Dendritic gold nanowires supported on SiO2 nanoparticles fabricated by a seed growth method

Abstract

Seed growth methods are useful for the preparation of various shape-controlled nanocrystals, such as rods, cubes, and plates. The seed growth method generally employs seed nanocrystals dispersed in solutions and capping agents with selective adsorption properties. This article describes a novel seed growth method using Au nanoparticles supported on SiO₂ nanoparticles with a diameter of ∼160 nm (SiO₂@Au NPs) and a long-chain amidoamine derivative (C18AA) with selective adsorption properties on gold. The selective growth of dendritic Au nanowires (Au DNWs) on the SiO₂@Au NPs took place, but growth of Au nanocrystals was not observed using bare SiO₂ NPs. The disadvantages of this method were a long time-consuming preparation and a lower yield of SiO₂@Au DNWs; for this reason, a co-reducing agent was used to increase the formation rate of Au DNWs. We found that the use of ascorbic acid, which has weak reducing powers, brought a considerable improvement to the preparation time and yield of SiO₂@Au DNWs. Furthermore, these SiO₂@Au DNWs showed high morphological and dispersion stabilities compared with unsupported Au DNWs, and this method is expected to be the preparation method of supported shape-controlled nanocrystals with high morphological and dispersion stabilities.