Novel two-step synthesis of various gold nanostructures using Langmuir monolayers

Ribbon-like, wedge-shaped, and spherical gold nanostructures were prepared via a novel two-step growth method. Various gold nanostructures were first pre-formed in aqueous solution by using β-cyclodextrin (β-CD) as both reducing and capping agent. Due to the continuous growth of the pre-formed gold nanostructures at the air/water interface with the help of the Langmuir monolayers of 1-hexadecyl-3-methylimidazolium bromide (C16mimBr), morphology changes can be observed obviously. The gold nanostructures were characterized by transmission electron microscopy (TEM) and UV–vis spectroscopy. A possible mechanism based on the interaction between β-CD and the pre-formed gold nanostructures is proposed.

Gold nanostructures of various morphologies were prepared via a two-step growth method. Controlled synthesis of gold nanostructures in aqueous solution was realized by varying the ratios of β-CD-to-HAuCl4, and the β-CD was as both reducing and capping agent. Through their continuous growth with the aid of Langmuir monolayers, ribbon-like, wedge-shaped and spherical gold nanostructures were obtained.Figure optionsDownload as PowerPoint slideHighlights
► Seed-mediated growth and Langmuir–Blodgett technique are combined to prepare the gold nanostructures.
► Various gold nanostructures were first pre-formed in aqueous solution by varying the ratio β-CD-to-HAuCl4.
► A delicate adsorbing equilibrium caused by the variety of molar ratios of β-CD-to-HAuCl4 plays a key role in the continuous growth at the air/water interface.