Synthesis Of Silver Nanowires Research Articles

银纳米线的可控合成及其应用

银纳米线的可控合成及其应用

Continuous, green, and room-temperature synthesis of silver nanowires in a helically-coiled millifluidic reactor

Over the past decade, silver nanowires (AgNWs) have been considered as promising alternatives for manufacturing flexible and transparent conductive films used in the production of various electronic and wearable devices. Nevertheless, the continuous and large-scale synthesis of AgNWs without the use of high-energy methods and hazardous reagents can be challenging. In this study, we report the continuous, green and sustainable synthesis of AgNWs at room temperature in a helically-coiled plug flow millifluidic reactor, using tannic acid as an environmentally-friendly reducing and capping agent. The synthesized AgNWs were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–visible spectroscopy (UV-Vis). We have showed that the presence of silicone oil and triton X-100 is necessary for the undisturbed synthesis of AgNWs. We further demonstrated that AgNWs synthesized in the millifluidic reactor had a higher yield (by 32%) compared to those synthesized in batch condition. We further showed how the synthesis of AgNWs can be affected by exposure to UV–visible light. Finally, we investigated the effect of coil diameter on the consumption of Ag+ ions, the morphology of silver nanostructures, and the yield of AgNWs. The proposed approach can serve as a promising technique for the continuous synthesis of AgNWs and further green and sustainable manufacturing in the field of nanomaterials synthesis.

Ag Nanostructure Morphologies and Physicochemical Properties Dictated by the Polyols Used in the Synthesis

: The mixing of ethylene glycol (EG) with diethylene glycol (DEG) has been studied to analyse the effect of viscosity rise of solvent on the Ag nanostructures and their morphologies. The rise of viscosity has been adjusted by increasing the molar ratio of DEG to EG under optimized conditions of temperature and capping agent- polyvinylpyrrolidone (PVP). It has been seen that increasing the proportion of DEG resulted increasing the viscosity of solution and thus decreased the diameter of nanowires. The production of quantum nanowires has further become possible during reaction. The synthesized material was characterized using UV−Vis spectroscopy, SEM, EDX, XRD, PL and DSC. Surface Plasmon resonance and luminescence was determined using UV−Vis spectroscopy and PL spectroscopy. The data showed that Ag nanowires have a strong absorption band at 356 nm and 401 nm which can be attributed to the transverse and longitudinal surface Plasmon resonance. The XRD results indicated that the prepared product is made of pure Ag with face centred cubic structure, and the DSC analysis demonstrated the presence of amorphous domain within metal nanostructures. Finally, temperature fluctuations have caused the formation of nanoparticle of different shapes and sizes which bears the synthetic mechanistic insights. Our research work supplies new evidence to illustrate the actual growth mechanism and kinetics of silver nanowires. The main objective of this study is to investigate the effect of solvent in polyol synthesis of silver nanowires (Ag NWs) on the nanostructures diameter and morphologies

Synthesis of silver nanowires and their utilization as a SERS substrate for the detection of lidocaine

Lidocaine, beside its usage as a local anesthetic and an antiarrhythmic agent, can be highly toxic and can lead to harmful side effects to the heart and nerve system. Reports in the literature reveal that there is lidocaine in cocaine, thus there are cases in which lidocaine presence is associated with drug usage. Moreover, according to the literature, lidocaine was detected in street drug samples as well. For this reason, detection of lidocaine at ultra-low concentrations has vital importance. Since SERS method is utilized for detection of organic and inorganic molecules at low concentrations, in this study, Ag Nanowires are used as SERS substrates. Since lidocaine is detected at even low concentrations such as 10-10 M, Ag nanowires exhibit high sensitivity. Even after 25 days of storage in ambient environment, Ag nanowires still exhibit peaks at high sensitivities when they are utilized for lidocaine detection. As a result, Ag Nanowires, which exhibit significant reproducibility, chemical stability and recyclability, can be utilized as possible/potential SERS substrates for detecting lidocaine at ultra-low concentrations.

Relationship of photocatalysis with flavonoids in silver nanowire synthesis with herbal extract (Lavandula officinalis L.)

Nanoparticles with unique physiochemical properties can be produced using non-toxic precursors with phyto-nano synthesis. In this study, Nanowire (AgNW) was produced from silver nanoparticles (AgNP) reduced with Lavandula officinalis L. flower extract using the phyto-nano synthesis method. The length of the produced AgNW is 1-20 µm and its diameter is approximately 40-100 nm. Although the reduction of silver was quite fast in the light environment, it was found to be slow in the dark environment. However, the effect of darkness on AgNP stabilization and AgNW formation was quite important. In addition, it was revealed that the main physical factor that enables AgNW to elongate is the mechanics of the environment provided by the centrifuge. Optical and morphological characterization of nanoparticles was done with UV-visible spectrometry and SEM. The crystal structure of the particles was determined by XRD. Energy dispersion spectrums of nanoparticles were determined by EDS. Character and size analysis was performed by TEM. FTIR determination was performed on the extracts to guide the determination of the reduction factors in light and dark. The extracts were also determined by HPLC to give an idea about the role of flavonoid content in the Ag reduction due to light. Accordingly, it was found that aromatic ring compounds with alcoholic groups effectively reduce silver in the dark and promote AgNW formation.

Propylene Glycol Directed Synthesis of Silver Nanowires for Transparent Conducting Electrode Application

Propylene Glycol Directed Synthesis of Silver Nanowires for Transparent Conducting Electrode Application

Controllable synthesis of silver nanowires via an organic cation‐mediated polyol method and their application as transparent electrode for touch screen

AbstractAs an organic cation, quaternary ammonium salt was introduced as a control agent to synthesize silver nanowires. The important influence of quaternary ammonium salt on the preparation of silver nanowires was seriously investigated by varying the length of carbon chain and its amount. Results showed that using quaternary ammonium salt as the control agent can successfully control the growth of silver nanowires, of which the diameters ranging from 35.06 to 46.60 nm. The diameters of the as‐prepared silver nanowires tended to be smaller with a longer carbon chain. This work provides a new aspect for controllable preparation of silver nanowires. Furthermore, the as‐prepared silver nanowires were used to prepare transparent electrodes. They exhibited good optical performance with 95.6% transmittance at a low sheet resistance of 18 Ω/square, demonstrating their great potential in the application for touch screens.

Optical Properties of Colloidal Silver Nanowires.

Silver nanowires are used in many applications, ranging from transparent conductive layers to Raman substrates and sensors. Their performance often relies on their unique optical properties that emerge from localized surface plasmon resonances in the ultraviolet. To tailor the nanowire geometry for a specific application, a correct understanding of the relationship between the wire’s structure and its optical properties is therefore necessary. However, while the colloidal synthesis of silver nanowires typically leads to structures with pentagonally twinned geometries, their optical properties are often modeled assuming a cylindrical cross-section. Here we highlight the strengths and limitations of such an approximation by numerically calculating the optical and electrical response of pentagonally twinned silver nanowires and nanowire networks. We find that our accurate modeling is crucial to deduce structural information from experimentally measured extinction spectra of colloidally synthesized nanowire suspensions and to predict the performance of nanowire-based near-field sensors. On the contrary, the cylindrical approximation is fully capable of capturing the optical and electrical performance of nanowire networks used as transparent electrodes. Our results can help assess the quality of nanowire syntheses and guide in the design of optimized silver nanowire-based devices.

Silver Nanowire Synthesis and Applications in Composites: Progress and Prospects

AbstractSilver nanowires (AgNWs) have gained increased interest as highly conductive and transparent nanomaterials with numerous applications across various fields. Owing to their unique properties (e.g., optical transparency, electrical conductivity, mechanical characteristics, and ease of processing), AgNWs have been extensively investigated for application in light‐emitting diodes, solar cells, electrocatalysis, liquid crystal displays, wearable electronic devices, flexible nanosensors, and supercapacitors. In this review, recent advances in the synthesis of AgNWs (including the polyol, template, wet chemical, and photoreduction methods) are discussed, with a focus on their advantages and disadvantages in terms of AgNW structural regulation. Furthermore, the advantages and applications of AgNW composites, are comprehensively reviewed and analyzed, with a focus on energy storage and optoelectronics, sensors, electromagnetic interference shielding and absorbing materials, nanogenerators, and other applications. The prospects and challenges of AgNW composites in emerging applications are also proposed.

Green, sustainable, and room-temperature synthesis of silver nanowires using tannic acid – Kinetic and parametric study

This study reports the green, room-temperature and light-assisted synthesis of silver nanowires (AgNWs) using tannic acid as both the reducing and capping/stabilizing agents. Although the green synthesis of silver nanowires can offer several advantages in terms of simplicity, environmental friendliness, and cost-effectiveness, most of these processes suffer from substantial variability due to uncertain experimental factors, which makes their reproduction challenging. One of the factors that is often neglected in such processes is light, which can significantly affect the synthesis process and as a result alter the morphology of the final nanostructures. In this study, three different light conditions including dark (0 LUX), partially illuminated (90 LUX), and fully illuminated (676 LUX) were considered for the synthesis of silver nanostructures, and the change in morphology with respect to light intensity was evaluated. The results suggested that light intensity can significantly change the reduction capability of tannic acid, and that a relatively weak illumination condition is necessary for the growth of AgNWs when tannic acid is used as the reducing agent. The AgNWs were found to have an average diameter and length of 24.4 ± 6.6 nm and 11.4 ± 3.2 µm, respectively in partially illuminated condition. The synthesized silver nanostructures and nanowires were characterized using scanning electron microcopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and UV–visible spectroscopy (UV–vis). In addition, the consumption of Ag+ ions for all illumination conditions was measured to observe how the reduction rate is affected by illumination. The results suggested that the reduction rate has a direct relation with respect to light intensity. The Ag+ concentration with respect to time was analyzed by the pseudo-first order kinetics model, a modified pseudo-first order model previously introduced by Finke and Watzky, and a new proposed empirical model. Furthermore, the effect of other factors such as the tannic acid/silver nitrate molar ratio, pH, and stirring rate were investigated to observe how the morphology of silver nanostructures and the yield of AgNWs change. Considering tannic acid, a green and abundantly available compound, as the only reducing and capping/stabilizing agent, while using merely light as a reduction assisting input, this procedure can serve as a useful approach towards the scalable, inexpensive, and sustainable synthesis of AgNWs with relatively high yield and aspect ratio, which has not been reported before to the best of the authors’ knowledge. The green and sustainably synthesized AgNWs are promising candidates for manufacturing a new generation of transparent conductive films (TCFs) known as eco-friendly transparent conductive films (Eco-TCFs) for electronic applications. This study will shed light to the industrially-relevant sustainable metal nanostructures synthesis and fundamentally contributes to the advancement of the green nanotechnology field. These fundamental advances will eventually seek to solve two critical problems, namely that of capital investment and environmental footprints of metal nanostructures synthesis.

The effects of synthesized silver nanowires on the structure and esterase-like activity of human serum albumin and their impacts on human endometrial stem cells

Silver nanowires (AgNWs) were synthesized and fabricated then their effects on the structure and esterase-like activity of Human Serum Albumin (HSA) were evaluated in vitro. Afterward, their impacts on the growth of human endometrial stem cells (hEnSCs) were studied. The results showed that AgNWs could form a complex with HSA and did not affect the secondary structure of HSA only at lower concentrations. The binding constant for the AgNWs-HSA complex was found to be 1.4 × 104 M−1. The distance between HSA and AgNWs was acquired according to the Förster theory. The value of ΔG ° displayed that AgNWs interact with HSA and the hydrophobic force plays a major role in this interaction. HSA lost its esterase-like activity at a higher concentration of AgNWs. Cell viability assays indicated that AgNWs were toxic toward hEnSCs at higher concentrations. This study demonstrated that AgNWs can be utilized in nanotechnology-based bio-applications only at lower concentrations.

Silver nanowire synthesis analyzing NaCl, CuCl2, and NaBr as halide salt with additional thermal, acid, and solvent post-treatments for transparent and flexible electrode applications

Silver nanowire synthesis analyzing NaCl, CuCl2, and NaBr as halide salt with additional thermal, acid, and solvent post-treatments for transparent and flexible electrode applications

UV-Light Mediated Biosynthesis of Silver Nanowires; Characterization, Dye Degradation Potential and Kinetic Studies

Herrin, a simple and eco-friendly method for the synthesis of silver nanowires (Ag-NWs) has been reported. Silver nanowires were synthesized using Psidium guajava seed extract that acted as a reducing agent as well as a stabilizing agent for silver nitrate solution. Synthesis was carried out at 50 °C temperature under continuous UV-irradiation. Silver nanowires were initially characterized by a UV-visible and FTIR spectrophotometer. In addition, morphology and particle size of synthesized Ag-NWs were determined using Field Emission Scanning Electron Microscopy and X-ray diffraction (XRD) techniques. Nanowires were found to have 12.8 μm length and 200–500 nm diameter and cubic phase morphology. Furthermore, the catalytic potential of Ag-NWs for the degradation of methyl orange dye (MO) was determined. The selected dye was degraded successfully that confirmed the catalytic potential of Ag-NWs. The authors concluded that Ag-NWs can be synthesized using plant extract having excellent morphological features as well as impressive catalytic potential.

Transition Metal Salt Promoted, Green, and High‐Yield Synthesis of Silver Nanowires for Flexible Transparent Conductive Electrodes

AbstractSilver nanowires (AgNWs) have attracted considerable interest from both academia and industry owing to their excellent electrical, optical, and chemical properties. For large‐scale synthesis of AgNWs, the polyol method involving ethylene glycol, a toxic alcohol, has been widely used. We herein report on a facile, green, high yield, transition metal salt promoted, open atmosphere method for the synthesis of high quality AgNWs in a glycerol‐water mixture. We have shown that transition metal salts have a strong influence on the morphology of AgNWs. Importantly, in the presence of copper(II) chloride, AgNWs with a high aspect ratio of around 400 (length, 36 μm; diameter, 90 nm) were obtained. Additionally, for the first time, we have demonstrated AgNWs based flexible transparent conductive electrodes (TCEs) on poly(sodium 4‐styrenesulfonate) (PSS) treated polyethylene terephthalate (PET) substrate with a sheet resistance of 34 Ω/sq and transmittance of 91 % at 550 nm. The PSS layer on the PET substrate generated a highly hydrophilic surface, which boosts interaction of AgNWs with the PET surface. We envision that our results would play a significant role both in the synthesis of AgNWs with high aspect ratio and also in designing new rigid and flexible TCEs having high transmittance and low sheet resistance for applications especially in printable solar cells, organic light emitting diodes, and high performance flexible electronics.

Optimization of polyol synthesized silver nanowires for transparent conducting electrodes application

Silver nanowires (AgNWs) based electrode are the potential candidates to replace expensive ITO electrodes in the next generation of flexible electronics. Herein, AgNWs of ∼1000 aspect ratio were synthesised by using simple and cost-effective salt mediated polyol synthesis method. The AgNWs based transparent conducting electrodes (TCEs) have demonstrated the transparency and sheet resistance of 81% and 20 Ω/sq. The effect of AgNO3 injection rate, PVP/AgNO3 molar ratio, and NaCl/KBr ratio on the AgNWs morphology was extensively studied and optimized to 0.2 mL/min, 4.5:1 and 3.8:1, respectively. The effect of post annealing on TCE has also been studied and optimized to 150 °C.

High-yield synthesis of silver nanowires for transparent conducting PET films.

Silver nanowires (AgNWs) with ultrahigh purity and high yield were successfully synthesized by employing a modified facile polyol method using PVP as a capping and stabilizing agent. The reaction was carried out at a moderate temperature of 160 °C under mild stirring for about 3 h. The prepared AgNWs exhibited parallel alignment on a large scale and were characterized by UV–vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and PL spectroscopy. The luminescent AgNWs exhibited red emission, which was accredited to deep holes. The SEM results confirmed the formation of AgNWs of 3.3 to 4.7 µm in length with an average diameter of about 86 nm, that is, the aspect ratio values of the AgNWs exceeded 45. An ink consisting of hydroxyethyl cellulose (HEC) and AgNWs was transferred to polyethylene terephthalate (PET) films by simple mechanical pressing. The PET films retained transparency and flexibility after the ink coating. The maximum transmittance value of as-prepared PET films in the visible region was estimated to be about 92.5% with a sheet resistance value of ca. 20 Ω/sq. This makes the films a potential substitute to commonly used expensive indium tin oxide (ITO) in the field of flexible optoelectronics.

Bulk Nanostructured Metal from Multiply-Twinned Nanowires.

Using chemically synthesized silver nanowires with 5-fold twinning planes as a model system, a bottom-up process to generate a bulk nanostructured metal has been demonstrated. Although the nanowires would be shortened and deformed during densification, they are chosen as a model system because they are currently the most scalable and convenient way to obtain Ag particles with high twinning densities. Direct cold pressing of a silver nanowire filter cake did not generate a sufficiently cohesive sample, while hot pressing at 190 °C for 8 h resulted in extensive sintering, eliminating the nanowire morphology. Copper was then electroplated on the silver nanowires as a binder and filler to increase the densification upon hot pressing; despite nonuniform plating across the thickness of the filter cake, the thermal stability of the nanowires was increased, allowing hot pressing at 390 °C. Finally, a uniform copper coating on silver nanowires was achieved by electroless plating, leading to cohesive bulk metal after hot pressing.

Rapid synthesis of silver nanowires during the polyol-microwave method and COMSOL multiphysics simulation of electromagnetic heating

To date, various methods have been used to synthesize silver nanowires, but some require long reaction times. In this work, we synthesized widely used silver nanowires with high efficiency and with the least time and energy during the polyol-microwave method. Also, the effects of microwave irradiation time, silver nitrate concentration, and type of etching agent on the shape and size of nanostructures were investigated experimentally. In fact, the shape and production efficiency of silver nanowires were controlled and the optimal conditions were obtained at the microwave irradiation time of 210 s. The characterization of the silver nanowires showed that silver nanowires with an average diameter of 80 nm and an average length of 20 µm can be produced with high efficiency under optimal conditions. Finally, for the first time, in the microwave-based synthesis method, electromagnetic heating was studied and simulated with the help of the “finite element” method implemented by the COMSOL Multiphysics software. The results showed that with increasing time, the temperature increases, and as a result, the number density of glycolaldehyde reducing agents increases. This could also explain the fast growth of silver nanowires during this method.

Silver nanowire-embedded PDMS with high electrical conductivity: nanowires synthesis, composite processing and electrical analysis

A simple, fast, and ecofriendly polyol method for the synthesis of silver nanowires (AgNWs) with high aspect ratios is presented. Besides, the effects of reaction parameters on the synthesis process, namely reaction temperature, PVP molecular weight, sodium chloride content, as well as solution mixing rate on the morphology and dimensions of silver nanowires, are thoroughly investigated. AgNWs were fully characterized using FE-SEM, TEM, XRD, FT-IR, and UV–Vis analysis and showed an average diameter of 50 nm. Polymer nanocomposites were fabricated through mixing and curing of the AgNWs, PDMS, and curing agents. The prepared nanocomposites were analyzed microscopically, and their electrical conductivity was measured. PDMS containing 25 wt% AgNWs was considered as an optimal composite, mainly because it possessed a combination of flexibility and transparency, accompanied by the high electrical conductivity of 5840.4 S/cm. This composite can be deemed as a potential candidate in lab-on-a-chip and biosensing applications.

Controlling plasmon propagation and enhancement via reducing agent in wet chemistry synthesized silver nanowires.

Silver nanowires with varying diameters and submillimeter lengths were obtained by changing a reducing agent used during hydrothermal synthesis. The control over the nanowire diameter turns out to play a critical role in determining their plasmonic properties, including fluorescence enhancement and surface plasmon polariton propagation. Advanced fluorescence imaging of hybrid nanostructures assembled of silver nanowires and photoactive proteins indicates longer propagation lengths for nanowires featuring larger diameters. At the same time, with increasing diameter of the nanowires, we measure a substantial reduction of fluorescence enhancement. The results point at possible ways to control the influence of plasmon excitations in silver nanowires by tuning their morphology.