Copper Nanowire Electrodes Research Articles

High-performance copper nanowire electrode for efficient flexible organic light-emitting diode

Highly conductive and robust polyvinyl alcohol/copper nanowire (PVA/CuNW) flexible transparent conductive electrode (FTCE) is fabricated via a simple and low-cost process at room temperature. The CuNW film is formed on a mixed cellulose ester (MCE) membrane by vacuum filtration. Subsequently, the flowing glacial acetic acid (GAA)-toluene solution passes through them to remove the oxide layer without damaging nanowires. The final PVA/CuNW FTCE is constructed by embedding the treated CuNWs into a pre-prepared PVA binding layer on the polyethylene terephthalate (PET) substrate, which presents excellent conductivity with a low sheet resistance of 46.2 Ω / s q and a high transparency of 90.5% at 550 nm. Meanwhile, the chemical and mechanical stability have been significantly enhanced compared with the bare CuNW FTCE attributed to the protective effect of the PVA binding layer. A flexible phosphorescent OLED device using such PVA/CuNW FTCE as the anode exhibits a current efficiency of 26.4 cd/A at 1000 cd/m 2 , which is comparable to that of the reference device (27.1 cd/A) based on indium tin oxide anode on glass, indicating its high potential for application in flexible optoelectronics. • Highly conductive PVA/CuNW electrodes are fabricated at room temperature. • The electrode shows excellent optoelectronic properties. • Low roughness as well as significantly enhanced chemical and mechanical stability has been achieved. • The flexible OLED device using PVA/CuNW exhibits high luminance and efficiency.

Flexible triboelectric nanogenerators using transparent copper nanowire electrodes: energy harvesting, sensing human activities and material recognition.

Triboelectric nanogenerators (TENGs) have emerged as a promising green technology to efficiently harvest otherwise wasted mechanical energy from the environment and human activities. However, cost-effective and reliably performing TENGs require rational integration of triboelectric materials, spacers, and electrodes. The present work reports for the first time the use of oxydation-resistant pure copper nanowires (CuNWs) as an electrode to develop a flexible, and inexpensive TENG through a potentially scalable approach involving vacuum filtration and lactic acid treatment. A ∼6 cm2 device yields a remarkable open circuit voltage (Voc) of 200 V and power density of 10.67 W m-2 under human finger tapping. The device is robust, flexible and noncytotoxic as assessed by stretching/bending maneuvers, corrosion tests, continuous operation for 8000 cycles, and biocompatibility tests using human fibroblast cells. The device can power 115 light emitting diodes (LEDs) and a digital calculator; sense bending and motion from the human hand; and transmit Morse code signals. The robustness, flexibility, transparency, and non-cytotoxicity of the device render it particularly promising for a wide range of energy harvesting and advanced healthcare applications, such as sensorised smart gloves for tactile sensing, material identification and safer surgical intervention.

Simple, Fast, and Scalable Reverse-Offset Printing of Micropatterned Copper Nanowire Electrodes with Sub-10 μm Resolution.

Copper nanowires (CuNWs) possess key characteristics for realizing flexible transparent electronics. High-quality CuNW micropatterns with high resolution and uniform thickness are required to realize integrated transparent electronic devices. However, patterning high-aspect-ratio CuNWs is challenging because of their long length, exceeding the target pattern dimension. This work reports a novel reverse-offset printing technology that enables the sub-10 μm high-resolution micropatterning of CuNW transparent conducting electrodes (TCEs). The CuNW ink for reverse-offset printing was formulated to control viscoelasticity, cohesive force, and adhesion by adjusting the ligands, solvents, surface energy modifiers, and leveling additives. An inexpensive commercial adhesive handroller achieved a simple, fast, and scalable micropatterning of CuNW TCEs. Easy production of high-quality CuNW micropatterns with various curvatures and shapes was possible, regardless of the printing direction. The reverse-offset-printed CuNW micropatterns exhibited a minimum of 7 μm line width and excellent pattern qualities such as fine line spacing, sharp edge definition, and outstanding pattern uniformity. In addition, they exhibited excellent sheet resistance, high optical transparency, outstanding mechanical durability, and long-term stability. Flexible light-emitting diode (LED) circuits, transparent heaters, and organic LEDs (OLEDs) can be fabricated using high-resolution reverse-offset-printed CuNW micropatterns for applications in flexible transparent electronic devices.

Efficient Hydrogen Generation and Total Nitrogen Removal for Urine Treatment in a Neutral Solution Based on a Self-Driving Nano Photoelectrocatalytic System.

Urine is the main source of nitrogen pollution, while urea is a hydrogen-enriched carrier that has been ignored. Decomposition of urea to H2 and N2 is of great significance. Unfortunately, direct urea oxidation suffers from sluggish kinetics, and needs strong alkaline condition. Herein, we developed a self-driving nano photoelectrocatalytic (PEC) system to efficiently produce hydrogen and remove total nitrogen (TN) for urine treatment under neutral pH conditions. TiO2/WO3 nanosheets were used as photoanode to generate chlorine radicals (Cl•) to convert urea-nitrogen to N2, which can promote hydrogen generation, due to the kinetic advantage of Cl−/Cl• cyclic catalysis. Copper nanowire electrodes (Cu NWs/CF) were employed as the cathode to produce hydrogen and simultaneously eliminate the over-oxidized nitrate-nitrogen. The self-driving was achieved based on a self-bias photoanode, consisting of confronted TiO2/WO3 nanosheets and a rear Si photovoltaic cell (Si PVC). The experiment results showed that hydrogen generation with Cl• is 2.03 times higher than in urine treatment without Cl•, generating hydrogen at 66.71 μmol h−1. At the same time, this system achieved a decomposition rate of 98.33% for urea in 2 h, with a reaction rate constant of 0.0359 min−1. The removal rate of total nitrogen and total organic carbon (TOC) reached 75.3% and 48.4% in 2 h, respectively. This study proposes an efficient and potential urine treatment and energy recovery method in neutral solution.

Thermally grown copper nanowire electrodes modified by electropolymerization

Controlled electrosynthesis of poly(N-ethylaniline) (PNEA) layer is demonstrated on copper nanowires supported by a copper foil. Copper nanowires were grown by thermal oxidation/reduction of copper foil support. Potentiodynamic electropolymerization provides control over morphology resulting in the formation of polymer layer on copper nanowire electrode showing stable adhesion and homogeneous deposition. The resulting polymer coating can support electrochemically active metal nanoparticles (NPs) that can be introduced in a separate step. Here, we chose copper nanoparticles as electrocatalyst. The Cu NP/PNEA/Cu nanowire electrode was characterized for glucose and methanol electrochemical oxidation to demonstrate the versatility of the polymer-coated copper nanowire structure for electrochemical reactions in aqueous solution.

Plasma Activation of Copper Nanowires Arrays for Electrocatalytic Sensing of Nitrate in Food and Water.

Electrochemical methods for nitrate detection are very attractive since they are suitable for in-field and decentralized monitoring. Copper electrodes are often used to this aim as this metal presents interesting electrocatalytic properties towards nitrate reduction. In this research, we study improvements in the electrochemical analysis of nitrate in natural water and food by taking advantage of the detection capabilities of ensembles of copper nanowire electrodes (CuWNEEs). These electrodes are prepared via template electrodeposition of copper within the nanopores of track-etched polycarbonate (PC) membranes. A critical step in the preparation of these sensors is the removal of the template. Here, we applied the combination of chemical etching with atmospheric plasma cleaning which proved suitable for improving the performance of the nanostructured copper electrode. Analytical results obtained with the CuWNEE sensor for nitrate analyses in river water samples compare satisfactorily with those achieved by standard chromatographic or spectroscopic methods. Experimental results concerning the application of the CuWNEEs for nitrate analysis in food samples are also presented and discussed, with focus on nitrate detection in leafy vegetables.

Highly reliable copper nanowire electrode with enhanced transmittance and robustness for organic light emitting diodes

Abstract A highly conductive and robust copper nanowire (CuNW) composite film is fabricated through a simple welding and reduction process. The nanowires are welded to a unit and reduced into pure metal copper without oxide layer on the surface by poly(ethylene glycol) (PEG). The electrical conductivity of the film significantly increases and the film's surface roughness decreases greatly since the wire junctions are well welded. When the polymethyl methacrylate (PMMA) is coated on the CuNWs as a protecting layer, the nanowires are tightly bonds to the substrate, and the transmittance of the film increases dramatically. The whole process can be accomplished within 10 min and the obtained film shows a low sheet resistance of 22 Ω/sq with a transmittance of 88%, which is among the top values to the best of our knowledge. This obtained CuNW/PMMA composite film can resist air, water and ethanol exposure without obviously conductivity deterioration. With this CuNW/PMMA composite film as anode for the organic light-emitting diode, the device shows better performance than that with ITO anode.

A Transparent and Flexible Capacitive‐Force Touch Pad from High‐Aspect‐Ratio Copper Nanowires with Enhanced Oxidation Resistance for Applications in Wearable Electronics

AbstractCopper nanowires are widely utilized for flexible electronics applications due to their excellent electrical conductivity, mechanical flexibility, and optical transparency with very low material cost. While many previous studies are dedicated to developing effective synthesis routes for copper nanowires, most of them have focused on the control of the morphology including length and diameter rather than synthesis yields. Although many postprocessing methods have been established to make use of the copper nanowires, there still remains crucial weakness in the nanowires against oxidation stability. In this study, a new synthesis method for the morphology control of copper nanowires as well as synthesis yields is introduced. After optimizing of the copper nanowire synthesis, a copper‐nanowire‐based flexible transparent conductor is fabricated as a highly robust electrode by using UV‐curable polyurethane acrylate resin. As a proof‐of‐concept, a flexible transparent capacitive‐force‐detection touch pad is demonstrated. The developed flexible transparent copper nanowire electrode with enhanced oxidation resistance is expected to be applied in various flexible and wearable electronics applications.

Extremely Simple and Rapid Fabrication of Flexible Transparent Electrodes Using Ultralong Copper Nanowires

Recently, flexible transparent electrodes have been fabricated successfully by using silver and copper nanowires. Silver is expensive and scarce, while copper is inexpensive but it requires a complex post-treatment process to obtain copper nanowire electrodes with an equivalent performance. In this study, by using polyvinylpyrrolidone-based ink and ultralong copper nanowires, a simple and low-cost approach has been presented for the fabrication of excellent copper nanowire-based flexible transparent electrodes. When ultrahigh aspect ratio copper nanowires and 0.5 wt % polyvinylpyrrolidone-based ink are applied to coat onto a substrate, the post-treatment process can be simplified to dipping once in acetic acid for 60 s. When compared to previously reported studies, our copper nanowire electrodes proved to be one of the best quality transparent electrodes. Moreover, these electrodes were applied successfully in the fabrication of self-capacitance button touch sensors.

Highly conductive and transparent copper nanowire electrodes on surface coated flexible and heat-sensitive substrates

Copper nanowire (CuNW) based flexible transparent electrodes have been extensively investigated due to their outstanding performances and low price. However, commonly used methods for processing CuNW transparent electrodes such as thermal annealing and photonic sintering inevitably damage the flexible substrates leading to low transmittance. Herein, a surface coating layer was demonstrated to protect the heat-sensitive polyethylene terephthalate (PET) polymer from being destroyed by the instantaneous high temperature during the photonic sintering process. The stable ceramic surface coating layer avoided the direct exposure of PET to intense light, further reduced the heat releasing to the bottom part of the PET, protecting the flexible PET base from destruction and ensuring high transparency for the CuNW transparent electrodes. A CuNW transparent electrode on surface coated PET (C-PET) substrates with a sheet resistance of 33 Ohm sq−1 and high transmittance of 82% has been successfully fabricated by the photonic sintering method using light intensity of 557 mJ cm−2 within several seconds in ambient conditions. The surface coating layers open a novel method to optimize the rapid photonic sintering technique for processing metal nanomaterials on heat-sensitive substrates.

Highly robust and ultrasmooth copper nanowire electrode by one-step coating for organic light-emitting diodes

A highly smooth, conductive, and uniform transparent CuNW/chitosan composite electrode is fabricated via a one-step solution process in ambient air.

The Properties of a Three-Dimensional Porous Electrode Made from Cu Nanowires

The high surface area per unit volume and large mass-transfer rates offered by three-dimensional porous electrodes have resulted in their use in a wide variety of electrochemical processes, including organic electrosynthesis, water electrolysis, water treatment, fuel cells, and redox flow batteries.1-4 Many types of porous electrodes are commercially available, including carbon paper, graphite felt, reticulated vitreous carbon (RVC), metal mesh, and metal foam. Metal foam offers relatively high conductivity (1.5x10-5 ohm m) but low surface area (<4x104 m-1),5 whereas carbon paper has one of the highest surface areas (up to 1.6x105 m-1) but lower conductivity (4.7x10-5 ohm m).6 This presentation will describe the characteristics of a copper nanowire electrode (Fig. 1) that has 15 times more surface area (2.4x106 m­-1) and is 33 times more conductive (1.6x10-6ohm m) than carbon paper. The improvement in surface area is due to the small diameter of the nanowires relative to carbon fibers in carbon paper, whereas the high conductivity is due to intrinsically higher conductivity of Cu, and the fact that the metal nanowires can be sintered together, forming highly conductive inter-nanowire contacts. The porosity of the nanowire electrode is 0.94, and its permeability was only 4 times lower than carbon paper. This presentation will report the electrochemical performance of the Cu nanowire electrode relative to carbon paper for the reduction of Cu ions in a flow-through geometry. The high-conductivity, high surface area, and high porosity that can be achieved with Cu nanowire electrodes creates new opportunities for improving the performance of electrochemical systems for energy storage, hydrogen production, water treatment and the production of fine chemicals.

레이저를 이용한 구리나노와이어 패터닝 공정 개발

This paper introduces a facile method to enhance the functionality of a patterned metallic transparent conductor through selective laser ablation of the metal nanowire percolation network. By scanning focused nanosecond pulsed laser a on copper nanowire percolation network, the copper nanowires are selectively ablated and patterned without resorting to any conventional chemical etching or photolithography steps. Several arbitrary patterns of copper nanowire transparent conductors are readily created on the percolation network by changing various laser parameters, such as repetition rate and power. Finally, in a few seconds, the copper nanowire electrode is continuously ablated to a 1 × 1 mm square area. This research thereby proves the advantage of the laser fabrication method.

Enhanced compatibility between a copper nanowire-based transparent electrode and a hybrid perovskite absorber by poly(ethylenimine).

Copper nanowires (CuNWs) have been applied to hybrid perovskite solar cells (PSCs) as a window electrode. By sandwiching the CuNW network between aluminum-doped zinc oxide and adopting a poly(ethylenimine) buffer layer, the compatibility between the CuNWs and the perovskite layer could be dramatically improved. PSCs containing the CuNW-based composite electrode exhibited an average power conversion efficiency of 8.65%.

One-step preparation of porous copper nanowires electrode for highly sensitive and stable amperometric detection of glyphosate

AbstractA simple and sensitive amperometric method for the detection of glyphosate based on a porous copper nanowire electrode is presented. The porous nanowires were fabricated simply by a one-step electrodeposition using hydrogen bubbles generated during the deposition to produce pores. These porous nanowires provided a 1.4 times larger surface area than a porous copper film. After the fabrication process the porous copper nanowires can be applied directly as a working electrode with the same custom-built flow cell. The detection was carried out by measuring the oxidation signal of copper; this increased with the concentration of glyphosate due to dissolution of the copper from the electrode. Under optimal conditions, the responses of the sensor were linear between 0.010-5.0 μmol L

Arrays of copper nanowire electrodes: Preparation, characterization and application as nitrate sensor

Ensembles of copper nanowire electrodes (CuWNEEs) are prepared via electrodeposition in track-etched polycarbonate membranes. Three different preparation methods are compared showing that the better results in terms of sensor durability and reproducibility are achieved by pre-sputtering a thin gold film on the templating membrane and attaching it to a supporting electrode by exploiting the adhesion property and ionic conductivity of a thin Nafion interlayer. SEM-EDS analyses together with double layer charging currents measurements indicate that these arrays are formed by copper nanowires with 400nm diameter, 10μm length distributed with a spatial density of 1×108 nanowires/cm2. The voltammetric reduction of nitrate at CuWNEEs is characterized by a well-resolved cathodic peak at approximately −0.680V vs Ag/AgCl, whose current scales linearly with the nitrate concentration in the 10–400μM range. The limit of detection (LOD) achieved by simple linear sweep voltammetry is in the 1.7–3.0μM range, depending on the CuWNEE preparation method, such LOD values being among the lowest reported up to now in the literature. The possibility to use CuWNEEs in chloride and nitrite containing water samples is demonstrated.

Flexible transparent conducting hybrid film using a surface-embedded copper nanowire network: a highly oxidation-resistant copper nanowire electrode for flexible optoelectronics.

We report a flexible high-performance conducting film using an embedded copper nanowire transparent conducting electrode; this material can be used as a transparent electrode platform for typical flexible optoelectronic devices. The monolithic composite structure of our transparent conducting film enables simultaneously an outstanding oxidation stability of the copper nanowire network (14 d at 80 °C), an exceptionally smooth surface topography (R(rms) < 2 nm), and an excellent opto-electrical performances (Rsh = 25 Ω sq(-1) and T = 82%). A flexible organic light emitting diode device is fabricated on the transparent conducting film to demonstrate its potential as a flexible copper nanowire electrode platform.

ITO‐Free, Small‐Molecule Organic Solar Cells on Spray‐Coated Copper‐Nanowire‐Based Transparent Electrodes

The great potential of solution‐processed metal nanowire networks utilized as a transparent electrode has attracted much attention in the last years. Typically, silver nanowires are applied, although their replacement by more abundant and cheaper materials is of interest. Here, a hydrazine‐free synthesis route for high aspect ratio copper nanowires is used to prepare conductive networks showing an enhanced electrode performance. The network deposition is done with a scalable spray‐coating process on glass and on polymer foils. By a pressing or an annealing step, highly conductive transparent electrodes are obtained, and they reveal transmittance‐resistance values similar to indium tin oxide (ITO) and networks made of silver nanowires. The application potential of the copper nanowire electrodes is demonstrated by integrating them into an evaporated small‐molecule organic solar cell with 3% efficiency.

Template-free electrochemical preparation of dendritic copper nanowire and its capacitor properties

One-dimensional copper nanomaterials are expected to play important roles in fabricating nanoscale electronic devices. In this study, we show that the electro-reduction of copper compounds in water at room temperature produces dendritic copper nanowires in the presence of ammonia without using templates. The nanowires consist of a stalk part (500nm thick and 80μm long on average) and a branch part (250nm thick and 40μm long on average). Microanalyses revealed that the nanowires are mainly composed of metallic copper. A preliminary study of the electrochemical capacitor properties of the copper nanowire electrode demonstrated its specific capacitance of 117Fg−1.