Synthesis of Micronsized Gold Nanoplates at Low Precursor Concentration Using Ionic Liquid as Novel Subphase Solvent

The micronsized gold nanoplates were successfully synthesized under Langmuir monolayer of 1-hexadecyl-3-methylimidazolium bromide (C16mimBr) when the room temperature ionic liquid ethylammonium nitrate (EAN) was used as the novel subphase solvent. Due to strong electrostatic interaction, the C16mim+ cations can arrange closely at the EAN surface to form a compact monolayer. At the low precursor concentration, the sizes of obtained gold nanoplates in EAN solution are much larger than that in aqueous solution. The effects of the novel subphase solvent were further demonstrated with the assistance of the energy calculation methods. The delicate equilibrium among nucleation, diffusion and growth rates plays the key role in the formation of larger nanoplates. By the control experiment with a cationic fluorocarbon surfactant, the mechanism was proposed and further demonstrated.