Fabrication of Hierarchical Nanostructure of Silver via a Surfactant-Free Mixed Solvents Route

Abstract

The dendritic Ag nanostructure with ordered branches and a “clean” surface has been successfully prepared via a facile surfactant-free and acetone-based mixed solvents route at room temperature. Experiments and structural characterizations reveal that the dendritic Ag nanostructure is evolved from the initially generated triangular nanoplates by the reaction of AgNO3 with l-ascorbic acid to the dendrites through both the Ostwald ripening and the oriented attachment growth processes. The acetone plays the key role in controlling the nucleation, growth, conversion, and assembly of the Ag nanoparticles. In the absence of acetone, only the polyhedral particles can be obtained. The yield of the dendrites is dependent on the volume ratio of acetone to water. The present work provides an example for the synthesis of a novel metal nanostructure by simply adjusting the solvent components, which is important for the qualitative understanding of the solvent effect on the morphology of nanostructures and the controllable synthesis of desired nanostructures. The dendritic Ag nanostructure possesses surface-enhanced Raman scattering (SERS) performance similar to that from triangular Ag nanoplates, and they both show much better SERS enhancement ability than that of polyhedral Ag particles which might be relative to their different geometric shapes and microstructures. It is expected that the dendritic Ag nanostructure may find potential applications such as in catalysis, molecular probe, and biological sensing.