Sodium sulfite-mediated controllable synthesis of Ag@Au core-shell nanoparticles

• 1、Collge of Chemistry and Chemical Engineering, Hunan University, Changsha 410082

Abstract：Plasmonic metallic nanoparticles are characterized by their unique surface catalytic properties and adjustable light absorption ability. Bimetallic core-shell nanoparticles can combine the chemical and optical properties of two metal materials at the same time. By controlling the size and morphology of the metal core and the thickness of the shell, the core-shell nanoparticles have both wavelength-tunable light absorption and scattering properties in the whole visible and near-infrared bands. Due to the difference in reduction potential, the galvanic replacement of Ag and Au limits the synthesis of Ag@Au core-shell nanostructure. In this paper, by adding sodium sulfite into chloroauric acid, the reduction potential was reduced to prevent the occurrence of galvanic replacement reactions during the synthesis process. The homogeneous growth of Au shell on Ag nanoparticle core was confirmed by UV-vis spectroscopy, transmission electron microscopy, and inductively coupled plasma mass spectrometry. By changing the amount of growth solution, Ag@Au nanospheres with different shell thicknesses could be obtained. If sodium sulfite is absent in the growth solution, Ag nanoparticles will be etched by chloroauric acid. This method provides a general strategy for the synthesis of hollow Ag@Au core-shell structure with tunable maximum absorption wavelength.

Keywords： gold silver plasmonic core-shell nanoparticle controllable synthesis