【作者】 许俊翠；

【导师】 张卫新；

【作者基本信息】 合肥工业大学 ， 材料学， 2013， 博士

【摘要】 随着社会经济的快速发展和人民生活水平的提高,环境污染问题越来越成为世界各国共同关注的焦点问题,而水体有机污染更是各国亟待解决的重要问题之一。半导体光催化氧化技术由于半导体催化剂价格低廉和能使多种有机物完全矿化而被认为是处理有机废水的最有前途的技术之一。但半导体催化剂在实际应用中普遍存在一个难题,即电子空穴容易复合,从而导致光催化效果不理想,所以提高半导体光催化性能尤为重要。本论文围绕“过渡金属氧化物(即Cu20和ZnO)纳米材料的设计、制备及相关性能”展开研究工作,主要包括以下几方面的研究内容：1.采用室温液相法合成了立方相Cu20纳米方块。X射线衍射、透射电镜和扫描电镜表明产物是由形貌和大小高度均匀、边长约为170nm的Cu20纳米方块组成。以高浓度酸性品红溶液(100mg/L)为研究体系对材料的光催化性能进行测试表征,研究表明,体系中添加适量H202能够大大提高Cu20纳米方块的光催化性能,这是由于适量H202的加入不但能够提供较多的羟基自由基(·OH),而且可以阻止Cu20半导体中电子和空穴的复合效率。此光催化路线对提高半导体Cu2O的光催化活性是非常有效的。2.以H2O2为还原剂,CoCl2为氯(Cl)源,采用乙醇的水溶液为溶剂,采用水热法分别合成了Cu20薄膜和CuCl/Cu2O复合物薄膜,可以通过控制CoCl2的浓度控制复合物的组成。将制备的薄膜用于光催化降解罗丹明B溶液,发现CuCl/Cu2O复合物薄膜的光催化性能明显优于纯Cu20薄膜,主要由于CuCl/Cu2O复合物薄膜的形成提高了Cu20的光生电子空穴的分离效率。3.采用一步水热法,在银氨溶液里合成Ag/ZnO复合物薄膜,并用作光催化剂降解罗丹明B溶液。研究发现,与纯ZnO薄膜相比,Ag/ZnO复合物薄膜对罗丹明B溶液的光降解表现出更好的光催化性能。另外,也测试了Ag/ZnO复合物薄膜与纯ZnO薄膜室温下的荧光光谱和氨气传感性能。结果发现,与纯ZnO薄膜相比较,Ag/ZnO复合物薄膜具有更弱的荧光发射峰强度,对氨气具有更好的荧光传感性能。Ag/ZnO复合物薄膜光催化性能和氨气传感性能的提高是由于贵金属Ag的存在提高了半导体ZnO内的电子-空穴分离效率。4.以锌片作模板和还原剂,在银氨缓冲溶液里制备形貌均一、总长度为3-10μm、主干和分支分别为100和50nm的Ag纳米枝晶。并将制备的Ag纳米枝晶组装成荧光型传感器,室温下测试材料对水汽的传感性能。研究发现,与Ag颗粒相比,Ag纳米枝晶传感器表现出更高的灵敏度、更快的恢复时间和更理想的灵敏度和湿度之间的线性关系。更多还原

【Abstract】 With the quick development of social economy and the enhancement of living standard of people, environmental problem has increasingly become a focus in many countries of the world. More important, organic pollution in water is one of the most vexing problems to be resolved. Photocatalytic oxidation with semiconductors is proven to be a promising technology because the semiconductors are inexpensive and can easily mineralize various organic compounds. However, the electron and hole in the semiconductors easily recombine, which results in unsatisfactory photocatalytic efficiency in practical application. Therefore, how to enhance the photocatalytic performance of semiconductors is quite important.In this dissertation, the work was carried out centreing on the theme of design, preparation and properties of transitional metal oxide nanomaterials. The main researches are as following.1. Cubic cuprous oxide nanocubes were prepared by liquid phase method at room temperature. X-ray diffraction patterns, transmission electron microscopy and scanning electron microscopy images have verified that the products consists of uniform Cu2O nanocubes with edge length of170nm. Moreover, the photocatalytic performance of Cu2O nanocubes was investigated by photodegrading acid fuchsin. The results reveal that the phtotocatalytic activity of Cu2O nanocubes was greatly enhanced by adding moderate hydrogen peroxide in the system. Because moderate hydrogen peroxide can not only provide more·OH but also prohibit the recombination of electron and hole as oxidant. Therefore, the method to enhance photocatalytic activity of semiconductors is propagable.2. The Cu2O and CUCl/Cu2O films based on the copper substrate were respectively obtained by an easy hydrothermal method, in which hydrogen peroxide was used as reducing agent, cobalt chloride (CoCl2) as chlorine source as well as ethanol aqueous solution as solvent. The composition of CuCl/Cu2O films can be successful controlled by adjusting the concentration of cobalt chloride. The four films obtained with different concentration of cobalt chloride were used as photocatalyst degrading Rhodamin B solution, and it was discovered that the CuCl/Cu2O films exhibit higher photocatalytic performance than pure Cu2O film, which is attributed to the higher separation of electron and hole. Moreover, the initial concentration of cobalt chloride during preparation has a great effect on the photocatalytic performance of the CUCI/Cu2O films.3. The Ag/ZnO film based on the zinc substrate was synthsized in the Tollen’s reagent by a hydrothermal method via one step. The photocatalytic performance of the Ag/ZnO film was studied by photodegrading Rhodanmin B solution. The results demonstrate that in the degradation of Rhodamin B solution, the Ag/ZnO film exhibits ehancement of photocatalytic activity in comparsion with the pure ZnO film. In additon, the PL peformance and gas sensitivity to ammonia of the Ag/ZnO film were measured at room temperature. The Ag/ZnO film shows weaker PL intensity and better gas sensitivity than the pure ZnO film. The enhanced performance of the Ag/ZnO film was attributed to the more effective seperation of electron and hole resulting from the presence of metal silver.4. Cubic Ag dendritic nanostructure with ordered branches have been successfully prepared by soaking Zn plate into silver ammonia buffer solution and via a facile reduction reaction at room temperature. The overall length of the Ag nanodendrites is3-10μm, and the average diameter of the stems and the branches are100nm and50nm, respectively. A room temperature photoluminescence-type gas sensing device based on the pure Ag nanodendrites has been established to investigate their humidity sensing properties. Compared with Ag particles, the sensor based on the Ag nanodendrites presents better sensitivity, more excellent linearity, quicker recovery and reliable repeatability in a very wide humidity range at room temperature.更多还原