Tuning the surface enhanced Raman scattering performance of anisotropic Au core−Ag shell hetero-nanostructure: The effect of core geometry

Qu, Ying; Xing, Tingyang; Zhao, Jun; Weng, Guo-jun; Li, Jianjun; Zhu, Jian; Zhao, Jing

doi:10.1016/j.jallcom.2018.10.321

Cited by 25 publications

(10 citation statements)

References 51 publications

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“…A comparison between SERS spectra of standard solutions from the pesticides that were left to dry onto Ag NSPs_0.05/tape and those of the same analytes obtained from contaminated apple peels through the "paste and peel off" method, are shown in Figure 4. The characteristic peaks of Phosmet (606, 653, 1014, 1189, 1260, 1381, 1409, and 1772 cm −1 ) and Carbaryl (713, 1380, and 1582 cm −1 ), as listed in Table S1 [12,[22][23][24], are clearly identified in all cases, being the most distinct at 10 −2 M. Relatively strong peaks of each pesticide, 606, 653, and 1189 cm −1 for Phosmet and 1380 and 1582 cm −1 for Carbaryl, were still recognizable at lower concentrations, indicating that the limit of detection of both pesticides is close to 10 −6 -10 −7 M; it is lower than the maximum residue limits of pesticides in food products as set by the World Health Organization (WHO), which is established to be around 10 −4 -10 −5 [15]. However, this detection limit still remains higher than that obtained by, e.g., utilizing Ag NPs deposited on porous silicon, in which detection limits were competent to go down to 10 −9 -10 −10 M [21].…”

Section: Detection Of Pesticides From Apple Peel With the Flexible Agmentioning

confidence: 99%

Ag Nanostructures with Spikes on Adhesive Tape as a Flexible Sers-Active Substrate for In Situ Trace Detection of Pesticides on Fruit Skin

et al. 2019

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Nanostructures with spikes (NSPs) have been a subject of several surface-enhanced Raman scattering (SERS) applications owing to their significant Raman signal enhancement brought about by the combined effects of interspike coupling and the accumulated induction on the tips of spikes. Thus, NSPs offer great potential as a SERS-active substrate for relevant applications that require a high density of enhanced “hot spots”. In this study, Ag NSPs were synthesized in varying degrees of agglomeration and were thereafter deposited onto a transparent adhesive tape as a flexible substrate for SERS applications, specifically, in the detection of trace amounts of pesticides. These flexible substrates were referred to as Ag NSPs/tape and optimized with an enhancement factor (EF) of ca. 1.7 × 107. A strong resulting signal enhancement could be attributed to an optimal degree of agglomeration and, consequently, the distances among/between spikes. Long spikes on the synthesized core of Ag NSPs tend to be loosely spaced, which are suitable in detecting relatively large molecules that could access the spaces among the spikes where “hot spots” are generally formed. Since one side of the transparent tape is adhesive, the paste-and-peel off method was successful in obtaining phosmet and carbaryl residues from apple peels as reflected in the acquired SERS spectra. In situ trace detection of the pesticides at low concentrations down to 10−7 M could be demonstrated. In situ trace detection of mixed pesticides was possible as the characteristic peaks of both pesticides were observed in equimolar mixtures of the analytes at 10−2 to 10−4 M. This study is, thus, premised upon applying for in situ trace detection on e.g., fruit skin.

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Section: Detection Of Pesticides From Apple Peel With the Flexible Agmentioning

confidence: 99%

Ag Nanostructures with Spikes on Adhesive Tape as a Flexible Sers-Active Substrate for In Situ Trace Detection of Pesticides on Fruit Skin

et al. 2019

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“…4 Similarly, the bimetallic constitution facilitates spectral tunability for SERS-based sensing. 26,27 While spectral tunability is an advantage, plasmonic hot carrier generation is strongly dependent on the nanoparticle composition. 2 In the present work, a comparative simulation study is performed on the plasmonic characteristics of Au-Ag bimetallic alloy and core-shell nanoparticles, and includes both spherical and anisotropic (nanorods and 4 nanotriangles) shapes.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, spectral tunability of Ag–Au alloy nanoparticles enables wider coverage of the visible light spectrum for plasmon-assisted photocatalysis . Similarly, the bimetallic constitution facilitates spectral tunability for SERS-based sensing. , While spectral tunability is an advantage, plasmonic hot carrier generation is strongly dependent on the nanoparticle composition …”

Section: Introductionmentioning

confidence: 99%

Silver–Gold Bimetallic Alloy versus Core–Shell Nanoparticles: Implications for Plasmonic Enhancement and Photothermal Applications

Borah

Verbruggen

2020

J. Phys. Chem. C

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Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination of optical constants of Au-Ag alloys reported in literature. Although both Au-Ag core-shell and alloy nanoparticles exhibit an intermediary optical response between that of pure Ag and Au nanoparticles, there are noticeable differences in the spectral characteristics. Also, the effect of the bimetallic constitution in anisotropic nanoparticles is starkly different from that in spherical nanoparticles due to the absence of Au interband transitions in the former case. In general, the improved chemical stability of Ag nanoparticles by incorporation of Au comes with a cost of reduction in plasmonic enhancement, also applicable to anisotropic nanoparticles with a weaker effect. A photothermal heat transfer study confirms that increased absorption by the incorporation of Au in spherical Ag nanoparticles also results in an increased steady state temperature. On the other hand, anisotropic nanoparticles are inherently better absorbers, hence better photothermal sources and their photothermal properties are apparently not strongly affected by the incorporation of one metal in the other. This study of the optical/spectral and photothermal characteristics of bimetallic Au-Ag alloy versus core-shell nanoparticles provides a detailed physical insight for the development of new taylor-made plasmonic nanostructures.

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“…33,34 On the other hand, each silver nanoparticle was not a perfect spherical shape, and its orientation had a certain anisotropy, which could also cause a subtle difference in Raman sensing performance. 35,36 The response sensitivity for R6G molecules on the assynthesized silver films was characterized by measuring SERS spectra of R6G molecules with the varied concentrations from 10 −9 to 10 −14 M. As shown in Figure 9c, the intensity of the Raman characteristic peaks in the Raman shift between 500 and 1900 cm −1 decreases gradually with the decrease of the concentration from 10 −9 to 10 −14 M. The characteristic Raman signals of R6G molecules were still evident as detected concentration down to 10 −13 M. When the sample concentration reduced to 10 −14 M, there was no characteristic Raman signal available. The above results indicated that the limit of detection (LOD) of the substrates for R6G molecules could reach about 10 −13 M. To quantitatively evaluate the SERS enhancement ability of as-prepared SERS-active substrates, the analytical enhancement factor (AEF) was calculated (Figure S4).…”

Section: Resultsmentioning

confidence: 99%

“…The brighter regions under the optical microscope observation were usually the spots where some nanoparticles were aggregated. Therefore, the nanogaps among the nanoparticles might be formed, and these nanogaps had an important Raman enhancement effect. , On the other hand, each silver nanoparticle was not a perfect spherical shape, and its orientation had a certain anisotropy, which could also cause a subtle difference in Raman sensing performance. , …”

Section: Results and Discussionmentioning

confidence: 99%

Uniform Near-Spherical Nanoscale Silver Films for Surface-Enhanced Raman Spectroscopy Sensing

Zhang

Zhao

Ming-nan

et al. 2020

ACS Appl. Nano Mater.

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Uniform near-spherical nanoscale silver films (NSFs) as a very sensitive and stable SERS-active substrate were synthesized by a facile and efficient in situ liquid−solid−solid (LSS) reaction method without expensive equipment and harmful reagent assistance. In this method, the in situ formation and thermal decomposition reactions of the Ag− melamine coordination polymer (AgM CP) nanowires was utilized to control the morphology and microstructure of the NSFs. The sensing performances of the synthetic NSFs as SERS substrates were investigated by using R6G as a probe molecule. The research results showed that the prepared NSFs possessed a very low detection limit down to 10 −13 M, a high analytical enhancement factor, and stable detection capabilities for the R6G molecule, which made them promising as cost-effective and highperformance SERS sensing platforms for trace molecular species detection.

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Tuning the surface enhanced Raman scattering performance of anisotropic Au core−Ag shell hetero-nanostructure: The effect of core geometry

Cited by 25 publications

References 51 publications

Ag Nanostructures with Spikes on Adhesive Tape as a Flexible Sers-Active Substrate for In Situ Trace Detection of Pesticides on Fruit Skin

Ag Nanostructures with Spikes on Adhesive Tape as a Flexible Sers-Active Substrate for In Situ Trace Detection of Pesticides on Fruit Skin

Silver–Gold Bimetallic Alloy versus Core–Shell Nanoparticles: Implications for Plasmonic Enhancement and Photothermal Applications

Uniform Near-Spherical Nanoscale Silver Films for Surface-Enhanced Raman Spectroscopy Sensing

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