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Stabilization of 4H hexagonal phase in gold nanoribbons.

Fan Z, Bosman M, Huang X, Huang D, Yu Y, Ong KP, Akimov YA, Wu L, Li B, Wu J, Huang Y, Liu Q, Png CE, Gan CL, Yang P, Zhang H - Nat Commun (2015)

Bottom Line: These gold nanoribbons undergo a phase transition from the original 4H hexagonal to face-centred cubic structure on ligand exchange under ambient conditions.Furthermore, the 4H hexagonal phases of silver, palladium and platinum can be readily stabilized through direct epitaxial growth of these metals on the 4H gold nanoribbon surface.Our findings may open up new strategies for the crystal phase-controlled synthesis of advanced noble metal nanomaterials.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.

ABSTRACT
Gold, silver, platinum and palladium typically crystallize with the face-centred cubic structure. Here we report the high-yield solution synthesis of gold nanoribbons in the 4H hexagonal polytype, a previously unreported metastable phase of gold. These gold nanoribbons undergo a phase transition from the original 4H hexagonal to face-centred cubic structure on ligand exchange under ambient conditions. Using monochromated electron energy-loss spectroscopy, the strong infrared plasmon absorption of single 4H gold nanoribbons is observed. Furthermore, the 4H hexagonal phases of silver, palladium and platinum can be readily stabilized through direct epitaxial growth of these metals on the 4H gold nanoribbon surface. Our findings may open up new strategies for the crystal phase-controlled synthesis of advanced noble metal nanomaterials.

No MeSH data available.


TEM analysis and crystal models of 4H Au NRBs.(a) A typical TEM image of 4H Au NRBs (scale bar, 100 nm). (b,c) TEM image (scale bar, 100 nm) and the corresponding SAED pattern taken along the [110]4H zone axis of a typical Au NRB. (d,e) Aberration-corrected HRTEM images taken in the centre and at the edge of an Au NRB, respectively (scale bars, 1 nm). (f) Schematic illustration of a unit cell of 4H Au. The simulated unit cell parameters are a=2.866 Å and c=9.662 Å. (g) Crystallographic models illustrating the top view (top panel) and side view (bottom panel) of a typical 4H Au NRB. The close-packed planes along the [001]4H direction show a characteristic stacking sequence of ‘ABCB'.
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f1: TEM analysis and crystal models of 4H Au NRBs.(a) A typical TEM image of 4H Au NRBs (scale bar, 100 nm). (b,c) TEM image (scale bar, 100 nm) and the corresponding SAED pattern taken along the [110]4H zone axis of a typical Au NRB. (d,e) Aberration-corrected HRTEM images taken in the centre and at the edge of an Au NRB, respectively (scale bars, 1 nm). (f) Schematic illustration of a unit cell of 4H Au. The simulated unit cell parameters are a=2.866 Å and c=9.662 Å. (g) Crystallographic models illustrating the top view (top panel) and side view (bottom panel) of a typical 4H Au NRB. The close-packed planes along the [001]4H direction show a characteristic stacking sequence of ‘ABCB'.

Mentions: The Au NRBs were prepared by heating the mixture of HAuCl4, oleylamine, hexane and 1,2-dichloropropane in a closed glass vial at 58 °C for 16 h (see Methods for details). The obtained Au NRBs with length of 0.5–6.0 μm and width of 15.0–61.0 nm are confirmed using the transmission electron microscope (TEM) images (Fig. 1a,b and Supplementary Fig. 1). The thickness of the Au NRBs is estimated to be 2.0–6.0 nm from TEM images of their folded edges (Supplementary Fig. 2), which is further confirmed using atomic force microscopy (AFM) imaging (Supplementary Fig. 3). Scanning TEM-energy dispersive X-ray spectrum (STEM-EDS) reveals that the chemical composition of as-prepared NRBs is pure Au (Supplementary Fig. 4). The surface of Au NRBs is capped by the oleylamine molecules, as evidenced using the X-ray photoelectron spectroscopy analysis (Supplementary Fig. 5). Note that the use of 1,2-dichloropropane is essential for the synthesis of Au NRBs. Without the addition of 1,2-dichloropropane, only twinned fcc Au NPs and very small amount of ultrathin Au nanowires (NWs) were obtained (Supplementary Fig. 6).


Stabilization of 4H hexagonal phase in gold nanoribbons.

Fan Z, Bosman M, Huang X, Huang D, Yu Y, Ong KP, Akimov YA, Wu L, Li B, Wu J, Huang Y, Liu Q, Png CE, Gan CL, Yang P, Zhang H - Nat Commun (2015)

TEM analysis and crystal models of 4H Au NRBs.(a) A typical TEM image of 4H Au NRBs (scale bar, 100 nm). (b,c) TEM image (scale bar, 100 nm) and the corresponding SAED pattern taken along the [110]4H zone axis of a typical Au NRB. (d,e) Aberration-corrected HRTEM images taken in the centre and at the edge of an Au NRB, respectively (scale bars, 1 nm). (f) Schematic illustration of a unit cell of 4H Au. The simulated unit cell parameters are a=2.866 Å and c=9.662 Å. (g) Crystallographic models illustrating the top view (top panel) and side view (bottom panel) of a typical 4H Au NRB. The close-packed planes along the [001]4H direction show a characteristic stacking sequence of ‘ABCB'.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4525209&req=5

f1: TEM analysis and crystal models of 4H Au NRBs.(a) A typical TEM image of 4H Au NRBs (scale bar, 100 nm). (b,c) TEM image (scale bar, 100 nm) and the corresponding SAED pattern taken along the [110]4H zone axis of a typical Au NRB. (d,e) Aberration-corrected HRTEM images taken in the centre and at the edge of an Au NRB, respectively (scale bars, 1 nm). (f) Schematic illustration of a unit cell of 4H Au. The simulated unit cell parameters are a=2.866 Å and c=9.662 Å. (g) Crystallographic models illustrating the top view (top panel) and side view (bottom panel) of a typical 4H Au NRB. The close-packed planes along the [001]4H direction show a characteristic stacking sequence of ‘ABCB'.
Mentions: The Au NRBs were prepared by heating the mixture of HAuCl4, oleylamine, hexane and 1,2-dichloropropane in a closed glass vial at 58 °C for 16 h (see Methods for details). The obtained Au NRBs with length of 0.5–6.0 μm and width of 15.0–61.0 nm are confirmed using the transmission electron microscope (TEM) images (Fig. 1a,b and Supplementary Fig. 1). The thickness of the Au NRBs is estimated to be 2.0–6.0 nm from TEM images of their folded edges (Supplementary Fig. 2), which is further confirmed using atomic force microscopy (AFM) imaging (Supplementary Fig. 3). Scanning TEM-energy dispersive X-ray spectrum (STEM-EDS) reveals that the chemical composition of as-prepared NRBs is pure Au (Supplementary Fig. 4). The surface of Au NRBs is capped by the oleylamine molecules, as evidenced using the X-ray photoelectron spectroscopy analysis (Supplementary Fig. 5). Note that the use of 1,2-dichloropropane is essential for the synthesis of Au NRBs. Without the addition of 1,2-dichloropropane, only twinned fcc Au NPs and very small amount of ultrathin Au nanowires (NWs) were obtained (Supplementary Fig. 6).

Bottom Line: These gold nanoribbons undergo a phase transition from the original 4H hexagonal to face-centred cubic structure on ligand exchange under ambient conditions.Furthermore, the 4H hexagonal phases of silver, palladium and platinum can be readily stabilized through direct epitaxial growth of these metals on the 4H gold nanoribbon surface.Our findings may open up new strategies for the crystal phase-controlled synthesis of advanced noble metal nanomaterials.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.

ABSTRACT
Gold, silver, platinum and palladium typically crystallize with the face-centred cubic structure. Here we report the high-yield solution synthesis of gold nanoribbons in the 4H hexagonal polytype, a previously unreported metastable phase of gold. These gold nanoribbons undergo a phase transition from the original 4H hexagonal to face-centred cubic structure on ligand exchange under ambient conditions. Using monochromated electron energy-loss spectroscopy, the strong infrared plasmon absorption of single 4H gold nanoribbons is observed. Furthermore, the 4H hexagonal phases of silver, palladium and platinum can be readily stabilized through direct epitaxial growth of these metals on the 4H gold nanoribbon surface. Our findings may open up new strategies for the crystal phase-controlled synthesis of advanced noble metal nanomaterials.

No MeSH data available.