Gold Microplates with Well‐Defined Shapes

Kan, Caixia; Wang, Changshun; Li, Hongchen; Qi, Jingshan; Zhu, Jun; Li, Zhaosheng; Shi, Dan

doi:10.1002/smll.201000600

Cited by 48 publications

(27 citation statements)

References 64 publications

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“…Hence, the polar etchant like O2/Br -may not able to attack the {111} facets. In addition, higher surface energy of the Au{100} facet also facilitates selective etching of the {100} facet [4]. Atmospheric oxygen in combination with the halide anion available in the reaction medium (see Fig.…”

Section: Adsorption Of Tetraoctylammonium Cation (Toa + ) On the {111mentioning

confidence: 98%

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Facet selective etching of Au microcrystallites

Mettela

2015

Nano Res.

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Selectively, the {100} and {111} facets of Au microcrystallites are etched using a capping method. The specific etchants etch the facets that are free of capping agents and produce crystallites with well-defined corrugation involving high-index microfacets. Such facets exhibit enhanced Raman activity compared to smooth facets. Provide the authors' website if possible. ABSTRACTHigh symmetry crystals, by nature, exhibit isotropic properties. Inducing anisotropy for example by facet selective etching, is considered implausible in face centered cubic (FCC) metals, particularly in gold, which besides being FCC, is also noble. Here, for the first time, facet selective etching of Au microcrystals obtained in the form of cuboctahedrons and pentagonal rods from thermolysis of a gold-organic precursor is reported. The selective etching of {111} and {100} facets has been achieved via a capping method. In this method, tetraoctylammonium cations selectively cap the {111} facets, while Br -ions protect the {100} facets. The exposed facets are oxidized by O2/Cl -, producing a variety of interesting geometries. Facet selective etching of Au microcrystallites is governed only by the nature of the facets as geometry does not seem to play any significant role. Etched surfaces appear rough but a closer examination reveals well-defined corrugations indexable to high hkl values. Such surfaces exhibit enhanced Raman activity.

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Section: Adsorption Of Tetraoctylammonium Cation (Toa + ) On the {111mentioning

confidence: 98%

“…There are few reports on anisotropic etching of nanoparticles of noble metals. Etching of a nanoparticle facet is dependent on its surface energy () and the general trend is (110)>(100)>(111) [4]. Hence, it is expected that the {110}, {100} and {111} facets show high, medium and low reactivities with a given etchant.…”

Section: Introductionmentioning

confidence: 97%

Facet selective etching of Au microcrystallites

Mettela

2015

Nano Res.

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“…In this case, solution-phase crystal growth is usually far from the thermodynamic theory in which the final crystal shape is determined such that the total free energy of the system is minimized; rather, the growth rate of each face is determined by kinetics [32]. In particular, capping agents have been widely used to control the growth rate of different crystal facets.…”

Section: Introductionmentioning

confidence: 99%

Alkylamine-mediated synthesis and optical properties of copper nanopolyhedrons

Gao

Kan

et al. 2016

Res Chem Intermed

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An alkylamine-mediated hydrothermal synthesis method is proposed for fabrication of copper (Cu) nanopolyhedrons (including tetrahedral and cubic shapes) with well-defined facets and controllable size by modulating the coordination chemistry of a sole ligand (hexadecylamine, HDA) or dual ligands [HDA and octadecylamine (ODA)]. The size of the nanopolyhedrons increases with decreasing HDA/ODA mole ratio. Both the nanocubes and nanotetrahedrons are single-crystal structures, bound by six {100} or four {111} facets, respectively. The complexation reaction temperature plays a vital role in determining the final morphology of the as-prepared nanocrystals. High complexation reaction temperature is suitable for generation of single-crystalline Cu nuclei and their further growth into nanocubes and nanotetrahedrons, while low temperature leads to formation of multitwinned crystal seeds that finally develop into nanowires. Moreover, the probable aggregative growth is discussed to explain the growth mechanism of the Cu nanopolyhedrons. In addition, double surface plasmon resonance peaks are observed in the absorbance spectra for the Cu nanopolyhedrons with relatively large size. Finitedifference time-domain simulations reveal that the experimental absorption spectra are the superposition of those for nanocubes and nanotetrahedrons in different proportions. The peak at about 600 nm in the experimental spectra mainly originates from the Cu nanocubes, while the absorption from 750 to 950 nm derives from the Cu nanotetrahedrons. These angular Cu nanocubes and nanotetrahedrons may have potential applications in surface-enhanced Raman scattering and catalysis.Electronic supplementary material The online version of this article (

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“…The {110} and {211} faces have surface energies of 0.0991 and 0.0908 eV/Å −2 respectively. Hence a faster growth along the <110> direction is expected30. The growth rate along the <112> direction comes next29.…”

Section: Resultsmentioning

confidence: 98%

Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

Mettela

Radha

Singh

et al. 2013

Sci Rep

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Focusing light at sub-wavelength region opens up interesting applications in optical sensing and imaging beyond the diffraction limit. In the past, tapered Au wires with carved gratings have been employed to achieve nanofocusing. The fabrication process however, is expensive and the obtained wires are polycrystalline with high surface roughness. A chemical synthetic method overcoming these hurdles should be an attractive alternative. Here, we report a method to chemically synthesize Au microcrystals (~10 μm) bearing pentagonal bipyramidal morphology with surface corrugations assignable to high index planes. The method is a single step solid state synthesis at a temperature amenable to common substrates. The microcrystals are tapered at both ends forming sharp tips (~55 nm). Individual microcrystals have been used as pick and probe SERS substrates for a dye embedded in a polymer matrix. The unique geometry of the microcrystal also enables light propagation across its length.

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Gold Microplates with Well‐Defined Shapes

Cited by 48 publications

References 64 publications

Facet selective etching of Au microcrystallites

Facet selective etching of Au microcrystallites

Alkylamine-mediated synthesis and optical properties of copper nanopolyhedrons

Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

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