Solution-Phase Synthesis of Sub-10 nm Au−Ag Alloy Nanoparticles

Mallin, Michael; Murphy, Catherine J.

doi:10.1021/nl025774n

Cited by 558 publications

(476 citation statements)

References 40 publications

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“…In case Au and Ag NPs would form separately, two separate plasmon peaks of Au and Ag would have been expected, which are however not observed experimentally. 7 The nature of the carbon matrix was resolved by μ-Raman spectroscopy (cf. SI_4B) and showed D and G bands, typical of carbonaceous materials, centered at 1350 cm −1 and 1587 cm −1 , respectively, which are typical of amorphous and hydrogenated carbon (a-C:H).…”

Section: Chemistrymentioning

confidence: 99%

Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

et al. 2015

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Micro-chips based on organic-inorganic hybrid nanoparticles (NPs) composed of nanoalloys of gold (Au) and silver (Ag) embedded in an amorphous carbonaceous matrix (C-Au-Ag NPs) were prepared directly on a substrate by the laser-induced deposition (for short: LID) method. The C-Au-Ag NPs show a unique plasmon resonance which enhances Raman scattering of analytes, making the μ-chips suitable to detect ultra-low-volumes (10 −12 liter) and concentrations (10 −9 M) of bio-agents and a hazardous compound.These micro-chips constitute a novel, flexible solid-state device that can be used for applications in pointof-care diagnostics, consumer electronics, homeland security and environmental monitoring.Detection and identification of low concentrations in small volumes of hazardous and biological substances are currently important to address challenges in environmental monitoring, homeland security and medicine. Recently, different groups have developed devices based on metal nanoparticles (NPs) with the capacity to detect low concentrations of substances. 1 However, devices associated with NPs require two stage development: (i) synthesis of NPs and (ii) integration of the NPs into devices. Even though the synthesis of NPs is well established (especially for Au and Ag) and different integrating approaches of NPs into devices have been demonstrated (such as Layer-by-Layer and drop casting, optical and nano lithography, direct laser writing of optofluidic and multifunctional microfluidic chips, laser ablation of Si wafer surfaces, followed by coating with metal thin films such as gold etc.), 2 the state-of-the art sensors/devices still suffer from a lack of control over parameters. Moreover, chemical functionalities on the NP surfaces are not stable over time and react with H 2 O/O 2 in ambient conditions and impair the device performance. 1e Here, we propose a new method for the fabrication of micro-chip devices (for short μ-devices) based on nanoalloys of Au-Ag NPs that are simultaneously synthesized by direct laser writing and embedded in a carbonaceous matrix (hereinafter, C-Au-Ag NPs). It should be noted that the suggested process is photoinduced that allows avoiding side effects of thermal phenomena (delocalization of the deposition process, thermal decomposition, etc.). The C-Au-Ag NPs provide high stability and new functionalities of combined properties of the metals and the carbon that opens the door for new applications. 3 For example, a core of gold-silver nanoalloys coated with a carbon shell demonstrates excellent efficiency as a Raman tag for quantitative immunoassays and high catalytic activity. 3 However, the preparation of metal NPs or nanoalloys in a carbonaceous matrix is complicated, time consuming and requires the use of dangerous chemical compounds and chemical equipment. 4 In our case, we present a fast and coherent Laser-Induced liquid phase Deposition (LID) method for direct writing of μ-chips based on NPs from solutions on any desired substrate with controlled assembly of elements i.e. of active ...

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Section: Chemistrymentioning

confidence: 99%

Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

et al. 2015

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“…[32][33][34] However, when plotted in energy scale (wavenumber) a non-linear trend is obtained as shown in Figure 1(b), which, in this scale, should show a linear dependence if electron density were the sole contributor to the observed spectral shifts. We use the wavenumber scale in all of our figures for meaningful and direct visual comparison with the changes in the plasmon frequency, since a 10 nm shift around 400 nm and around 500 nm correspond to different extent of shifts in the frequency scale.…”

Section: Resultsmentioning

confidence: 94%

Optical Response of Ag-Au Bimetallic Nanoparticles to Electron Storage in Aqueous Medium

Tunç¹,

Güvenç²,

Sezen³

et al. 2008

j nanosci nanotechnol

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Composition and structure dependence of the shift in the position of the surface plasmon resonance band upon introduction of NaBH 4 to aqueous solutions of gold and silver nanoparticles are presented. Silver and gold nanoalloys in different compositions were prepared by co-reduction of the corresponding salt mixtures using sodium citrate as the reducing agent. After addition of NaBH 4 to the resultant nanoalloys, the maximum of their surface plasmon resonance band, ranging between that of pure silver (ca. 400 nm) and of pure gold (ca. 530 nm), is blue-shifted as a result of electron storage on the particles. The extent of this blue shift increases non-linearly with the mole fraction of silver in the nanoparticle, parallel to the trends reported previously for both the frequency and the extinction coefficient of the plasmon band shifts. Gold(core)@silver(shell) nanoparticles were prepared by sequential reduction of gold and silver, where addition of NaBH 4 results in relatively large spectral shift in the plasmon resonance band when compared with the nanoalloys having a similar overall composition. The origin of the large plasmon band shift in the core-shell is related with a higher silver surface concentration on these particles. Hence, the chemical nature of the nanoparticle emerges as the dominating factor contributing to the extent of the spectral shift as a result of electron storage in bimetallic systems.

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“…Capped metal nanoparticles show surface plasmon resonance (SPR), due to the interaction between light and metal electrons in the conduction band which collectively oscillate in resonance at specific wavelength. SPR wavelength varies with particle size, shape, and metal type [24,25]. The continuous change in the SPR absorption maximum as a function of the Au : Ag molar ratio can be used to accurately quantify the composition of alloy nanoparticles [23].…”

Section: Resultsmentioning

confidence: 99%

Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles

Pierini

Lanzi

Nakielski

et al. 2017

Journal of Nanomaterials

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Composite nanofibers made of a polyaniline-based polymer blend and different thiol-capped metal nanoparticles were prepared using ex situ synthesis and electrospinning technique. The effects of the nanoparticle composition and chemical structure on the electrical properties of the nanocomposites were investigated. This study confirmed that Brust's procedure is an effective method for the synthesis of sub-10 nm silver, gold, and silver-gold alloy nanoparticles protected with different types of thiols. Electron microscopy results demonstrated that electrospinning is a valuable technique for the production of composite nanofibers with similar morphology and revealed that nanofillers are well-dispersed into the polymer matrix. X-ray diffraction tests proved the lack of a significant influence of the nanoparticle chemical structure on the polyaniline chain arrangement. However, the introduction of conductive nanofillers in the polymer matrix influences the charge transport noticeably improving electrical conductivity. The enhancement of electrical properties is mediated by the nanoparticle capping layer structure. The metal nanoparticle core composition is a key parameter, which exerted a significant influence on the conductivity of the nanocomposites. These results prove that the proposed method can be used to tune the electrical properties of nanocomposites.

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Solution-Phase Synthesis of Sub-10 nm Au−Ag Alloy Nanoparticles

Cited by 558 publications

References 40 publications

Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

Direct laser writing of μ-chips based on hybrid C–Au–Ag nanoparticles for express analysis of hazardous and biological substances

Optical Response of Ag-Au Bimetallic Nanoparticles to Electron Storage in Aqueous Medium

Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles

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