Characterization by transmission electron microscopy and small-angle X-ray scattering of Au clusters formed in ionic liquids

Au vapor was deposited on the surface of ionic liquids such as 1-ethyl-3-methyl-imidazolium dicyanamide (Emim-DCA) and 1-buthyl-3-methyl-imidazolium bis(trifluorosulpheniy)imide (Bmim-TFSI). Au clusters were formed in the ionic liquid by adjusting the deposition rate. Transmission electron microscope measurements showed that the large Au clusters formed in Emim-DCA had a face-centered cubic crystal structure, while the small Au clusters had a decahedral structure. Furthermore, small-angle X-ray scattering measurements showed that the average diameter of Au clusters was in the range of 1 to 6 nm, and the cluster size decreased with increasing deposition rate. The average diameter of Au clusters formed in Bmim-TFSI was in the range of 0.5 to 4.5 nm, which is smaller than that of Au clusters in Emim-DCA, and most of the crystal structures were decahedrons. Copyright © 2016 John Wiley & Sons, Ltd.