Synthesis,Characterization And Properties Of Au@SiO₂ Core/Shell Nanocomposites

Core/shell nanoparticles are widely used in biomedicine,pharmaceutical,catalysis due to the dual characteristics of core particles and shell materials.In view of the excellent optical properties of gold nanoparticles and the good biocompatibility of silica,Au@SiO₂ core/shell structure and yolk/shell structure are often studied and applied as typical core/shell nanocomposites.The general preparation method of this type of nanoparticles is complicated.Therefore,exploring a simple and efficient experimental preparation method is of great significance for its further research and application.In this paper,we focus on exploring a simpler,greener method to prepare Au@SiO₂core/shell structures with uniform size,good dispersion,and better reproducibility.The Au@SiO₂ core/shell structure was synthesized by one-pot method,and the Au@SiO₂yolk/shell structure was successfully prepared by self-transformation method.The obtained samples were characterized by UV-visible absorption spectroscopy,X-ray powder diffractometry,scanning electron microscopy and transmission electron microscopy.The catalysis,surface-enhanced Raman scattering and surface-enhanced fluorescence properties were also studied.The main research contents are as follows:?1?In an alcoholic water system,a one-pot method was used to prepare Au@SiO₂core/shell structure by using cetyltrimethylammonium bromide as a surfactant,choline for reducing chloroauric acid and catalyzing the hydrolysis of tetraethyl orthosilicate.Au@SiO₂yolk/shell structure was synthesised by the method of self-transformation.The results show that Au@SiO₂ with yolk/shell structure is superior to core/shell structure in catalyzing p-nitrophenol and surface-enhanced Raman scattering of p-Aminothiophenol.?2?Au@SiO₂ core/shell structure was synthesized by one-pot one-step method,which2-?methylamino?ethanol was used as a reducing agent for chloroauric acid and a catalyst for the hydrolysis of tetraethyl orthosilicate.The effects of different experimental conditions on the formation of core/shell structure were also explored.The size of the gold core and the thickness of the SiO₂ shell were colltroed by adjusting the amount of chloroauric acid and tetraethyl orthosilicate added.In addition,the Au@SiO₂ core/shell structure with different shell thicknesses were used to enhance the fluorescence intensity of isothiocyanate molecules.The results show that the fluorescence intensity increases first and then decreases with the increase of shell thickness.When the shell thickness is 34.2 nm,the fluorescence intensity is the highest and the enhancement factor can reach 5.04.