Colloidal Hybrid Nanostructures: A New Type of Functional Materials

Costi, Ronny; Saunders, Aaron E.; Banin, Uri

doi:10.1002/anie.200906010

Cited by 753 publications

(667 citation statements)

References 188 publications

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“…Integrating different metallic NCs into a HMNC can introduce new and enhanced properties, or multi-functionality not found in the parent metal NCs [1][2][3][4][5][6][7] . The properties of a HMNC are clearly architecture dependent [7][8][9][10][11][12][13][14][15][16][17] .…”

Section: Spatial Arrangement Edge Satellitementioning

confidence: 99%

Engineering the architectural diversity of heterogeneous metallic nanocrystals

et al. 2013

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Similar to molecular engineering where structural diversity is used to create more property variations for application explorations, the architectural engineering of heterogeneous metallic nanocrystals (HMNCs) can likewise increase the versatility of metallic nanocrystals (NCs). Here we present a synthesis strategy capable of engineering the architectural diversity of HMNCs through rational and independent programming of every architecture-determining element, that is, the shape and size of the component NCs and their spatial arrangement. The strategy is based on the galvanic replacement reaction of a self-sustaining layer formed by underpotential deposition on a polyhedral NC. The selective deposition of satellite NCs on specific site of the central NC is realized by creating a geometry-dependent heterogeneous electron distribution. This site-selective deposition approach is applicable to central NCs in various polyhedral shapes and sizes. The satellite NCs can further develop their own shape and size through crystal growth kinetics control.

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Section: Spatial Arrangement Edge Satellitementioning

confidence: 99%

Engineering the architectural diversity of heterogeneous metallic nanocrystals

et al. 2013

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“…[1][2][3][4][5][6] Catalytic activity of the supported catalyst is dependent on not only the size of metal NPs but also the metal-support interaction. [7][8][9][10][11][12][13] Strong metal-support interaction in which metals are anchored on active transition metal oxides such as TiO 2 , 14-19 CeO 2 , 20-24 and Fe 2 O 3 25-27 provides high activity for several reactions such as hydrogenation, [28][29][30] CO oxidation, [31][32][33][34][35] and water-gas shift reaction.…”

Section: Introductionmentioning

confidence: 99%

Confined Pt and CoFe₂O₄Nanoparticles in a Mesoporous Core/Shell Silica Microsphere and Their Catalytic Activity

Kang¹,

Eum²,

Lee³

et al. 2011

Bulletin of the Korean Chemical Society

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Confined Pt and CoFe 2 O 4 nanoparticles (NPs) in a mesoporous core/shell silica microsphere, Pt-CoFe 2 O 4 @meso-SiO 2 , were prepared using a bi-functional linker molecule. A large number of Pt NPs in Pt-CoFe 2 O 4 @meso-SiO 2 , ranging from 5 to 8 nm, are embedded into the shell and some of them are in close contact with CoFe 2 O 4 NPs. The hydrogenation of cyclohexene over the Pt-CoFe 2 O 4 @meso-SiO 2 microsphere at 25 o C and 1 atm of H 2 yields cyclohexane as a major product. In addition, it gives oxygenated products. Control experiments with 18O-labelled water and acetone suggest that surface-bound oxygen atoms in CoFe 2 O 4 are associated with the formation of the oxygenated products. This oxidation reaction is operative only if CoFe 2 O 4 and Pt NPs are in close contact. The Pt-CoFe 2 O 4 @meso-SiO 2 catalyst is separated simply by a magnet, which can be re-used without affecting the catalytic efficiency.

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“…4 Interest in the synthesis of colloidal semiconductorÀmetal hybrid nanostructures has grown exponentially in recent years. 1 33 Some of these reports build upon earlier work on the surface modification of microcrystalline semiconductors using platinum group metals as a way to generate hydrogen evolving photocatalysts, for example, CdSÀPt doped wth Zn and Ag sulfides, 34,35 and powders made of MS/CdS/M(M = Pt, Ir), 36Received: May 27, 2011 Revised:June 27, 2011ABSTRACT: Reliable synthesis of semiconductorÀmetal heterostructures would increase their availability for fundamental studies and applications in catalytic, magnetic, and opto-electronic devices. Here, we demonstrate there are three main pathways for the formation of Pt and Pd nanoparticles on CdS and CdS 0.4 Se 0.6 nanorods.…”

mentioning

confidence: 99%

Controlled Fabrication of Colloidal Semiconductor–Metal Hybrid Heterostructures: Site Selective Metal Photo Deposition

2011

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Reliable synthesis of semiconductor-metal heterostructures would increase their availability for fundamental studies and applications in catalytic, magnetic, and opto-electronic devices. Here, we demonstrate there are three main pathways for the formation of Pt and Pd nanoparticles on CdS and CdS 04 Se 0.6 nanorods. A thermal pathway and photochemical pathway occur when the metal precursor is heated or irradiated directly in the presence of an electron donor, leading to homogeneous nucleation and formation of freestanding metal nanoparticles. A separate photochemical pathway occurs in the presence of semiconductor nanorods, leading to exciton formation and quenching by electron trapping at surface defect sites. The localized electrons act as seeding points, leading to heterogeneous nucleation and formation of surface-bound metal nanoparticles. Careful selection of synthetic conditions allows deposition of Pt and Pd particles on CdS and CdS 0.4 Se 0.6 nanorods with a high degree of selectivity (90-95% surface-bound obtained photochemically) over the formation of freestanding metal particles (70-94% unattached under thermal conditions). In addition, metal photo deposition occurs on specific segments of CdS 0.4 Se 0.6 nanorods with compositional anisotropy by taking advantage of the band gap differential between different nanodomains. Irradiation at short wavelengths favors formation of Pd nanoparticles on the large band gap CdS-rich region of the nanorods (57% and 55% at 350 and 420 nm, respectively), while irradiation at longer wavelengths favors the formation of Pd nanoparticles on the small band gap CdSe-rich region of the nanorods (83% at 575 nm). The ability to tune the spatial composition of these and similar heterostructures will impact the ability to engineer and direct energy flows at the nanoscale. ' INTRODUCTIONSemiconductorÀmetal hybrid heterostructures are promising building blocks for applications in catalytic, magnetic, and optoelectronic devices. 1À7 The semiconductor's tunable band gap (300À4000 nm 4.1À0.3 eV), 8,9 broad and intense absorption (ε ≈ 10 5 À10 6 L mol À1 cm À1 ), 10 and long-lived exciton (up to 40 ns for CdSe, 1.8 μs for PbS) 11,12 provide unmatched light absorption and emission capabilities. Large aspect ratio semiconductors such as nanorods are of particular interest because of their ability to generate multiple excitons. 13,14 The metal can serve as an additional chromophore, fluorescence enhancer, paramagnet, or charge-collecting material where carriers localize after exciton quenching. For example, semiconductorÀmetal hybrid heterostructures have been shown to convert solar energy into potential and chemical energy. They become redox-active upon illumination and remain redox-active after being stored in the dark for several hours. 15 In addition, semiconductor and metal nanocrystals display a high degree of chemical-, photo-, and colloidal-stability (solubility) unmatched by other materials such as organic polymers and transition metal complexes. The ability to selecti...

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Colloidal Hybrid Nanostructures: A New Type of Functional Materials

Cited by 753 publications

References 188 publications

Engineering the architectural diversity of heterogeneous metallic nanocrystals

Engineering the architectural diversity of heterogeneous metallic nanocrystals

Confined Pt and CoFe₂O₄Nanoparticles in a Mesoporous Core/Shell Silica Microsphere and Their Catalytic Activity

Controlled Fabrication of Colloidal Semiconductor–Metal Hybrid Heterostructures: Site Selective Metal Photo Deposition

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Colloidal Hybrid Nanostructures: A New Type of Functional Materials

Cited by 753 publications

References 188 publications

Engineering the architectural diversity of heterogeneous metallic nanocrystals

Engineering the architectural diversity of heterogeneous metallic nanocrystals

Confined Pt and CoFe2O4Nanoparticles in a Mesoporous Core/Shell Silica Microsphere and Their Catalytic Activity

Controlled Fabrication of Colloidal Semiconductor–Metal Hybrid Heterostructures: Site Selective Metal Photo Deposition

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Confined Pt and CoFe₂O₄Nanoparticles in a Mesoporous Core/Shell Silica Microsphere and Their Catalytic Activity