Novel Fabrication of Silver-Coated Copper Nanowires with Organic Compound Solution

Copper nanowires and Cu-Ag nanowires have various potential applications, such as transparent conductive film, flexible electronics, and conductive filler. In this study, we developed a new green fabrication method for silver-coated copper nanowires using methylsulfonylmethane (DMSO2), which is an environmentally friendly chemical at the food-grade level, to replace toxic chemicals, including ammonia, in the silver coating process. Copper nanowires were synthesized under various reaction temperatures and concentrations of hydrazine (N2H4), ethylenediamine (EDA), sodium hydroxide (NaOH), and copper precursor. The reaction temperature higher than 70 °C caused the oxidation of copper products and evaporation of the sample solution. The optimal conditions to synthesize copper nanowires more than 18 µm in length and 25-45 nm in diameter were determined: 9 M of NaOH, 50 µL of EDA, 17 mM of CuCl2, 5.7 mM of N2H4, and 70 °C reaction temperature. Cu-Ag nanowires, which have about a 12 nm thick silver shell, were successfully fabricated at room temperature under 1 mM of silver nitrate (AgNO3) and 1 wt % of DMSO2. Synthesis conditions for copper and silver-coated copper nanowires have been optimized.

Nanowire Genome: A Magic Toolbox for 1D Nanostructures

1D nanomaterials with high aspect ratio, i.e., nanowires and nanotubes, have inspired considerable research interest thanks to the fact that exotic physical and chemical properties emerge as their diameters approach or fall into certain length scales, such as the wavelength of light, the mean free path of phonons, the exciton Bohr radius, the critical size of magnetic domains, and the exciton diffusion length. On the basis of their components, aspect ratio, and properties, there may be imperceptible connections among hundreds of nanowires prepared by different strategies. Inspired by the heredity system in life, a new concept termed the "nanowire genome" is introduced here to clarify the relationships between hundreds of nanowires reported previously. As such, this approach will not only improve the tools incorporating the prior nanowires but also help to precisely synthesize new nanowires and even assist in the prediction on the properties of nanowires. Although the road from start-ups to maturity is long and fraught with challenges, the genetical syntheses of more than 200 kinds of nanostructures stemming from three mother nanowires (Te, Ag, and Cu) are summarized here to demonstrate the nanowire genome as a versatile toolbox. A summary and outlook on future challenges in this field are also presented.

Highly Stretchable Metallic Nanowire Networks Reinforced by the Underlying Randomly Distributed Elastic Polymer Nanofibers via Interfacial Adhesion Improvement

On-skin electronics require conductive, porous, and stretchable materials for a stable operation with minimal invasiveness to the human body. However, porous elastic conductors that simultaneously achieve high conductivity, good stretchability, and durability are rare owing to the lack of proper design for good adhesion between porous elastic polymer and conductive metallic networks. Here, a simple fabrication approach for porous nanomesh-type elastic conductors is shown by designing a layer-by-layer structure of nanofibers/nanowires (NFs/NWs) via interfacial hydrogen bonding. The as-prepared conductors, consisting of Ag NWs and polyurethane (PU) NFs, simultaneously achieve high conductivity (9190 S cm^-1 ), high stretchability (310%), and good durability (82% resistance increase after 1000 cycles of deformation at 70% tensile strain). The direct contact between the Ag NWs enables the high conductivity. The synergistic effect of the layer-by-layer structure and good adhesion between the Ag NWs and the PU NFs enables good mechanical properties. Furthermore, without any adhesive gel/tape, the conductors can be utilized as breathable strain sensors for precise joint motion monitoring, and as breathable sensing electrodes for continuous electrophysiological signal recording.

Advancements in Copper Nanowires: Synthesis, Purification, Assemblies, Surface Modification, and Applications

Copper nanowires (CuNWs) are attracting a myriad of attention due to their preponderant electric conductivity, optoelectronic and mechanical properties, high electrocatalytic efficiency, and large abundance. Recently, great endeavors are undertaken to develop controllable and facile approaches to synthesize CuNWs with high dispersibility, oxidation resistance, and zero defects for future large-scale nano-enabled materials. Herein, this work provides a comprehensive review of current remarkable advancements in CuNWs. The Review starts with a thorough overview of recently developed synthetic strategies and growth mechanisms to achieve single-crystalline CuNWs and fivefold twinned CuNWs by the reduction of Cu(I) and Cu(II) ions, respectively. Following is a discussion of CuNW purification and multidimensional assemblies comprising films, aerogels, and arrays. Next, several effective approaches to protect CuNWs from oxidation are highlighted. The emerging applications of CuNWs in diverse fields are then focused on, with particular emphasis on optoelectronics, energy storage/conversion, catalysis, wearable electronics, and thermal management, followed by a brief comment on the current challenges and future research directions. The central theme of the Review is to provide an intimate correlation among the synthesis, structure, properties, and applications of CuNWs.

Sintering mechanism of the Cu–Ag core–shell nanoparticle paste at low temperature in ambient air

Cu–Ag core–shell nanoparticles owned good anti-oxidation ability, and as-fabricated joints using the Cu–Ag core–shell nanoparticles paste showed high shear strength.