铜、银负载二氧化钛纳米花的制备及光催化性能研究

发布时间：2018-02-03 16:57

本文关键词： 水热法微波 Ag/TiO_2纳米花 Cu/TiO_2纳米花 Ag/TiO_2纳米微球表面等离子体光解水制氢　出处：《西北大学》2015年硕士论文　论文类型：学位论文

【摘要】：现如今与有机污染物有关的环境问题和能源短缺问题已引起国内外的广泛关注。为了解决这些问题,光催化作为一种绿色的节能环保技术吸引了物理、化学、材料等领域学者的广泛关注。TiO2光催化技术作为一种绿色技术,可缓解能源危机,减缓环境污染,已被广泛用于光分解水制氢、光催化还原二氧化碳、污水处理、空气净化及杀菌等领域。由于TiO2禁带宽度较大(Eg=3.2 eV),光生电子和空穴(载流子)容易发生复合,阻碍了TiO2光催化技术的实际应用。本文将TiO2自身结构调控和金属负载相结合,共同促进TiO2光催化分解水制氢性能,主要开展了以下研究内容。首先采用水热法制备得到TiO2纳米花和微球,进一步借助微波辅助化学还原法将Cu和Ag颗粒分别负载于TiO2表面得到Cu/TiO2纳米花、Ag/TiO2纳米花和Ag/TiO2微球。将制备得到的样品用于光催化实验,采用X-射线粉末衍射(XRD)、扫描电子显微镜(SEM)、光致发光光谱(PL)、比表面积测试仪(BET)、拉曼散射光谱(Raman)、紫外-可见光吸收光谱(UV-Vis)等测试方法对制备得到的催化剂进行了一系列的表征,分别探究了它的整体形貌特征、表面晶体结构以及所反映的光谱性能,揭示了样品的光催化活性与其结构之间的关系。研究发现,所制备的TiO2纳米花和微球由有序的棒状结构和纳米颗粒分别簇拥而成,两者的直径分别为1μm和4μm,其独特的三维结构提高了光捕获性能。XRD分析发现,TiO2颗粒为金红石相结构,其特征衍射峰2θ=27.5°。荧光光谱分析发现,Cu和Ag颗粒的存在使得TiO2荧光发生淬灭现象,位于400nm (3.18 eV)和475nm (2.67 eV)的发射峰强度明显降低。拉曼光谱表明,Cu和Ag颗粒可以增强Ti02的拉曼散射强度,和TiO2在可见光区的吸收强度,这可能与两种金属的局域表面等离子体效应有关。本文重点考察了Ag和Cu负载量对TiO2的光催化性能的影响,(紫外+可见光)光解水制氢实验结果表明,在较优条件下,c=0.03mol/L Ag/TiO2纳米花的制氢产率是纯TiO2纳米花的3.9倍,c=0.05mol/L Cu/TiO2纳米花制氢产率是纯二氧化钛的2.4倍。Ag/TiO2 NBs-Ⅱ的光催化效率是纯TiO2微球的1.7倍。最后,本文对上述结构的光催化分解水制氢机制进行了初步分析。
[Abstract]:Now the organic pollutants and related environmental problems and energy shortage has attracted widespread attention at home and abroad. In order to solve these problems, photocatalysis is a kind of green energy saving and environmental protection technology has attracted wide attention in physics, chemistry,.TiO2 photocatalytic technology scholars materials and other fields as a kind of green technology, can alleviate the energy crisis. To mitigate the environmental pollution, has been widely used in light water splitting, photocatalytic reduction of carbon dioxide, wastewater treatment, air purification and sterilization and other fields. Because the TiO2 large band gap (Eg=3.2 eV), the photogenerated electrons and holes (carrier) to the composite, practical application hindered TiO2 photocatalytic technology. In this paper TiO2 structure control and metal load combination, and jointly promote the TiO2 photocatalytic decomposition of water to hydrogen performance, the main research contents are as following. Firstly prepared by hydrothermal method to obtain TiO2 nano flowers And with the help of microspheres, microwave assisted chemical reduction method Cu and Ag particles were loaded on the surface of TiO2 Cu/TiO2 nanoflower, Ag/TiO2 nano flower and Ag/TiO2 microspheres. The prepared samples were used for the photocatalytic experiments, using X- ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence the spectrum (PL), specific surface area analyzer (BET), Raman scattering spectroscopy (Raman), UV Vis absorption spectroscopy (UV-Vis) catalyst prepared by the method of testing were characterized respectively, to explore the overall appearance characteristics, crystal structure and surface reflection the spectral properties, reveals the relationship between the photocatalytic activity of samples and structure. The study found that the prepared TiO2 nano flowers and the morphology of microspheres and nanoparticles were orderly surrounded by, the diameters of 1 m and 4 m, its unique three-dimensional node The improved light trapping properties of.XRD analysis showed that TiO2 particles were rutile phase structure, the characteristic diffraction peak of 2 DEG theta =27.5. The fluorescence spectra analysis showed that the presence of Cu and Ag particles makes the TiO2 fluorescence quenching phenomenon in 400nm (3.18 eV) and 475nm (2.67 eV) emission peak intensity decreased significantly. Raman spectra show that enhanced Raman scattering intensity of Ti02 Cu and Ag particles can, and TiO2 absorption intensity in the visible light, this may be related to surface plasmons and two kinds of metal. This paper focuses on the effects on Photocatalytic Performance of the amount of TiO2 Ag and Cu load, (+ UV visible) photolysis hydrogen production from water. The experimental results show that under the optimum conditions, the c=0.03mol/L Ag/TiO2 nano flowers hydrogen yield is 3.9 times of pure TiO2 nanoflower, c=0.05mol/L Cu/TiO2 nanoflower hydrogen yield is photocatalytic efficiency 2.4 times.Ag/TiO2 NBs- II is pure titanium dioxide 1.7 times of pure TiO2 microspheres. Finally, a preliminary analysis of the mechanism of photocatalytic decomposition of water for hydrogen production by the above structure was carried out in this paper.

【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O614.411;TQ116.2

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