氧化锌及其复合材料的制备与光催化性能研究

发布时间：2018-03-02 15:06

  本文选题：微米级ZnO　切入点：ZnO/CuO复合粉体　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着人类文明的高速发展与进步,由此带来了一系列的资源短缺、环境污染问题,特别是水资源的污染问题已经引起人们的广泛关注。其中研究的热点之一是采用ZnO和TiO2等半导体氧化物材料作为光催化剂催化处理污水中有机污染物。ZnO属于直接宽禁带半导体材料(Eg=3.37eV),其热力学稳定晶体结构为纤锌矿结构。ZnO具有化学性质稳定、安全廉价、易合成及较高的光催化效率等特点,是一种光催化领域中应用较广泛的新型半导体材料。但是ZnO的催化效率存在着一些不足,一方面其只对太阳光中的紫外区域有很好的吸收,不能有效吸收可见光部分;另一方面,ZnO电子-空穴对容易复合,降低了光催化性能。所以,一些基于ZnO的复合光催化材料被相继研究,这些材料拥有更宽的光响应范围和更高的光催化降解活性。本文以ZnO为研究主体,对微米级ZnO及ZnO/CuO复合粉体的结构,形貌,性能进行了一系列研究。具体如下:(1)以硝酸锌为原料,通过超声喷雾热解法制备球形ZnO粉体。对前驱体进行TG-DSC测试,分析了硝酸锌热分解得到ZnO的过程。实验结果表明:通过改变电阻炉温度及前驱体溶液浓度,能够有效控制产物粒子的粒径与形貌。较高的反应温度,有助于合成出表面更加光洁,球形度更好的ZnO粉体,但温度不宜过高;提高硝酸锌溶液浓度所制得产物的粒径较大,球形度也会变差;并且在前驱体溶液中添加不同的添加剂也会对样品的形貌产生明显的影响。(2)以硝酸锌、硝酸铜的混合水溶液作为前驱体溶液,通过改变两者的复合比例,在炉子温度恒定为700℃下采用喷雾热解技术成功制备了ZnO/CuO复合中空球形颗粒。利用X射线衍射仪、扫描电子显微镜、能谱仪、紫外可见分光光度计对所合成的复合材料的结构、形貌及UV-Vis吸收性能进行了表征,并对复合样品光催化降解甲基橙(MO)进行了考察。实验结果证明:ZnO/CuO复合材料在整个紫外与可见光区都有良好的吸收,显著增大了光谱的吸收范围。其光催化性能明显比纯ZnO更高,其中又以复合5%CuO的复合样品的催化效率最高。
[Abstract]:With the rapid development and progress of human civilization, this has brought about a series of resource shortages and environmental pollution problems. In particular, the pollution of water resources has attracted widespread attention. One of the research hotspots is that the use of semiconductor oxide materials such as ZnO and TiO2 as photocatalysts for the treatment of organic pollutants in wastewater. The thermodynamically stable crystal structure of Wurtzite structure. ZnO has stable chemical properties. It is a new semiconductor material widely used in the field of photocatalysis, such as safe and cheap, easy to synthesize and high photocatalytic efficiency. However, there are some shortcomings in the catalytic efficiency of ZnO. On the one hand, it only absorbs the ultraviolet region of sunlight, and it can't absorb visible light effectively. On the other hand, ZnO electron-hole pair is easy to compound, which reduces the photocatalytic performance. Some composite photocatalytic materials based on ZnO have been studied one after another, and these materials have wider photoresponse range and higher photocatalytic degradation activity. In this paper, the structure and morphology of micron ZnO and ZnO/CuO composite powders are studied with ZnO as the main body. A series of studies were carried out on the properties of spherical ZnO powders prepared by ultrasonic spray pyrolysis with zinc nitrate as raw material. The precursor was tested by TG-DSC. The process of obtaining ZnO by thermal decomposition of zinc nitrate was analyzed. The experimental results show that the particle size and morphology of the product can be effectively controlled by changing the temperature of the resistor furnace and the concentration of the precursor solution. It is helpful to synthesize ZnO powder with more smooth surface and better sphericity, but the temperature should not be too high, the particle size of the product prepared by increasing the concentration of zinc nitrate solution is larger, and the sphericity will also become worse. In addition, adding different additives to the precursor solution also had a significant effect on the morphology of the sample. (2) the mixed aqueous solution of zinc nitrate and copper nitrate was used as the precursor solution, and by changing the composite ratio of the two solutions, ZnO/CuO composite hollow spherical particles were successfully prepared by spray pyrolysis at a constant furnace temperature of 700 鈩，

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