Preparation And Characterization Of Au@SiO₂Composite Structure

Silica–metal nanostructures consisting of silica cores and metal nanoshells attracta lot of attention because of their unique properties and potential applicationsranging from catalysis and biosensing to optical devices and medicine. Theimportant feature of these nanostructures is the monodispersity, stability,modification, self-assembly behavior and possibility of controlling their propertiesby the variation of their geometry, the physical and chemical properties is notincluded by Single material. This review is devoted to silica–noble metal core–shellnanostructures.Through the electrostatic self-assembly method,we preparedSiO₂@Au core-shell structure composite materials and SiO₂@Au@SiO₂three layercomposite structure,discussing the different conditions on the influence of thecomposite material preparation, and carriing on the representation. Based on theseresearch ideas，research works were mainly carried out in the following aspects.1.Preparation and characterization of Au nanoparticlesGold nanoparticles can be prepared by the reaction of gold chloride acid andtri-sodium using the following two methods: heating reflux method and lightingreaction method. By research on these two methods, the results show that, the size ofthe gold nanoparticles prepared by heating reflux method can be controlled by theproportion of the two reactants, and lighting reaction method has a rapid response, soit was suitable for direct preparation of gold nanoparticles in carrier.2.Preparation and characterization of monodisperse SiO₂@AuSiO₂@Au composite particles can be prepared by standing, shaking, stirring andultrasonic. By comparing these preparation methods, a much simpler method--ultrasound perturbation method have been proposed, and by this method,SiO₂@Au composite particles with better dispersed Au nanoparticles adsorbed in theabove can be prepared.3. Preparation and characterization of the three-layer composite materialSiO₂@Au@SiO₂In the mixed solution of water, TEOS, ammonia, the three-layer compositematerial can be prepared by the hydrolysis of the TEOS. By research on this method,the result shows that the shell thickness changes with the quantity of TEOS, and thesilicon shell morphology changes when the pre-hydrolysis time of TEOS changes.