Highly size-controlled synthesis of Au/Pd nanoparticles by inert-gas condensation

Pérez‐Tijerina, E.; Gracia-Pinilla, M.A.; Mejía-Rosales, Sergio; Ortiz-Méndez, Ubaldo; Torres, Alejandro; José–Yacamán, Miguel

doi:10.1039/b705913m

Cited by 99 publications

(60 citation statements)

References 22 publications

(18 reference statements)

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“…1͑A͒ does not show such a discrete boundary but a more homogeneous gray value. 20 Additionally, many nanoclusters of similar size have different HAADF intensities. A HAADF profile of a representative collection is given in Fig.…”

Section: Resultsmentioning

confidence: 99%

Compositional changes of Pd-Au bimetallic nanoclusters upon hydrogenation

et al. 2009

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Changes in the size distribution and composition of bimetallic Pd-Au nanoclusters have been observed after hydrogen exposure. This effect is caused by hydrogen-induced Ostwald ripening whereby the hydrogen reduces the binding energy of the cluster atoms leading to their detachment from the cluster. The composition changes due to a difference in mobility of the detached palladium and gold atoms on the surface. Fast palladium atoms contribute to the formation of larger nanoclusters, while the slower gold atoms are confined to the smaller nanoclusters. These transformations in the Pd-Au nanocluster size and composition set a limit for chemical reactions in which such nanoclusters are involved together with hydrogen.

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Section: Resultsmentioning

confidence: 99%

Compositional changes of Pd-Au bimetallic nanoclusters upon hydrogenation

et al. 2009

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“…On the other hand, Au/Pd particles grown by sputtering show an alloy structure with an icosahedral structure. 13 It is also possible to produce a three-layer structure, as shown by Marzan et al 14,15 In this work we describe a novel three-layer structure in Au/Pd nanoparticles, and demonstrate that by combining aberrationcorrected imaging with conventional techniques such as theoretical simulation and single particle diffraction, we can obtain significant new information about nanoscale colloids.…”

Section: -8mentioning

confidence: 97%

Atomic structure of three-layer Au/Pd nanoparticles revealed by aberration-corrected scanning transmission electron microscopy

et al. 2008

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Aberration-corrected imaging is employed under the scanning transmission electron microscopy (STEM) mode to precisely determine the chemical ordering of Au/Pd nanoparticles. These colloids exhibit a core-shell structure with a three-layer arrangement that surprisingly presents alloying events in the observed layers. Aberration-corrected imaging is employed under the scanning transmission electron microscopy (STEM) mode to precisely determine the chemical ordering of Au/Pd nanoparticles. These colloids exhibit a coreshell structure with a three-layer arrangement that surprisingly presents alloying events in the observed layers. The study of nanomaterials can be greatly improved with the use of aberration-corrected transmission electron microscopy (TEM), which provides image resolutions at the level of 1 Å and lower. Sub-Å ngströ m image resolution can yield a new level of understanding of the behavior of matter at the nanoscale. For example, bimetallic nanoparticles are extremely important in catalysis applications; the addition of a second metal in many cases produces much-improved catalysts. In this paper, we study the structure and morphology of Au/Pd bimetallic particles using primarily the high-angle annular dark-field (HAADF) imaging mode in an aberration-corrected STEM/TEM. It is well established that, when recorded under appropriate illumination and collection geometries, incoherent HAADF-STEM images are compositionally sensitive and provide direct information on atomic positions. We matched the experimental intensities of atomic columns with theoretical models of three-layer Au/Pd nanoparticles, in different orientations. Our findings indicate that the surface layer of the nanoparticle contains kinks, terraces and steps at the nanoscale. The effect of adding a second metal induces the formation of such defects, which might very likely promote the well-known improved catalytic activity of this system.

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“…On the other hand, physical methods of synthesis such as inert gas condensation (IGC) allow even narrower size distributions than those obtained by chemical methods, and the elemental proportions follow those of the original alloy used as target. Previous results from our group 5 show that for the case of Au/Pd particles produced by IGC at room temperature both metals are distributed throughout the entire particle with a fairly homogeneous distribution; nevertheless, at the time there was not enough information to estimate the concentration profiles at high resolution.…”

Section: Introductionmentioning

confidence: 95%

Effect of Temperature on AuPd Nanoparticles Produced by Inert Gas Condensation

et al. 2010

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Bimetallic nanoparticles of AuPd were synthesized using the inert gas condensation technique, where the material is sputtered from a target and the particles are formed in an inert condensation zone. Throughout the synthesis process and jointly with the control of the atmosphere conditions, the region after the condensation chamber was kept at a fixed temperature, and several experimental runs were performed at 700 and 1000°C. The synthesis conditions were set to produce particles of 5 nm of diameter, and almost all of the resulting nanoparticles were icosahedral in shape with small deviations from the mean size. We analyzed the particles by high-angle annular dark field and bright field scanning electron microscopy imaging with a resolution high enough to acquire atomic detail and to measure the distance between planes. From the micrographs and their fast Fourier transform patterns, we found that the lattice detail depends on the thermal treatment with larger lattice fringe displacements in the particles produced at 700°C. Electron energy loss spectroscopy analysis in one and two dimensions shows that irrespective of the temperature the particles keep their icosahedral shape, and both chemical species are distributed nonuniformly all over the volume of the particles, but without forming core-shell structures.

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Highly size-controlled synthesis of Au/Pd nanoparticles by inert-gas condensation

Cited by 99 publications

References 22 publications

Compositional changes of Pd-Au bimetallic nanoclusters upon hydrogenation

Compositional changes of Pd-Au bimetallic nanoclusters upon hydrogenation

Atomic structure of three-layer Au/Pd nanoparticles revealed by aberration-corrected scanning transmission electron microscopy

Effect of Temperature on AuPd Nanoparticles Produced by Inert Gas Condensation

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