Au Ag Alloy Nanoparticles Research Articles

Asymmetric Dichroic Colors in Stretchable Film with Embedded Au/Ag Alloy Nanoparticles.

We present a new type of stretchable dichroic film in which Au and Ag alloy nanoparticles (NPs) are dispersed in polydimethylsiloxane (PDMS). The alloy NPs are synthesized with different atomic compositions and sizes to modulate their plasmonic resonance frequencies and absorption and scattering cross sections. The PDMS dichroic film in which 100 nm alloy NPs with a Au/Ag ratio of 7:3 are dispersed shows exotic optical properties under tensile strain. When 40% tensile strain is applied, the film exhibits a strain-sensitive transmission and strain-insensitive reflection behavior in which the transmittance is increased up to 2.6 times, whereas the reflectance remains unchanged. Moreover, we demonstrate a stretchable anticounterfeiting film and a flexible dichroic sculpture fabricated with the PDMS composite. This work demonstrates a new type of plasmonic application that has great potential in various applications, such as special-purpose optical films, security patterns, and smart windows.

Laser Assisted Synthesis of Surfactant-Free Au-Ag Alloy Nanoparticles in Water

Surfactant-free nontoxic Au-Ag alloy nanoparticles were synthesized via re-irradiation of laser generated mono metallic colloidal mixtures with 532 nm radiations from Nd: YAG nanosecond laser. The impact of re-irradiating laser energy in alloy formation kinetics was investigated. The alloy formation process was analyzed with UV-Visible absorption spectra at different time intervals of laser irradiation. The generated nanoparticles were characterized with dynamic light scattering size analysis, zeta potential studies, and HRTEM imaging. Photothermal properties of the samples were investigated employing thermal lens method. Alloy formation became faster with a slight blue shift in the plasmonic band wavelength with increase in irradiation energy. Reduction in nanoparticle size and stability were also observed at high irradiation energies.

Improving Quantitative EDS Chemical Analysis of Alloy Nanoparticles by PCA Denoising: Part II. Uncertainty Intervals.

Analytical studies of nanoparticles (NPs) are frequently based on huge datasets derived from hyperspectral images acquired using scanning transmission electron microscopy. These large datasets require machine learning computational tools to reduce dimensionality and extract relevant information. Principal component analysis (PCA) is a commonly used procedure to reconstruct information and generate a denoised dataset; however, several open questions remain regarding the accuracy and precision of reconstructions. Here, we use experiments and simulations to test the effect of PCA processing on data obtained from AuAg alloy NPs a few nanometers wide with different compositions. This study aims to address the reliability of chemical quantification after PCA processing. Our results show that the PCA treatment mitigates the contribution of Poisson noise and leads to better quantification, indicating that denoised results may be reliable from the point of view of both uncertainty and accuracy for properly planned experiments. However, the initial data need to be of sufficient quality: these results can only be obtained if the signal-to-noise ratio of input data exceeds a minimal value to avoid the occurrence of random noise bias in the PCA reconstructions.

Boron nitride nanosheets supported highly homogeneous bimetallic AuPd alloy nanoparticles catalyst for hydrogen production from formic acid

Formic acid (FA) has been recently regarded as a safe and stable source of hydrogen (H2). Selective and efficient dehydrogenation of FA by an effective catalyst under mild conditions is still a challenge. So, different molar ratios of bimetallic Pd–Au alloy nanoparticles were effectively stabilized and uniformly distributed on boron nitride nanosheets (BNSSs) surface via the precipitation process. Obtained catalysts were employed in FA decomposition for H2 production. Pd–Au@BNNS containing 3% Au and 5% Pd (Au.03Pd.05@BNNS) exhibited high activity and 100% H2 selectivity for H2 production from FA at 50 °C. In order to optimize the reaction conditions, various factors including, time, temperature, solvent, base type, and amount of catalyst, were examined.

Facile fabrication of Au-Ag alloy nanoparticles on filter paper: Application in SERS based swab detection and multiplexing

Facile fabrication of flexible substrates containing high concentration of nanoparticles (NPs) is very promising owing to their capability of swab-based surface-enhanced Raman scattering (SERS) trace detection. However, the background signal of the substrate could compromise the trace-detection capabilities. Moreover, the presence of fluorescent molecules may result in intense fluorescence background which could overshadow the Raman peaks. Herein, we demonstrate that the surfactant-free bimetallic (Ag and Au) NPs, synthesized directly on the filter paper, are very effective in reducing the background signal in SERS-based trace detection. Simple soaking of filter paper in a mixture of HAuCl4 and AgNO3 solution, and its immediate drying and reduction produces Au-Ag alloy NPs on the filter paper. Interestingly, the substrates are very effective in quenching the background fluorescence of both filter paper and the analyte, thereby effectively detecting the SERS signature of the fluorescent molecules. In particular, Rhodamine6G (R6G) concentrations down to 10−10 M were detected under resonance excitation, both by solution drying and swabbing. The swab detection of ammonium nitrate, which is usually used in homemade explosives, was also demonstrated. Moreover, owing to the fluorescence quenching properties, the Au-Ag alloy substrates (AuAgS) were able to carry out the swab-based multiplex-detection of crystal violet (CV), Brilliant Cresyl Blue (BCB), and R6G upon resonance excitation of R6G. Finally, the substrates have shown good reproducibility, stability, and signal uniformity. This verifies the potential of AuAgS for real-world trace-detection applications.

Facile antisolvent crystallization synthesis of small Cu–Au alloy nanoparticles at room temperature

Metal nanoparticles (NPs) are typically synthesized via crystallization by exploiting the difference in the solution solubilities of the metal ions (precursors) and the metal atoms (monomers) that are formed during reduction reactions. However, in this method, it is difficult to control the size and composition of the NPs, as the rate of the reduction reactions of the precursors into monomers affects the supersaturation, which is the greatest variable in crystallization. In this study, antisolvent crystallization was used to separate the reduction reaction and crystallization processes in the synthesis of metal alloy NPs. Salt NPs of Cu and Au precursors were first synthesized by adding ethanol as an antisolvent to an aqueous solution of Cu and Au precursors and stabilizers. Then, Cu–Au alloy NPs were synthesized via the reduction of the salt NPs. Overall, this new antisolvent-based synthesis is facile and the composition of the synthesized NPs can be well controlled.

Coupling Natural Halloysite Nanotubes and Bimetallic Pt-Au Alloy Nanoparticles for Highly Efficient and Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

The aerobic oxidation of 5-hydroxymethylfurfural (HMF), a key platform compound derived from biomass, to 2,5-furandicarboxylic acid (FDCA) is a highly important reaction in the production of green and sustainable chemicals. Here, we developed a highly efficient and stable halloysite-supported Pt-Au alloy catalyst for the selective oxidation of HMF to FDCA. The catalyst was synthesized through the organosilane functionalization of halloysite nanotubes, followed by the in situ formation and dispersion of Pt-Au alloy nanoparticles on the internal and external surfaces of nanotubes. The composition, morphology, and structure of the prepared catalyst were characterized. The catalyst with the optimal composition of Pt/Au molar ratio of 1/4 and metal loading of 1.5 wt % exhibited outstanding catalytic activity for the oxidation of HMF to FDCA using O2 as an oxidant with 100% conversion of HMF and 99% selectivity of FDCA. This excellent catalytic performance is mainly attributed to the high dispersion and alloying effects of bimetallic nanoparticles, which promoted the activation of reactants or intermediates and further improved FDCA selectivity. Furthermore, the halloysite-supported Pt/Au bimetallic catalyst showed high stability and reusability. This study provides a promising strategy by combining clay mineral halloysite and bimetallic alloys for developing efficient catalysts with high FDCA selectivity and stability for the oxidation of HMF to FDCA.

Localized surface plasmon-enhanced blue electroluminescent device based on ZnSeTe quantum dots and AuAg nanoparticles

Localized surface plasmon resonance-enhanced Cd-free blue electroluminescent devices integrated with ZnSeTe quantum dots and AuAg alloy nanoparticles were demonstrated.

Sensitive Detection of SARS-CoV-2 Using a Novel Plasmonic Fiber Optic Biosensor Design.

The coronavirus (COVID-19) pandemic has put the entire world at risk and caused an economic downturn in most countries. This work provided theoretical insight into a novel fiber optic-based plasmonic biosensor that can be used for sensitive detection of SARS-CoV-2. The aim was always to achieve reliable, sensitive, and reproducible detection. The proposed configuration is based on Ag-Au alloy nanoparticle films covered with a layer of graphene which promotes the molecular adsorption and a thiol-tethered DNA layer as a ligand. Here, the combination of two recent approaches in a single configuration is very promising and can only lead to considerable improvement. We have theoretically analyzed the sensor performance in terms of sensitivity and resolution. To highlight the importance of the new configuration, a comparison was made with two other sensors. One is based on gold nanoparticles incorporated into a host medium; the other is composed of a bimetallic Ag-Au layer in the massive state. The numerical results obtained have been validated and show that the proposed configuration offers better sensitivity (7100 nm\\RIU) and good resolution (figure of merit; FOM = 38.88 {RIU}^{-1} and signal-to-noise ratio; SNR = 0.388). In addition, a parametric study was performed such as the graphene layers’ number and the size of the nanoparticles.

Influence of the photodeposition sequence on the photocatalytic activity of plasmonic Ag-Au/TiO2 nanocomposites.

Bimetallic Ag-Au/TiO2 nanocomposites were synthesized by sequential photodeposition in order to investigate the effect of surface plasmon resonance (SPR) properties on photocatalytic activity for solar water splitting and methylene blue (MB) degradation. The photodeposition times were optimized for monometallic Ag/TiO2 and Au/TiO2 nanocomposites to yield maximum SPR absorption in the visible range. It was found that the photocatalytic activity of bimetallic Ag-Au/TiO2 nanocomposites outperformed monometallic nanocomposites only when Au was photodeposited first on TiO2, which was attributed to Au-core-Ag-shell nanoparticle morphology. In contrast, reversing the photodeposition order resulted in Ag-Au alloy nanoparticle morphology, which was mediated by the galvanic replacement reaction during the second photodeposition. Alloying was not beneficial to the photocatalytic activity. These results demonstrate alloying during sequential photodeposition providing new insights for the synthesis of TiO2-based photocatalysts with plasmon-enhanced absorption in the visible range.

Constructing a novel AuAg/BiOBr/BaTiO3 composite via selective decoration route with enhanced visible-light photoatalytic performance

In this work, the BaTiO3 nanoparticles (hole acceptor) were firstly decorated on the surface of BiOBr nanoplates by hydrothermal method, and then AuAg alloy nanoparticles (electron acceptor) are selectively deposited on the uncovered surface of BiOBr nanoplates to form AuAg/BiOBr/BaTiO3 composite using visible-light photodeposition method. It is found that the BaTiO3 (∼55 nm) and AuAg (7–16 nm) nanoparticles are uniformly dispersed on the BiOBr surface, which are disconnected without direct contact between them. The visible-light photocatalytic degradation and reduction activity of products were evaluated using methyl orange (MO), acid orange 7 (AO7), rhodamine B (RhB) and Cr(VI) as the target reactant. After the combination of BiOBr with BaTiO3, the BiOBr/BaTiO3 composites exhibit enhanced photocatalytic activity. When the content of BaTiO3 reaches about 10%, the BiOBr/10%BaTiO3 composite exhibits best photocatalytic efficiency. Notably, the selective deposition of Au, Ag and AuAg alloy nanoparticles leads to the further enhancement of photocatalytic activity for BiOBr/10%BaTiO3 composite, and the optimal photocatalytic activity can be achieved over AuAg/BiOBr/10%BaTiO3 sample. The AuAg/BiOBr/10%BaTiO3 composite is demonstrated to be an stable photocatalyst, which also exhibits efficient synergistic photocatalytic activity for the purification of the RhB/Cr(VI) and AO7/Cr(VI) mixture. The photogenerated charges performance of products was measured by electrochemical work station. The main active species participated in the photocatalytic reaction of AuAg/BiOBr/10%BaTiO3 was detected. Based on above results, the synergistic modification mechanism of BaTiO3 and AuAg alloy nanoparticles on the photocatalytic activity of BiOBr was proposed.

Porous Au-Ag Nanoparticles from Galvanic Replacement Applied as Single-Particle SERS Probe for Quantitative Monitoring.

Plasmonic nanostructures have raised the interest of biomedical applications of surface-enhanced Raman scattering (SERS). To improve the enhancement and produce sensitive SERS probes, porous Au-Ag alloy nanoparticles (NPs) are synthesized by dealloying Au-Ag alloy NP-precursors with Au or Ag core in aqueous colloidal environment through galvanic replacement reaction. The novel designed core-shell Au-Ag alloy NP-precursors facilitate controllable synthesis of porous nanostructure, and dealloying degree during the reaction has significant effect on structural and spectral properties of dealloyed porous NPs. Narrow-dispersed dealloyed NPs are obtained using NPs of Au/Ag ratio from 10/90 to 40/60 with Au and Ag core to produce solid core@porous shell and porous nanoshells, having rough surface, hollowness, and porosity around 30-60%. The clean nanostructure from colloidal synthesis exhibits a redshifted plasmon peak up to near-infrared region, and the large accessible surface induces highly localized surface plasmon resonance and generates robust SERS activity. Thus, the porous NPs produce intensely enhanced Raman signal up to 68-fold higher than 100nm AuNP enhancement at single-particle level, and the estimated Raman enhancement around 7800, showing the potential for highly sensitive SERS probes. The single-particle SERS probes are effectively demonstrated in quantitative monitoring of anticancer drug Doxorubicin release.

Plasmonic alloy nanochains assembled via dielectrophoresis for ultrasensitive SERS.

It is great challenge and interesting for researchers to fabricate substrates for enhanced Raman and sensor, and assemble some easy-to-synthesize metallic nanomaterials into controllable nanostructures with special morphologies and arrangements, via alternating current (AC) electric field. The Au-Ag alloy nanoparticles (Au-Ag alloy NPs) colloidal suspension with excellent dispersibility synthesized by wet chemical method, and the morphology of the assembly can be well controlled by regulating the frequency of the AC electric field. Au-Ag alloy nanochains array (Au-Ag ANCs) with dense plasmonic "hot spots" is formed when the AC electric field of 4Vpp-30kHz is applied, which is supported by the result of finite element method (FEM) numerical simulation. Experimental results demonstrate that Au-Ag ANCs show excellent SERS activity: Au-Ag ANCs can detect both Rhodamine 6G (Rh6G) and crystal violet (CV) in the magnitude order of 10-10 M, and the Raman peaks intensity and analyte concentration has a strong linear correlation (R2 is 0.99339 and 0.95916, respectively). Besides, the introduction of Au-Ag ANCs makes the Raman spectra intensity of thiram (a pesticide) with a concentration of 30 ppm on the surface of the blank ITO glass significantly enhanced, and it can detect thiram with a concentration as low as 0.03 ppm. In addition, Au-Ag ANCs substrate exhibits great uniformity and stability, so they have considerable application potential in the field of quantitative detection of trace substances.

Thermodynamic Stabilities of PdRuM (M = Cu, Rh, Ir, Au) Alloy Nanoparticles Assessed by Wang–Landau Sampling Combined with DFT Calculations and Multiple Regression Analysis

Abstract Unique features of alloy nanoparticles (NPs) originate from the configuration of elements within NPs; solid solution and segregated configurations show different properties even with the same overall composition of elements. The configuration space of an alloy NP is exponentially expanded by an increase of the constituent elements. Besides, the configurational entropy in an alloy NP cannot be analytically estimated due to the heterogeneous surface. Revealing the stable configuration and the corresponding entropy in the extensive configuration space is difficult. Herein, Wang–Landau sampling, combined with density functional theory (DFT) calculations and multiple regression analysis, was used to assess the thermodynamic stabilities of PdRuM (M = Cu, Rh, Ir, Au) ternary alloy NPs. Specifically, the excess energies calculated by DFT were subjected to multiple regression analysis, and the obtained regression equations were used for Wang–Landau sampling. The thus-obtained configurational densities of states allowed us to estimate thermodynamic quantities, and hence, to predict stable configurations at a finite temperature. We conclude that the developed method is well suited to probing the stable configurations of multinary alloy NPs at a finite temperature.

One-step fabrication of Au-Ag alloys and its application for catalysts and SERS sensors

Au-Ag alloy nanoparticles (NPs) with controllable size and composition were synthesized by a facile, one-pot hydrothermal method. Various characterization techniques including TEM, UV–vis, EDX, HAADF-STEM and XPS were used to discuss the influencing factors for the size and composition of Au-Ag alloy NPs. It is obvious that the size and composition of Au-Ag alloy NPs could be adjusted by the experimental parameters. Catalytic and SERS performance of the Au-Ag alloy NPs were further investigated. Ideal catalytic and SERS performance could be also obtained via optimizing the size and composition of Au-Ag alloy. This work is of importance in theory research and practical application of the noble metal nanocomposites.

One Pot Synthesis of PEGylated Bimetallic Gold-Silver Nanoparticles for Imaging and Radiosensitization of Oral Cancers.

BackgroundRadiotherapy is an important treatment modality for many types of head and neck squamous cell carcinomas. Nanomaterials comprised of high atomic number (Z) elements are novel radiosensitizers enhance radiation injury by production of free radicals and subsequent DNA damage. Gold nanoparticles are upcoming as promising radiosensitizers due to their high (Z) biocompatibility, and ease for surface engineering. Bimetallic nanoparticles have shown enhanced anticancer activity compared to monometallic nanoparticles.Materials and MethodsPEG-coated Au–Ag alloy nanoparticles (BNPs) were synthesized using facile one pot synthesis techniques. Size of ~50±5nm measured by dynamic light scattering. Morphology, structural composition and elemental mapping were analyzed by electron microscopy and SAXS (small-angle X-ray scattering). The radiosensitization effects on KB oral cancer cells were evaluated by irradiation with 6MV X-rays on linear accelerator. Nuclear damage was imaged using confocal microscopy staining cells with Hoechst stain. Computed tomography (CT) contrast enhancement of BNPs was compared to that of the clinically used agent, Omnipaque.ResultsBNPs were synthesized using PEG 600 as reducing and stabilizing agent. The surface charge of well dispersed colloidal BNPs solution was −5mV. Electron microscopy reveals spherical morphology. HAADF-STEM and elemental mapping studies showed that the constituent metals were Au and Ag intermixed nanoalloy. Hydrodynamic diameter was ~50±5nm due to PEG layer and water molecules absorption. SAXS measurement confirmed BNPs size around 35nm. Raman shift of around 20 cm−1 was observed when BNPs were coated with PEG. 1H NMR showed extended involvement of −OH in synthesis. BNPs efficiently enter cytoplasm of KB cells and demonstrated potent in vitro radiosensitization with enhancement ratio ~1.5–1.7. Imaging Hoechst-stained nuclei demonstrated apoptosis in a dose-dependent manner. BNPs exhibit better CT contrast enhancement ability compared to Omnipaque.ConclusionThis bimetallic intermix nanoparticles could serve a dual function as radiosensitizer and CT contrast agent against oral cancers, and by extension possibly other cancers as well.

Monitoring allergic reaction to penicillin based on ultrasensitive detection of penicilloyl protein using alkyne response SERS immunosensor

The evaluation of true penicillin allergy is significant to reduce its occurrence and the overdiagnosis before anti-infective treatment. However, the currently available methods with high specificity still face the problem of low sensitivity, thereby easily leading to false negatives. Herein, an alkyne responsive surface-enhanced Raman scattering (SERS) immunosensor is reported for ultrasensitive detection of penicillin allergen penicilloyl protein (P-protein) by using Au-Ag alloy nanoparticles@(antibody + alkyne probe) (as SERS immunoprobe) together with Ag nanofilm modified by antibody (as SERS capture substrate). The SERS immunoassay integrates the interference-free Raman response of high wavenumber region (2212 cm−1) and specific capture antibody with high affinity to selectively recognize P-protein from complicated sample. Meanwhile, the target-induced near-field coupling effect between localized surface plasmon resonances of individual SERS immunoprobe and capture substrate enables the detection of P-protein as low as pg/mL level, and the limit of detection can reach 0.329 pg/mL that is about 6 orders of magnitude lower than the limit defined protein residue (causing penicillin allergy). With the ultrasensitivity and specific selectivity, the proposed SERS immunoassay platform can precisely evaluate the content of P-protein in blood sample or penicillin drugs. It will be a potential tool to monitor allergic reaction to penicillin and better understand the mechanism of penicillin hypersensitivity.

Use of single particle inductively coupled plasma mass spectrometry for understanding the formation of bimetallic nanoparticles

Bimetallic nanoparticles (NPs), including core-shell structure and bimetallic alloy nanoparticles, were synthesized and characterized using flow field-flow fractionation (FlFFF), single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), and transmission electron microscope (TEM) with energy-dispersive x-ray spectroscopy (EDS). For the core-shell particles, a nominal 80 nm commercial core-shell AuAg bimetallic nanoparticle was used to examine the applicability of SP-ICP-MS to determine the core size of Au and shell thickness of Ag. Then, the method was applied to estimate the core size of Au and shell thickness of Ag for the laboratory synthesized particles. The results were compared with those obtained from TEM-EDS. For the alloy nanoparticles, two synthesis protocols, based on the galvanic replacement of Ag seed particles with Au, were used. One was to prepare a hollow AgAu particle by varying the volume of dissolved Au in basic solution (K-gold) to etch some parts of AgNPs to dissolved ionic silver with the formation of AuNPs covering the remaining AgNPs, producing a hole inside the core nanoparticles. Another protocol was to prepare AgAu alloy nanoparticles. SP-ICP-MS was used in combination with FlFFF to provide information on the changes of particle size with varying volume of K-gold reagent. Hydrodynamic diameter increased with increasing K-gold, as observed by FlFFF. With SP-ICP-MS without prior FlFFF, bimodal distributions were observed in the size distribution of Au and Ag. With prior FlFFF, monomodal distributions were observed by SP-ICP-MS, which allow the use of particle concentration and size to estimate the mass concentration of elements on the fractionated bimetallic nanoparticles. This study illustrates the potential use of SP-ICP-MS for gaining information about particle transformation during the synthesis of bimetallic nanoparticles.

Monomer driven growth of catalytically active AgAu plasmonic nanoalloys

Ag–Au alloy nanoparticles were effortlessly synthesized with the seed Ag nanoparticles acting as sacrificial template for the effective reduction of Au3+ ions to Au0 atoms, augmented in the presence of the monomer, NVP (N-vinyl pyrrolidone) assimilated in specific solvents. The conventional spherical morphology of the different Ag–Au alloy molar compositions confirmed using TEM corroborates their red-shifted optical absorption spectra along with the strain induced XRD patterns in accordance with Vegard's law. FTIR spectroscopy depicts clearly the solvation property of NVP and also its respective molecular interaction of individual metal and alloy nanostructures. The amine group of NVP despite its possible steric hindrance seems to coordinate well with monometallic Ag nanoparticles; while for bimetallic Ag–Au nanoparticles, the combined amine and carbonyl groups plays a major role in stabilizing the nanostructure. No evidence of oligomerization/polymerization is observed even after the formation of respective nanoparticles, representing the intriguing configuration of the monomer NVP, the behavior of which seems equivalent to that of its long chain polymer counterpart, PVP. The catalytic properties of the as-synthesized Ag–Au alloy nanoparticles were carefully analyzed in comparison with other polymer/surfactant coated alloy nanoparticles and their significance is established in a cohesive manner.

Highly sensitive multiplex-detection of surface-enhanced Raman scattering via self-assembly arrays of porous AuAg nanoparticles with built-in nanogaps

Designing and fabricating highly dense porous nanoparticles (p-NPs) arrays with nanogaps are crucial for ultra-sensitive surface-enhanced Raman scattering (SERS) detection as they can provide both abundant built-in and inter nanogap-induced hotspots. Here, we demonstrate highly sensitive multiplex-detection of organic dyes using SERS substrates with the self-assembly arrays of porous AuAg alloy (p-AuAg) NPs. The p-AuAg NPs were fabricated by a thermal dewetting method of very thin Au/Ag bilayers and a subsequent dealloying approach, which result in multiple built-in and inter nanogaps between the nano-granules with a porous structure and the adjacent NPs as well as excellent porosity and a high surface-to-volume ratio. The SERS substrates with p-AuAg NPs for the detection of Rhodamine 6 G (R6G) molecules exhibited an excellent enhancement factor of approximately 7.8 × 106, good reproducibility with relative standard deviation<6.5%, and limit of detection of dye molecules down to 2.37 × 10−9 M concentration in comparison with the AuAg alloy NPs. This is attributed to the generation of significant enhancement of electromagnetic field at the highly-dense built-in and inter nanogap in the self-assembly arrays of p-AuAg NPs, which is supported by the finite-difference time-domain (FDTD) simulation results. In addition to the detection of R6G molecules, the multiplex detection capability of R6G and crystal violet (CV) molecules at low concentrations for the p-AuAg NPs-based SERS substrates was also demonstrated. These findings present a potential pathway towards the development of an excellent SERS platform for practical applications such as bioscience, food, and environmental safety.