Synthesis of gold nanostructures using Langmuir monolayers of ionic liquid-type Gemini imidazolium surfactants

Gold nanostructures are successfully synthesised under Langmuir monolayers of ionic liquid-type Gemini imidazolium surfactants [Cnim-4-Cnim][Br₂] (n=10, 16) through interfacial reduction of AuCl₄^- by formaldehyde gas. The Au nanostructures are characterised using transmission electron microscopy and UV-vis spectroscopy. It is found that the concentration of HAuCl₄ aqueous solution, the surface pressure and the length of the hydrophobic chains of the surfactants strongly influence the formation of Au nanostructures. A potential mechanism of such diverse morphologies is also discussed.