Formation of Rectangularly Shaped Pd/Au Bimetallic Nanorods:  Evidence for Competing Growth of the Pd Shell between the {110} and {100} Side Facets of Au Nanorods

Xiang, Yanjuan; Wu, Xiaochun; Liu, Dongfang; Jiang, Xingyu; Chu, Weiguo; Li, Zhiyuan; Ma, Yuan; Zhou, Weiya; Xie, Sishen

doi:10.1021/nl061722c

Cited by 190 publications

(183 citation statements)

References 22 publications

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“…Recently, by coating Pd on the Au NR, we synthesized rectangular Au@Pd nanobars with a single-crystalline structure. [16] The lattice mismatch between Pt and Au (3.8 %) is smaller than that between Pd and Au (4.7 %). Therefore, the lattice mismatch Tuning the LSPR positions of the Au@Pt nanorods by varying Pt thickness: As shown in Figure 2, at Pt/Au ratios lower than 0.25, the LSPR band of the Au@Pt nanorods is redshifted with decreasing overall aspect ratio.…”

Section: Resultsmentioning

confidence: 93%

Well‐Controlled Synthesis of Au@Pt Nanostructures by Gold‐Nanorod‐Seeded Growth

Feng

Ren

et al. 2008

Chemistry A European J

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105

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Pt nanodots were formed on Au nanorods (NRs) by using a simple seed-mediated growth. Their density and distribution on the Au NR can be finely tuned by varying the reaction parameters. At lower Pt/Au ratios, the Pt nanodots mainly appear at endcaps and side edges of the Au rod. At higher Pt/Au ratios, they distribute homogeneously over the whole Au rod. The obtained Pt nanostructure is a single crystal owing to the epitaxial growth of Pt on the Au rod. Due to the unique surface plasmon resonance (SPR) features of the Au NRs, the Au core/Pt shell (Au@Pt) nanostructures also exhibit well-defined and red-shifted longitudinal SPR bands in the visible and near-infrared region. The position and intensity can be regulated by the thickness and amount of the Pt shell. At a thinner Pt thickness, the Au@Pt NRs show higher dielectric sensitivity than the corresponding Au NRs. It thus opens up the potential of Pt nanostructures for SPR-based sensing.

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Section: Resultsmentioning

confidence: 93%

Well‐Controlled Synthesis of Au@Pt Nanostructures by Gold‐Nanorod‐Seeded Growth

Feng

Ren

et al. 2008

Chemistry A European J

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105

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“…[14][15][16][17] This unique feature of metallic nanorods has already found several applications in nanotechnology [21] and biomedical research. [22,23] Moreover, four examples of bimetallic nanorods [24][25][26][27] have been described in the last few years. It is believed that bimetallic platinum-on-gold and palladium-on-gold nanostructures may open a new direction in the area of catalysis.…”

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confidence: 99%

Polymer‐Functionalized Platinum‐On‐Gold Bimetallic Nanorods

Khanal

Zubarev

2009

Angew Chem Int Ed

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Physical and chemical properties of nanosized crystals are known to be a function of their size, morphology, and chemical composition. [1][2][3][4][5][6] Hence, over the past decade many research groups have focused on controlling the shape of inorganic nanostructures, [7][8][9][10][11][12] and many low-symmetry nanocrystals have been produced. [13][14][15][16][17][18][19][20] In this respect, one-dimensional structures are particularly interesting objects whose optical and catalytic properties strongly depend on their shape anisometry. [14][15][16][17] This unique feature of metallic nanorods has already found several applications in nanotechnology [21] and biomedical research. [22,23] Moreover, four examples of bimetallic nanorods [24][25][26][27] have been described in the last few years. It is believed that bimetallic platinum-on-gold and palladium-on-gold nanostructures may open a new direction in the area of catalysis. [28][29][30] However, all bimetallic nanorods reported to date are only soluble in water and therefore cannot catalyze any reactions in organic solvents. In fact, there are no examples of any platinum or palladium nanostructures covalently functionalized with polymer chains, which could render them soluble in organic media. Herein we describe the first example of polymer-functionalized platinum-on-gold nanostructures. We use gold nanorods as templates and demonstrate how a polycrystalline continuous shell of platinum can be deposited on their surface and subsequently functionalized with organic molecules. In addition, we provide conclusive evidence of the functionalization of the platinum shell by direct visualization of the polymer surface layer by electron microscopy and its detection by 1 H NMR spectroscopy.The seed-mediated method developed by Murphy and coworkers [1] and later modified by El-Sayed and Nikoobakht [2] produces single-crystalline gold nanorods (Au NRs). However, the conversion of Au I ions to Au 0 in this method is only 10-15 %, [31] and the majority of ions remains in solution after the growth of Au NRs is complete. Our systematic studies revealed that the amount of ascorbic acid used for the reduction of Au I ions is critically important, and addition of 10 mol % ascorbic acid after completed nanorod growth makes their size distribution much narrower. Figure 1 a shows a representative TEM image of Au NRs prepared by this modified method. The analysis of 250 nanorods shown in Figure 1 a revealed that their average length and width measure 52.8 and 11.4 nm, respectively, and the standard deviation (SD) for both dimensions is less than 9 %. These results represents a significant improvement in comparison with Au nanorods prepared under the standard conditions (SD % 20 %). [1,2] Further introduction of ascorbic acid allows conversion of Au I ions remaining in the growth solution into metallic gold and its deposition onto the surface of Au NRs.[32] However, this rapid addition of ascorbic acid results in a nonuniform deposition of gold, and the shape of the nanorods changes to...

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“…Additionally, the same technique can be exploited for the synthesis of magnetic nanoshells, which are rare [9] but can be expected to display a large magnetic anisotropy, with potential uses in data storage. [10][11][12][13] The surface modification of gold nanorods has often been accomplished through coating with various materials, such as Ag, [14][15][16] Ag 2 S/Ag 2 Se, [17] SiO 2 , [18,19] Pd, [20] or Pt. [21] However, the synthesis of composite nanomaterials containing gold nanoparticles and a magnetic material (transition metals in particular) is complicated, [22] especially in the case of gold nanorods, [23] since they easily reshape at moderately high temperatures [24] that are typically used for synthesis in organic solvents.…”

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confidence: 99%

“…The gold nanorods used for this experiment (average aspect ratio 5.1) display a longitudinal surface-plasmon resonance band (LPB) centered at 895 nm, which during platinum tip growth was red-shifted by almost 80 nm, with a slight damping and broadening, as expected from our previous studies on this system. [21,29] The red-shift is associated to an increase in aspect ratio, while broadening and damping effects could be related to the inter- overcoating with Pd [20] and Pt. [21] These optical changes can be faithfully reproduced through simulations based on the boundary element method (BEM), [30,31] which has proven useful for several configurations, [32,33] including the modeling of platinum-overcoated and tip-coated gold nanorods.…”

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confidence: 99%

Quasi‐Epitaxial Growth of Ni Nanoshells on Au Nanorods

et al. 2007

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Magnetic nickel shells can be grown on gold nanorods with platinum tips by reduction of Ni2+ with hydrazine in aqueous cetyl‐trimethylammonium bromide (CTAB) solution, using Pt tips as catalysts. The plasmon absorption of the starting gold nanorods can be totally quenched by the metallic layer of nickel, while the magnetic character of these anisotropic, hybrid nanocrystals is demonstrated through alignment under an external magnetic field. Quasi‐epitaxial growth is demonstrated by HRTEM and electron diffraction (see figure).

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Formation of Rectangularly Shaped Pd/Au Bimetallic Nanorods: Evidence for Competing Growth of the Pd Shell between the {110} and {100} Side Facets of Au Nanorods

Cited by 190 publications

References 22 publications

Well‐Controlled Synthesis of Au@Pt Nanostructures by Gold‐Nanorod‐Seeded Growth

Well‐Controlled Synthesis of Au@Pt Nanostructures by Gold‐Nanorod‐Seeded Growth

Polymer‐Functionalized Platinum‐On‐Gold Bimetallic Nanorods

Quasi‐Epitaxial Growth of Ni Nanoshells on Au Nanorods

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