二氧化铈及其复合材料光催化性能的研究

发布时间：2018-02-05 22:46

本文关键词： 光催化空心二氧化铈氮化碳可见光　出处：《扬州大学》2015年硕士论文　论文类型：学位论文

【摘要】：能源危机和环境恶化是人类二十一世纪面临的两个重要的问题,寻找新型的可再生的能源已经成为了研究热点。自1972年,藤岛昭与本多健一首先发现了二氧化钛在紫外光照射下分解水的现象,二氧化钛作为一种新型材料,引起了人们的关注。进而,光催化领域得到了蓬勃的发展。二氧化铈作为稀土元素中最丰富的元素,尤其在我国含量更是丰富,并且以其稳定的化学性质、无毒、简单的制备方法,使它成为一种新型的光催化材料而备受关注。通过简单的无模板的溶剂热法,我们通过一步合成了均一尺寸的单分散孔状空心二氧化铈微球(CeO2-PH)。与此同时,我们同样通过溶剂热法合成了八面体,海胆状,和纳米结构的CeO2。使用比表面积(BET),X射线衍射(XRD),场发射扫面电镜(FES EM)和透射电镜(TEM)等仪器对孔状空心二氧化铈微球和纳米二氧化铈微球(CeO2-NP)的结构和性能进行了表征,并且利用光分解乙醛(气体)的实验评价了样品的光催化性能。确定了比表面积、形貌和亚微观结构对样品光催化性能的影响。孔状空心二氧化铈微球的平均粒径大约为160 nm,并且由10 nm左右的小晶粒组成。另外,光性能,缺陷和表面化学性能将通过紫外-可见光谱(UV-vis),拉曼光谱(RAMAN),X射线光电光子能谱分析(XPS)表征手段观测,解释了性能与结构的紧密联系。较多的三价铈(Ce3+)含量降低了能带带宽,提高了光子收率,提高了光催化性能：与此同时,合成的CeO2-PH含有较多的氧缺陷,为光催化反应提供了较多的活性点,提高了光催化活性。本文中,为了进一步测试光电性能,我们测试了Ce02的光电流响应,其结果与活性一致。类石墨型氮化碳(g-C3N4)以其稳定的化学性质、无毒、廉价的原材料、简单的制备方法,尤其是可见光响应,使它成为一种新型的光催化剂而备受关注。为了进一步提高可见光的光催化性能,我们选取类石墨型氮化碳(g-C3N4)作为改性剂,通过物理混合(行星混合机)的方法合成了CeO2/g-C3N4共混复合材料,从而来提高整体的可见光吸收。其性能表征同样是光分解乙醛(气体)的实验,正如我们预料的,原本的二氧化铈的活性得到了很大的提高。其光催化机理有两种可能,P-N Junction和Z-Scheme.其真正的机理探讨将在今后的研究中继续深入。
[Abstract]:Energy crisis and environmental deterioration are two important problems that human beings face in 21th century. The search for new renewable energy has become a research hotspot since 1972. Fujima Akira and Bentojianichi first discovered the phenomenon of titanium dioxide decomposing water under ultraviolet light. As a new material, titanium dioxide has attracted people's attention. As the most abundant elements in rare earth elements, especially in China, cerium oxide is rich in content, and its stable chemical properties, non-toxic, simple preparation method. It has become a new type of photocatalytic material and has attracted much attention through a simple template-free solvothermal method. In one step, we have synthesized a uniform size of monodisperse hollow cerium dioxide microspheres CeO2-PHN. At the same time, we have also synthesized octahedron and sea urchin by solvothermal method. And the nanostructure of CEO _ 2. The specific surface area (BET) was used for X-ray diffraction (XRD). The structure and properties of hollow cerium dioxide microspheres and nano-cerium oxide microspheres were characterized by field emission scanning electron microscopy (FES EMM) and transmission electron microscopy (TEM). The photocatalytic properties of the samples were evaluated by photodecomposition of acetaldehyde (gas) and the specific surface area was determined. The effect of morphology and microstructure on the photocatalytic properties of the samples. The average particle size of the hollow cerium oxide microspheres is about 160 nm and consists of about 10 nm small grains. In addition, the optical properties of the hollow cerium dioxide microspheres are investigated. The defects and surface chemical properties will be characterized by UV-vis spectra and Raman spectra by X-ray photoelectron photonic spectroscopy (XPS). The close relationship between the properties and the structure is explained. The higher content of cerium trivalent Ce3 decreases the band bandwidth, increases the photon yield, and improves the photocatalytic performance at the same time. The synthesized CeO2-PH has more oxygen defects, which provides more active points for photocatalytic reaction and improves photocatalytic activity. We have measured the photocurrent response of Ce02, and the results are consistent with the activity. Graphite-like carbon nitride (GN) g-C3N4) has stable chemical properties, nontoxic, cheap raw materials and simple preparation method. In order to further improve the photocatalytic performance of visible light, graphite-like carbon nitride (g-C3N4) is chosen as the modifier. CeO2/g-C3N4 composites were synthesized by physical mixing (planetary mixer). Thus, the absorption of visible light is improved. Its performance is also characterized by experiments of photodissociation of acetaldehyde (gas), as we expected. The activity of the original cerium oxide has been greatly improved. There are two possible photocatalytic mechanisms. The real mechanism of P-N Junction and Z-Schema will be further studied in the future.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ133.3;O643.36

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