Synthesis Of AgNWs Research Articles

Investigating the optical and electrical performance of rod coated silver nanowire-based transparent conducting films

Silver nanowires (Ag NWs) are highly promising building blocks for developing transparent conducting films (TCFs) due to their high electrical conductivity and good optical transparency. The large-scale production of Ag NW-based high-quality TCFs using low-cost processing methods can replace the traditional oxide based TCFs. Therefore, developing a reliable technique for large-scale fabrication of Ag NW-based TCFs is vital. This work involves the synthesis of Ag NWs, the fabrication of large-area Ag NW-based TCFs using a simple rod coating process, its optimization, and the performance analysis of the fabricated TCFs, including their demonstration as transparent heaters. The polyol synthesis method produces Ag NWs of lengths ranging from 25-110µm and diameters from 80-180 nm. The effect of Ag NW length, the number of coating passes, and the volume of the NW dispersion used per coating pass on the electrical and optical properties of the TCFs are studied by quantifying sheet resistance(Rs)and transmittance (T) of the film. The performance of the fabricated film is evaluated by estimating the figure of merit (FoM) in both percolative and bulk regimes. The TCF made with NWs of length 25.7µm and diameter 85.1 nm had the largest value of bulk FoM (101.3), percolative FoM (43.9), and, conductivity exponent (0.6). This elucidated the superior performance of the fabricated TCFs over those fabricated by other techniques. The critical thickness of the film (tmin), at the crossover between the percolation and bulk, scales with the shortest dimension of the NW, namely its diameter. The percolative FoM showed an increase, with a decrease in both sheet resistance and diameter of the NWs, with lowern. The fabricated TCF is tested as a transparent heater and the demonstration proves that rod coated Ag NW-based TCFs can be used for transparent electrode applications.

Decoding the Effect of Synthesis Factors on Morphology of Nanomaterials: A Case Study to Identify and Optimize Experimental Conditions for Silver Nanowires

Silver nanowires (AgNWs) are one kind of nanomaterials for various applications such as solar panel cells and biosensors. However, the morphology of AgNWs, particularly their length and diameter, plays a critical role in determining the efficiency of energy storage systems and the transmittance of biosensors. Thus, it is imperative to study synthesis strategy for morphology control. This study focuses on synthesizing AgNWs through the solvothermal approach and aims to understand the individual and combined effects of three nucleants, NaCl, Fe(NO3)3 and NaBr, on the morphology of AgNWs. Using a modified successive multistep growth (SMG) approach and fine-tuning the nucleant concentrations, this study synthesized AgNWs with controllable aspect ratios, while minimizing the presence of undesirable byproducts like nanoparticles. Our results demonstrated the successful synthesis of AgNWs with favorable morphologies, including lengths of approximately 180 µm and diameters of 40 nm, thus resulting in aspect ratios of 4500. In addition, to assess the quality of the synthesized AgNWs, this work developed computational tools that uses MATLAB to automate the analysis of scanning electron microscope (SEM) images for detecting silver nanoparticles. This automated approach provides a quantitative analysis tool for material characterization and holds the promise for long-term evaluation of diverse AgNW samples, thereby paving the way for advancements in their synthesis and application. Overall, this study demonstrates the significance of morphology control in AgNW synthesis and presents a robust framework for material characterization and quality analysis.

Polyol synthesis of one-dimensional Ag nanowires for the photocatalytic degradation of textile dye and effective removal of microbes.

Due to the excess release of hazardous pollutants to the environment, the quest for the synthesis of effective nanomaterials for wastewater treatment is never-ending. Present study reports the polyol synthesis of Ag NWs of ~ 85nm diameter and average length of 4.08µm using PVP and ethylene glycol. The experimental data on the methylene blue dye degradation substantiated the photocatalytic efficiency of Ag NWs (88% degradation in 120min). Furthermore, the Ag NWs exhibited microbial load reducing property in air conditioner condensate water (ACW) within a time period of 60min. Also, the anti-bacterial effect of Ag NWs was estimated using two human pathogenic bacterial strains, namely Staphylococcus aureus and Bacillus cereus. The antibacterial potential of Ag NWs against Staphylococcus aureus and Bacillus cereus was revealed significant with an inhibition zone size of 14 ± 0.1mm and 9 ± 0.1mm, respectively. Hence, the present work validates the potential efficiency of Ag NWs in the degradation of textile dyes and reduction of microbial population.

Synergism of Cl− and Br− on the controllable synthesis of flexible silver nanowires

Silver nanowires (AgNWs) exhibit excellent electrical conductivity and hold significant potential for usage in flexible electronics. AgNs can possess a suitable aspect ratio, uniformity, and flexibility that are essential for achieving high-performance flexible transparent conductive films. However, the synthesis of AgNWs presents a challenge in controlling its morphology, often resulting in varying lengths and aspect ratios that are difficult to regulate. Thus, the controlled preparation of AgNWs holds great significance. Herein, AgNWs were synthesized via a polyol method with FeCl3 and KBr composite metal salt as control agents, silver nitrate as a silver source, ethylene glycol as a reducing agent and solvent, and polyvinylpyrrolidone (PVP) as a growth director. By adjusting the ratio and dosage of FeCl3 and KBr, the morphology controllability of AgNWs was realized, and the obtained AgNWs can be straight or bendable. The surface morphology and microstructure of the AgNWs were analyzed by scanning electron microscopy (SEM). Due to the synergistic effect of FeCl3 and KBr, flexible AgNWs with an average diameter of 25–35 nm, an average length of 35–45 um, and an aspect ratio of over 1000 can be obtained. Mechanism studies have shown that through electrostatic interactions, AgCl, AgBr, NO3−, and PVP in the reaction mixture can form binding sites for AgCl-PVP-NO3− and AgBr-PVP-NO3−, thus causing the silver nanowires to become flexible. Meanwhile, the strong polarization effect caused by Br− in the reaction causes the chain growth to become subject to the dual effects of electrostatic repulsion and external forces, resulting in the formation of flexible and soft silver nanowires.

Preparation of highly pure and homogeneous silver nanowires via a secondary heating method

In recent years, silver nanowires (AgNWs) have been widely studied and used as nanofillers in various advanced composite materials due to their excellent properties. The addition of AgNWs can lead to electronic devices with enhanced performance; thus, it is highly desirable to synthesize silver nanowires with high purity. However, the AgNWs synthesized by the conventional polyol method inevitably produce impurities that weaken the performance of these materials. For this reason, the conventional polyol method was improved into a secondary heating method, and AgNWs with high purity, excellent homogeneity, and an aspect ratio of 2000 were obtained via the secondary heating method. In addition, the AgNWs synthesized by the secondary heating method were compared with those synthesized by the direct heating method, and the AgNWs produced by the secondary heating method had higher purity and fewer impurities. The principles of AgNWs production via the secondary heating method were investigated, and the conditions required for the synthesis of AgNWs with high purity, great homogeneity, and high aspect ratio, such as reaction time, starting temperature, secondary temperature, and the molar ratio of NaCl to AgNO3, were also investigated.

Halide-Salt-Free Synthesis of Silver Nanowires with High Yield and Purity for Transparent Conductive Films.

To date, silver nanowires (AgNWs) are routinely synthesized. However, the controllable preparation of AgNWs without any halide salts has not reached a similar level. In particular, the halide-salt-free polyol synthesis of AgNWs commonly occurs above 413 K, and the property of AgNWs obtained is not so easy to control. In this study, a facile synthesis of AgNWs with a yield of up to ∼90% in an average length of 75 μm was successfully performed without any halide salts. The fabricated AgNW transparent conductive films (TCFs) show a transmittance of 81.7% (92.3% for the AgNW network only without substrate) at a sheet resistance of 12.25 Ω/square. In addition, the AgNW films show distinguished mechanical properties. More importantly, the reaction mechanism for AgNWs was briefly discussed, and the importance of reaction temperature, the mass ratio of poly(vinylpyrrolidone) (PVP)/AgNO3, and the atmosphere was emphasized. This knowledge will help enhance the reproducibility and scalability of polyol synthesis of high-quality AgNWs.

Synthesis of Silver Nanowires Using a Polyvinylpyrrolidone-Free Method with an Alpinia zerumbet Leaf Based on the Oriented Attachment Mechanism.

In this study, silver nanowires (AgNWs) were successfully synthesized by using a polyvinylpyrrolidone (PVP)-free hydrothermal method with an Alpinia zerumbet leaf chunk as a reducing agent and template. Meanwhile, the mechanism of biomass synthesis of AgNWs is also explored. The AgNWs have a diameter of ∼77 nm and a length of ∼10 μm. During the hydrothermal process, the biomass initially serves as a reducing agent to reduce silver ions. As the reaction proceeds, the biomass will form a pipe-shaped soft template by hydrothermal carbonization. Silver ions are adsorbed and reduced along the pipe-shaped soft templates to form silver nanorods, and adjacent nanorods are merged to AgNWs. Thus, AgNWs are grown along the pipeline soft template based on the oriented attachment mechanism. Inspired by this, the mechanism of the polyol method was further investigated. In the initial growth stage, AgNWs synthesized by the polyol method have a V-shaped notch. Therefore, AgNWs synthesized by the polyol method may also grow on the basis of the oriented attachment mechanism with PVP as a template.

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.

Facile macro fabrication of ultra-fine, ultra-long silver nanowire and growth mechanism

Silver nanowire (AgNWs) with a fine diameter (< 20 nm) and large aspect ratio (>1000) is one of the requirements for good optoelectronic properties of a transparent conductive film. Herein we report a facile and high yield modified polyol synthesis of AgNWs with average diameters of ∼ 17 nm, aspect ratios up to 2600. And the synthesized AgNWs were applied in flexible transparent conductive films (TCF). Some crucial factors, such as illumination, solvent, and stirring impacting the diameter, and yield of AgNWs were discussed in detail. Illumination is the main factor that impact the yield of AgNWs. The probable growth mechanism of AgNWs was proposed. The sheet resistance of the AgNWs was 92 Ω/sq and the transmittance and haze were 90 % and 1.74 %, respectively.

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.

Investigation of freshly prepared AgCl for high yield silver nanowires under polyol method

Silver nanowires (Ag NWs) have attracted much interest in academics and industries because of their potential applications in electronic devices such as flexible displays, pressure sensors, temperature sensors, and conductive layers. Generally, silver nanowire synthesized by the polyol method is the most common and promising chemical reaction. However, its by-products, a mixture of Ag NWs and silver nanoparticles, reduced Ag NWs performance. In this work, we reported the chemical method that is a fast and straightforward synthesis of Ag NWs by using freshly prepared silver chloride to avoid its degradation. The result showed that the freshly prepared silver chloride plays an essential role in promoting the formation of Ag NWs. The by-product was lower compared to using commercial silver chloride. We also found that avoiding boiling bubbles in flask via controlling temperature and reaction time by injecting ethylene glycol, resulting in decreased nanowires degradation. Furthermore, instantaneously decreasing temperature after finishing the cooking time helps reduce its by-product. A high yield of Ag NWs is noticeable under the observed synthetics.

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.

Coating Cellulosic Material with Ag Nanowires to Fabricate Wearable IR-Reflective Device for Personal Thermal Management: The Role of Coating Method and Loading Level.

Textiles coated with silver nanowires (AgNWs) are effective at suppressing radiative heat loss without sacrificing breathability. Many reports present the applicability of AgNWs as IR-reflective wearable textiles, where such studies partially evaluate the parameters for practical usage for large-scale production. In this study, the effect of the two industrial coating methods and the loading value of AgNWs on the performance of AgNWs-coated fabric (AgNWs-CF) is reported. The AgNWs were synthesized by the polyol process and applied onto the surface of cotton fabric using either dip- or spray-coating methods with variable loading levels of AgNWs. X-ray diffraction, scanning electron microscopy (SEM), infrared (IR) reflectance, water vapor permeability (WVP), and electrical resistance properties were characterized. The results report the successful synthesis of AgNWs with a 30 μm length. The results also show that the spray coating method has a better performance for reflecting the IR radiation to the body, which increases with a greater loading level of the AgNWs. The antibacterial results show a good inhibition zone for cotton fabric coated by both methods, where the spray-coated fabric has a better performance overall. The results also show the coated fabric with AgNWs maintains the level of fabric breathability similar to control samples. AgNWs-CFs have potential utility for cold weather protective clothing in which heat dissipation is attenuated, along with applications such as wound dressing materials that provide antibacterial protection.

Synthesis of AgNWs using copper bromide as stabilizing agent and oxygen scavenger and their application in conductive thin films

Silver nanowires (AgNWs) have attracted growing interest because of their wide range of applications in modern nano electronic appliances. During polyol method, the presence of cations and anions in the reaction solution has influence on the final morphology of AgNWs. Here we report a feasible way to prepare AgNWs by polyol method. Copper bromide (CuBr2) salt was used to provide anions and cations in the reaction solution. The anions (Br−) helps in reducing the amount of free Ag+ by forming silver bromide (AgBr) during initial silver seeds formation and the cations scavenge oxygen from the surface of AgNWs during preferential growth of the AgNWs. Ethylene glycol (EG) was used as a solvent and reducing agent, silver nitrate (AgNO3) was used as Ag source and polyvinyl pyrrolidone (PVP) was used as a capping agent. The effects of various factors which influence the final morphology of AgNWs were studied. AgNWs were successfully synthesized in the presence of CuBr2 salt. The morphology of the synthesized AgNWs was characterized by the SEM and TEM. The crystallinity was characterized by HRTEM, SAED and XRD. The LSPR peaks of Ag nanostructures were revealed by UV–Vis spectroscopy. The conductive properties of AgNWs thin conductive films were studied by coating the synthesized nanowires on polyethylene terephthalate (PET) substrate.

The Quenching and Sonication Effect on the Mechanical Strength of Silver Nanowires Synthesized Using the Polyol Method.

This study aims to determine the effect of fast cooling (quenching) on thermal properties, mechanical strength, morphology and size of the AgNWs. The synthesis of AgNWs was carried out at three different quenching-medium temperatures as follows: at 27 °C (ambient temperature), 0 °C (on ice), and −80 °C (in dry ice) using the polyol method at 130 °C. Furthermore, the AgNWs were sonified for 45 min to determine their mechanical strength. Scanning electron microscopy analysis showed that the quenched AgNWs had decreased significantly; at 27 °C, the AgNWs experienced a change in length from (40 ± 10) to (21 ± 6) µm, at 0 °C from (37 ± 8) to (24 ± 8) µm, and at −80 °C from (34 ± 9) to (29 ± 1) µm. The opposite occurred for their diameter with an increased quenching temperature: at 27 °C from (200 ± 10) to (210 ± 10) nm, at 0 °C from (224 ± 4) to (239 ± 8) nm, and at −80 °C from (253 ± 6) to (270 ± 10) nm. The lower the temperature of the quenching medium, the shorter the length and the higher the mechanical strength of AgNWs. The UV-Vis spectra of the AgNWs showed peak absorbances at 350 and 411 to 425 nm. Thermogravimetric analysis showed that AgNWs quenched at −80 °C have better thermal stability as their mass loss was only 2.88%, while at the quenching temperatures of 27 °C and 0 °C the mass loss was of 8.73% and 4.17%, respectively. The resulting AgNWs will then be applied to manufacture transparent conductive electrodes (TCEs) for optoelectronic applications.

Silver Nanowire Synthesis and Strategies for Fabricating Transparent Conducting Electrodes.

One-dimensional metal nanowires, with novel functionalities like electrical conductivity, optical transparency and high mechanical stiffness, have attracted widespread interest for use in applications such as transparent electrodes in optoelectronic devices and active components in nanoelectronics and nanophotonics. In particular, silver nanowires (AgNWs) have been widely researched owing to the superlative thermal and electrical conductivity of bulk silver. Herein, we present a detailed review of the synthesis of AgNWs and their utilization in fabricating improved transparent conducting electrodes (TCE). We discuss a range of AgNW synthesis protocols, including template assisted and wet chemical techniques, and their ability to control the morphology of the synthesized nanowires. Furthermore, the use of scalable and cost-effective solution deposition methods to fabricate AgNW based TCE, along with the numerous treatments used for enhancing their optoelectronic properties, are also discussed.

Synthesis of AgNWs Using High Molecular Weight PVP As a Capping Agent and Their Application in Conductive Thin Films

High molecular weight polyvinylpyrrolidone (PVP) and seeding conditions are considered to have important roles in the synthesis of AgNWs. In this work, we report a versatile synthesis of AgNWs in a salt-free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process. The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets. The seeding step facilitates the formation of seeds such as multiple twinned nanoparticles (MTPs) and single crystal seeds, which promoted the feasible formation of AgNWs. The shape and size of the synthesized AgNWs were characterized by SEM and TEM. The crystalline nature of the synthesized AgNWs was characterized by HRTEM, SAED and XRD, and their LSPR peaks were confirmed by UV-Vis spectroscopy. The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate. The prepared AgNWs thin films exhibited good sheet resistance.

Ascorbic Acid-Assisted One-Step Chemical Reaction To Design an Ultralong Silver Nanowire Structure for a Highly Transparent Flexible Conducting Film.

Increasing the length of silver nanowires (AgNWs) has been demonstrated as an effective measure to enhance their optoelectronic properties by reducing light attenuation. Herein, we report a unique modified polyol synthesis of AgNWs with average length as long as ∼270 μm in a high yield of ∼90%. The synthesis of ultralong AgNWs involves the employment of ascorbic acid in the polyol approach. The strong reducing action of ascorbic acid allows the reduction of silver precursors to occur at a relatively low temperature, wherein the lateral growth of AgNWs is restrained because of efficient surface passivation via the dual function of poly-vinylpyrrolidone and ascorbic acid. The photoelectric properties of the as-synthesized ∼270 μm AgNW film show a noteworthy transmittance of 92.61% with a low haze of 1.35% at a sheet resistance of ∼322 Ω sq–1. In addition, the AgNW film shows distinguished mechanical property and relatively high electrical stability. The breakthrough in the length confinement of AgNWs is a highly expected step to prepare AgNW films with excellent performance.

Simple and Fast High-Yield Synthesis of Silver Nanowires.

Silver nanowires (AgNWs) combine high electrical conductivity with low light extinction in the visible and are used in a wide range of applications, from transparent electrodes, to temperature and pressure sensors. The most common strategy for the production of AgNWs is the polyol synthesis, which always leads to the formation of silver nanoparticles as byproducts. These nanoparticles degrade the performance of AgNWs' based devices and have to be eliminated by several purification steps. Here, we report a simple and fast synthesis of AgNWs with minimal formation of byproducts, as confirmed by the spectral purity of the final solution. Our synthetic strategy relies on the use of freshly prepared AgCl and on the minimization of gas evolution inside the reaction vessel. The observed synthetic improvements can be of general validity for the polyol synthesis of metallic nanostructures of different shapes and compositions.

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.