Synthesis Of Gold, Silver Coated Silica And α-Fe₂O₃ Nanocomposites

Material science is always in pursuit of the crossing field of many subjects in recent years, which is not confined by the conventional compounds and devotes to the composite of organic, inorganic, macromolecular and biological materials. Designing and synthesizing controllable nanocomposites with ordered configuration have received intensive attention. To acquire nanocomposites with fine structure and component to satisfy the need of nanotechnology in the nanocomposite synthesis and industrial manufacture, it is crucial to develop an effective preparation method in the nanocomposite research. Meanwhile it will improve the catalytic activities and realize selective catalysis by making catalysts to be core-shell materials such as metal-inorganic composites due to the unique properties of nanocomposites such as high area ratio, ordered shape, controllable size, steady performance and recyclable product, which opens up a fascinating foreground in the catalysis field.In this paper we have first prepared monodispersed SiO2 nanoparticles with different sizes using a modified St?ber method and gold and silver nanoparticles based on chemical reduction method, and then fabricated different kinds of Au/SiO2 and Ag/SiO2 nanocomposites through gold and silver nanoparticles adsorbing on the surface of SiO2 modified by APTMS or PEI.We have systematically investigated the influence of Au/SiO2 nanocomposites to the catalysis performance of the following reaction by adding the Au/SiO2 nanocomposites with various sizes into the mixture solution of K3Fe(CN)6 and NaBH4, and observing the changes of reaction rate. We have also researched the catalytic properties of Ag/SiO2 nanocomposites in the reaction of R6G and NaBH4 using the similar method.We have demonstrated the preparation of spindle-like Fe2O3 bars by a thermal method. Different shapes of spindle-like Fe2O3 bars have been obtained on varying the concentration of KH2PO4. After 3.5 nm gold nanoparticles were adsorbed on the amino-surface of spindle-like Fe2O3 bars, various thickness of gold shell was tuned using both direct-reduction and indirect-reduction methods, which were in comparison as well.