【作者】 汪洋；

【导师】 沈玉华；

【作者基本信息】 安徽大学 ， 无机化学， 2011， 硕士

【摘要】 磁性纳米复合材料的制备是当今纳米新材料研究的一个重要领域。本论文首次利用L-半胱氨酸修饰Fe304颗粒,成功地得到了超顺磁性的Fe3O4/Au复合物的微米球；还利用了溶剂热的方法制备出了三维花状的Fe3O4@Bi2O3核壳结构和Fe3O4@SiO2@CeO2@Au的多壳层的复合材料,并对产物的组成、结构和性能进行了研究。具体内容如下：1.在水溶液中,利用L-半胱氨酸修饰Fe304纳米球使其表面功能化带上巯基(-SH)和氨基(-NH2),再利于Au纳米颗粒与巯基(氨基)间的强的配位作用将Au纳米颗粒吸附在Fe304球的表面,成功地制备出了Fe3O4/Au复合物。实验结果表明,合成出来的Fe3O4/Au复合物在近红外区有强的吸收,并且可通过调节内核Fe304的直径大小来控制其光学性质从可见光区到近红外区。制备的Fe3O4/Au纳米复合物在光热治疗、催化、生物传感、探针等领域具有潜在的应用。此外,这种制备磁性复合物的方法还可能为合成其他纳米复合材料提供了一种简便的合适的途径。2.将制备的Fe304颗粒分散在溶有Bi(NO3)3的乙二醇与乙醇的混合溶剂中(体积比为1：2),利用溶剂热的方法,合成出了三维花状的Fe3O4@Bi2O3核壳结构的复合材料的光催化剂。这种复合材料的形貌为420nm左右的花状的微米球,并且这些花状的微米球的表层是由一些厚度约为4-10nm、宽度约为100-140nm的纳米片组装而成。在室温下,这种复合材料具有超顺磁性。值得强调的是我们合成的这种复合材料的光催化剂不但可以容易的通过外加磁场来回收,而且在降解罗丹明B的过程中呈现出非常强的催化活性。我们制备的Fe3O4@Bi2O3复合材料的催化剂的催化效率大约为商品的Bi203催化效率的7-10倍,并且当光照时间达到50分钟时,复合材料的催化剂降解罗丹明B的效率接近到了100%。此外,由于其特殊的形貌结构,这种复合材料还有望在污水处理、传感器、微电子学、能源储备等方面得到应用。3.通过水解的方法在Fe304微米球的表面生成了一层Si02的壳层,接着再利用Ce4+在碱性条件下水解生成Ce02的溶胶,吸附在Si02壳层的表面,水热180℃保持36小时后成功制备出了Fe3O4@SiO2@CeO2双壳层的磁性复合物；而Fe3O4@SiO2@CeO2@Au复合物的制备则是用APTS(3-氨基丙基三乙氧基硅烷)修饰Ce02壳层使其表面氨基化,利用Au纳米颗粒与氨基间的强的配位作用将Au纳米颗粒吸附在Ce02壳层的表面。通过分步制备出来的Fe3O4@SiO2@CeO2@Au复合物可用于CO的催化氧化,有机染料的降解,传感等诸多领域。更多还原

【Abstract】 The synthesis of magnetic nanocomposites is a very important research field in new nano-materials at present. In the thesis, we have first demonstrated a simple method to construct Fe3O4/Au composite microspheres by using L-cysteine as a linker to modify Fe3O4 nanoparticles; the solvothermal method was used to synthesize 3D flowerlike hierarchical Fe3O4@Bi2O3 core-shell architectures and Fe3O4@SiO2@CeO2@Au composite with multi-shell. The composition, construction and properties of the products have also been investigated.The main contents are summarized as follows:1. In the solution, the surface of Fe3O4 nanospheres was modified by L-cysteine. The gold nanoparticles were successfully adsorbed on the surface of Fe3O4 spheres due to strong coordinative interactions between the NH2 and SH groups of L-cysteine and Au nanoparticles. The results indicated that the Fe3O4/Au composite spheres showed a strong absorption in the NIR region and novelty tuned optical properties from the visible to the NIR by simply controlling the diameter of Fe3O4. This Fe3O4/Au hybrid nanostructure will be used as potential photothermal therapeutic agents and for catalysis, biological sensing, probing, and so on. Furthermore, this experiment also suggested a simple way to synthesize various bifunctional or multifunctional composite nanomaterials through simply linking two or several kinds of nanomaterials by chemical bonds.2. The 3D flowerlike Fe3O4@Bi2O3 core-shell structure composite photocatalyst was fabricated by a solvothermal method in the component solvent of glycol and ethanol (Vglycol/Vethanol=1:2). The size of these flowerlike hierarchical microspheres is about 420 nm, and the shells are composed of several nanosheets with a thickness of 4-10 nm and a width of 100-140 nm. These composite microspheres are superparamagnetic at room temperature. It is worth noting that the obtained composite photocatalysts can not only be easily recycled by applying an external magnetic field, but also exhibit powerful visible-light photocatalytic activity for the degradation of RhB. The photodegradation rates of the as-synthesized Fe3O4@Bi2O3 hierarchitectures are much higher (7-10 times) than the commercial Bi2O3 particles. Moreover, it is important to point out that the RhB degradation reaches about 100% for the as-prepared Fe3O4@Bi2O3 composite microspheres under visible-light irradiation after 50 min. In addition, due to their unique architectures, the as-obtained products may have potential applications in water treatment, sensors, microelectronics, energy storage, and other related micro- or nanoscale devices.3. The Fe3O4@SiO2 core-shell microspheres were prepared through a modified Stober process. Then, CeO2 colloids were adsorbed on the surface of Fe3O4@SiO2 microspheres by means of the hydrolyzation of Ce4+ under alkaline solution, and the above mixed solution was sealed in a Teflon-lined stainless-steel autoclave and maintained at 160℃for 5 h, the Fe3O4@SiO2@CeO2 multi-shell magnetic composite were obtained. The gold nanoparticles were successfully adsorbed on the surface of APTS-functionalized Fe3O4@SiO2@CeO2 spheres due to strong coordinative interactions between the NH2 of APTS and Au NPs. This Fe3O4@SiO2@CeO2@Au hybrid nanostructure will be used as catalyst for CO oxidation, sensors and so on.更多还原