Synthesis Of Cu Nanowires Research Articles

Facile Fabrication of Transparent Conductor of Cu Nanowire-PEDOT:PSS

Facile Fabrication of Transparent Conductor of Cu Nanowire-PEDOT:PSS

Synthesis of Cu Nanowires by Template Electrodeposition and Their Application in Pressure Sensors

Synthesis of Cu Nanowires by Template Electrodeposition and Their Application in Pressure Sensors

Template-assisted electrodeposited cupric oxide nanotubes and hierarchical nanospikes for tailoring electrode-electrolyte interfacial charge transfer

Morphological modification in materials aids multi-channel electron access sites for easier electrolyte ion access for many electrochemical devices including energy storage devices. Controlled synthesis of such multichannel morphologies of metal oxides offers significant challenges. Herein, we report a template-assisted electrodeposition technique for the synthesis of Cu nanowires, which are transformed into either CuO nanotubes by controlled annealing or CuO hierarchical nanospikes using a simple hydroxyl ion impregnation technique and subsequent annealing. These materials are tested as electrodes in charge storage systems in 6 M KOH electrolyte in a three-electrode system; both electrodes have shown battery-type charge storage behaviour. Despite the chemical similarity between the two materials, the CuO nanospikes electrodes showed improved charge transport between electrode-electrolyte interface compared to the CuO nanotubes. With the cost-effectiveness, easy availability, and multi-channel morphology of CuO nanospikes along with the promising performance of the electrode in a three-electrode system, the present research offers future potential in developing low cost and high performing energy storage devices.

Facile electrochemical fabrication of Ag/Cu bi-metallic catalysts and the dependence of their selectivity for electrochemical CO2 reduction on the surface composition

Herein, bimetallic Ag/Cu nanowires (NWs) are prepared by electrochemical synthesis of Cu NWs and subsequent Ag galvanic displacement for the electrochemical reduction of CO2 to CO. The delicate execution of the displacement fabricates bimetallic NWs that possess controlled surface composition. The surface composition of NW is precisely controlled by varying the displacement time, and it is revealed by numerical and experimental methods that the catalytic activity is closely affected by the composition. The surface coverage of Ag measured based on under potential deposition according to the displacement time ranges from 70% to 94.3%. An increase in the Ag surface composition results in an improvement in the CO Faradaic efficiency from 29.8% to 39.6% and a significant increase in CO partial current density compared with Cu NWs and Ag foil. Namely, the catalytic activity of Ag/Cu NWs is dependent on the Ag coverage, and is governed by scaling relation.

Template Based Electrochemical Synthesis of Copper (Cu) Nanowires as CH2Cl2 Sensor

In this work, Copper (Cu) nanowires were synthesized electrochemically from aqueous acidic solution of 1 M copper (II) sulfate (CuSO4·5H2O) on a copper substrate by template-assisted electrodeposition method. The electrodeposition was conducted at room temperature and the length of nanowires was controlled by adjusting the deposition time. Different Structural and morphological characteristics were examined using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDX) that confirmed the successful synthesis of Cu nanowires. Moreover, the synthesized Cu nanowires were investigated for CH2Cl2 chemical sensing using different electrochemical techniques. The results showed that Cu nanowires can sense CH2Cl2 very effectively.

Structure-controlled synthesis of one-dimensional PdCu nanoscatalysts via a seed-mediated approach for oxygen reduction reaction

Herein, we introduce a facile strategy for the structure-controlled synthesis of one-dimensional PdCu nanocrystals via a seed-mediated approach. This developed strategy involves the synthesis of Cu nanowires with penta-twinned structure, and subsequent growth of Pd metal on Cu nanowires. The obtained one-dimensional PdCu nanocrystals are of rough surfaces and core-shell like architecture. Upon the tuning reactivity of (111) and (100) crystal faces on Cu nanowires in absence or presence of capping agent, one-dimensional PdCu nanocrystals with solid or hollow interiors (nanowires or nanotubes) can be controllably synthesized through galvanic displacement reaction, respectively. It is found that both PdCu nanowires and PdCu nanotubes exhibit better performance for oxygen reduction reaction compared with self-synthesized PdCu nanoparticles and commercial Pd/C in 0.1 M KOH electrolyte. Particularly, PdCu nanotubes show Pt-like performance, and achieve an onset potential of 0.941 V (vs. RHE) and a half potential of 0.825 V. The electron transfer number during oxygen reduction is close to 4 on PdCu nanotubes. Moreover, the catalytic stability of the obtained one-dimensional PdCu nanocrystals is much superior to that of commercial Pd/C and Pt/C catalysts.

Sophorolipid induced hydrothermal synthesis of Cu nanowires and its modulating effect on Cu nanostructures

Cu nanowires are important class of one dimensional metal nanowires with high electrical conductivity comparable to silver nanowires. Sophorolipid (SL), a well-known biosurfactant and glycolipid, plays significant role in the synthesis of nanomaterials as reducing and capping agent. Herein, we report the synthesis of Cu nanowires using sophorolipid by alkyl amine mediated hydrothermal synthesis and in this process, octadecylamine (ODA) used as alkyl amine. Cu nanowires of length ∼5−40μm and width ∼50−250 nm are produced at SL/ODA weight ratio of 0.13:1. Further structural investigations suggest that the morphology of these Cu nanostructures changes from nanowires to micron size rods and decahedron particles by modulating the weight ratio of SL and ODA.

Synthesis of Cu Nanowires Using Ascorbic Acid in Aqueous Solution and Their Applications for Flexible Transparent Conductive Films

Cu nanowires (NWs) have been extensively studied to produce flexible, low-cost and high-conductivity transparent films because of their flexibility, low cost and high conductivity. Most synthetic procedures are based on chemical reduction, which often requires high temperature, organic solvents, and toxic reagents such as N2H4. It is desirable to develop a cost-efficient and environmentally friendly synthetic procedure for practical use. Furthermore, Cu NWs with high aspect ratios are required to improve performances of the transparent conductive films. Previously, we synthesized Cu nanoparticles based on chemical aqueous reduction employing ascorbic acid (vitamin C) as a reducing agent instead of commonly used toxic reducing agents. The key to the wire-like morphologies is the adsorption of surface ligands to metal crystal facets during the nucleation of NWs. Surface ligands selectively adsorbs onto {100} facets and consequently the anisotropic growth along the <110> direction occurs. In addition, reaction speed control and additives are also important for syntheses of NWs with high aspect ratios. In this study, we examined to synthesize Cu NWs by chemically reducing aqueous Cu chloride complexes using ascorbic acid as a mild reducing agent instead of the commonly employed toxic reducing agent. We chose polyvinylpyrrolidone (PVP) and NaCl as a surface ligand and an additive, respectively. In addition, we controlled aspect ratios of Cu NWs by changing type of capping agent, optimizing additives and atmosphere. Cu chloride complexes were reduced to Cu metal through CuCl by ascorbic acid. The shape of the Cu metal particles highly depended on pH in the presence of PVP. Cu NWs were synthesized in the pH range of 3 to 4 while Cu nanoparticles were synthesized above pH 4. The reduction speed accelerated with increasing pH because the reduction capability of ascorbic acid increased with increasing pH. In fast reduction, all Cu chloride complexes were reduced to Cu particles before the anisotropic growth. In slow reduction, PVP effectively stabilized {110} facets of Cu rather than {111} facets, resulting in Cu NWs. The length and diameter of the Cu NWs were affected by atmosphere rather than additives and type of PVP. In the case of using ascorbic acid in aqueous solution, dissolved oxygen reacted with ascorbic acid to form hydrogen peroxide. Subsequently, hydrogen peroxide oxidized Cu metal surface and consequently prevented the anisotropic growth, resulting in Cu NWs with low aspect rations. By changing atmosphere from air to N2, we synthesized Cu NWs (length: 36 µm, diameter: 124 nm) from the reaction using ascorbic acid in aqueous solution. In our presentation, detailed results and discussion about the synthesis mechanism and performances as transparent conductive films will be introduced.

Environmentally friendly synthesis and formation mechanism of copper nanowires with controlled aspect ratios from aqueous solution with ascorbic acid

Copper (Cu) nanowires (NWs) were synthesized by the reduction of Cu–chloride complexes using ascorbic acid (AA) as a mild reducing agent, polyvinylpyrrolidone (PVP) as a capping agent, and NaCl as an additive under atmospheric conditions at 80 °C. Surface analyses revealed that both Cl ions and PVP were required for the synthesis of Cu NWs. Together, the Cl ions and PVP capped the Cu (1 0 0) side faces, leading to anisotropic growth of Cu NWs along the [1 1 0] direction. To obtain Cu NWs with high aspect ratios, we evaluated the synthetic mechanism under different reaction conditions. The results indicated that the presence of dissolved oxygen (DO) was the dominant factor affecting aspect ratio of Cu NWs. DO and hydrogen peroxide resulting from the reaction between DO and AA oxidized the surfaces of the growing Cu NWs, preventing further growth. Decreasing the amount of oxides on the Cu NW surfaces and removing DO increased the aspect ratios of the Cu NWs. The results indicated that DO should be removed from the reaction solution to obtain high-aspect-ratio Cu NWs in aqueous solutions containing AA.

Determining the Facet-Selective Electrochemistry That Drives Anisotropic Growth of Cu Nanowires

Cu nanowires are being studied for use in many applications, including transparent/flexible/stretchable conductors, electrochemical sensors, electrocatalysts, and batteries.1-3 Solution-phase synthesis of Cu nanowires could enable the low-cost production of Cu nanowires at large scales under mild reaction conditions. Despite many articles on the synthesis of Cu nanowires, the driving force for anisotropic growth of nanowires and the rate limiting step in nanowire growth is not well understood. The solution-phase synthesis of Cu nanowires is based on two electrochemical reactions: the reduction of Cu ion complexes, and the oxidation of reducing agents. In addition, organic additives are necessary for inducing the anisotropic growth of Cu nanowires; such additives are typically regarded as facet-selective capping agents.4 It is thought that capping agents selectively adsorb on the side of nanowires and suppress deposition of Cu while leaving the ends of growing nanowires active for Cu deposition.4 The ends and sides of Cu nanowires consist of (111) and (100) surfaces, respectively. Although the anisotropic growth of Cu nanowires is hypothesized to be the result of facet-dependent electrochemical reactions, there has been very few electrochemical tests of the capping agent hypothesis. Cu nanowires can be produced with (I) ethylenediamine (EDA) in an alkaline solution5,6 or with (II) an alkylamine (e.g., hexadecylamine) in a neutral solution.7,8 In synthesis I, hydrazine (N2H4) is used as the reducing agent for the reduction of a hydroxocuprate complex to metallic Cu. It has been hypothesized that EDA acts as a capping agent, but we recently proved by electrochemical analyses with Cu(111) and (100) single crystals that EDA is actually a facet-dependent promotor for Cu deposition.6 EDA prevents surface oxidation of Cu(111) (i.e. the ends of Cu nanowires) more effectively than Cu(100) surface, which enables anisotropic deposition of Cu onto the ends of growing nanowires. The growth of Cu nanowires in this alkaline synthesis is mass-transport limited.5,6 In synthesis II, alkylamines act as capping agents, driving anisotropic growth by selectively adsorbing on the sides of Cu nanowires. Glucose or ascorbic acid have been reported as reducing agents in this reaction,7,8 however it was found that glucose cannot act as the reducing agent.9 Instead, the Malliard reaction between glucose and alkylamines produces reductones (such as ascorbic acid), which can reduce Cu-alkylamine complexes to metallic Cu. Interestingly, it was also found that chloride ions, such as in the CuCl2 precursor, are necessary for anisotropic growth (Figure 1). Without chloride ions, only Cu nanoparticles were obtained. Thus, it seems the presence of chloride is necessary for the facet-selective adsorption of alkylamine, but more work is necessary to understand the role of chloride and alkylamine in the Cu nanowire synthesis. This presentation will discuss the fundamental chemistry behind the alkylamine-mediated growth of Cu nanowires. New evidence will be presented to (1) show alkylamine-mediated growth of Cu nanowires is kinetically limited due to surface adsorption of alkyamines, and (2) clarify the role halide ions play in the anisotropic growth of Cu nanowires.

Oleylamine-Mediated Hydrothermal Growth of Millimeter-Long Cu Nanowires and Their Electrocatalytic Activity for Reduction of Nitrate

While high-aspect-ratio metal nanowires are essential for producing nanowire-based electrodes of good performance used in electronics and electrocatalysis, the synthesis of millimeter-long Cu nanowires remains a challenge. This work demonstrates an oleylamine-mediated hydrothermal method for synthesis of Cu nanowires with an average diameter of ~80 nm and a length up to several millimeters. An investigation on the role of oleylamine in nanowire formation by mass spectroscopy, small angle X-ray diffraction and transmission electron microscopy reveals that oleylamine serves as a mild reducing agent for slow reduction of Cu(II) to Cu, a complexing agent to form Cu(II)-oleylamine complex for guiding the nanowire growth, as well as a surfactant to generate lamellar phase structure for the formation of nanowire bundles. The growth mechanism of these millimeter-long Cu nanowire bundles is proposed based on the experimental observations. Electrochemical measurements by linear sweep voltammetry indicate that the self-supported nanowire electrode prepared from as-formed Cu nanowire bundles shows high catalytic activity for electroreduction of nitrate in water.

Kinetically controlled synthesis of Cu nanowires with tunable diameters and their applications in transparent electrodes

High quality Cu nanowires with tunable diameters were synthesized through adjusting the reaction kinetics to construct high-performance transparent electrodes.

A Single-Crystal Electrochemical Study of the Facet-Selective Chemistry That Drives Anisotropic Growth of Cu Nanowires

Anisotropic growth of metal nanostructures in liquid solutions is generally thought to be due to the presence of a capping agent blocking the addition of atoms to certain facets. For example, in the solution-phase synthesis of Cu nanowires, ethylenediamine (Fig. 1) and alkylamines are generally used as capping agents, and it has been hypothesized that these capping agents selectively block the addition of Cu atoms to the (100) facets on the sides of the nanowires, leaving the (111) facets at the ends of the nanowire open to atomic addition.1,2 However, it has been difficult to definitively prove the capping agent hypothesis, and the facet-selective chemistry that drives anisotropic growth generally remains poorly understood. In comparison, there is a long and quickly growing list of applications for metal nanostructures. For example, Cu nanowires have been used in transparent electrodes,3 battery electrodes,4 electrocatalysts,5 and electrochemical sensors.6Given that the properties and performance in a given application can be highly dependent on the morphology of a nanostructure, a better understanding of their growth mechanism could aid the rational development of improved nanostructure syntheses. This presentation will report the first electrochemical studies of Cu nanowire growth utilizing Cu(100) and Cu(111) single crystal electrodes as proxies for the sides and ends of Cu nanowires, respectively. These studies show that, rather than acting as a capping agent, ethylenediamine selectively inhibits the formation of Cu oxide on Cu(111), and thereby selectively promotes reduction of Cu ions onto Cu(111). Reduction of Cu ions onto Cu(100) is inhibited due to the formation of a Cu oxide layer in the highly basic (15 M NaOH) reaction solution.7In contrast, the alkylamine-based synthesis of Cu nanowires takes place in a solution with a neutral pH, and the formation of Cu oxide does not play a role in anisotropic growth. Instead, preliminary results indicate alkylamines act as a capping agent by increasing the charge transfer resistance on Cu(100) to a greater extent than on Cu(111). These results demonstrate that single crystal electrochemistry can be a powerful tool for elucidating the facet-selective chemistry of capping agents in nanostructure syntheses, and can provide a rational basis for the discovery of novel capping agents for directing anisotropic growth.

Pentatwinned Cu Nanowires with Ultrathin Diameters below 20 nm and Their Use as Templates for the Synthesis of Au‐Based Nanotubes

AbstractWe report a one‐pot method for the facile synthesis of Cu nanowires in high purity, together with ultrathin diameters well below 20 nm. Selected area electron diffraction and high‐resolution transmission electron microscopy studies confirm that the Cu nanowires are grown along the &lt;110&gt; direction to give pentatwinned, one‐dimensional nanostructures, enclosed by five {100} facets on the side surface. A systematic study further indicates that it is critical to conduct the synthesis under an argon atmosphere in order to improve the purity and uniformity of the nanowires while keeping their diameters thinner than 20 nm. We also demonstrate the use of these nanowires as sacrificial templates for the synthesis of Au‐based nanotubes through a galvanic replacement process.

Ethylenediamine Promotes Cu Nanowire Growth by Inhibiting Oxidation of Cu(111).

The synthesis of metal nanostructures usually requires a capping agent that is generally thought to cause anisotropic growth by blocking the addition of atoms to specific crystal facets. This work uses a series of electrochemical measurements with a quartz crystal microbalance and single-crystal electrodes to elucidate the facet-selective chemistry occurring in the synthesis of Cu nanowires. Contrary to prevailing hypotheses, ethylenediamine, a so-called capping agent in the synthesis of Cu nanowires, causes anisotropic growth by increasing the rate of atomic addition to (111) facets at the end of a growing nanowire relative to (100) facets on the sides of a nanowire. Ethylenediamine increases the reduction rate of Cu(OH)2- on a Cu(111) surface relative to Cu(100) by selectively inhibiting the formation of Cu oxide on Cu(111). This work demonstrates how studying facet-selective electrochemistry can improve the understanding of the processes by which atoms assemble to form anisotropic metal nanostructures.

Cost-effective aqueous-phase synthesis of long copper nanowires

This work describes a simple and cost-effective aqueous-phase synthesis of Cu nanowires with long-term stability. Chloride ions and branched polyethyleneimine (BPEI) were found to be of great importance to the formation and stabilization of Cu nanowires.

Synthesis of Cu Nanowires by the Self-Assembly Growth Process

The ultralong copper nanowires (Cu NWs) with diameter of 90±10 nm and length over 20 μm were synthesized by the self-assembly growth process, in which the copper ions were reduced with hydrazine in an aqueous solution containing NaOH and ethylenediamine (EDA). The prepared Cu NWs were characterized by XRD, SEM and TEM. The results indicate that the ultralong Cu NWs product almost containing no particles can be obtained at 80 °C for 1 h with a proper concentration of EDA. During the growth of Cu NWs, as the EDA moleculars are possibly preferentially absorbed onto the crystal plane of (110), the gowth of Cu NW will be oriented along the crystal plane of (111).

Economical and green synthesis of Cu nanowires and their use as a catalyst for selective hydrogenation of cinnamaldehyde

The reduction of Cu(OH)2 by hydrazine in a concentrated NaOH solution containing ethylenediamine at 70 °C has been employed to prepare Cu nanowires. The net change during nanowire synthesis is that the consumption of Cu(OH)2 and hydrazine gives rise to the formation of Cu nanowires, N2 and H2O, which make it possible for us to endlessly reuse the produced wastewater after the removal of Cu nanowires. By controlling the re-added amounts of hydrazine and ethylenediamine in the case of reusing the wastewater, we have found that the morphology of Cu nanowires is kept almost unchanged even though the wastewater is recycled more than ten times. The recycle of the endlessly reusable wastewater not only significantly reduces the cost of Cu nanowires but also makes this approach environmentally friendly. In addition, as a catalyst for selective hydrogenation of cinnamaldehyde, the as-formed Cu nanowires show different catalytic performance in comparison with the unsupported Cu nanoparticles.

Cu(II)-alkyl amine complex mediated hydrothermal synthesis of Cu nanowires: exploring the dual role of alkyl amines.

Ligands/surfactants play an important role in the synthesis of anisotropic nanomaterials. Other than site specific binding to the crystal plane, they can also undergo complexation with metal ions, altering the nature of the metal complex. The ligand-metal complex formation could be sufficient to modify the reaction kinetics and could affect the size and morphology of the nanostructures. In this article, we investigated such a change in the metal precursor caused by ligands (i.e., alkyl amines) in the hydrothermal synthesis of Cu nanowires in the presence of glucose as a reducing agent. Comparative studies were carried out with other nitrogen-based surfactants such as cetyl trimethyl ammonium bromide and polyvinyl pyrrolodine. Our experimental results confirmed the complex formation of Cu(2+) ions with alkyl amines and its application for nanowire synthesis. Slow reduction of this complex allows for the generation of twinned seeds, which are later grown into nanowires by consuming newly generated seeds in the presence of excess alkyl amine.

A Facile Non-Aqueous Approach for the Synthesis of Cu Nanowires

A non-aqueous synthetic route has been developed for the preparation of uniform Cu nanowires with length up to tens of micrometers. Unlike commonly used one-pot synthesis approach that usually involve a fast reduction of metal precursors in the presence of reducing agents, a continuous-injection approach has been to utilized to control the speed of reaction and the concentration of Cu nuclei. In this approach, copper (II) chloride dihydrate and nickel (II) acetylacetone which are dissolved in oleylamine solutions have been injected into octadecene by a syringe-pump. The as-prepared samples have been characterized by transmission electron microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results show that the products are pure Cu nanowires which have preferred &lt;110&gt; growth directions. The formation mechanism and major influencing factors on the synthesis of Cu nanowires have been discussed.