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Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

Tsai CH, Chen SY, Song JM, Haruta M, Kurata H - Nanoscale Res Lett (2015)

Bottom Line: Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study.High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1.It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan.

ABSTRACT
Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

No MeSH data available.


Synthetic process of a Au-Ag zero-dimensional structure and b Au-Ag one-dimensional structure
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Fig1: Synthetic process of a Au-Ag zero-dimensional structure and b Au-Ag one-dimensional structure

Mentions: The processes for preparing Au-Ag nanostructures with different dimensions are illustrated in Fig. 1. AgNO3 and HAuCl4 aqueous solutions with the same concentrations (0.4 mM) are the precursors. Figure 1a shows the procedures for the synthesis of 0-D Au-Ag structures. The templates, Ag NPs, were obtained from the reduction of AgNO3 using a mixed solution with 1 wt% of NaBH4 and 1 wt% of Na3C6H5O7. 0.29 mM (MW 55,000 g/mol) PVP, the surfactant to prevent particle aggregation, was dissolved in water by stirring for 6 min at 95 °C. As indicated in Fig. 2a, b, the Ag NPs thus produced are heavily twinned with an average particle size of 14 nm. The interplanar distance of 0.23 nm can be referred to {111} planes of Ag. HAuCl4 aqueous solution was then mixed with the Ag NP suspensions and agitated at 95 °C for 15 min.Fig. 1


Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

Tsai CH, Chen SY, Song JM, Haruta M, Kurata H - Nanoscale Res Lett (2015)

Synthetic process of a Au-Ag zero-dimensional structure and b Au-Ag one-dimensional structure
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644130&req=5

Fig1: Synthetic process of a Au-Ag zero-dimensional structure and b Au-Ag one-dimensional structure
Mentions: The processes for preparing Au-Ag nanostructures with different dimensions are illustrated in Fig. 1. AgNO3 and HAuCl4 aqueous solutions with the same concentrations (0.4 mM) are the precursors. Figure 1a shows the procedures for the synthesis of 0-D Au-Ag structures. The templates, Ag NPs, were obtained from the reduction of AgNO3 using a mixed solution with 1 wt% of NaBH4 and 1 wt% of Na3C6H5O7. 0.29 mM (MW 55,000 g/mol) PVP, the surfactant to prevent particle aggregation, was dissolved in water by stirring for 6 min at 95 °C. As indicated in Fig. 2a, b, the Ag NPs thus produced are heavily twinned with an average particle size of 14 nm. The interplanar distance of 0.23 nm can be referred to {111} planes of Ag. HAuCl4 aqueous solution was then mixed with the Ag NP suspensions and agitated at 95 °C for 15 min.Fig. 1

Bottom Line: Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study.High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1.It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, 106, Taiwan.

ABSTRACT
Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

No MeSH data available.