【作者】 张瑛洧；

【导师】 庞广生；

【作者基本信息】 吉林大学 ， 无机化学， 2010， 博士

【摘要】 本论文中,通过对低成本Nb源的改性处理,我们在温和的水热条件下,合成了一系列化学式为MNb₂O₆的铌酸盐,同时制备出具有特殊分级微纳米结构的光催化材料。论文的具体内容:水热合成了CaNb₂O₆分级微纳米结构,因其独特的结构特征可以有效地促进光生电子和空穴的分离,使其光催化降解染料的性质有很大的增强。探讨了分级结构的形成机理,证实其经历了一个两步的成核-生长过程,前提是这种分步成核-生长所需的过饱和度和温度条件得到满足。这种由过饱和度来诱导多步成核-生长的策略,为构筑其它分级结构提供了一个新思路。（第2章）通过对各种反应条件的调控,在水热条件下完成了一系列过渡金属铌酸盐（MnNb₂O₆、CdNb₂O₆、ZnNb₂O₆和Pb₂Nb₂O₇）的合成,得到了合成纯相所需的合适的反应温度、反应时间和pH值范围。接着对MnNb₂O₆的磁学性质和Pb₂Nb₂O₇的光催化性质进行了表征。在钒酸盐的水热合成中,在无模板剂的条件下得到了InVO₄的单分散自组装的微米球。（第3章）采用热注射和溶剂热的方法合成了二元和三元硫化物的纳米晶。通过对反应条件的调控（配体和原料的比例、反应温度、反应时间等）,得到了不同形貌及尺寸可调的单分散的PbS纳米晶,以及CuInS₂的纳米粒子和纳米棒。（第4章）更多还原

【Abstract】 In recent years, a series of niobates semiconductor materials have attracted widespread attention for their high photocatalytic activities and good luminescence properties, as well as the tremendous application prospect in the field of microwave dielectric ceramics. However, most of niobates are synthesized by traditional solid-state reaction （SSR） method. Their practical applications are limited due to the cumbersome synthesis conditions and the lower active surface areas. In this thesis, after improving the activity of Nb₂O₅, we investigated the synthesis of columbite niobates in the mild hydrothermal conditions, systematically. The major research work is as follows:1. Hydrothermal synthesis and photocatalytic properties of CaNb₂O₆ hierarchical micro/nanostructure.Hierarchical micro/nanostructures, which are assembled from zero-dimensional （0D）, 1D, and 2D micro/nanoscale building blocks, have attracted significant attention due to their unique physical and chemical properties. Research on hierarchical structures provides potential applications in the bottom-up fabrication of advanced functional devices, including sensors, fuel cells, and photocatalysts. The photocatalytic superiority of the hierarchical micro/nanostructures can be attributed to their special structural features. The special structural features can prevent aggregation to maintain a large active surface area and enhance the charge-transfer rates in materials. In this article, CaNb₂O₆ hierarchical micro/nanostructure was successfully fabricated under mild hydrothermal conditions in the absence of templates or organic additives. In this hierarchical micro/nanostructure, the nanosheets grow vertically on the surface of the one-dimensional microneedles. At the same time, selective synthesis of CaNb₂O₆ and Ca₂Nb₂O₇ could also be facilely achieved only by adjusting pH value. We investigated the effect of the reaction temperature, time and concentration on the growth of hierarchical structure, in order to explore the mechanism of its formation. We believe that the hierarchical structure is formed in a two step nucleation–growth process, at appropriate supersaturation and temperature conditions. Our result may provide a new route for the construction of a new hierarchical structure from a multistep nucleation–growth process dependent on the degree of supersaturation. The hierarchical structured CaNb₂O₆ exhibits a stronger enhancement of photocatalytic activity in the degradation of rhodamine B （RhB） than other CaNb₂O₆ samples with different morphologies, for the unique structural features of the CaNb₂O₆ hierarchical micro/nanostructure could efficiently promote the separation of photo-generated electron-hole pairs.2. Hydrothermal synthesis of transition-metal niobates.Based on the work of previous chapter, we synthesized the transition metal ions columbite niobates using low-cost hydrothermal method. After changing a variety of reaction conditions, such as reaction time, temperature and pH value, we got the suitable reaction conditions required for the synthesis of niobates. Ultimately, MnNb₂O₆, CdNb₂O₆, ZnNb₂O₆ and Pb₂Nb₂O₇ were synthesized under the low-temperature hydrothermal system. Compared with the traditional high temperature solid state reaction method, hydrothermal synthesis reactions are performed at lower temperature and samples with good purity and crystallinity could be obtained. The samples synthesized in the hydrothermal reaction usually showed regular morphologies with smaller size and good dispersion property. We also studied the properties of these niobates products, and found that the MnNb₂O₆ product presents paramagnetism and the Pb₂Nb₂O₇ product has good photocatalytic activity. Additionally, we have synthesized the InVO4 self-assembled microspheres in the hydrothermal conditions without templates.3. The controllable synthesis of binary and ternary sulfide nanocrystals.We synthesized the binary and ternary sulfide nanocrystals by hot injection and solvothermal method. Monodispersed PbS and CuInS2 nanocrystals with different morphologies and controllable sizes could be obtained by changing the reaction conditions, such as the concentration of ligand, reaction time and temperature.更多还原