Cart
Article
Size-Dependent Spontaneous Alloying of Au−Ag Nanoparticles
Full Text HTML
Hi-Res PDFPurchase the full-text
- PDF/HTML,
figures/images,
references and tables,
(where available)
Section:Abstract
We report on systematic studies of size-dependent alloy formation of silver-coated gold nanoparticles (NPs) in aqueous solution at ambient temperature using X-ray absorption fine structure spectroscopy (XAFS). Various Au-core sizes (2.5−20 nm diameter) and Ag shell thicknesses were synthesized using radiolytic wet techniques. The equilibrium structures (alloy versus core−shell) of these NPs were determined in the suspensions. We observed remarkable size dependence in the room temperature interdiffusion of the two metals. The interdiffusion is limited to the subinterface layers of the bimetallic NPs and depends on both the core size and the total particle size. For the very small particles (≤4.6 nm initial Au-core size), the two metals are nearly randomly distributed within the particle. However, even for these small Au-core NPs, the interdiffusion occurs primarily in the vicinity of the original interface. Features from the Ag shells do remain. For the larger particles, the boundary is maintained to within one monolayer. These results cannot be explained either by enhanced self-diffusion that results from depression of the melting point with size or by surface melting of the NPs. We propose that defects, such as vacancies, at the bimetallic interface enhance the radial migration (as well as displacement around the interface) of one metal into the other. Molecular dynamics calculations correctly predict the activation energy for diffusion of the metals in the absence of vacancies and show an enormous dependence of the rate of mixing on defect levels. They also suggest that a few percent of the interfacial lattice sites need to be vacant to explain the observed mixing.
Citing Articles
Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder.
This article has been cited by 57 ACS Journal articles (5 most recent appear below).
Pt@PdxCuy/C Core–Shell Electrocatalysts for Oxygen Reduction Reaction in Fuel Cells
T. Cochell and A. ManthiramLangmuir2012 28 (2), 1579-1587Pt@PdxCuy/C Core–Shell Electrocatalysts for Oxygen Reduction Reaction in Fuel Cells
T. Cochell and A. ManthiramLangmuir2012 28 (2), 1579-1587A series of carbon-supported core–shell nanoparticles with PdxCuy-rich cores and Pt-rich shells (Pt@PdxCuy/C) has been synthesized by a polyol reduction of the precursors followed by heat treatment to obtain the PdxCuy/C (1 ≤ x ≤ 3 and 0 ≤ y ≤ 5) cores ...
Fabrication of nanoporous Cu–Pt(Pd) core/shell structure by galvanic replacement and its application in electrocatalysis
Caixia Xu, Yunqing Liu, Jinping Wang, Haoran Geng, and Huajun QiuACS Applied Materials & Interfaces2011 3 (12), 4626-4632Fabrication of nanoporous Cu–Pt(Pd) core/shell structure by galvanic replacement and its application in electrocatalysis
Caixia Xu, Yunqing Liu, Jinping Wang, Haoran Geng, and Huajun QiuACS Applied Materials & Interfaces2011 3 (12), 4626-4632We describe a general strategy to fabricate a new type of nanoporous core/shell structured bimetallic nanocomposites with controllable metal components. Nanoporous copper (NPC) obtained by dealloying Cu/Al alloy is used as both reducing agent and three-...
Determining Quantitative Kinetics and the Structural Mechanism for Particle Growth in Porous Templates
Haiyan Zhao, Tina M. Nenoff, Guy Jennings, Peter J. Chupas, and Karena W. ChapmanThe Journal of Physical Chemistry Letters2011 2 (21), 2742-2746Determining Quantitative Kinetics and the Structural Mechanism for Particle Growth in Porous Templates
Haiyan Zhao, Tina M. Nenoff, Guy Jennings, Peter J. Chupas, and Karena W. ChapmanThe Journal of Physical Chemistry Letters2011 2 (21), 2742-2746Understanding the formation of nanoparticles and how they are influenced by a support is critically important for optimizing their activity. In situ pair distribution function (PDF) methods were used to probe the kinetics, mechanism, and energetics for Ag ...
Nanosize-Induced Hydrogen Storage and Capacity Control in a Non-Hydride-Forming Element: Rhodium
Hirokazu Kobayashi, Hitoshi Morita, Miho Yamauchi, Ryuichi Ikeda, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, and Masaki TakataJournal of the American Chemical Society2011 133 (29), 11034-11037Nanosize-Induced Hydrogen Storage and Capacity Control in a Non-Hydride-Forming Element: Rhodium
Hirokazu Kobayashi, Hitoshi Morita, Miho Yamauchi, Ryuichi Ikeda, Hiroshi Kitagawa, Yoshiki Kubota, Kenichi Kato, and Masaki TakataJournal of the American Chemical Society2011 133 (29), 11034-11037We report the first example of nanosize-induced hydrogen storage in a metal that does not absorb hydrogen in its bulk form. Rhodium particles with diameters of <10 nm were found to exhibit hydrogen-storage capability, while bulk Rh does not absorb ...
Au–Ag Bimetallic Nanoparticles: Surface Segregation and Atomic-Scale Structure
Lei Deng, Wangyu Hu, Huiqiu Deng, Shifang Xiao, and Jianfeng TangThe Journal of Physical Chemistry C2011 115 (23), 11355-11363Au–Ag Bimetallic Nanoparticles: Surface Segregation and Atomic-Scale Structure
Lei Deng, Wangyu Hu, Huiqiu Deng, Shifang Xiao, and Jianfeng TangThe Journal of Physical Chemistry C2011 115 (23), 11355-11363Monte Carlo simulations were performed to study systematically the surface segregation behaviors and atomic-scale structural features of Au–Ag nanoparticles for a range of alloy compositions, particle sizes, and temperatures. Segregation of Ag to the ...
Tools
-
Add to Favorites
-
Download Citation
-
Email a Colleague -
Permalink
Order Reprints
Rights & Permissions
Citation Alerts
History
- Published In Issue October 09, 2002
- Received May 2, 2002
ACS
Network
Facebook
Tweet This
CiteULike
Newsvine
Digg This
Delicious
