Research

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8 pages, 3761 KiB

Open AccessArticle

Ultrasonic Modification of Ag Nanowires and Their Applications in Flexible Transparent Film Heaters and SERS Detectors

by Jie Sun, Xinxiang Yu, Zhutie Li, Junfeng Zhao, Pengcheng Zhu, Xiaoyan Dong, Zhigang Yu, Zhiguo Zhao, Dandan Shi, Junqin Wang and Han Dai

Materials 2019, 12(6), 893; https://doi.org/10.3390/ma12060893 - 18 Mar 2019

Cited by 10 | Viewed by 2877

Abstract

Ultrasonic morphology modification of silver (Ag) nanowires and their applications in transparent film heaters for defogging in electric vehicles and surface-enhanced Raman scattering (SERS) detectors have been studied. With 10 min ultrasonic treatment of Ag nanowires, the electro-thermal conversion capability of Ag nanowire [...] Read more.

Ultrasonic morphology modification of silver (Ag) nanowires and their applications in transparent film heaters for defogging in electric vehicles and surface-enhanced Raman scattering (SERS) detectors have been studied. With 10 min ultrasonic treatment of Ag nanowires, the electro-thermal conversion capability of Ag nanowire based transparent film heaters is efficiently improved (about 50% increase in temperature rise), which can be mainly attributed to the cross-section area reduction and the serious agglomerations of the ultrasonic modified Ag nanowire films. Furthermore, the bending or fracture caused by deformation of Ag nanowires after ultrasonic treatment provides more hot spots for SERS, and therefore lead to a significant SERS signal enhancement. This work not only greatly improves the performance of Ag nanowire based transparent film heaters and SERS detectors, but provides a new way for the functional modification of Ag nanowires. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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12 pages, 2719 KiB

Open AccessArticle

Optical Properties of Submillimeter Silver Nanowires Synthesized Using the Hydrothermal Method

by Michał Ćwik, Dorota Buczyńska, Karolina Sulowska, Ewa Roźniecka, Sebastian Mackowski and Joanna Niedziółka-Jönsson

Materials 2019, 12(5), 721; https://doi.org/10.3390/ma12050721 - 01 Mar 2019

Cited by 15 | Viewed by 4719

Abstract

We report on the synthesis of long silver nanowires using the hydrothermal method, with H₂O₂ as the reducing agent. Our approach yields nanowires with an average diameter and length of about 100 nm and 160 µm, respectively, reaching the maximum [...] Read more.

We report on the synthesis of long silver nanowires using the hydrothermal method, with H₂O₂ as the reducing agent. Our approach yields nanowires with an average diameter and length of about 100 nm and 160 µm, respectively, reaching the maximum length of 800 µm. Scanning electron microscopy (SEM) measurements revealed the presence of a thick, inhomogeneous poly(vinylpyrrolidone) (PVP) layer covering the nanowires, which with time becomes much more uniform, leading to well-defined extinction peaks in the ultraviolet-visible (UV-Vis) spectra. This change in morphology is evidenced also by the fluorescence enhancement behavior probed using protein complexes. Wide-field and confocal fluorescence microscopy measurements demonstrate strong, 10-fold enhancement of the protein emission intensity, accompanied by a reduction of the fluorescence decay time. In addition, for the aged, one-month-old nanowires, the uniformity of the intensity profile along them was substantially improved as compared with the as-synthesized ones. The results point towards the importance of the morphology of plasmonically active silver nanowires when considering their application in enhancing optical properties or achieving energy propagation over submillimeter distances. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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11 pages, 3917 KiB

Open AccessArticle

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

by Yuxiu Li, Ximin Yuan, Hongwei Yang, Yunxiu Chao, Shuailong Guo and Chuan Wang

Materials 2019, 12(3), 401; https://doi.org/10.3390/ma12030401 - 28 Jan 2019

Cited by 35 | Viewed by 5873

Abstract

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, [...] Read more.

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. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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10 pages, 2718 KiB

Open AccessArticle

Quantifying Joule Heating and Mass Transport in Metal Nanowires during Controlled Electromigration

by Mamiko Yagi and Jun-ichi Shirakashi

Materials 2019, 12(2), 310; https://doi.org/10.3390/ma12020310 - 19 Jan 2019

Cited by 5 | Viewed by 3914

Abstract

The nanoscale heat dissipation (Joule heating) and mass transport during electromigration (EM) have attracted considerable attention in recent years. Here, the EM-driven movement of voids in gold (Au) nanowires of different shapes (width range: 50–300 nm) was directly observed by performing atomic force [...] Read more.

The nanoscale heat dissipation (Joule heating) and mass transport during electromigration (EM) have attracted considerable attention in recent years. Here, the EM-driven movement of voids in gold (Au) nanowires of different shapes (width range: 50–300 nm) was directly observed by performing atomic force microscopy. Using the data, we determined the average mass transport rate to be 10⁵ to 10⁶ atoms/s. We investigated the heat dissipation in L-shaped, straight-shaped, and bowtie-shaped nanowires. The maximum Joule heating power of the straight-shaped nanowires was three times that of the bowtie-shaped nanowires, indicating that EM in the latter can be triggered by lower power. Based on the power dissipated by the nanowires, the local temperature during EM was estimated. Both the local temperature and junction voltage of the bowtie-shaped nanowires increased with the decrease in the Joule heating power and current, while the current density remained in the order of 10⁸ A/cm². The straight-shaped nanowires exhibited the same tendency. The local temperature at each feedback point could be simply estimated using the diffusive heat transport relationship. These results suggest that the EM-driven mass transport can be controlled at temperatures much lower than the melting point of Au. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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13 pages, 4780 KiB

Open AccessArticle

Determination of Activation Overpotential during the Nucleation of Hcp-Cobalt Nanowires Synthesized by Potentio-Static Electrochemical Reduction

by Ryusei Saeki and Takeshi Ohgai

Materials 2018, 11(12), 2355; https://doi.org/10.3390/ma11122355 - 22 Nov 2018

Cited by 11 | Viewed by 3804

Abstract

The crystal growth process and ferromagnetic properties of electrodeposited cobalt nanowires were investigated by controlling the bath temperature and cathodic overpotential. The cathodic overpotential during electrodeposition of cobalt nanowire arrays, ΔE^cath, was theoretically estimated by the difference between the cathode [...] Read more.

The crystal growth process and ferromagnetic properties of electrodeposited cobalt nanowires were investigated by controlling the bath temperature and cathodic overpotential. The cathodic overpotential during electrodeposition of cobalt nanowire arrays, ΔE^cath, was theoretically estimated by the difference between the cathode potential, E^cath, and the equilibrium potential, E^eq, calculated by the Nernst equation. On the other hand, the activation overpotential, ΔE^act, was experimentally determined by the Arrhenius plot on the growth rate of cobalt nanowire arrays, R_g, versus (vs.) reciprocal temperature, 1/T. The ferromagnetic cobalt nanowire arrays with a diameter of circa (ca.) 25 nm had the preferred crystal orientation of (100) and the aspect ratio reached up to ca. 1800. The average crystal grain size, Ds, of (100) peaks was estimated by X-ray diffraction patterns and was increased by decreasing the cathodic overpotential for cobalt electrodeposition by shifting the cathode potential in the noble direction. Axial magnetization performance was observed in the cobalt nanowire arrays. With increasing Ds, coercivity of the film increased and reached up to ca. 1.88 kOe. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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13 pages, 17962 KiB

Open AccessArticle

Annealing Behaviour of Pt and PtNi Nanowires for Proton Exchange Membrane Fuel Cells

by Peter Mardle and Shangfeng Du

Materials 2018, 11(8), 1473; https://doi.org/10.3390/ma11081473 - 19 Aug 2018

Cited by 9 | Viewed by 4998

Abstract

PtNi alloy and hybrid structures have shown impressive catalytic activities toward the cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, such promise does not often translate into improved electrode performances in PEMFC devices. In this contribution, a Ni [...] Read more.

PtNi alloy and hybrid structures have shown impressive catalytic activities toward the cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, such promise does not often translate into improved electrode performances in PEMFC devices. In this contribution, a Ni impregnation and subsequent annealing method, translatable to vertically aligned nanowire gas diffusion electrodes (GDEs), is shown in thin-film rotating disk electrode measurements (TFRDE) to enhance the ORR mass activity of Pt nanowires (NWs) supported on carbon (Pt NWs/C) by around 1.78 times. Physical characterisation results indicate that this improvement can be attributed to a combination of Ni alloying of the nanowires with retention of the morphology, while demonstrating that Ni can also help improve the thermal stability of Pt NWs. These catalysts are then tested in single PEMFCs. Lower power performances are achieved for PtNi NWs/C than Pt NWs/C. A further investigation confirms the different surface behaviour between Pt NWs and PtNi NWs when in contact with electrolyte ionomer in the electrodes in PEMFC operation. Indications are that this interaction exacerbates reactant mass transport limitations not seen with TFRDE measurements. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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Review

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36 pages, 9418 KiB

Open AccessReview

Silver Nanowire Networks: Mechano-Electric Properties and Applications

by Hiesang Sohn, Chulhwan Park, Jong-Min Oh, Sang Wook Kang and Mi-Jeong Kim

Materials 2019, 12(16), 2526; https://doi.org/10.3390/ma12162526 - 08 Aug 2019

Cited by 45 | Viewed by 6329

Abstract

With increasing technological demand for portable electronic and photovoltaic devices, it has become critical to ensure the electrical and mechano-electric reliability of electrodes in such devices. However, the limited flexibility and high processing costs of traditional electrodes based on indium tin oxide undermine [...] Read more.

With increasing technological demand for portable electronic and photovoltaic devices, it has become critical to ensure the electrical and mechano-electric reliability of electrodes in such devices. However, the limited flexibility and high processing costs of traditional electrodes based on indium tin oxide undermine their application in flexible devices. Among various alternative materials for flexible electrodes, such as metallic/carbon nanowires or meshes, silver nanowire (Ag NW) networks are regarded as promising candidates owing to their excellent electrical, optical, and mechano-electric properties. In this context, there have been tremendous studies on the physico-chemical and mechano-electric properties of Ag NW networks. At the same time, it has been a crucial job to maximize the device performance (or their mechano-electric performance) by reconciliation of various properties. This review discusses the properties and device applications of Ag NW networks under dynamic motion by focusing on notable findings and cases in the recent literature. Initially, we introduce the fabrication (deposition process) of Ag NW network-based electrodes from solution-based coating processes (drop casting, spray coating, spin coating, etc.) to commercial processes (slot-die and roll-to-roll coating). We also discuss the electrical/optical properties of Ag NW networks, which are governed by percolation, and their electrical contacts. Second, the mechano-electric properties of Ag NW networks are reviewed by describing individual and combined properties of NW networks with dynamic motion under cyclic loading. The improved mechano-electric properties of Ag NW network-based flexible electrodes are also discussed by presenting various approaches, including post-treatment and hybridization. Third, various Ag NW-based flexible devices (electronic and optoelectronic devices) are introduced by discussing their operation principles, performance, and challenges. Finally, we offer remarks on the challenges facing the current studies and discuss the direction of research in this field, as well as forthcoming issues to be overcome to achieve integration into commercial devices. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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37 pages, 12257 KiB

Open AccessReview

Multifunctional Metallic Nanowires in Advanced Building Applications

by Kwok Wei Shah and Teng Xiong

Materials 2019, 12(11), 1731; https://doi.org/10.3390/ma12111731 - 28 May 2019

Cited by 22 | Viewed by 4339

Abstract

Metallic nanowires (NWs) have attracted great attention in the frontiers of nanomaterial science due to their extraordinary properties, such as high thermal and electrical conductivity, high aspect ratio, good mechanical flexibility, and excellent optical transparency. The metallic NWs and their nanocomposites, as a [...] Read more.

Metallic nanowires (NWs) have attracted great attention in the frontiers of nanomaterial science due to their extraordinary properties, such as high thermal and electrical conductivity, high aspect ratio, good mechanical flexibility, and excellent optical transparency. The metallic NWs and their nanocomposites, as a promising alternative for conventional building materials, have been extensively studied recently, but review works on these novel versatile nanostructures and their various uses in the building and construction industry are still lacking. We present a comprehensive review on current state-of-the-art research and progress regarding multifunctional metallic NWs and their specific building applications, including thermal energy storage (TES), thermal transport, electrochromic windows (ECW), as well as photovoltaic (PV) cells. The nanosynthesis techniques and nanocharacterization of silver nanowires (AgNWs) and copper nanowires (CuNWs) are overviewed and compared with each other. In addition, the fundamentals of different NWs for advanced building applications are introduced. Further discussion is presented on the improved performance of base materials by using these nanostructures, highlighting the key factors exhibiting their superior performance. Finally, the key benefits and limitations of metallic NWs for new generation building materials are obtained. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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21 pages, 4072 KiB

Open AccessReview

Plasmonics with Metallic Nanowires

by Joanna Niedziółka-Jönsson and Sebastian Mackowski

Materials 2019, 12(9), 1418; https://doi.org/10.3390/ma12091418 - 01 May 2019

Cited by 10 | Viewed by 3177

Abstract

The purpose of this review is to introduce and present the concept of metallic nanowires as building-blocks of plasmonically active structures. In addition to concise description of both the basic physical properties associated with the electron oscillations as well as energy propagation in [...] Read more.

The purpose of this review is to introduce and present the concept of metallic nanowires as building-blocks of plasmonically active structures. In addition to concise description of both the basic physical properties associated with the electron oscillations as well as energy propagation in metallic nanostructures, and methods of fabrication of metallic nanowires, we will demonstrate several key ideas that involve interactions between plasmon excitations and electronic states in surrounding molecules or other emitters. Particular emphasis will be placed on the effects that involve not only plasmonic enhancement or quenching of fluorescence, but also propagation of energy on lengths that exceed the wavelength of light. Full article

(This article belongs to the Special Issue Metallic Nanowires and Their Applications)

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