Gold hierarchical nanostructures formed at the solid/liquid interfaces via electroless deposition and their SERS properties

Flowerlike, dendritic and snowflake-like gold hierarchical nanostructures were prepared at the carbon-coated copper grid/Langmuir monolayer/HAuCl4 aqueous solution interfaces under different Langmuir monolayers through an electroless deposition process. The morphology and structure of these nanostructures were characterized by using transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and scanning electron microscopy (SEM), and the surface enhanced Raman scattering performance of these nanostructures was tested. It was found Langmuir monolayers between the copper grids and the aqueous solutions played an important role in the formation of the nanostructures and affected the morphology and structure of the nanostructures greatly. The formation of these nanostructures was attributed to the galvanic reduction between AuCl4− and Cu and electrochemical deposition, the conductivity of the carbon layer for electrons, non-equilibrium growth of the nanostructures, and templating effect of the Langmuir monolayers. These nanostructures exhibited high surface enhanced Raman scattering (SERS) performance.