Ag-Cu Nanoparticles Research Articles

Fusion behaviour and mechanism of ultrafine Ag-Cu nanoparticles induced by electron beam irradiation

Understanding the thermal evolution mechanisms of metal nanoparticles (NPs) at the quantum-dot-scale is arrestive and meaningful for utilization of nanomaterials. Herein, an interesting fusion evolution phenomenon of Ag-Cu NPs induced by in-situ TEM high-energy electron beam illumination has been observed and investigated. It turned out that a rapid fusion process was in progress as reflected by the significant morphological change as the electron beam illumination time increased. The Ag-Cu NPs clusters tended to shrink their overall surface area along with the increase of sintering neck radii and decrease of neck curvature which was dominated by lattice diffusion mechanism. In addition, the necks among three Ag-Cu NPs continuously grew until the three particles became a short nanorod with a relatively uniform lateral diameter of about 20 nm after 300 sʹ illumination. It was also worthy of note that the smaller particles disappeared faster than bigger ones due to their highest surface energy.

Synthesis of Ag-Cu and Ag-Cu2O alloy nanoparticles using a seed-mediated polyol process, thermodynamic and kinetic aspects

In this paper, Ag, Ag-Cu and Ag-Cu2O nanoparticles were synthesized using a modified polyol method. Size, shape and composition of the obtained nanostructures were effectively controlled by adjusting the kinetic and thermodynamic conditions. Response surface methodology was employed to consider the interaction of parameters and to develop a polynomial equation for predicting the size of the silver nanoparticles. The precisely controlled silver nanoaprticles were used as the seeds for the formation of alloyed nanoparticles. By manipulating the involved parameters, both spherical and cubical Ag-Cu and Ag-Cu2O nanostructures are obtainable in the size range of 90–100 nm. The morphological, optical and compositional characteristics of the obtained nanostructures were studied using SEM, FE-SEM, UV–Vis, EDS and XRD.

Highly sensitive electrochemical sensor for the food toxicant Sudan I based on a glassy carbon electrode modified with reduced graphene oxide decorated with Ag-Cu nanoparticles

The authors describe a method for room temperature preparation of reduced graphene oxide (rGO) decorated with Ag-Cu nanoparticles (NPs). The nanocomposite (Ag-CuNP/rGO) was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. A glassy carbon electrode (GCE) modified with this nanocomposite dispersed is shown to be a viable electrode for determination of Sudan I (best at a working voltage of −112 mV vs. Ag/AgCl), with remarkably increased electrochemical response to Sudan I compared to that of a plain GCE. The calibration plot is linear in the 1.0 nM to 10 µM concentration range, with a 0.4 nM detection limit (at a signal-to-noise ratio of 3). The method was successfully applied to the determination of Sudan I in ketchup and chili powder.

Preparation and characterization of agar-based nanocomposite films reinforced with bimetallic (Ag-Cu) alloy nanoparticles

Agar-based active nanocomposite films were prepared by incorporating silver-copper (Ag-Cu) alloy nanoparticles (NPs) (0.5–4wt%) into glycerol plasticized agar solution. Thermo-mechanical, morphological, structural, and optical properties of the nanocomposite films were characterized by texture analyzer, differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and surface color measurement. Tensile strength and the melting temperature of the film increased linearly with NPs loading concentration. Color, transparency and UV barrier properties of agar films were influenced by the reinforcement of Ag-Cu NPs. XRD analysis confirmed the crystalline structure of the Agar/Ag-Cu nanocomposite films, whereas the smoothness and the homogeneity of film surface strongly reduced as observed through the SEM. The nanocomposite films exhibited a profound antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Salmonella enterica sv typhimurium) bacteria. Overall, the agar nanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

Thermo-mechanical, rheological, structural and antimicrobial properties of bionanocomposite films based on fish skin gelatin and silver-copper nanoparticles

The paper focuses on the development and characterization of bionanocomposite films based on fish skin gelatin (FSG) and bimetallic Ag-Cu nanoparticles (Ag-Cu NPs). Effects of Ag-Cu NPs loadings on the thermal, mechanical, rheological, structural, and antibacterial properties of the gelatin-based films were investigated. An increase in tensile strength (TS), and a decrease in elongation at break (EAB) recorded while nanocomposite (NC) films were loaded with 2% (w/w) NPs. Nevertheless, both parameters (TS and EAB) dropped drastically with further addition of NPs (p < 0.05). Oscillatory rheological data also established that 2% NPs loading improved the mechanical property of the FSG/Ag-Cu nanocomposites. The NC films showed lower transparency, yellowness, and the total color difference over the control FSG film (p < 0.05), whereas the UV barrier property improved substantially. An interaction between NPs and gelatin matrix in the film was evidenced through Fourier transform infrared (FTIR) spectroscopy. Both differential scanning calorimetric (DSC) and thermogravimetric (TGA) analyses confirmed the incorporation of NPs significantly improved the glass transition temperature (Tg), and thermal stability of the NC films. X-ray diffraction (XRD) demonstrated a change in the crystallinity of FSG films with incorporation of NPs. However, the NC films became coarse with added NPs as indicated by scanning electron microscopy (SEM) micrographs. The NC films exhibited a strong antibacterial activity against both Gram-positive and Gram-negative bacteria. Overall, the NC films could be used as an active food packaging materials for food preservation by controlling foodborne pathogens and spoilage bacteria.

AuCu, AgCu and AuAg Bimetallic Nanoparticles: Synthesis, Characterization and Water Remediation

ABSTRACTSelf-assembling systems of amphiphilic molecules display structures similar to those of biomineralization natural systems. This allows to somehow mimic nature to synthesize nanomaterials with low polidispersity and with diverse morphologies. In this work we describe the synthesis and characterization of gold-copper, silver-copper, and gold-silver bimetallic nanoparticles by chemical reduction in self-assembling systems of two surfactants. The nanoparticles were characterized by Transmission Electron Microscopy and UV-Vis spectroscopy. We have prepared a composite material using mesoporous silica as support of the AuAg bimetallic nanoparticles. The system was used in photocatalysis experiments for water remediation applications. Our results show that the AuAg/SBA15 composite material degrades methyl orange in water from 17 ppm to 4 ppm in 30 minutes.

Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

TiO2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals’ precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Agcore-Cushell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

Ag-Cu Nanoparticles Encaptured by Graphene with Magnetron Sputtering and CVD for Surface-Enhanced Raman Scattering

An efficient surface-enhanced Raman scattering (SERS) substrate has been developed based on Ag-Cu nanoparticle-decorated graphene. The Ag-Cu-graphene (Ag-Cu@G) hybrid structure was prepared by magnetron sputtering for Ag and Cu film and chemical vapor deposition (CVD) for graphene, which avoided defects produced by graphene transferring process. The hybrid materials were confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), and Raman spectroscopy. With R6G as analyst molecule, the enhancement factor (EF) of the order of 106 for Ag-Cu@G sample was obtained. Meanwhile, the substrates had stable enhanced SERS signals after 78-day exposure in air, which could be explained by the fact that the graphene is efficient at maintaining chemical and optical stability. The formation of graphene can contribute a stabilization and fluorescence quenching effect. Moreover, the electromagnetic distribution based on AFM images was simulated by finite difference time domain (FDTD) method.

Influence of Different Percentages of Copper on the Size and Optical Properties of Ag-Cu Nanoparticles Formed by Wet-Chemical Method

In this work, Ag-Cu nanoparticles (with different percentages of copper, 10%, 25%, 50%, 75% Cu) were synthesized by wet chemical method. Copper(II) sulfate and silver nitrate were taken as metal precursors, ascorbic acid as reducing agent and anhydride maleic (MA) as a modifier. The prepared nanoparticles were characterized by means of X-ray diffraction (XRD) technique and scanning electron microscopy (SEM-EDAX), Fourier transform infrared spectroscopy (FT-IR) and UV-Vis spectroscopy. SEM indicated the formation of uniform spherical crystalline nanoparticle in a well distributed size and morphology. It can be seen from these pictures that the particle size decreased with increasing of the copper percent. When the molar ratio of Cu2+/Ag+ is 75/25 (>50%), mixture of the spherical and hexagonal nanoparticles was prepared. Three pronounced Ag diffraction peaks (111), (200) and (220) appeared at 2θ = 38°, 43.9° and 64.1°, respectively. The three most intense peaks of the XRD pattern of sample showed a slight shifting of the center of the diffraction peaks toward a lower angle. No shifting was observed in XRD lines with the increase of Cu2+ to Ag+ ratio in the Cu2+/Ag+ mixed solution (> 50% Cu). Fourier transform infrared spectroscopy (FT-IR) showed that nanoparticles are coordination between oxygen atoms and nanoparticles, because functional unit C=O present in MA, shifts to 1652.69 cm-1 after embedding nanoparticles. The position of the surface plasmon resonance (SPR) absorption band on the nanoparticles could be shifted from 380-350 nm via the change of their percentage of Cu.

O56] Fabrication of Ag-Cu Nanoparticles Based on the Nano-Phase Diagram and Anti-Oxidation Effects

O56] Fabrication of Ag-Cu Nanoparticles Based on the Nano-Phase Diagram and Anti-Oxidation Effects

Agglomeration in core-shell structure of CuAg nanoparticles synthesized by the laser ablation of Cu target in aqueous solutions

Metallic copper Cu and bimetallic copper–silver CuAg nanoparticles (NPs) are generated by the ablation of copper bulk target in water and aqueous Ag colloidal solution, respectively. The experiments were performed using nanosecond Nd:YAG laser operating at 1064 nm. The generated NPs are characterized by UV–vis absorption spectroscopy, laser-induced breakdown spectroscopy, dynamic light scattering and scanning electron microscopy. The conducted investigations can be summarized as follows: (i) CuAg NPs colloidal solution possess the absorption in UV–vis spectral region, which can be attributed to the Cu-component; (ii) the primary bimetallic CuAg NPs have near uniform dimensions with diameter of about 15 nm, and as a rule, they are grouped into larger agglomerates without defined morphology; (iii) the obtained Cu NPs have mainly spherical form with average diameters up to 20 nm. Both types of NPs show a tendency towards the formation of large agglomerates with different morphology. Bimetallic NPs show the plasmon resonance in the vicinity of 640 nm with a good coincidence with formation of the colloidal solution of pure Cu NPs. The results also demonstrate that the core–shell structure (Ag-rich core/Cu-rich shell) is important for the formation of the bimetallic NPs, also agreeing very well with theory.

Synthesis and thermodynamics of Ag-Cu nanoparticles.

Metallic silver, copper, and Ag-Cu nanoparticles (NPs) have been produced by a chemical reduction method. The obtained nanoparticles were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). A side-segregated configuration was observed for the one-pot synthesized Ag-Cu NPs, and the melting temperature depression of about 14 °C was found by differential scanning calorimetry (DSC). A comparison between the new experimental data, the literature data on Ag-Cu bimetallic NPs and the corresponding theoretical values obtained from the Ag-Cu nano-sized phase diagram was done, whereas the melting behaviour of Ag and Cu metal nanoparticles was discussed in the framework of the liquid layer model (LLM).

Optical Properties of Ag-Cu Alloy Nanoparticles Synthesized by DC Arc Discharge in Liquid

Alloy nanoparticles are much interesting because their properties are flexible and can be very distinct with the particles of their constituents. Optical properties of alloy nanoparticles can differ by size effects and composition of their pure components. The aim of this article is studying the alloying and optical properties of Cu-Ag nanoparticles prepared via DC arc discharge in water with two different experimental procedures. Arc discharge was ignited between two pure silver and copper electrodes and two types of sample productions were held. The first one was based on using copper and silver wire with 99.99% purity as an anode and cathode electrodes and at the same 3mm diameter in each part by two different 40, 50 A current. Second one was using reversed sited electrodes. Optical properties, size and crystal structure of nanoparticles were characterized by UV-visible spectroscopy, Field Emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) respectively. SEM images show the nanoparticles are spherical with the average size of lower than 30nm for all samples. XRD results shows there are some displacements in Bragg diffraction angles of silver XRD peaks which is due to the positioning of Cu atoms among silver atoms and synthesis of Ag-Cu alloy nanoparticles. However some Ag-Cu alloy peaks were also observed. In comparison with the optical extinctions of pure copper and silver nanoparticles the optical extinctions of samples have the characteristic optical extinction of Ag-Cu alloy nanoparticles with extinction peak due to surface plasmon resonance that was observed between silver and copper nanoparticles extinction peaks. In addition optical properties of Ag-Cu alloy are more adjustable with arc current when using copper and silver wire as anode and cathode electrode respectively. The results provide a simple and flexible method for preparation and tuning optical properties of Ag-Cu nanoparticles.

AgCu Bimetallic Nanoparticles under Effect of Low Intensity Ultrasound: The Cell Viability Study In Vitro

The effects of metallic nanoparticles as cytotoxicity or antibacterial activity are widely known. It is also obvious that ultrasound is one of the most widely used therapeutic modalities in medicine. The effect of application of therapeutical ultrasonic field in the presence of metallic nanoparticles AgCu &lt;100 nm modified by phenanthroline or polyvinyl alcohol was examined on human ovarian carcinoma cells A2780. Metallic nanoparticles were characterized by electron microscopy and by measuring of zeta potential. The cell viability was tested by MTT test. The experimental results indicate a significant decrease of cell viability, which was affected by a combined action of ultrasound field and AgCu nanoparticles. The maximum decrease of cells viability was observed for nanoparticles modified by phenanthroline. The effect of metallic nanoparticles on human cell in presence of ultrasound exposure was found—a potential health risk or medical advantage of targeted therapy in the future.

Alkyne-functionalized superstable graphitic silver nanoparticles for Raman imaging.

Noble metals, especially gold, have been widely used in plasmon resonance applications. Although silver has a larger optical cross section and lower cost than gold, it has attracted much less attention because of its easy corrosion, thereby degrading plasmonic signals and limiting its applications. To circumvent this problem, we report the facile synthesis of superstable AgCu@graphene (ACG) nanoparticles (NPs). The growth of several layers of graphene onto the surface of AgCu alloy NPs effectively protects the Ag surface from contamination, even in the presence of hydrogen peroxide, hydrogen sulfide, and nitric acid. The ACG NPs have been utilized to enhance the unique Raman signals from the graphitic shell, making ACG an ideal candidate for cell labeling, rapid Raman imaging, and SERS detection. ACG is further functionalized with alkyne-polyethylene glycol, which has strong Raman vibrations in the Raman-silent region of the cell, leading to more accurate colocalization inside cells. In sum, this work provides a simple approach to fabricate corrosion-resistant, water-soluble, and graphene-protected AgCu NPs having a strong surface plasmon resonance effect suitable for sensing and imaging.

Synthesis and Fabrication of PVA-Ag-Cu and PANI-Ag-Cu Nanocomposite Thin Film Sensor for Detection of &lt;i&gt;E. coli&lt;/i&gt; in Water

Polymers are excellent host materials for nanoparticles of metals and semiconductors. PVAAgCu nanocomposite was synthesized from chemical reduction, whereas PANIAgCu nanocomposite was synthesized by chemical oxidative polymerization. PVAAgCu and PANIAgCu thin films were deposited on the glass substrate by spin coating technique. The films were characterized by using XRD and AFM. The sensitivity of the samples was analyzed by IV measurement. The peaks in XRD patterns confirm the presence of Ag-Cu nanoparticles in face centered cubic structure. AFM images show the roughness of PVAAgCu and PANIAgCu increased as Ag concentration decreased and Cu concentration increased. I-V measurements indicate that the change in the current of the films increases with the presence of E. coli. The sensitivity on E. coli increases for PVAAgCu and PANIAgCu thin films with high concentration of Cu.

Ag‐Cu Colloid Synthesis: Bimetallic Nanoparticle Characterisation and Thermal Treatment

The Ag‐Cu bimetallic colloidal nanoparticles (NPs) were prepared by solvothermal synthesis from metalloorganic precursors in a mixture of organic solvents. The nanoparticles were characterized by dynamic light scattering (DLS) and small angle X‐ray scattering (SAXS). The properties of metallic core and organic shell of the nanoparticles were studied by direct inlet probe mass spectrometry (DIP/MS), Knudsen effusion mass spectrometry (KEMS), double‐pulse laser‐induced breakdown spectroscopy (DPLIBS), and differential scanning calorimetry (DSC). The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for particle characterization before and after thermal analysis. The experiment yielded results that were for AgCu nanoparticles for the first time. The detected liquidus temperature has been compared with the prediction obtained from calculation of the phase diagram of Ag‐Cu nanoalloy. The experimental results show that of near‐eutectic composition AgCu nanoparticles possess the fcc crystal lattice. Surprisingly, spinodal decomposition was not observed inside the AgCu nanoparticles at temperatures up to 230°C. The depression of the eutectic AgCu melting point was calculated but not observed. The eutectic AgCu microparticles are formed before melting.

Metal and Alloy Nanoparticles by Amine-Borane Reduction of Metal Salts by Solid-Phase Synthesis: Atom Economy and Green Process

A new solid state synthetic route has been developed toward metal and bimetallic alloy nanoparticles from metal salts employing amine-boranes as the reducing agent. During the reduction, amine-borane plays a dual role: acts as a reducing agent and reduces the metal salts to their elemental form and simultaneously generates a stabilizing agent in situ which controls the growth of the particles and stabilizes them in the nanosize regime. Employing different amine-boranes with differing reducing ability (ammonia borane (AB), dimethylamine borane (DMAB), and triethylamine borane (TMAB)) was found to have a profound effect on the particle size and the size distribution. Usage of AB as the reducing agent provided the smallest possible size with best size distribution. Employment of TMAB also afforded similar results; however, when DMAB was used as the reducing agent it resulted in larger sized nanoparticles that are polydisperse too. In the AB mediated reduction, BNH(x) polymer generated in situ acts as a capping agent whereas, the complexing amine of the other amine-boranes (DMAB and TMAB) play the same role. Employing the solid state route described herein, monometallic Au, Ag, Cu, Pd, and Ir and bimetallic CuAg and CuAu alloy nanoparticles of <10 nm were successfully prepared. Nucleation and growth processes that control the size and the size distribution of the resulting nanoparticles have been elucidated in these systems.

Formation and Mechanism of Ag/Cu Nanoparticles in Silicate Glass via Ion-Exchange and Reduction Treatment

Ag-Cu nanoparticles/silicate glass composites are synthesized by twice ion-exchange and reduction treatment. The as-produced glass slides were characterized by UV–Vis spectroscopy, electron probe microanalysis (EPM) and high resolution transmission electron microscopy (HRTEM). The studies show that Ag-Cu nanoparticles aggregate on the surface of the silicate glass, which size is from 2 nm to 8 nm. The copper layer on the surface of glass matrix is about 20 m by compared to Ag layer (120 m), indicating that it is more difficult for copper ions to enter into the interior. Ag-Cu migration in glass matrix cannot be simply ascribed to a direct interaction with hydrogen, but to a more complex process involving a charge balancing mechanism during hydrogen-sodium ion-exchange.

Polymer-Protected Cu-Ag Mixed NPs for Low-Temperature Bonding Application

A simple method has been proposed to prepare polymer-protected Cu-Ag mixed nanoparticles (NPs), which are suitable for use as low-temperature bonding materials. The polymer coated on the Cu-Ag mixed NPs can protect them from oxidation effectively when heated in air at temperature lower than 280°C. The low-temperature bonding process utilizing Cu-Ag mixed NPs as the bonding material is investigated. The bonding experiments show that robust joints are formed using Cu-Ag mixed NPs at 160°C in air. The shear test shows that addition of copper to silver is helpful for improving joint strength. This novel sintering-bonding technology using Cu-Ag mixed NPs as an interconnection material has potential for application in the electronics packaging industry.