比表面积增大,因而光催化活性大幅提高,片状和球状纳米CeO_2在可见光下光催化降解亚甲基蓝的3 h降解率由棒状结构CeO_2的12.3%分别提高至80.1%和91.2%。

Controllable Preparation and Photocatalytic Properties of Nano-CeO2 Sphere and Sheet

Using ethylene glycol, water and propanoic acid as solvent, precursor with sheet and sphere shape was first synthesized by template-free solvothermal method through varying the volume ratio of ethylene glycol under 180 ℃.Then CeO2 nano-sphere and nano-sheet was prepared by calcinating the precursor at 500 ℃ for 2 h in the air.The properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Ultraviolet-visible spectroscopy (UV-Vis DRS).The photocatalytic properties to methylene blue solution were investigated under visible light irradiation.The results show that the CeO2 still kept the shape of the precursor with sheet and spherical morphology after calcination, which was assembled by nanoparticles.The diameter of CeO2 nano-sheet is 0.3-1 μm and the thickness is 20-60 nm.The diameter of CeO2 nano-sphere is about 120-200 nm.CeO2 nanostructures could decrease the band gap energy, increase the specific surface and make the absorption edges red shifting, which significantly increase the photocatalytic activity.The photocatalytic degradation rate of MB in 3 h increased from 12.3% for rod-like CeO2 to 80.1% for CeO2 nano-sphere and 91.2% for CeO2 nano-sphere, respectively.