Synthesis Of Silver Nanowires Research Articles

A facile synthesis of silver nanowires and their evaluation in the mitochondrial membrane potential.

Silver nanowires (AgNWs) with a high-aspect-ratio were successfully synthesized by a green method using Lavandula angustifolia plant extract. The morphology of the AgNWs was evaluated as a function of the concentration of precursor salt and nucleating agent. Furthermore, AgNWs were analyzed in a biological model using rat liver mitochondria by measuring their effect on membrane potential. The scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques structurally characterized the nanowires obtained. Also, ultraviolet-visible spectroscopy (UV-Vis) investigated the optical properties of AgNWs. Structural studies show AgNWs fcc with lengths up to 100μm and diameters ranging from 60 to 130nm growing in the [110] orientation. Both the CuSO4 nucleating agent and the centrifugation process are essential for the growth of nanowires. Furthermore, inhibition of mitochondrial membrane potential (MMP) depends on the concentration of the nanowires (NWs), suggesting dissipation of the electron transport chain. In this way, AgNWs can be used as a potential tool to verify biological reactions, such as modulation of metabolic pathways, together with the evaluation of a possible influence of biotic or abiotic factors in organisms.

Polyol Silver Nanowire Synthesis and the Outlook for a Green Process

Silver nanowires (AgNWs) have a broad range of applications including nanoelectronics, energy conversion, health care, solar cells, touch screens, sensors and biosensors, wearable electronics, and drug delivery systems. As their characteristics depend strongly on their size and morphology, it is essential to find the optimal and most cost-effective synthesis method with precise control over the size and morphology of the wires. Various methods for AgNW synthesis have been reported along with process optimization and novel techniques to increase the yield and aspect ratios of synthesized AgNWs. The most promising processes for synthesis of AgNWs are wet chemical techniques, in which the polyol process is low cost and simple and provides high yield compared to other chemical methods. Reaction mechanism is one of the most important factors in strategies to control the process. Our purpose here is to provide an overview on the main findings regarding synthesis, preparation, and characterization of AgNWs. Recent efforts in the polyol synthesis of AgNWs are summarized with respect to product morphology and size, reaction conditions, and characterization techniques. The effect of essential factors such as reagent concentration and preparation, temperature, and reaction atmosphere that control the size, morphology, and yield of synthesized AgNWs is reviewed. Moreover, a review on the novel modified polyol process and reactor design such as continuous millifluidic and flow reactors to increase the yield of synthesized AgNWs on large scales is provided. The most recent proposed growth mechanisms and kinetics behind the polyol process are addressed. Finally, comparatively few available studies in green and sustainable development of 1D silver nanostructures through the application of natural products with inherent growth termination, stabilization, and capping characteristics are reviewed to provide an avenue to natural synthesis pathways to AgNWs. Future directions in both chemical and green synthesis approaches of AgNWs are addressed.

Thin Films of Silver Nanowires for Flexible, Transparent, and Conductive (FTC) Electrodes

In this research, we have succeeded in making thin-films for flexible, transparent, and conductive (FTC) electrodes based on silver nanowires. The synthesis of silver nanowires is carried out at low temperatures, namely at 60 to 130 oC. The materials used in the synthesis of AgNWs are polyvinyl pyrrolidone (PVP) as a capping agent and Iron (III) chloride hexahydrate (FeCl3”¢6H2O) as a precursor to controlling the size of silver nanowires. Furthermore, the silver nanowires colloid then created a thin layer over the polycarbonate (PC) substrate by the roll to roll process. The Result shows that the formation of silver nanowires occurred at low temperatures of about 90 °C. The optimum condition of silver nanowires has obtained synthesis at the temperature of 110 °C with the average diameter of (100 ± 20) nm and length (30 ± 15) μm. The silver nanowires will increase in length and diameter at low-temperature and decrease at high temperatures .The transmittance of FTC film silver nanowires about 76-95% at a wavelength of 550 nm. The absorbance coefficient of FTC film silver nanowires has increased from 2.7 to 29.2 cm-1 at wavelength range 400 to 700 nm. The sheet resistance of the FTC film by varying the number of layers obtained of 905.2, 340.7, 21.9, and 3.4 Ω.sq-1 with the transmittance obtained at 76.7 to 95.8%. The number of layers of silver nanowires will increase the sheet resistance and decrease the optical transmittance of the FTC film.

The synthesis of silver nanowires with tunable diameters using halide ions for flexible transparent conductive films

The diameter of Ag nanowires could be tuned in the range of 19 to 35 nm with the cooperation of Cl− and Br− ions.

In situ synthesis of silver nanowire gel and its super-elastic composite foams.

Noble-metal aerogels (NMAs) including silver aerogels have drawn increasing attention because of their highly conductive networks, large surface areas, and abundant optically/catalytically active sites. However, the current approaches of fabricating silver aerogels are tedious and time-consuming. In this regard, it is highly desirable to develop a simple and effective method for preparing silver aerogels. Herein, we report a facile strategy to fabricate silver gels via the in situ synthesis of silver nanowires (AgNWs). The obtained AgNW aerogels show superior electrical conductivity, ultralow density, and good mechanical robustness. AgNW aerogels with a density of 24.3 mg cm-3 display a conductivity of 2.1 × 105 S m-1 and a Young's modulus of 38.7 kPa. Furthermore, using an infiltration-air-drying-crosslinking technique, polydimethylsiloxane (PDMS) was introduced into 3 dimensional (3D) AgNW networks for preparing silver aerogel/elastomer composite materials. The obtained AgNW/PDMS aerogel composite exhibits outstanding elasticity while retaining excellent electrical conductivity. The fast piezoresistive response proves that the aerogel composite has a potential application for vibration sensors.

Morphology-controlled silver nanowire synthesis using a cocamidopropyl betaine-based polyol process for flexible and stretchable electronics.

Silver nanowire (AgNW) based transparent conductive films (TCFs) are promising building blocks for flexible and stretchable electronics to replace brittle metal oxides. Ultra-long AgNWs are preferred for enabling TCFs with excellent photoelectric properties and mechanical flexibility. Herein, a novel polyol process is proposed for the synthesis of ultra-long AgNWs, with the new finding that the addition cocamidopropyl betaine (CAB) to polyol synthesis allows the rapid production of AgNWs with an average length of ∼120 μm in a high yield of ∼90%. Also, a cocamidopropyl betaine assisted polyol method for the synthesis of ultra-long AgNWs is demonstrated with a possible mechanistic explanation. The prepared AgNWs are coated on a polyethylene glycol terephthalate (PET) substrate to fabricate a flexible transparent conductive film, which exhibits a low sheet resistance of ∼200 Ω sq−1 at 88.74% transmittance with a negligible change of sheet resistance after bending. In addition, flexible TCFs based on the resulting AgNWs reveal excellent mechanical flexibility and high cyclic stability after 300 cycles of bending. The new polyol process in this work will provide a greater possibility for the practical application of long AgNWs towards flexible and wearable optoelectronic devices.

Silver nanoparticle-decorated silver nanowires: a nanocomposite via green synthesis

This study reports an ecological approach for the synthesis of silver nanowires (AgNW) decorated with silver nanoparticles (AgNP) using Mangifera indica leaf extract. A composite material of AgNW with a length of more than 10 μm and a diameter of ~ 70 nm was obtained, surrounded by AgNP with sizes less than 10 nm. The material obtained was characterized using UV–Vis spectroscopy, transmission electron microscopy, X-ray energy dispersive spectrometry and Fourier transform infrared spectroscopy. The crystallinity of the nanoparticles was analyzed with high-resolution HRTEM images and with the SAED diffraction pattern, identifying crystalline planes (111), (200), (220), (311) and (222) corresponding to silver. Additionally, in the theoretical study, the adsorption energy (Eads) was analyzed from the interaction of the Ag2 clusters close to cross-sections of different sizes of AgNW in the presence of the glycine molecule. This analysis was made using the theories of Hartree Fock and DFT. On the other hand, the material obtained showed excellent antibacterial activity against the bacterium Escherichia coli, inhibiting the growth of the microorganism by 99.95%. According to our knowledge, this would be the first report where this type of nanocomposite is obtained through green synthesis, in the same colloidal medium, without the need to apply different methodologies to obtain any of the individual nanostructures mentioned separately.

Flow Rate and Volume Control of Fluid Based on Arduino for Synthesis of Silver Nanowires

In this study, we have successfully developed a flow rate and volume control system based on Arduino. This system consists of a container containing liquid, dc motor, keypad, and Arduino UNO that serves as a controller. The principle of this system is to control pulse width modulation (PWM) and delay time of dc motor using Arduino. This fluid flow and volume rate control system aims to control how much the fluid volume enters a chamber for mixing the solution. This system has an accuracy rate of 0.5 ml and has a measurement range of up to 100 ml for one process. For forward, the system will be applied to the medical as a substitute for syringe pump and research laboratory for controlling the manufacture of solutions on the synthesis of nanomaterials, especially silver nanowires.

Synthesis of Silver Nanowires by Using Tetrabutyl Ammonium Dibromochloride as the Auxiliary for Low-Haze Flexible Transparent Conductive Films.

Silver nanowires (AgNWs) with the diameter down to 16 nm have been synthesized by using tetrabutyl ammonium dibromochloride (TBADBC) as the organic auxiliary. Moderate dosage of TBADBC was proven to be favorable for the in situ growth of Ag pentahedral seeds on the surface of small AgClBr2 particles and have a passivation effect on the Ag{100} crystal facet during the growth of AgNWs, eventually resulting in the formation of thin AgNWs. Furthermore, the transparent conductive film fabricated by using the obtained AgNWs exhibited excellent photoelectric properties, which has a transmittance of 90.60%, a haze of 0.95%, and a sheet resistance of 110.8 Ω/sq, indicating large potential for application in flexible transparent conductors.

Synthesis of silver nanowires with controlled diameter and their conductive thin films

Silver nanowires (AgNWs) with high uniformity and controlled morphology were synthesized by employing silver nitrate as precursor and ethylene glycol as reducing agent and solvent. Polyvinyl pyrrolidone (PVP) was used as growth controlling agent and the synthetic process was carried out in salt free environment. The effect of reaction parameters like concentration of AgNO3 and the reaction temperature on the final morphology of AgNWs was studied. AgNWs obtained by changing different conditions were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), selected area electron diffraction pattern (SAED), X-ray diffraction (XRD) and UV–Vis spectroscopy. Synthesized AgNWs were coated on polyethylene terephthalate substrate by spin coating method to make thin conductive flexible film. The silver nanowires film was found to have a sheet resistance of 6.82 Ω/sq.

Poly(vinyl pyrrolidone)-mediated synthesis of silver nanowires decorated with silver nanospheres and their antimicrobial activity

Pathogenic infectious diseases, like bacterial infections, are one of the most prevalent types of diseases all over the world. Although antibiotics are commonly used and widely available drugs for the treatment of bacterial infections, bacteria show multiple drug resistance, have a tendency to get genetically mutated and become resistant to commonly employed antibiotic drugs. This makes the invention of novel drugs essential. One of the possible approaches is the use of nanomaterials for this purpose. The present study attempts to synthesize silver nanospheres and silver nanowires and compare their antibacterial activity. Silver nanospheres were synthesized by chemical reduction of silver nitrate in the presence of a suitable stabilizer. For the synthesis of silver nanowires, polyol method was employed. Silver nanowires neatly decorated with silver nanospheres were obtained. The antibacterial activity was estimated by separately determining the minimum inhibition concentration of the two nanostructures on Gram-positive bacteria Bacillus subtilis and Gram-negative bacteria Escherichia coli cultured on Luria Bertani agar media. The comparison shows that the antibacterial activity of silver nanospheres is better than that of silver nanowires which is attributed to its higher surface area and the difference in uptake mechanism by the bacterial cells.

One step synthesis of silver nanowires using fructose as a reducing agent and its antibacterial and antioxidant analysis

Silver nanowires were synthesised using hydrothermal method by reducing silver nitrate (AgNO3) using fructose in the presence of poly-vinylpyrrolidone (PVP). The parameters such as the effect of process temperature, AgNO3 molarity, PVP and fructose (C6H12O6) concentration influencing the synthesis of silver nanowires (Ag NWs) were investigated. The scanning electron microscope (SEM) images showed that ultra-long, uniform and thin silver nanowires were obtained under optimized conditions; 0.02 M AgNO3, 0.016 g ml−1 of fructose, 0.16 g ml−1 of PVP at 160 °C within 22 h. The dynamic light scattering (DLS) analysis revealed that the silver nanowires obtained have an average diameter of 77 nm possessing high level of crystallinity with face centered cubic (fcc) phase that is evident from the x-ray diffraction (XRD) patterns peaked at (111), (200), (220), (311) and (222) planes. FT-IR (Fourier transform infrared spectroscopy) results suggested that there is adsorption of PVP molecules on the silver atoms. Ag NWs exhibited better antibacterial activity against Escherichia coli and high antioxidant activity against 2,2-diphenyl-1- picrylhydrazyl (DPPH) free radical scavenger. This work gives a green approach to the hydrothermal synthesis of Ag NWs using fructose with a promising antibacterial and antioxidant properties.

Synthesis of Silver Nanowires with Controllable Diameter and Simple Tool to Evaluate their Diameter, Concentration and Yield

AbstractSimple solvothermal method was used to synthesize of uniform silver nanowires with the controllable diameter (17, 20, 35, 70 and 100 nm). It is the first report on the solvothermal synthesis of ultra‐thin silver nanowires (17 nm) with the high aspect ratio (>1000). Knowing silver nanowires diameter, length and yield after synthesis are a critical step to classify them for the final goal. Up to now, although the length of nanowires can be measured with the optical microscope, but to estimate the diameter, costly high‐resolution microscopic techniques are necessary. Herein, UV/Vis spectroscopy as an easy and cost‐effective tool is introduced to evaluate the diameter and yield of nanowires. For this purpose, after synthesis and purification of silver different nanowires; from their UV/Vis spectra, a new equation for evaluation nanowires diameter was extracted. In addition, for the first time, absorption coefficients (ϵ) of nanowires with different diameter thickness were reported and a new equation to estimate absorption coefficients to calculate concentration (mg/ml) and yield of silver nanowires was extracted. These equations have good agreement with real data and are independent of the length of nanowires.

One-Step Synthesis of Silver Nanowires with Ultra-Long Length and Thin Diameter to Make Flexible Transparent Conductive Films

High aspect ratio silver nanowires (AgNWs) with ultra-long length and thin diameter were synthesized through bromine ion (Br−)-assisted one-step synthesis method. The bromine ions were used as pivotal passivating agent. When the molar ratio of Br−/Cl− was 1:4, the average diameter of AgNWs was as low as ~40 nm, the average length was as high as ~120 μm, and the aspect ratio reached 2500. Networks of AgNWs were fabricated using as-prepared high-quality AgNWs as conducting material and hydroxyethyl cellulose (HEC) as the adhesive polymer. As a result, a low sheet resistance down to ~3.5 Ω sq−1 was achieved with a concomitant transmittance of 88.20% and a haze of 4.12%. The ultra-low sheet resistance of conductive film was attributed to the long and thin AgNWs being able to form a more effective network. The adhesion of the AgNWs to the substrate was 0/5B (ISO/ASTM). The insights given in this paper provide the key guidelines for bromine ion-assisted synthesis of long and thin AgNWs, and further designing low-resistance AgNW-based conductive film for optoelectronic devices.

Silver Nanowire Ink for Flexible Circuit on Textiles.

Low cost electronics implemented in textiles could pave the way to a fully new generation of smart products in the fields of healthcare, sport, fashion, and safety. Although many methods have found their way into the market, many problems still need to be solved and much progress has to be made to enable the commercial exploitation of such products. In this paper, silver nanowires of 60–100 nm in diameter and 8–15 μm in length were achieved by the polyol solvothermal method, and aqueous silver nanowire conductive inks were prepared with the synthesized silver nanowires as the conductive phase, in the presence of polyaniline, guar, and hydrochloric acid. The conductive inks were printed on cotton fabric substrate by screen printing process. The effects of the amount of silver nanowires, layers of coating, and treatment temperature on the microstructure and electrical properties of samples were investigated by scanning electron microscopy and the four-point probe method. The results show that the conductivity and densification of the samples increased with increased amount of silver nanowires, layers of coating, and treatment temperature. The heat treatment helped to improve densification of the silver nanowires and conductivity of the sample. The resistance of the samples increased after bending due to loosening of the overlap between the silver nanowires.

A novel synthesis of silver nanowires by using 6-chlorohexylzinc bromide as an additive for low haze transparent conductive films

High-quality silver nanowires (AgNWs) with a small diameter of ∼20 nm and a length of ∼40 μm were prepared by using a novel organic 6-chlorohexylzinc bromide as an assistant additive. The diameter of as-synthesized AgNWs was confirmed to be strongly dependent on the dosage of 6-chlorohexylzinc bromide. Moreover, a two-dimensional (2D) transparent conductive film (TCF) with an excellent optical performance was fabricated by as-synthesized AgNWs, which has a 90.3% transmittance and low haze value of <1.0% at a sheet resistance of 48.7 Ω sq−1.

Rational synthesis of silver nanowires at an electrode interface by diffusion limitation

We report an approach to synthesize silver nanowires by diffusion limitation.

Recent progress in the synthesis of silver nanowires and their role as conducting materials

Synthesis of silver nanowires got much attention of researchers due to their promising applications in various fields of nanoelectronic devices. Many research articles focusing on silver nanowires synthesis have been reported since past decade. A number of techniques have been applied for successful synthesis of silver nanowires. Solution-based polyol process was proved as a dominant approach to the fabrication of silver nanowires with homogeneity and high aspect ratio. Various inorganic salts have been used in solution-based polyol synthesis of silver nanowires which play a key role in controlling the final morphology of silver nanowires and lead to uniform growth of silver nanowires. The different experimental parameters have been studied, which directly influence the final morphology of silver nanowires. The research on the development of an efficient synthesis approach of silver nanowires is still in progress to accomplish the need of advanced technology for controlled morphology and highest aspect ratio of silver nanowires. Moreover, the unique applications of silver nanowires in conducting polymers composites were discussed.

Synthesis of Silver Nanowires with Reduced Diameters Using Benzoin-Derived Radicals to Make Transparent Conductors with High Transparency and Low Haze.

Reducing the diameter of silver nanowires has been proven to be an effective way to improve their optoelectronic performance by lessening light attenuation. The state-of-the-art silver nanowires are typically around 20 nm in diameter. Herein we report a modified polyol synthesis of silver nanowires with average diameters as thin as 13 nm and aspect ratios up to 3000. The success of this synthesis is based on the employment of benzoin-derived radicals in the polyol approach and does not require high-pressure conditions. The strong reducing power of radicals allows the reduction of silver precursors to occur at relatively low temperatures, wherein the lateral growth of silver nanowires is restrained because of efficient surface passivation. The optoelectronic performance of as-prepared 13 nm silver nanowires presents a sheet resistance of 28 Ω sq-1 at a transmittance of 95% with a haze factor of ∼1.2%, comparable to that of commercial indium tin oxide (ITO).

Flexible Transparent Conductive Film Based on Random Networks of Silver Nanowires.

We synthesized silver nanowires (AgNWs) with a mean diameter of about 120 nm and 20–70 μm in length using a polyol process. The flexible transparent conductive AgNWs films were prepared using the vacuum filtration-transferring process, in which random AgNWs networks were transferred to a polyethylene terephthalate (PET) substrate after being deposited on mixed cellulose esters (MCEs). Furthermore, the photoelectric and mechanical properties of the AgNWs films were studied. The scanning electron microscopy images show that the AgNWs randomly, uniformly distribute on the surface of the PET substrate, which indicates that the AgNWs structure was preserved well after the transfer process. The film with 81% transmittance at 550 nm and sheet resistance about 130 Ω·sq−1 can be obtained. It is sufficient to be used as a flexible transparent conductive film. However, the results of the bending test and tape test show that the adhesion of AgNWs and PET substrate is poor, because the sheet resistance of film increases during the bending test and tape test. The 0.06 W LED lamp with a series fixed on the surface of the AgNWs-PET electrode with conductive adhesive was luminous, and it was still luminous after bent.