Facet Control of Gold Nanorods

Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A.; Lin, Ye; Xin, Huolin L.; Wang, Hui

doi:10.1021/acsnano.6b00258

Cited by 139 publications

(110 citation statements)

References 105 publications

(275 reference statements)

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“…The gradually formed Au ions may act as structure-directing foreign ions that preferentially adsorb onto the different BiVO 4 surfaces to engineer high-index surfaces via thermodynamic control, kinetic control, and selective chemical etching. [30] A similar Au ionguided formation of truncated octahedral and cuboctahedral Cu 2 O has been reported. [31] Interestingly, the direct addition of the same amount of AuCl 4 − into the reaction system leads to According to Steno's law, the Miller indices of the exposed polyhedra facets can be assigned according to the angles between corresponding facets because the angles are always constant.…”

Section: Polyhedral 30-faceted Bivo 4 Microcrystals Predominantly Encsupporting

confidence: 62%

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

et al. 2017

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High-index crystal facets, denoted by a set of Miller indices {hkl} with at least one index greater than unity, possess a high density of low-coordinated atoms, steps, edges, and kinks that serve as highly active catalytic sites. [1][2][3] High-index surfaces normally grow faster than lowindex ones and are usually lost during crystal growth due to minimization of the total surface energy. Although the selective exposure of high-index facets at the surface is an important and challenging research topic, much progress has been made in the formation of many kinds of relevant noble metal nanocrystals, which have been extensively applied in catalytic reactions, including those in fuel cells, [4] photocatalysis, [5][6][7] electrocatalysis, [8,9] and petroleum catalytic reforming. [10] However, the generation of metal oxide micro-and nanocrystallites with high-index surfaces is comparatively more difficult due to the presence of strong metal-oxygen bonds and diverse crystal packing structures. [11] Only a few binary metal oxides, such as Co 3 O 4 , [12] anatase TiO 2 , [13][14][15] Fe 3 O 4 , [16] Cu 2 O, [17,18] and SnO 2 , [19] have been successfully achieved. Multinary metal oxide crystals are relatively more meaningful than binary ones because they not only possess more complex functions, but their properties also be readily adjusted by tuning the ratio of the component elements. Bismuth vanadate (BiVO 4 ) attracts intense interest as one of the most promising visible-light-active photocatalysts for water oxidation, due to its appropriate valence band edge located at ≈2.4 eV versus normal hydrogen electrode (NHE). [20] Varieties of morphological BiVO 4 , which are generally enclosed by lowindex {111}, {110}, or {100} planes, were formed through control of the synthetic methods and experimental conditions. [21][22][23] The photocatalytic behavior of BiVO 4 is highly dependent on its surface structure, in which photogenerated electrons and holes can be preferentially separated and accumulated on {010} and {110} facets, respectively, via the driving force created by the different band energies of the two facets. [24,25] Herein, we report the synthesis unprecedented 30-faceted BiVO 4 polyhedra predominantly surrounded by high-index {132}, {321}, and {121} facets. These BiVO 4 materials exhibit 3-5 time enhancements in O 2 evolution from photocatalytic water oxidation, relatively to that of low-indexed counterparts. Theory calculations reveal that the high-index surfaces are energetically favorable for water dissociation and exhibit a notable reduction in the overpotential (0.77-1.14 V) of the oxygen Unprecedented 30-faceted BiVO 4 polyhedra predominantly surrounded by {132}, {321}, and {121} high-index facets are fabricated through the engineering of high-index surfaces by a trace amount of Au nanoparticles. The growth of high-index facets results in a 3-5 fold enhancement of O 2 evolution from photocatalytic water splitting by the BiVO 4 polyhedron, relative to its low-index counterparts. Theory calculations reveal th...

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Section: Polyhedral 30-faceted Bivo 4 Microcrystals Predominantly Encsupporting

confidence: 62%

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

et al. 2017

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“…In the absence of Ag + ions, the Au NRs transformed into elongated trisoctahedral nanoparticles (ETOH NPs) ( Figure 1B), which is in line with our previous observations. 69 Overgrowth of quasi-spherical Au nanoparticles under similar conditions resulted in the formation of high-index faceting nanotrisoctahedrons each of which was enclosed by 24 {221} facets. 34 In the presence of Ag + ions, strikingly different geometric transformations were observed upon NR overgrowth.…”

Section: Resultsmentioning

confidence: 99%

“…60 Recently, we further demonstrated that more rigorous control of Au NR facets with atomic level precision could be achieved using cuprous (Cu + ) foreign ions and halide-containing surfactants as unique pairs of surface capping competitors to maneuver the facet evolution during NR overgrowth. [68][69] In comparison to Cu + ions, Ag + ions have been more widely used in combination with various surfactants to guide the morphology-controlled overgrowth of Au NRs. A large variety of NR-derived anisotropic geometries, such as nanodumbbells, starfruit-shaped NRs, dogbone-like NRs, concave nanocuboids, and arrow-headed NRs, have been obtained through Ag + -and CTAB-coguided NR overgrowth processes.…”

Section: Introductionmentioning

confidence: 99%

Intertwining Roles of Silver Ions, Surfactants, and Reducing Agents in Gold Nanorod Overgrowth: Pathway Switch between Silver Underpotential Deposition and Gold–Silver Codeposition

Zhang

Jing

et al. 2016

Chem. Mater.

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The past two decades have witnessed great success achieved in the geometry-controlled synthesis of metallic nanoparticles using the seed-mediated nanocrystal growth method. Detailed mechanistic understanding of the synergy among multiple key structure-directing agents in the nanocrystal growth solutions, however, has long been lagging behind the development and optimization of the synthetic protocols. Here we investigate the foreign ion-and surfactant-coguided overgrowth of singlecrystalline Au nanorods as a model system to elucidate the intertwining roles of Ag + foreign ions, surface-capping surfactants, and reducing agents that underpin the intriguing structural evolution of Au nanocrystals. The geometry-controlled nanorod overgrowth involves two distinct underlying pathways, Ag underpotential deposition and Au-Ag electroless codeposition, which are interswitchable upon maneuvering the interplay of the Ag + ions, surfactants, and reducing agents. The pathway switch governs the geometric and compositional evolution of nanorods during their overgrowth, allowing the cylindrical Au nanorods to selectively transform into a series of anisotropic nanostructures with interesting geometric, compositional, and plasmonic characteristics. The insights gained from this work shed light on the mechanistic complexity of geometry-controlled nanocrystal growth and may guide the development of new synthetic approaches to metallic nanostructures with increasing architectural complexity, further enhancing our capabilities of fine-tuning the optical, electronic, and catalytic properties of the nanoparticles.

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“…9,22,23 Moreover, precise facet control is vital to the optimization of the catalytic performance of GNRs. Quantitative assignment of the crystallographic facets exposed on the surfaces of GNRs, however, has long been a subject under intense debate.…”

Section: -21mentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9] GNRs exhibit intense longitudinal surface plasmon resonance (LSPR), whose wavelength is controlled by the ratio of the length to the width of the GNRs (the aspect ratio, AR), as well as a weaker transverse surface plasmon resonance (TSPR) that is located at $520 nm. [2][3][4][5][6][7][8][9] The LSPR is tuned towards longer wavelengths and into the near-infrared spectrum as the AR increases. To date, a number of successful methods, such as electrochemical, 1 photochemical, 10,11 seed-mediated, 12 and template methods, 13 have been developed to synthesize GNRs.…”

Section: Introductionmentioning

confidence: 99%

High-yield synthesis and fine-tuning aspect ratio of (200) faceted gold nanorods by the pH-adjusting method

Leng

Yin

et al. 2017

RSC Adv.

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Tight-controlling of the aspect ratios (ARs) and fine-tailoring of the crystallographic facets of gold nanorods (GNRs) are critical for their further applications in material, biological, and medical fields. However, the highyield synthesis of GNRs with certain facets and ARs is still challenging because it requires grasping of various components and complicated interactions in the reaction system. Herein, we first report the pH-adjusting method to synthesize uniform and monodispersed GNRs in high yield with the (200) facet and fine-tuned their ARs within an optimal pH range. Through optimizing the experimental parameters, we found that the formation of GNRs was significantly influenced by the concentrations of silver ions and cetyltrimethylammonium bromide (CTAB). Based on the precise control over the quantity of silver ions and CTAB additives, we further optimized the pH in the buffer system. Under the optimized weakly acidic conditions (pH 5.5-7.0), HAuCl 4 was reduced by NH 2 OH to form single-crystalline GNRs with a preferential growth along the [200] facet (i.e.[100] direction), which was supported by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Interestingly, there was a linear relationship between the ARs and pH values over a narrow pH range of 5.5-6.5. The pH-dependent reducing ability of NH 2 OH enhanced with the increasing pH.

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Facet Control of Gold Nanorods

Cited by 139 publications

References 105 publications

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

Intertwining Roles of Silver Ions, Surfactants, and Reducing Agents in Gold Nanorod Overgrowth: Pathway Switch between Silver Underpotential Deposition and Gold–Silver Codeposition

High-yield synthesis and fine-tuning aspect ratio of (200) faceted gold nanorods by the pH-adjusting method

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Facet Control of Gold Nanorods

Cited by 139 publications

References 105 publications

Polyhedral 30‐Faceted BiVO4 Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

Polyhedral 30‐Faceted BiVO4 Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

Intertwining Roles of Silver Ions, Surfactants, and Reducing Agents in Gold Nanorod Overgrowth: Pathway Switch between Silver Underpotential Deposition and Gold–Silver Codeposition

High-yield synthesis and fine-tuning aspect ratio of (200) faceted gold nanorods by the pH-adjusting method

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Product

Resources

About

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity

Polyhedral 30‐Faceted BiVO₄ Microcrystals Predominantly Enclosed by High‐Index Planes Promoting Photocatalytic Water‐Splitting Activity