Formation Of Metallic Nanowires Research Articles

Electrodeposition of Cu Nanocubes in the Presence of Cl- and Br-

Electrodeposition is one of the simple methods for fabricating metal and alloy thin films. Electrodeposition is performed by applying external electrical energy to conductive substrates immersing in electrolytes containing metal precursors. Metal ions or complexes are reduced on a substrate surface and form metal films. The properties of metal thin films and surface morphology of the electrodeposit can be modulated by the parameters of electrodeposition, the composition of electrolytes, i.e., the concentrations of metal precursors and additives. Furthermore, the atomic composition of alloy films can also be easily controlled by electrochemical parameters in the electrodeposition process.1 As explained, the electrodeposition process has various advantages in producing metal thin films with desired properties. However, creating nanostructures with precisely controlling their shapes in the nm scale is relatively difficult. In colloidal syntheses, various nanocrystals, including nanowires, nanospheres, octahedrons, nanocubes, and nanoplates, can be obtained by introducing shape-directing agents.2-4 In the case of electrodeposition, the template-assisted electrodeposition method is the most common to form nanostructures,5,6 and relatively few examples of shape controlling by additives have been reported. Although the formation of metal nanowires in the presence of 3,5-diamino-1,2,4-triazole (DAT) has been recently reported,7 shape control of metal deposits by additives during the electrodeposition process is still limited to few nanostructures. Electrodeposition induces metal growth relatively faster than colloidal synthesis, and a precise nucleation step is not involved in the electrodeposition, which is critical in colloidal syntheses. In this study, we have adopted pulse-reverse electrodeposition to modulate metal nucleation at the initial stage of electrodeposition and also maximize the effects of additives. Pulse-reverse electrodeposition has been researched for controlling the properties of metal thin films and changing the adsorption of additives.8,9 Therefore, pulse-reverse electrodeposition can catch up with the shape control in colloidal syntheses. This presentation will introduce how the parameters in pulse-reverse electrodeposition and additives (halide ions) affect the shape of Cu nanocrystals. References 1) T. P. Moffat, J. J. Mallett, and S. M. Hwang, “Oxygen Reduction Kinetics on Electrodeposited Pt, Pt100− x Nix , and Pt100−xCox” J. Electrochem. Soc. 156, B238 (2009)2) Y. Xia, Y. Xiong, B. Lim, and S. E. Skrabalak, “Shape-Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets Complex Physics?” Angew. Chem. Int. Ed. 48, 60 (2009)3) K. A. Fichthorn, Z. Chen, Z. Chen, R. M. Rioux, M. J. Kim, and B. J. Wiley, “Understanding the Solution-Phase Growth of Cu and Ag Nanowires and Nanocubes from First Principles” Langmuir 37, 4419 (2021)4) D. Huo, M. J. Kim, Z. Lyu, Y. Shi, B. J. Wiley, and Y. Xia, “One-Dimensional Metal Nanostructures: From Colloidal Syntheses to Applications” Chem. Rev. 119, 8972 (2019)5) K. R. Yeo, J. Y. Eo, M. J. Kim and S.-K. Kim, “Shape Control of Metal Nanostructures by Electrodeposition and their Applications in Electrocatalysis” J. Electrochem. Soc. 169, 112502 (2022)6) C. Liu, Z. Li, P. Yu, H. W. Wong, and Z. Gu, “Vertically Aligned and Surface Roughed Pt Nanostructured Wire Array as High Performance Electrocatalysts for Methanol Oxidation” ACS Appl. Energy Mater. 1, 3973 (2018)7) T. T. H. Hoang, S. Ma, J. I. Gold, P. J. A. Kenis, and A. A. Gewirth “Nanoporous Copper Films by Additive-Controlled Electrodeposition: CO2 Reduction Catalysis” ACS Catal. 7, 3313 (2017)8) M. J. Kim, T. Lim, K. J. Park, S. K. Cho, S.-K. Kim, and J. J. Kim “Characteristics of Pulse-Reverse Electrodeposited Cu Thin Films: I. Effects of the Anodic Step in the Absence of an Organic Additive” J. Electrochem. Soc. 159, D538 (2012)9) M. J. Kim, T. Lim, K. J. Park, O. J. Kwon, S.-K. Kim, and J. J. Kim “Characteristics of Pulse-Reverse Electrodeposited Cu Thin Film: II. Effects of Organic Additives” J. Electrochem. Soc. 159, D544 (2012) Figure 1

Metallic Nanowires Self-Assembled in Quasi-Circular Nanomolds Templated by DNA Origami.

The self-assembly of conducting nanostructures is currently being investigated intensively in order to evaluate the feasibility of creating novel nanoelectronic devices and circuits using such pathways. In particular, methods based on so-called DNA Origami nanostructures have shown great potential in the formation of metallic nanowires. The main challenge of this method is the reproducible generation of very well-connected metallic nanostructures, which may be used as interconnects in future devices. Here, we use a novel design of nanowires with a quasi-circular cross-section as opposed to rectangular or uncontrolled cross-sections in earlier studies. We find indications that the reliability of the fabrication scheme is enhanced and the overall resistance of the wires is comparable to metallic nanostructures generated by electrochemistry or top-down methods. In addition, we observe that some of the nanowires are annealed when passing a current through them, which leads to a clear enhancement for the conductance. We envision that these nanowires provide further steps towards the successful generation of nanoelectronics using self-assembly.

Electrodeposition of Nickel From an Amide-Type Ionic Liquid Under a Magnetic Field

Aprotic ionic liquids are considered to be used as the promising electrolytes for electrodeposition of wide variety of metals and alloys. Nickel is one of the ferromagnetic metals and can be deposited in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing Ni(TFSA)2.[1] Furthermore, Ni nanoparticles were prepared in the ionic liquid by potentiostatic cathodic reduction at a negative potential region.[2] Recently, we reported that the nanowires of a ferromagnetic metal and alloy could be deposited electrochemically by applying a static magnetic field without any template.[3-5] The formation of metal nanowires is considered to be due to the magnetization and self-organization of the nanoparticles at the electrode-electrolyte interface. Thus, the similar nanowires are expected to be obtained for ferromagnetic metals like Ni. In the present study, electrodeposition of Ni was conducted in BMPTFSA containing Ni(TFSA)2 under a static magnetic field.The cathodic reduction of Ni(II) was observed in the cyclic voltammogram of a glassy carbon (GC) electrode in BMPTFSA containing Ni(TFSA)2, as reported previously.[1] An increase in the cathodic peak current and the positive shift of the onset potential of the cathodic current were observed when a magnet was attached on the backside of the GC electrode. Granular deposits were observed after potentiostatic cathodic reduction without the magnet. However, nanowires were deposited on the GC electrode with the magnet, verifying the electrodeposition of ferromagnetic metals in the ionic liquid under a magnetic field leads to the formation of the nanowires.

Prudent electrochemical pretreatment to promote the OER by catalytically inert "Iron incorporated metallic Ni nanowires" synthesized via the "non-classical" growth mechanism.

This study provides new insight towards the non-classical “amorphous to crystalline” growth mechanism for metal nanowire synthesis and reports an electrochemical strategy to activate inactive materials into efficient electrocatalysts for the OER. Despite considerable research on transition metal oxides/hydroxides, especially NiFe based hydroxides as OER electrocatalysts, poor conductivity of these materials plagues their catalytic efficiency. In contrast, lack of catalytic centers hinders the OER performance of conductive metals. Herein, we devised a suitable precondition strategy to transform only the surface of conductive metallic Ni nanowires into active catalytic centers. The resulting material with intimate contact between the electrically conductive core and electrocatalytically active surface showed promising “specific” and “geometric” electrocatalytic activity towards the alkaline OER at different pH. Upon iron incorporation, the Fe centers incorporated at the surface as well as in the bulk of the nanowires were found to further boost the OER activity of these materials. A one-pot strategy was adopted to produce iron free/incorporated Ni nanowires covered with nano-spikes. Growth analysis revealed a unique “non-classical amorphous-to-crystalline transformation” to be responsible for the formation of metallic nanowires.

Drift Mechanism of Formation of Metal Nanowires in Liquid Helium

The formation of nanowires or their system in liquid helium (in metal laser ablation products) and metal-enriched helium droplets is a particular case of the well-known diffusion-controlled anisotropic (in an electric field) aggregation of particles. Previously, we showed that the mechanism of rapid formation of metal nanowires in a single quantum vortex proposed by several authors is impossible because of the enormous heat release accompanying the fusion of nanoparticles, which leads to their separation from the vortex and destruction of quantum vortices in the vicinity of the fused particles. In the present work, it was shown theoretically that the formation of nanowires is described by the known drift mechanism under conditions when the drift of charged nanoparticles in an electric field substantially exceeds their diffusion. The charging of nanoparticles results from (a) ionization during laser ablation and (b) thermionic emission from nanoparticles extremely heated during coagulation (which is theoretically substantiated in the present work). The drift occurs due to the attraction of charged nanoparticles to any surfaces under the action of the electric field of the image (and occasionally also under the action of the external field) as well as due to the attraction of neutral particles to charged ones. We showed that in this case, the drift prevails over the diffusion. Under these conditions, nanoparticles aggregate into anisomeric structures acting as field concentrators, which, in turn, enhances the drift and provides positive feedback during the self-assembly of nanowires.

Effect of surface physics of metal oxides on the ability to form metallic nanowires

Through the control of surface physics of oxide films, nanowires of various metals can be readily grown on the surface of oxide films without templates and surfactants. To clarify how the characteristics of oxides affect the formation of metallic nanowires, this report investigated the influence of the surface physical characteristics, including morphological, electrical, optical and hydrophilic properties of the metal oxide substrates (TiO2, CeO2, and indium tin oxide), on the yield of Ag and Pt nanowires. In addition to the surface roughness, photo-induced defects were suggested to be the key factor dominating the number of nucleation sites and thus the population of nanowires.

Formation of metal nanowires using techniques of the selective removal of atoms and investigation into the electric properties of metal nanowires

The electric properties of films of the metals reduced from oxides using the selective removal of atoms (SRA) under proton irradiation were investigated. The electric characteristics of SRA films were found to correspond to characteristics of the deposited films of pure metals. The possibility of creating nanowires in a matrix of initial oxide under irradiation through a PMMA mask was shown. Individual nanowires and pairs of nanowires from bismuth were created. The electric characteristics of both nanowires and leak currents between closely located nanowires were measured. The possibility of creating two isolated nanowires at a distance of 70 nm was shown.

Formation of Metallic Nanowires by Laser Ablation in Liquid Helium

Laser ablation of metals in liquid helium results in the formation of metal filaments with diameters on the order of 2–10 nanometres and of spherical nanoparticles. In superfluid helium these nanowires aggregate into centimeter-sized networks. We study the morphology and the electric conductivity of these large aggregates, as well as extinction spectra and the crystalline structure of the individual nanofragments. We discuss the effect of superfluidity on the mechanisms of coalescence processes at the nanometer and centimeter scales.

Dependence of surface atomic arrangement of titanium dioxide on metallic nanowire nucleation by thermally assisted photoreduction

Through studying the optical, electrical and photocatalytic properties of anatase TiO(2) films with different preferred orientations, (101) and (004), this study clarified the relationship between the formation of metallic nanowires by thermally assisted photoreduction process and surface atomic bonding conditions of TiO(2). Experimental results show that the (101) anatase films which yielded much more Ag nanowires than the (004) oriented films and exhibited more complex superficial atomic bonding, which could be demonstrated by the Gaussian bands in photoluminescence spectra. This might lead to higher carrier concentration and mobility, as well as longer life time for photo-exited electrons and consequently a greater photocatalytic activity for reducing metallic ions. The fact that the anatase (101) surface acted as the preferred nucleation sites for Ag nanowires was supported by high resolution transmission electron microscopy lattice image of a TiO(2) nanofiber where an Ag nanowire was grown.

On the Mechanism of Formation of Metal Nanowires by Self‐Assembly

Model nanowires (Pdn)x were constructed from isolated cuboctahedral clusters Pdn (n=38, 79, 140, 225), as depicted for n=225. Periodic density functional calculations show that the elasticity of the nanoparticles plays a key role in the self-assembly mechanism. The results are also relevant to sintering in the catalysts by supported metal nanoparticles.

On the Mechanism of Formation of Metal Nanowires by Self‐Assembly

Modellnanodrähte (Pdn)x wurden aus isolierten fcc-gepackten kuboktaedrischen Clustern Pdn (n=38, 79, 140, 225) konstruiert, wie für n=225 gezeigt ist. Periodische Dichtefunktionalrechnungen belegen, dass die Elastizität der Nanopartikel den Mechanismus der Selbstorganisation entscheidend prägt. Die Ergebnisse sind auch in Hinblick auf Sinterprozessen in der Katalyse an trägerfixierten Metallnanopartikeln relevant.

Formation of Metallic Nanowires by Utilizing Electromigration

A technique for forming metallic nanowires by utilizing electromigration, which is the phenomenon of atomic diffusion due to high current densities, is presented. These diffused atoms can be used for creating metallic nanowires. To specify the position at which a nanowire is formed, some specific conditions need to be established. These conditions are, first, to control the atomic diffusion so the accumulation of atoms produces the desired higher compressive stress; second, to design the structure to control the areas in which diffusion takes place; third, to adjust the thickness of the passivation layer deposited on the metal; and fourth, to form a small slot in the passivation layer through which the compressive stress is released by discharging the diffused atoms. It is shown that when these factors are satisfied, an Al nanowire can be successfully generated in a passivated metal track composed of an Al line buried in a W line.

A simple method for formation of metal nanowires on flexible polymer film

A simple method is devised for forming metal nanowires on flexible polymer film. The metal nanowires are prepared by electrodeposition into nanopores of anodized aluminum oxide (AAO) template on a silicon substrate. After the free-standing metal nanowires on the substrate are formed, the nanowires are directly transferred to a flexible polymer substrate. The tips of metal nanowires are physically nailed into the polymer substrate and then taken off from the silicon substrate. This simple method for transferring nanowires to soft polymer film is demonstrated to be applicable to large area, depending on the area of metal nanowires on the silicon substrate. The fabricated metal nanowires on polymer film can be used as high surface area catalysts for fuel cell applications.

Single-Walled Carbon Nanotubes as Templates for Nanowire Conducting Probes

We describe a method for the formation of metal nanowires at the apex of scanning probe microscopy (SPM) tips using single-walled carbon nanotubes (SWNT) as templates. The SWNT-SPM tips are sputter coated with metal, here AuPd or Au, resulting in the formation of continuous nanowires as small as 30 nm in diameter and up to a few micrometers in length. In principle, nanowires of any metal, or indeed any material, compatible with the sputter-coating process could be formed. AuPd nanowire tips are shown to be robust enough to allow conducting-mode imaging, over prolonged periods of time, with measured electrical resistance through the AuPd nanowires of less than 10 kΩ and currents of up to 200 μA. The simplicity of this method and its general applicability to the formation of nanowires of a variety of materials make it a promising technique for the formation of a range of nanoelectrodes as well as scanning probes.

Iron–cobalt and iron–cobalt–nickel nanowires deposited by means of cyclic voltammetry and pulse-reverse electroplating

Metal nanowires composed of Fe–Co and Fe–Co–Ni alloys were successfully prepared by means of cyclic voltammetry (CV) and pulse-reverse (PR) electroplating techniques from acidic metal chloride solutions. The anodic dissolution process in the CVs or in the reverse electroplating period was found to be the key factor influencing the formation of metal nanowires. The addition of nickel into the Fe–Co alloy was found to extend the diameter of these nanowires. The morphology and crystalline information of these alloy deposits prepared by CV and PR deposition techniques were obtained from the field-emission scanning electron microscopic (FE-SEM) photographs and X-ray diffraction (XRD) patterns, respectively.

Formation of metal nanowires on suspended single-walled carbon nanotubes

Suspended single-wall carbon nanotubes are used as substrates for deposition of various metals by evaporation. Deposition of many types of metals normally forms discrete particles on nanotubes due to a weak interaction between the metals and nanotubes. However, continuous nanowires of virtually any metal are obtained by using titanium, a metal with strong interaction with carbon, as a buffer layer on nanotubes. The metal nanowires can be ⩽10 nm wide with continuous length up to tens of microns.

Preparation of Noble Metal Nanowires Using Hexagonal Mesoporous Silica SBA-15

We demonstrate a novel preparation method for the formation of metallic nanowires from gold, platinum, and silver using mesoporous silica SBA-15 as a template. SBA-15 controls the size and the growth direction of the nanowires and also prevents bulk aggregation of the metal. Nanowires can be isolated from the silica framework by treatment with HF.