Synthesis of anisotropic gold nano-micro crystals using by ionic liquid and water interface

Tetsuro Soejima, Nobuo Kimizuka

    Research output: Contribution to conferencePaperpeer-review


    A novel synthetic technique for gold nanosheets and hollow gold nanocapsules is developed. When aqueous HAuCl4 (pH 10, 1 mL) layered on C4mimPF6 (1-butyl-3-methylimidazolium hexafluorophosphate, 1 mL) was illuminated vertically with a super high pressure mercury lamp, gold nanosheets with thickness of ca. 30 nm are formed. The gold nanosheets are face-centered cubic (fee) single crystals with an atomically flat (111) surface as determined by electron diffraction analysis. Photoreduction of Au(III) ions did not proceed when aqueous HAuCl4 solution (pH 10) was photoirradiated in the absence of ionic liquid. Therefore, photoreduction occurs at the ionic liquid/water interface, and photo-excited C 4mimPF6 molecules may act as sacrificial electron donors to reduce Au(OH)4- ions. We also conducted the photoreduction by using microdroplets of C4mimPF6 in water. Ultrathin gold nanosheets with thickness of ca. 10 nm are obtained by photoilluminating mixture of C4mimPF6 (1 mL) and aqueous HAuCl4 (pH 10, 1 mL) under vigorous stirring. To our surprise, in the TEM observation of ultrathin gold nanosheets, moiré fringes are observed for overlapped portions. The observation confirms that the ultrathin gold nanosheets are single crystalline with homogeneous thickness. On the other hand, when a mixture of C4mimPF6 (1.8 mL) and aqueous HAuCl4 (pH 10, 0.2 mL) was illuminated under vigorously stirring, hollow gold microspheres with diameter less than 3 μm are obtained. In this case, water microdroplets in C4mimPF6 seem to act as template for the formation of hollow gold spheres.

    Original languageEnglish
    Number of pages2
    Publication statusPublished - Dec 1 2005
    Event54th SPSJ Symposium on Macromolecules - Yamagata, Japan
    Duration: Sept 20 2005Sept 22 2005


    Other54th SPSJ Symposium on Macromolecules

    All Science Journal Classification (ASJC) codes

    • Engineering(all)


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