Photochemical synthesis of bimetallic Au-Ag nanoparticles with “core-shell”type structure by seed mediated catalytic growth

The colloidal Au core/Ag shell structure composite nanoparticles were synthesized in PEG-acetone solution by photochemical route. The monodispersed Au nanoparticles with average diameter of 3. 9 nm were used as growth seeds. The optical property of colloids and the sizes of composite nanoparticles were characterized when the molar ratio of Au to Ag ranges from 4：1 to 1：4. The results show that a composite nanoparticle structure similarto strawberry shape is formed at the molar ratio of Au to Ag from 4 : 1 to 1：1；the composite nanoparticles consisting of a core of Au and shell of Ag were generated at the 1：4 molar ratio, having a striking feature of forming interconnected network structure.