Bimetallic Nanowires Research Articles

Cu-Ni Bimetallic Nanowires with Various Structures Originating from Ni Reduction Kinetics.

Bimetallic nanowires play important roles in the fields of electronics and mechanics. However, their structure types and morphological control methods are limited, especially for systems with low lattice mismatch. Herein, for a Cu-Ni bimetallic system with lattice mismatch ratio less than 2.5%, a novel preparation approach of various Cu-Ni nanowires dominated by Ni(II) reduction kinetics is presented. With the increase of Ni(II) reduction rate, the core-shell Cu@Ni straight nanowires, the asymmetric Cu-Ni nanocurves, and asymmetric Cu-Ni nanocoils can be prepared, respectively. The formation of Cu-Ni nanowires with different structures can be divided into the growth of Cu nanowires and the deposition of Ni. The regulatory effects were revealed by establishing a kinetic model for Ni(II) reduction. For the novel Cu-Ni asymmetrically distributed nanocurves and nanocoils, the formation mechanism was proposed by considering the Cu nanowire bending due to the rearrangement of surface ligand and bending-induced symmetry breaking of Ni(II) reduction.

MOF˗derived sulfur˗doped iron˗nickel bimetallic phosphide nanowires: A bifunctional electrode for hydrogen and oxygen evolution reactions

Creating affordable and efficient bifunctional electrocatalysts is crucial for producing clean hydrogen energy through complete water splitting. We describe a way to make S-doped carbon-encapsulated iron-nickel phosphide nanowires (S/FeNiP@C) using metal-organic frameworks. These nanowires exhibit exceptional electrocatalytic performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions. The optimized S/FeNiP@C nanowires exhibit low overpotentials of 53 mV and 270 mV at a current density of 10 mA cm˗2 for HER and OER, respectively. They also have tiny Tafel slopes of 159 mV dec˗1 for HER and 50 mV dec˗1 for OER. The water electrolyzer uses S/FeNiP@C nanowires as both the anode and the cathode to reach a current density of 10 mA cm˗2 at a voltage of 1.61 V and stays very stable for 48 h. The great catalytic performance is mostly due to the simple carbon framework and low sulfur integration. This creates a large surface area for the catalyst and electrolyte to interact, allowing charge and mass to move quickly, and a lot of active sites that last a long time.

An energy‐based finite‐strain model for 3D heterostructured materials and its validation by curvature analysis

AbstractThis paper presents a comprehensive study of the intrinsic strain response of 3D heterostructures arising from lattice mismatch. Combining materials with different lattice constants induces strain, leading to the bending of these heterostructures. We propose a model for nonlinear elastic heterostructures such as bimetallic beams or nanowires that takes into account local prestrain within each distinct material region. The resulting system of partial differential equations (PDEs) in Lagrangian coordinates incorporates a nonlinear strain and a linear stress‐strain relationship governed by Hooke's law. To validate our model, we apply it to bimetallic beams and hexagonal hetero‐nanowires and perform numerical simulations using finite element methods (FEM). Our simulations examine how these structures undergo bending under varying material compositions and cross‐sectional geometries. In order to assess the fidelity of the model and the accuracy of simulations, we compare the calculated curvature with analytically derived formulations. We derive these analytical expressions through an energy‐based approach as well as a kinetic framework, adeptly accounting for the lattice constant mismatch present at each compound material of the heterostructures. The outcomes of our study yield valuable insights into the behavior of strained bent heterostructures. This is particularly significant as the strain has the potential to influence the electronic band structure, piezoelectricity, and the dynamics of charge carriers.

Tuning the Structure of Pd@Ni-Co Nanowires and Their Electrochemical Properties.

One-dimensional transition metal materials are promising supports for precious metals used in energy production processes. Due to their electrochemical properties, 3d-group metals (such as Ni, Co, and Fe) can actively interact with catalysts by a strong metal-support interaction. This study shows that changing the Ni:Co ratio makes it possible to modulate the structure of the catalyst supports, which, in turn, provides a tool for designing their electrical and electrochemical properties. For example, Ni1-Co9 shows the highest electrical conductivity (5.8-10-4 S/cm) among all of the materials examined. On the contrary, the Pd@Ni7-Co3 system presents the highest mass activity (>2000 mA mg-1) at 0.7 V, exceeding by several times that of commercial Pt/C (>300 mA mg-1) at the same potential. Our study opens the gateway for applications of bimetallic transition metal nanowires in catalytic conversion and energy production processes.

Cation substitution for enhanced pseudocapacitance performance of spinel bimetallic sulfides porous nanowires for increased energy storage

Cation substitution for enhanced pseudocapacitance performance of spinel bimetallic sulfides porous nanowires for increased energy storage

Co─Mn Bimetallic Nanowires by Interfacial Modulation with/without Vacancy Filling as Active and Durable Electrocatalysts for Water Splitting.

Active and stable nonnoble electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required for water splitting by sustainable electricity. Here, Mn bonded with O and P is incorporated to modulate Co3S4 and Co2P respectively to enhance the catalytic activity and extend the catalyst lifetime. Mn3O4 adjusts the electronic structure of Co3S4 and Co atom fills the oxygen vacancy in Mn3O4. The interfacial interaction endows Co3S4/Mn3O4 to a lower reaction barrier due to ideal binding energies for OER intermediates. Structure stability of active sites and enhanced Co─S bonds by Operando Raman spectroscopy and theoretical calculations reduce the dissolution of Co3S4/Mn3O4, resulting in a lifetime of 500h at 50mAcm-2 for OER. The modulation of Co2P by MnP weakens the interaction between Co sites and adsorbed H*, achieving a high activity under a large current for HER. The assembled electrolyzer affords 50mAcm-2 at 1.58V and exhibits a lifetime of 350h at 50mAcm-2. The calculations disclose the electron interaction for the activity and stability, as well as the enhanced conductivity. The findings develop new avenues toward promoting catalytic activity and stability, making Co─Mn bimetallic nanowires efficient electrocatalysts for nonnoble water electrolyzers.

Morphology dependent EMI shielding performance of Ag-Ni core-shell nanowires

The proposed work reports a facile chemical reduction method for synthesizing the hierarchical silver-nickel core-shell nanowire structures with controllable morphologies by varying the Ag concentration. The growth of Ni shells around the Ag core to make thorny and smooth Ag-Ni core-shell nanowires is studied for addressing electromagnetic interference (EMI). The synthesized Ag-Ni nanowires show better EMI shielding effectiveness (SE) than Ni nanowires with much-improved absorption loss (SEA). Due to high electrical conductivity (8630 S cm−1), magnetic permeability (44.1 emu/g), and heterojunction core-shell interfaces, the bimetallic nanowires flakes exhibit exceptional average EMI SE of 90.5 dB in the X-band frequency range (8–12 GHz) with a thickness of 0.11 mm, taking specific EMI SE to 822.72 dB/mm. In addition, the EMI shielding performance of the smooth Ag-Ni nanowires showed a 45% enhancement in SEA with marginal change in reflection loss (SER) compared to the thorny ones, indicating high absorption of EM waves. The unique core-shell nanowires with high aspect ratio with tunable physical properties can be ideal candidates for futuristic applications in microwave absorption and electromagnetic interference shielding.

Catalytic and SERS Properties of Gold and Silver Bimetallic Nanowires

Catalytic and SERS Properties of Gold and Silver Bimetallic Nanowires

Iron-doped nickel–cobalt bimetallic phosphide nanowire hybrids for solid-state supercapacitors with excellent electromagnetic interference shielding

The development of flexible and wearable electronics subjects to the limited energy density and accompanying electromagnetic pollution. With a high theoretical specific capacity, nickel–cobalt bimetallic phosphide (NiCoP) is considered to be potential cathode materials for supercapacitor. However, the pristine NiCoP fails to display excellent electrochemical performance due to its inferior rate performance and cycling stability. Herein, we design Fe doped NiCoP nanowire arrays on carbon cloth (Fe-NiCoP/CC) as the cathode for supercapacitors. The introduced Fe doping enable to increase in the electronic conductivity and enhance the adsorption of OH−, supported by the density functional theory (DFT) analysis. As a result, Fe-NiCoP/CC electrode displays a high areal capacity of 3.18 F cm−2 at 1 mA cm−2, superb rate capability (86.3 % capacity retention at 20 mA cm−2) and outstanding structure stability, superior to the NiCo/CC, FeNiCo/CC, and NiCoP/CC counterparts. Moreover, the assembled Fe-NiCoP/CC||VN/CNT/CC hybrid supercapacitor (HSC) device delivers a high energy density of 176.9 μWh cm−2 at the power density of 750 μW cm−2. More importantly, the designed electrodes and assembled HSC device exhibits excellent electromagnetic interference (EMI) shielding performance. This design concept presented in this paper can provide insights into the construction of multifunctional and high-performance flexible electronic devices.

Au/Pt Bimetallic Nanowires with Stepped Pt Sites for Enhanced C-C Cleavage in C2+ Alcohol Electro-oxidation Reactions.

Efficient C-C bond cleavage and oxidation of alcohols to CO2 is the key to developing highly efficient alcohol fuel cells for renewable energy applications. In this work, we report the synthesis of core/shell Au/Pt nanowires (NWs) with stepped Pt clusters deposited along the ultrathin (2.3 nm) stepped Au NWs as an active catalyst to effectively oxidize alcohols to CO2. The catalytic oxidation reaction is dependent on the Au/Pt ratios, and the Au1.0/Pt0.2 NWs have the largest percentage (∼75%) of stepped Au/Pt sites and show the highest activity for ethanol electro-oxidation, reaching an unprecedented 196.9 A/mgPt (32.5 A/mgPt+Au). This NW catalyst is also active in catalyzing the oxidation of other primary alcohols, such as methanol, n-propanol, and ethylene glycol. In situ X-ray absorption spectroscopy and infrared spectroscopy are used to characterize the catalyst structure and to identify key reaction intermediates, providing concrete evidence that the synergy between the low-coordinated Pt sites and the stepped Au NWs is essential to catalyze the alcohol oxidation reaction, which is further supported by DFT calculations that the C-C bond cleavage is indeed enhanced on the undercoordinated Pt-Au surface. Our study provides important evidence that a core/shell structure with stepped core/shell sites is essential to enhance electrochemical oxidation of alcohols and will also be central to understanding electro-oxidation reactions and to the future development of highly efficient direct alcohol fuel cells for renewable energy applications.

Dual Lewis Acid-Base Sites Regulate Silver-Copper Bimetallic Oxide Nanowires for Highly Selective Photoreduction of Carbon Dioxide to Methane.

Highly selective photoreduction of CO2 to valuable hydrocarbons is of great importance to achieving a carbon-neutral society. Precisely manipulating the formation of the Metal1 ⋅⋅⋅C=O⋅⋅⋅Metal2 (M1 ⋅⋅⋅C=O⋅⋅⋅M2 ) intermediate on the photocatalyst interface is the most critical step for regulating selectivity, while still a significant challenge. Herein, inspired by the polar electronic structure feature of CO2 molecule, we propose a strategy whereby the Lewis acid-base dual sites confined in a bimetallic catalyst surface are conducive to forming a M1 ⋅⋅⋅C=O⋅⋅⋅M2 intermediate precisely, which can promote selectivity to hydrocarbon formation. Employing the Ag2 Cu2 O3 nanowires with abundant Cu⋅⋅⋅Ag Lewis acid-base dual sites on the preferred exposed {110} surface as a model catalyst, 100 % selectivity toward photoreduction of CO2 into CH4 has been achieved. Subsequent surface-quenching experiments and density functional theory (DFT) calculations verify that the Cu⋅⋅⋅Ag Lewis acid-base dual sites do play a vital role in regulating the M1 ⋅⋅⋅C=O⋅⋅⋅M2 intermediate formation that is considered to be prone to convert CO2 into hydrocarbons. This study reports a highly selective CO2 photocatalyst, which was designed on the basis of a newly proposed theory for precise regulation of reaction intermediates. Our findings will stimulate further research on dual-site catalyst design for CO2 reduction to hydrocarbons.

Dual Lewis Acid‐Base Sites Regulate Silver‐Copper Bimetallic Oxide Nanowires for Highly Selective Photoreduction of Carbon Dioxide to Methane

AbstractHighly selective photoreduction of CO2 to valuable hydrocarbons is of great importance to achieving a carbon‐neutral society. Precisely manipulating the formation of the Metal1⋅⋅⋅C=O⋅⋅⋅Metal2 (M1⋅⋅⋅C=O⋅⋅⋅M2) intermediate on the photocatalyst interface is the most critical step for regulating selectivity, while still a significant challenge. Herein, inspired by the polar electronic structure feature of CO2 molecule, we propose a strategy whereby the Lewis acid‐base dual sites confined in a bimetallic catalyst surface are conducive to forming a M1⋅⋅⋅C=O⋅⋅⋅M2 intermediate precisely, which can promote selectivity to hydrocarbon formation. Employing the Ag2Cu2O3 nanowires with abundant Cu⋅⋅⋅Ag Lewis acid‐base dual sites on the preferred exposed {110} surface as a model catalyst, 100 % selectivity toward photoreduction of CO2 into CH4 has been achieved. Subsequent surface‐quenching experiments and density functional theory (DFT) calculations verify that the Cu⋅⋅⋅Ag Lewis acid‐base dual sites do play a vital role in regulating the M1⋅⋅⋅C=O⋅⋅⋅M2 intermediate formation that is considered to be prone to convert CO2 into hydrocarbons. This study reports a highly selective CO2 photocatalyst, which was designed on the basis of a newly proposed theory for precise regulation of reaction intermediates. Our findings will stimulate further research on dual‐site catalyst design for CO2 reduction to hydrocarbons.

PdM (M = Fe, Co, Ni) bimetallic nanowires enhances oxygen reduction catalysis in acid medium

PdM (M = Fe, Co, Ni) bimetallic nanowires enhances oxygen reduction catalysis in acid medium

Bifunctional bimetallic oxide nanowires for high-efficiency electrosynthesis of 2,5-furandicarboxylic acid and ammonia

It is an appealing avenue for electrosyntheis of high-valued chemicals at both anode and cathode by coupling 5-hydroxymethylfurfural (HMF) oxidation and nitrate reduction reactions simultaneously, while the development such bifunctional electrocatalysts is still in its infancy with dissatisfied selectivity and low yield rate. Here, we first report that Zn-doped Co3O4 nanowires array can be served as an efficient and robust dual-functional catalyst for HMF oxidation and nitrate reduction at ambient conditions. Specifically, the catalyst shows a faradaic efficiency of 91 % and a yield rate of 241.2 μmol h−1 cm−2 for 2,5-furandicarboxylic acid formation together with a high conversion of nearly 100 % at a potential of 1.40 V. It also displays good cycling stability. Besides, the catalyst is capable of catalyzing the reduction of nitrate to NH3, giving a maximal faradaic efficiency of 92 % and a peak NH3 yield rate of 4.65 mg h−1 cm−2 at a potential of –0.70 V. These results surpass those obtained using pristine Co3O4 and are comparable to those of state-of-the-art electrocatalysts. Moreover, the catalyst is further employed as the cathode catalyst to assemble a Zn–nitrate battery, giving a peak power density of 5.24 mW cm−2 and a high yield rate of 0.72 mg h−1 cm−2. Theoretical simulations further reveal that Zn-doping favors the adsorption and dissociation of nitrate and HMF species and reduces the energy barrier as well. Our work demonstrates the potential interest of Co3O4-based materials for the highly selective production of valuable feedstocks via ambient electrolysis.

Electrospun bimetallic PtNi nanowires as electrocatalyst for oxygen reduction reaction in PEMFCs

The present investigation attempts to prepare bimetallic PtNi nanowires by electrospinning method and explore their possible utilization in the cathode catalyst layer for a proton exchange membrane fuel cell as electrocatalysts for oxygen reduction reaction. The influences of manipulation parameters in the electrospinning procedure on the resultant nanowire morphology are examined, including the PVP concentration, the strength of electric field, and the atomic ratio of Pt:Ni. The tests of cyclic voltammetry, linear sweep voltammetry, and accelerated degradation are performed to estimate the electrochemically active surface area (ECSA), oxygen reduction reaction (ORR) activity, and electrochemical performance durability. A membrane electrode assembly (MEA) is further built to test the single cell performance in which the cathode catalyst layer is made of the prepared alloy nanowires. The results reveal that the bimetallic PtNi nanowires can be produced successfully by the electrospinning technique, and the minimum mean diameter of the nanowires could reach 23 nm under the condition of 8 wt% PVP and 1 wt% metal precursors in the polymer solution with applied voltage 14 kV, collection distance 10 cm, and atomic ratio 2:1 of Pt:Ni. Comparing with the conventional Pt/C catalyst, the prepared Pt2Ni1 nanowires present less ECSA but better ORR activity and superior durability in both ECSA and ORR performance. The preliminary test of single cell performance using the Pt2Ni1 nanowires indicates that the electrospun PtNi alloy nanowires are a promising electrocatalyst for ORR, while the optimal structure and compositions in the cathode catalyst layer need to be further resolved.

Nucleation and Growth Mechanisms of Bimetallic Sm-Co Nanowires and Nanotubes

Nucleation and growth mechanisms of bimetallic Sm-Co magnetic nanowires and nanotubes, electrocrystallizing into hard anodic alumina templates, are described. Nanowires are produced at two overpotentials −0.9 V and −3 V, into templates with pore diameters of 20 nm and 40 nm; for larger pores, 200 nm in diameter, nanowires result at −0,9 V while at −3 V nanotubes form. The electrodeposition process mainly develops under diffusional control, with the current monotonically decreasing with time. Experimental current/time curves are described by suitable models adapted to bimetallic phases, considering successive stages in the pore filling process. In membranes with small pore diameter, a linear diffusion zone ahead the growing nanowire surface allows to apply a modified Cottrell equation. Models based on recessed microelectrodes behaviour are proposed, considering the overlap of diffusion zones at the porous mouth. For large pore diameter (>100 nm), current transitory is described by a 1D model for nanowires grown at −0.9 V, while a new expression is derived for nanotubes developing at −3 V, where the hydrogen evolution provides an important contribution to the mechanism. The mechanisms proposed are consistent with nanowires´ and nanotubes´ morphology details observed in SEM images.

Frequency shifts of surface plasmon resonances in calculating the absorption coefficient of a composite based on bimetallic 1D-systems

In this paper analyzes the electromagnetic radiation absorption by a composite based on bimetallic nanowires. Using the Drude-Lorentz theory it was obtained the relationship for the polarizability frequency dependences, as well as real and imaginary parts of the dielectric function of layered 1D-systems was obtained. It is shown that the structure in the form of a metal core covered with a layer of another metal leads to splitting and the appearance of two maxima in the frequency dependence of the absorption coefficient. The magnitude and position of the maxima are determined by the composition of bimetallic nanowires and the volume content of metals. The influence of the dimensionality of the systems has been established by comparing the frequency dependences of the composite absorption coefficient based on bimetallic nanowires and nanoparticles. Calculations were performed for Ag@Au and Au@Ag nanowires immersed in Teflon.

Surface strain-regulated twin-rich Au-Pt bimetallic nanowire for highly efficient alcohol oxidation reaction

Metallic nanocrystals with abundant metastable twin boundaries have demonstrated great potential in prompting the improvement of electrocatalytic reactivity, such as alcohol oxidation reaction (AOR) in fuel cell applications. However, modulating the lattice and electronic structures of such twin-rich nanocatalysts to optimize the AOR activity remains a huge challenge. Herein, jagged Au-Pt bimetallic nanowires with abundant twin boundaries along the 〈111〉 direction have been constructed via a seeded synthesis method. Importantly, the lattice strain and electronic structures of Pt in the twin-rich nanowires have been feasibly tuned, resulting in the regulation of AOR performances. Impressively, the jagged AuPt3 nanowires, with an atomic ratio of ∼1:3, exhibit the highest mass activity toward ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR), outperforming AuPt9, AuPt, Pt nanowires and commercial Pt/C catalysts. The structure–activity correlation for the AOR follows a volcano-shaped curve with the increase of Pt ratios. Theoretical results suggest the weakened bonding of Pt-CO and strengthened Pt-OH on the AuPt3 (111)-twin site. Our work develops a simple yet effective method to synthesize twin-rich bimetallic nanostructures with controlled lattice strain and illustrates their structure-dependent properties, opening the way to develop high-performance electrocatalysts for promising applications.

Atom-stepped surface-regulated Pd nanowires for boosting alcohol oxidation activity

A highly active surface can endow the electrocatalysts with extraordinary catalytic performances. However, it remains challenging to tailor the atomic packing characteristics and thus the physical and chemical characteristics of the electrocatalysts. Herein, penta-twinned Pd nanowires (NWs) with abundant high-energy atomic steps (i.e., stepped Pd) are synthesized by seeded synthesis on Pd NWs enclosed by (100) facets. Benefiting from the catalytically active atomic steps, such as [n(100) × m(111)] on the surface, the resultant stepped Pd NWs can work as an effective electrocatalyst for the ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR), which are essential anode reactions in direct alcohol fuel cells (DAFCs). Compared with commercial Pd/C, the Pd nanowires bound by (100) facets and atomic steps both display enhanced catalytic activity and stability towards the EOR and EGOR. Importantly, the mass activities of the stepped Pd NWs toward the EOR and EGOR are 6.38 and 7.98 A mgPd−1, which are 3.1 and 2.6 times those of Pd NWs enclosed by (100) facets, respectively. Besides, our synthetic strategy also enables the formation of bimetallic Pd-Cu nanowires with abundant atomic steps. This work not only demonstrates a simple yet effective strategy to obtain mono- or bi-metallic nanowires with abundant atomic steps, but also highlights the significant role of atomic steps for boosting the activity of electrocatalysts.

Structural evolution and mechanical stabilities of head-to-side nanowelding of Cu-Ag bimetallic nanowires via atomistic simulations.

Nanowelding, self-healing and mechanical stabilities of conductive networks of Cu-Ag core-shell nanowires are of vital importance for their extensive applications. In this study, atomistic simulations are used to reveal the head-to-side cold welding behavior, ranging from the welding mechanism, mechanical stabilities of the obtained junction and effects of various conditions. The results show that head-to-side cold welding of Cu-Ag bimetallic nanowires can be excellently completed via atomic interaction and diffusion of atoms. Initial deformation in the junction induced in the welding process and welding temperature are proven to exert a significant influence on the mechanical stabilities of the obtained junction. Three different deformation mechanisms are proposed due to various motivations of dislocations. During the uniaxial tensile test of the junction, the plastic deformation map of initial deformation and welding temperature are expounded in detail. It is revealed that for all the involved welding temperatures explored in our study, the highest tensile strength always belongs to the T-junction with no initial deformation. Otherwise, the intersection will become a serious obstacle to a further process of plastic deformation and lead to abnormally larger elongation and lower strength. These findings are expected to provide an in-depth understanding of the deformation mechanism of bimetallic nanowires and provide valuable theoretical guidance for engineering applications.