Preparation And Characterization Of C@Au Nano-particles With The Controllable Morphology

Gold nanoparticles have a wide range of applications in the fields of biomedical,environmental protection and energy utilization.In particular,gold nanoparticles have been used in industrial catalysis.At presen,the preparation of controllable morphology C@Au nanoparticles has become a hot spot in the field of catalytic materials.The purpose of this study is to prepare controllable C@Au nanoparticles by one step method and two step method at room temperature.In this thesis,firstly,the controllable morphology of carbon coated gold nanoparticles was prepared by two-step method.gold nanoparticles were prepared by reducing chlorauric acid at room temperature,then resorcinol and formaldehyde were used as carbon source,ammonia as catalyst and ethanol as dispersant to prepare controllable morphology carbon coated gold nanoparticles.The effects of ethanol concentration,ammonia concentration,reaction temperature and reaction time on the particle size,morphology and dispersion degree of the product were studied.Ultraviolet visible spectrophotometer,Scanning electron microscopy,Transmission electron microscopy and X-ray diffraction were employed to characterize the product.The products synthesized by two-step method are controlled morphology carbon coated gold nanoparticles,but the particle size is larger and the dispersion between particles is slightly poor.In order to improve the particle size and dispersity of the product,The modified two-step method is one-step method for the preparation of controllable morphology carbon-coated gold nanoparticles.In one step method,chlorau acid was used as gold source,resorcinol and formaldehyde solution as carbon source and anhydrous ethanol as dispersant.The gold source,carbon source and dispersant were placed in the reaction system at one time,gold ions were reduced in situ to gold nanoparticles in the system solution.The resin coated layer formed by the polymerization of resorcinol and formaldehyde solution on its outer surface was synthesized with high monodispersity.Spherical core-shell carbon coated gold nanoparticles with uniform morphology.The experimental resultsshow that the optimum reaction conditions are as follows: the concentration of chloruronic acid is 0.25 mmol/L,and the concentration of resorcinol is 5mmol/L,The concentration of ethanol is 0.4 mol/L,the concentration of ammonia is 0.2mol/L,the reaction temperature is room temperature and the reaction time is 3hours.Carbon coated gold nanoparticles with good dispersion were synthesized under the optimum conditions,and the particle size was about 50 nm.