Growth of Monodisperse Gold Nanospheres with Diameters from 20 nm to 220 nm and Their Core/Satellite Nanostructures

Abstract

Gold nanocrystals and nanoassemblies have attracted extensive attention for various applications, including chemical and biological sensing, solar energy harvesting, and plasmon‐enhanced spectroscopies, due to their unique plasmonic properties. It is of great importance to prepare shape‐controlled Au nanocrystals with high monodispersity over a large range of sizes. In this work, Au nanospheres with sizes ranging from 20 nm to 220 nm are prepared using a simple seed‐mediated growth method aided with mild oxidation. As‐prepared Au nanospheres are remarkably uniform in size. The resultant Au nanospheres of different sizes are ideal building blocks for constructing plasmonic nanoassemblies. Core/satellite nanostructures are assembled out of differently sized Au nanospheres with molecular linkers. The core/satellite nanostructures show a red‐shifted plasmon resonance peak in comparison to that of the Au cores, which is consistent with the results calculated according to Mie theory. As predicted by finite‐difference time‐domain simulations, the assembled core/satellite nanostructures exhibit strongly enhance Raman signals. This facile growth of Au nanospheres and assembly of core/satellite nanostructures are expected to facilitate the design of new nanoassemblies with desired plasmonic properties and functions.