Substrate-based galvanic replacement reactions carried out on heteroepitaxially formed silver templates

Gilroy, Kyle D.; Farzinpour, Pouyan; Sundar, Aarthi; Tan, Teng; Hughes, Robert A.; Neretina, Svetlana

doi:10.1007/s12274-013-0319-5

Cited by 25 publications

(31 citation statements)

References 51 publications

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“…Assembly of Heterogeneous Nucleation Sites : Au and Ag heterogeneous nucleation sites were formed on (0001)‐oriented sapphire substrates (MTI) or Si 3 N 4 support films (EMS) as both periodic arrays and as structures with randomized size and position. These assembly processes have been described in detail elsewhere . It should be noted that the Au and Ag assembly processes were each carried out in a dedicated quartz tube to prevent cross‐contamination.…”

Section: Methodsmentioning

confidence: 99%

“…These assembly processes have been described in detail elsewhere. [ 24,25,29 ] It should be noted that the Au and Ag assembly processes were each carried out in a dedicated quartz tube to prevent cross-contamination.…”

Section: Methodsmentioning

confidence: 99%

“…In order to facilitate elemental mapping, Au nanostructures were fabricated directly on transmission electron microscope (TEM) grids equipped with Si 3 N 4 support fi lms as described previously. [ 29 ] The grid was then placed facedown on a Ge substrate and the assembly process was carried out at 700 °C for 2 hours. The shorter duration and lower process temperature was chosen to compensate for the fragility of the support fi lm.…”

Section: Elemental and Morphological Characterizationmentioning

confidence: 99%

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Eutectic Combinations as a Pathway to the Formation of Substrate‐Based Au‐Ge Heterodimers and Hollowed Au Nanocrescents with Tunable Optical Properties

Sundar

Farzinpour

Gilroy

et al. 2014

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Pairs of immiscible elements with deep eutectics are used to synthesize periodic arrays of heterodimers and hollowed metal nanocrescents. In the devised route, substrate-immobilized Au or Ag nanostructures act as heterogeneous nucleation sites for Ge adatoms. At elevated temperatures the adatoms collect in sufficient quantities to transform each site into a AuGe liquid alloy which, upon cooling, phase separates into elemental components sharing a common interface. The so-formed Au-Ge and Ag-Ge heterodimers exhibit a complex morphology characterized by a noble metal nanocrescent which partially encapsulates one end of the Ge domain. Through the use of a selective etch the Ge component is removed, leaving behind a periodic array of hollow noble metal nanocrescents on the surface of the substrate. Optical characterization of both the heterodimers and nanocrescents indicates that the presence of Ge gives rise to a relative blue-shift in the localized surface plasmon peak, a result that is in stark contrast to the red-shifts typically observed when plasmonic nanostructures are in contact with a dielectric medium. Simulations are used to both rationalize the observed shift and show the potential for deriving unexpected behaviors when semishell-like noble metal structures are in contact with high permittivity dielectric mediums.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Elemental and Morphological Characterizationmentioning

confidence: 99%

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Eutectic Combinations as a Pathway to the Formation of Substrate‐Based Au‐Ge Heterodimers and Hollowed Au Nanocrescents with Tunable Optical Properties

Sundar

Farzinpour

Gilroy

et al. 2014

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“…The presence of singly‐twinned particles is not surprising because theoretical work often treats them as stable as Sc particles . It is expected that the Sc structure should continue to be the favorable products for sizes >11 nm, as evident from the work carried out previously, where annealing sapphire‐supported Ag films resulted in the formation of weakly‐faceted, single‐crystalline, Wulff‐shaped nanocrystals for sizes ranging from 30 to 250 nm . This is in agreement with top‐view TEM images, as shown in Figure E, which reveal that the nanocrystals have six‐fold hexagonal symmetry, suggesting that most of the Ag nanocrystals are oriented with the [111]‐axis normal to the surface of the substrate.…”

Section: Figurementioning

confidence: 99%

On the Thermodynamics and Experimental Control of Twinning in Metal Nanocrystals

et al. 2017

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This work demonstrates a new strategy for controlling the evolution of twin defects in metal nanocrystals by simply following thermodynamic principles. With Ag nanocrystals supported on amorphous SiO2 as a typical example, we establish that twin defects can be rationally generated by equilibrating nanoparticles of different sizes through heating and then cooling. We validate that Ag nanocrystals with icosahedral, decahedral, and single‐crystal structures are favored at sizes below 7 nm, between 7 and 11 nm, and greater than 11 nm, respectively. This trend is then rationalized by computational studies based on density functional theory and molecular dynamics, which show that the excess free energy for the three equilibrium structures correlate strongly with particle size. This work not only highlights the importance of thermodynamic control but also adds another synthetic method to the ever‐expanding toolbox used for generating metal nanocrystals with desired properties.

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“…In some applications such as catalysis, sensors, and SERS, it is favorable for metal nanomaterials to be supported by a solid substrate. Although the fabrication of Au NCs from Ag templates dispersed in solution using galvanic replacement reactions has been carried out extensively, there are few reports for the preparation of Au NCs supported on a solid substrate through the galvanic replacement method [ 16 – 17 ]. Furthermore, in many cases, some residual Ag remains in the final Au NCs, which maybe limit their applications.…”

Section: Introductionmentioning

confidence: 99%

Formation of substrate-based gold nanocage chains through dealloying with nitric acid

Yan¹,

Wu²,

Di³

2015

Beilstein J. Nanotechnol.

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SummaryMetal nanocages have raised great interest because of their new properties and wide applications. Here, we report on the use of galvanic replacement reactions to synthesize substrate-supported Ag–Au nanocages from silver templates electrodeposited on transparent indium tin oxide (ITO) film coated glass. The residual Ag in the composition was dealloyed with 10% nitric acid. It was found that chains of Au nanocages were formed on the substrate surface during dealloying. When the concentration of HNO3 increased to 20%, the structures of nanocages were damaged and formed crescent or semi-circular shapes. The transfer process on the substrate surface was discussed.

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Substrate-based galvanic replacement reactions carried out on heteroepitaxially formed silver templates

Cited by 25 publications

References 51 publications

Eutectic Combinations as a Pathway to the Formation of Substrate‐Based Au‐Ge Heterodimers and Hollowed Au Nanocrescents with Tunable Optical Properties

Eutectic Combinations as a Pathway to the Formation of Substrate‐Based Au‐Ge Heterodimers and Hollowed Au Nanocrescents with Tunable Optical Properties

On the Thermodynamics and Experimental Control of Twinning in Metal Nanocrystals

Formation of substrate-based gold nanocage chains through dealloying with nitric acid

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