【作者】 弓莹；

【导师】 张卫华；

【作者基本信息】 西安理工大学 ， 材料科学与工程， 2009， 硕士

【摘要】 纳米半导体光催化材料能够完全氧化有机和无机污染物,在水和空气的净化、细菌和病毒的破坏、利用太阳能分解水等方面得到了广泛研究。其中ZnO、TiO2是最具代表性的光催化材料,具有很高的光催化活性、化学稳定性、热稳定性等特点,在光催化降解、污染治理的领域有广泛研究和应用背景。同时利用两种半导体性质差异的互补性可以提高催化剂的活性,因此ZnO-TiO2也是极具应用前景的热点材料。以二水合乙酸锌和硫酸氧钛为出发原料,以氢氧化钠调节pH值,采用NAC-FAS工艺直接合成了形貌近似为球形、平均粒径分别为15nm的纤锌矿ZnO纳米晶和5nm的锐钛矿TiO2纳米晶,采用NAC-FAS分步合成工艺合成了形貌近似为球形、平均粒径为12nm-15nm的ZnO-TiO2纳米晶。并研究了醇水比、pH值、反应时间、微波处理等工艺参数对所合成的纳米晶的晶粒尺寸,晶体结构及形貌的影响,讨论了NAC-FAS工艺合成纳米晶的化学合成机制。讨论了微波处理、热处理以及不同Zn/Ti比例、pH值对所合成的纳米晶ZnO、TiO2和ZnO-TiO2的光催化性能的影响,研究发现：NAC-FAS工艺合成简单氧化物纳米晶的过程中,首先形成含—OH基团的盐或氢氧化物,然后通过脱水—缩聚反应形成固相析出物,部分较大尺寸的固相达到临界固相形核尺寸析出；随着脱水—缩聚反应的进行,固相核心逐渐长大,这种析出可以是晶体相或是无定形非晶态相,其中的非晶相随着反应时间的延续,通过“溶解—再析出”形成晶体相。NAC-FAS工艺制备的ZnO纳米晶、TiO2纳米晶及ZnO-TiO2纳米晶具有良好的光催化性能,TiO2百分含量为42%-50%的ZnO-TiO2纳米晶光催化活性较高,热处理通过提高结晶度可提高光催化性能。酸性环境可提高TiO2纳米晶及ZnO-TiO2纳米晶光催化性能,ZnO纳米晶及TiO2百分含量低于50%的ZnO-TiO2纳米晶易于光腐蚀。更多还原

【Abstract】 The nano semiconductor photocatalyst can oxidize organic and inorganic pollutants completely, and have widespread research in purging the water and the air, destructing the bacterium and virus, decomposeing water using solar energy and so on. ZnO and TiO2 are the most representative photocatalysts, with high photo catalytic activity, chemical stability, the thermal stability and so on, and have the widespread research and the application in photocatalysis degradation and pollution treatment. Simultaneously using the difference between two semiconductors to be possible to enhance the photocatalyst property, therefore ZnO-TiO2 also has the application prospect.In this paper, using TiOSO4 and Zn(Ac)2-2H2O as the starting materials, adjusting the pH value by NaOH, subsphaeroidal wurtzite ZnO nanocrystalline、anatase TiO2 nanocrystalline and ZnO-TiO2 nanocrystalline were direct prepared through NAC-FAS process, and the respective average particle size are 15nm,5nm and 12nm-15nm; and technological parameters to the influence of particle size, the crystal structure and the morphology of nanocrystalline had studied, such as EtOH/H2O ratio, pH value, reaction time, microwave treatment, and the chemical synthesis mechanism of synthesis nanocrystalline through NAC-FAS process had discussed; and microwave treatment、heattreatment、Zn/Ti ratio and pH value to the influence of photocatalytic property had studied. Research shows that:through NAC-FAS process synthesis simple oxide nanocrystalline, first forms the salt or the hydroxide including with-OH groups, then forms the solid phase precipitate through the dehydrated-condensation course, and the part great size’s solid phase achieving critical nucleation size precipitates; going on with the dehydrated-condensation, the solid phase precipitate grows up gradually, this kind of precipitate could be the crystal or the amorphous state, in which amorphous phase forms the crystal adopting "the dissolution-reprecipitation" along with reaction time’s extension; ZnO、TiO2 and ZnO-TiO2 nanocrystalline have high photocatalytic property, and the ZnO-TiO2 nanocrystalline which TiO2 percentage are 42%-50% have the best photocatalysis performance, heat treatment can enhance photocatalytic property for enhance crystallinity, and the acidic environment can enhance photocatalytic property of TiO2 and ZnO-TiO2 nanocrystalline, and ZnO and ZnO-TiO2 nanocrystalline which TiO2 percentage is lower than 50% are prone to photoetch.更多还原