Synthesis of Sphere-Like Silver Nanostructures Composed of Self-Assembled Nanosheets

Abstract

Sphere-like silver nanostructures composed of self-assembled nanosheets were rapidly synthesized through adding ferrous sulfate into the mixture of silver nitrate and citric acid aqueous solution by magnetic stirring at room temperature for 20 min. The effects of the concentrations of the ferrous sulfate and citric acid on the morphology of the silver nanostructures were investigated in detail. The characterization of the sphere-like silver nanostructures composed of self-assembled nanosheets have been discussed by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and differential scanning calorimetry. Furthermore, the possible formation mechanism of sphere-like silver nanostructures composed of self-assembled nanosheets was explored. The experimental results show that the high concentration of citric acid and the low concentration of ferric sulfate are better for obtaining the sphere-like silver nanostructures composed of self-assembled nanosheets due to a low diffusion rate of silver atoms to the silver nucleus and a low growth rate of silver flakes along the {111} facets. Such sphere-like silver nanostructures exhibit a strong surface-enhanced Raman scattering effect associated with their geometries, which is much stronger than that from nanosheets.