Direct electrodeposition of ionic liquid-based template-free Sn Co alloy nanowires as an anode for Li-ion batteries

Sn Co alloy nanowires were successfully electrodeposited from Sn Cl2-Co Cl2-1-ethyl-3-methylimidazolium chloride(EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for Sn Cl2(25)Co Cl2(25)EMIC at-0.55 V and showed a minimum diameter of about 50 nm and lengths of over 20 μm. The as-fabricated SnCo nanowires were about 70 nm in diameter and featured a Sn/Co weight ratio of 3.85:1, when used as an anode for a Li-ion battery, they presented respective specific capacities of 687 and 678 m Ah·g^(-1) after the first charge and discharge cycle and maintained capacities of about 654 m Ah·g^(-1) after 60 cycles and 539 m Ah·g^(-1) after 80 cycles at a current density of 300 m A·g^(-1). Both the nanowire structure and presence of elemental Co helped buffer large volume changes in the Sn anode during charging and discharging to a certain extent, thereby improving the cycling performance of the Sn anode.

Au core-PtAu alloy shell nanowires for formic acid electrolysis

Inefficient electrocatalysts and high-power consumption are two thorny problems for electrochemical hydrogen(H2)production from acidic water electrolysis.Herein we report the one-pot precise synthesis of ultrafine Au core-Pt Au alloy shell nanowires(Au@PtxAu UFNWs).Among them,Au@Pt_(0.077) Au UFNWs exhibit the best performance for formic acid oxidation reaction(FAOR)and hydrogen evolution reaction(HER),which only require applied potentials of 0.29 V and-22.6 m V to achieve a current density of 10 m A cm^(-2),respectively.The corresponding formic acid electrolyzer realizes the electrochemical H2 production at a voltage of only 0.51 V with 10 m A cm^(-2) current density.Density functional theory(DFT)calculations reveal that the Au-riched Pt Au alloy structure can facilitates the direct oxidation pathway of FAOR and consequently elevates the FAOR activity of Au@Pt_(0.077) Au UFNWs.This work provides meaningful insights into the electrochemical H_(2) production from both the construction of advanced bifunctional electrocatalysts and the replacement of OER.

Electrochemical Fabrication of Pd-Ag Alloy Nanowire Arrays in Anodic Alumina Oxide Template

The synthesis of Pd-Ag alloy nanowires in nanopores of porous anodic aluminum oxide （AAO） template by electrochemical deposition technique was reported. Pd-Ag alloy nanowires with 16%-25% Ag content are expected to serve as candidates of useful nanomaterials for the hydrogen sensors. Scanning electron microscopy （SEM） and energy dispersed X-ray spectroscopy （EDX） were employed to characterize the morphologies and compositions of the Pd-Ag nanowires. X-ray diffraction （XRD） was used to characterize the phase properties of the Pd-Ag nanowires. Pd-Ag alloy nanowire arrays with 17.28%-23.76% Ag content have been successfully fabricated by applying potentials ranging from -0.8 to -1.0 V （vs SCE）. The sizes of the alloy nanowires are in agreement with the diameter of AAO nanopores. The underpotential deposition of Ag＋ on Pd and Au plays an important role in producing an exceptionally high Ag content in the alloy. Alloy compositions can still be controlled by adjusting the ion concentration ratio of Pd^2＋ and Ag＋ and the electrodeposition processes. XRD shows that nanowires obtained are in the form of alloy of Pd and Ag.

Optoelectronic properties of single-crystalline GaInAsSb quaternary alloy nanowires

Bandgap engineering of semiconductor nanomaterials is critical for their applications in nanoelectronics, opto- electronics, and photonics. Here we report, for the first time, the growth of single-crystalline quaternary alloyed Ga0.75In0.25As0.49Sb0.51 nanowires via a chemical-vapor-deposition method. The synthesized nanowires have a uniform composition distribution along the growth direction, with a zinc-blende structure. In the photoluminescence investigation, these quaternary alloyed semiconductor nanowires show a strong band edge light emission at 1950 nm （0.636 eV）. Photodetectors based on these alloy nanowires show a strong light response in the near-infrared region （980 nm） with the external quantum efficiency of 2.0 × 104% and the responsivity of 158 A/W. These novel near-infrared photodetectors may find promising applications in integrated infrared photodetection, information communication, and processing.

Preparation and characterization of La-Co alloy nanowire arrays by electrodeposition in AAO template under nonaqueous system

La-Co alloy nanowires can be made in pulse reversal current(PRC) and direct current(DC) electrodepositions under nonaqueous system, with the porous anodic aluminum oxide(AAO) as template. This membrane is subject to the dual-oxidation (two-step) anodizing. Scanning electron microscope(SEM) examination shows that all of the nanowires have uniform diameter about 200 nm, and their diameters are determined by the pore diameter of applied AAO template. X-ray energy dispersion analysis indicates that the chemical composition of La and Co elements is very close to 1-2 in stoichiometry. X-ray diffraction pattern investigation demonstrates that La-Co nanowire is the face-centered cubic(FCC) LaCo13.

Pt-Te alloy nanowires towards formic acid electrooxidation reaction

The high-performance anodic electrocatalysts is pivotal for realizing the commercial application of the direct formic acid fuel cells.In this work,a simple polyethyleneimine-assisted galvanic replacement reaction is applied to synthesize the high-quality PtTe alloy nanowires(PtTe NW)by using Te NW as an efficient sacrificial template.The existence of Te atoms separates the continuous Pt atoms,triggering a direct reaction pathway of formic acid electrooxidation reaction(FAEOR)at PtTe NW.The one-dimensional architecture and highly active sites have enabled PtTe NW to reveal outstanding electrocatalytic activity towards FAEOR with the mass/specific activities of 1091.25 mA mg^(-1)/45.34 A m^(-2)at 0.643 V potential,which are 44.72/23.16 and 20.26/11.75 times bigger than those of the commercial Pt and Pd nanoparticles,respectively.Density functional theory calculations reveal that Te atoms optimize the electronic structure of Pt atoms,which decreases the adsorption capacity of CO intermediate and simultaneously improves the durability of PtTe NW towards FAEOR.This work provides the valuable insights into the synthesis and design of efficient Pt-based alloy FAEOR electrocatalysts.

Fe48Co52 Alloy Nanowire Arrays： Effects of Magnetic Field Annealing

The effects of magnetic field annealing on the properties of Fe48Co52 alloy nanowire arrays with various interwire distances （Di=30-60 nm） and wire diameters （Dw=22-46 nm） were investigated in detail. It was found that the array＇s best annealing temperature and crys- talline structure did not show any apparent dependence on the treatment of applying a 3 kOe magnetic field along the wire during the annealing process. For arrays with small Dw or with large Di, the treatment of magnetic field annealing also had no obvious influence on their magnetic performances. However, such a magnetic field annealing constrained the shift of the easy magnetization direction and improved the coercivity and the squareness obviously for arrays with large Dw or with small Di. The difference in the intensity of the effective anisotropic field within the arrays was believed to be responsible for this different variation of the array＇s magnetic properties after magnetic field annealing.

Density of Liquid Ni-Mo Alloys Measured by a Modified Sessile Drop Method

The density of liquid binary Ni-Mo alloys with molybdenum concentration from 0 to 20% (mass fraction) wasmeasured by a modified sessile drop method. It has been found that the density of the liquid Ni-Mo alloys decreaseswith increasing temperature, but increases with the increase of molybdenum concentration in the alloys. The molarvolume of liquid Ni-Mo binary alloys increases with the increase of temperature and molybdenum concentration. Thepartial molar volume of molybdenum in Ni-Mo binary alloy has been approximately calculated as [13.18-2.65×10^(-3)T+(-47.94+3.10×10^(-2)T)×10^(-2)X_(Mo)]×10^(-6)m^3·mol^(-1). The molar volume of Ni-Mo alloy determined inthe present work shows a negative deviation from the ideal linear mixing molar volume.

Ⅲ–Ⅴ ternary nanowires on Si substrates: growth, characterization and device applications

Over the past decades, the progress in the growth of materials which can be applied to cutting-edge technologies in the field of electronics, optoelectronics and energy harvesting has been remarkable. Among the various materials, group Ⅲ–Ⅴ semiconductors are of particular interest and have been widely investigated due to their excellent optical properties and high carrier mobility. However, the integration of Ⅲ–Ⅴ structures as light sources and numerous other optical components on Si,which is the foundation for most optoelectronic and electronic integrated circuits, has been hindered by the large lattice mismatch between these compounds. This mismatch results in substantial amounts of strain and degradation of the performance of the devices. Nanowires(NWs) are unique nanostructures that induce elastic strain relaxation, allowing for the monolithic integration of Ⅲ–Ⅴ semiconductors on the cheap and mature Si platform. A technique that ensures flexibility and freedom in the design of NW structures is the growth of ternary Ⅲ–Ⅴ NWs, which offer a tuneable frame of optical characteristics, merely by adjusting their nominal composition. In this review, we will focus on the recent progress in the growth of ternary Ⅲ–Ⅴ NWs on Si substrates. After analysing the growth mechanisms that are being employed and describing the effect of strain in the NW growth, we will thoroughly inspect the available literature and present the growth methods, characterization and optical measurements of each of the Ⅲ–Ⅴ ternary alloys that have been demonstrated. The different properties and special treatments required for each of these material platforms are also discussed. Moreover, we will present the results from the works on device fabrication, including lasers, solar cells, water splitting devices, photodetectors and FETs, where ternary Ⅲ–Ⅴ NWs were used as building blocks. Through the current paper, we exhibit the up-to-date state in this field of research and summarize the important accomplishments of the past few years.

Revealing the role of mo doping in promoting oxygen reduction reaction performance of Pt_(3)Co nanowires

Highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)are imperative for the commercialization application of proton exchange membrane fuel cells.By manipulating ligand effect,structural control,and strain effect,we report here the precise preparation of Mo-doped Pt_(3)Co alloy nanowires(Pt_(3)Co-Mo NWs)as the efficient catalyst towards ORR with high specific activity(0.596 mA cm^(−2))and mass activity(MA,0.84 A mg^(−1)_(Pt)),much higher than those of undoped counterparts.Besides activity,Pt_(3)Co-Mo NWs also demonstrate excellent structural stability and cyclic durability even after 50,000 cycles,again surpassing control samples without Mo dopants.According to the strain maps and DFT calculations,Mo dopants could modify the electronic structure of both Pt and Co to achieve not only optimized oxygen-intermediate binding energy on the interface but also increased the vacancy formation energy of Co,together leading to enhanced activity and durability.This work provides not only a facile methodology but also an in-depth investigation of the relationship between structure and properties to provide general guidance for future design and optimization.

SYNTHESIS OF Ni-Mo ALLOYS BY MECHANICAL ALLOYING

Ni_(100-x)Mo_x(x=20,30,38)alloys have been synthesized by mechanical alloying.The structure evolution of powders in mechanical alloying process has been monitored by X-ray diffraction,scanning electron microscopy and transmission electron microscopy analyses.The results show that the Ni_(62)Mo_(38)sample becomes partially amorphous after high energy ball milling,while the Ni_(80)Mo_(20)and Ni_(70)Mo_(30)become non-equilibrium nanocrystals.

Atomistic evaluation of tension–compression asymmetry in nanoscale body-centered-cubic AlCrFeCoNi high-entropy alloy

The tension and compression of face-centered-cubic high-entropy alloy(HEA) nanowires are significantly asymmetric, but the tension–compression asymmetry in nanoscale body-centered-cubic(BCC) HEAs is still unclear. In this study,the tension–compression asymmetry of the BCC Al Cr Fe Co Ni HEA nanowire is investigated using molecular dynamics simulations. The results show a significant asymmetry in both the yield and flow stresses, with BCC HEA nanowire stronger under compression than under tension. The strength asymmetry originates from the completely different deformation mechanisms in tension and compression. In compression, atomic amorphization dominates plastic deformation and contributes to the strengthening, while in tension, deformation twinning prevails and weakens the HEA nanowire.The tension–compression asymmetry exhibits a clear trend of increasing with the increasing nanowire cross-sectional edge length and decreasing temperature. In particular, the compressive strengths along the [001] and [111] crystallographic orientations are stronger than the tensile counterparts, while the [110] crystallographic orientation shows the exactly opposite trend. The dependences of tension–compression asymmetry on the cross-sectional edge length, crystallographic orientation,and temperature are explained in terms of the deformation behavior of HEA nanowire as well as its variations caused by the change in these influential factors. These findings may deepen our understanding of the tension–compression asymmetry of the BCC HEA nanowires.

模板法电化学共沉积Ni-Mo合金纳米线的研究

使用多孔阳极氧化铝模板, 电沉积制备了Ni-Mo合金纳米线. 用扫描电镜（SEM）和表面能谱（XPS）表征沉积物形貌和组成, 用伏安法研究了Ni-Mo合金纳米线的沉积条件及催化性能. 结果表明, Ni-Mo合金纳米线的直径在20～30 nm之间. Ni-Mo共沉积的伏安图上在-1.4 V（vs Ag/AgCl）左右出现一个扩散电流平台. 光电子能谱（XPS）表明, Ni-Mo合金纳米线的共沉积电位出现在-1.4 V以后, 大于这个电位钼以低价氧化物存在. Mo-Ni离子浓度比大于2时扩散电流平台消失. 柠檬酸盐浓度达到2～3倍镍盐浓度时, 扩散电流平台趋于稳定. 在较优条件下电沉积的Ni-Mo合金纳米线显示较高的析氢催化活性.

Modulating the alloying mode in the doping-induced synthesis of Au-Pd nanowires

Heterogeneous doping is one effective strategy for synthesizing metal alloy nanowires.Herein,the heterogeneous doping processes of Pd on the ultrathin Au nanowires were systematically modulated and investigated.Au-Pd alloy nanowires with various morphologies and lattice structures can be obtained by adjusting the morphology of the precursor Au nanowires and the kinetics of the heterogeneous doping processes.The effects of the rate of Pd reduction and the concentration of the ligand oleylamine(OAm)on the Pd deposition and alloying mode were articulated.Generally,as the Pd deposition rate decreases,the Pd deposition and alloying mode switches from the island-forming Stransky–Krastanov(SK)mode to the epitaxial Frank-van der Merwe(FM)mode,and eventually to an unconventional twisting alloying mode,where the interdiffusion of Pd and Au causes drastic rearrangement of the lattice structure and formation of helical structures.The kinetics-related variation of alloying mode could also be observed in the Au-Ag nanowires,demonstrating a general design principle for the synthesis of alloy nanostructures.In addition,the electrocatalytic performance of various Au-Pd nanowires was evaluated,and the alloy nanowire formed via the SK mode was found to be an excellent electrocatalyst for oxygen reduction and ethanol oxidation.

Ultrathin PdAu Nanowires with High Alloying Degree for the Direct Oxidation of Methane to C1 Oxygenates

The direct oxidation of methane(CH_(4))into high-valued C1 oxygenates production has garnered increased attention in effectively using vast CH_(4)and alleviating the global energy crisis.However,due to the high cleavage energy of C—H bond and low polarity of CH_(4)molecule,it is difficult to activate the first C—H bond.Furthermore,C1 oxygenates are readily inclined to be oxidized to CO_(2),because their weaker C—H bond comparing with CH_(4)molecule,resulting in poor selectivity.Herein,we designed ultrathin PdxAuy alloy NWs supported on ZSM-5(Z-5)to investigate the direct oxidation of CH_(4)to high value-added oxygenate under mild conditions.By precisely adjusting the molar ratio of Pd/Au and alloying degree,Pd9Au1NWs/Z-5 showed an excellent yield of 11.57 mmol·g^(–1)·h^(–1)and the outstanding selectivity of 95.1%for C1 oxygenates(CH_(3)OH,CH_(3)OOH and HCOOH).The in-situ spectroscopic and mechanism analysis proved that the enhanced catalytic performance of Pd_(9)Au_(1)NWs/Z-5 was ascribed to the stable one-dimensional nanostructure and the strong synergy effect with high alloying PdAu,which could increase the adsorption capacity of CH_(4)molecules on Pd atoms to promote the CH_(4)conversion.This work offers valuable insights into the design concept of high-efficient catalysts and the structure-activity relationship for the direct oxidation of CH_(4).

Ternary metal-metalloid-nonmetal alloy nanowires:a novel electrocatalyst for highly efficient ethanol oxidation electrocatalysis

We report rational design and syntheses of ternary noble metal-metalloid-nonmetal alloy nanowires(NWs)as a novel electrocatalyst for electrochemical ethanol oxidation reaction(EOR).This novel electrocatalyst is formed in an aqueous solution via anisotropic nucleation and growth of ternary PdBP alloy NWs along assembled cylinder template of Plurolic F127 on a nitrogen-functionalized graphene support(denoted as PdBP NWs@N-G).We find that uniformly alloying B and P intrinsically modulates the electronic states of Pd catalyst and also introduces new functions into the catalyst,while NW structure supported on the N-G exposes more electrocatalytic active sites and accelerates electron/mass transfers.Such add-in synergies of PdBP NWs@N-G kinetically facilitate the removal and/or further oxidation of CO-based poisoning intermediates,thus remarkably enhancing the electrocatalytic EOR performance.They exhibit a high mass activity of 4.15 A mgPd^-1 and superior cycling and chronoamperometric stability for electrocatalytic EOR,much better than previously reported monometallic Pd-based nanocatalysts.More interestingly,this design strategy can be easily extended to develop more sophisticated NWs catalysts with more compositions(for example quaternary PdCuBP NWs@N-G)that further tunes the electronic and bifuntional effects for various desired catalysis and electrocatalysis.

纳米晶NiTi形状记忆合金/Nb纳米线复合材料超弹应力的温度依赖性

NiTi形状记忆合金因其超弹性已经得到广泛应用,然而传统NiTi合金马氏体相变的超弹应力随温度的降低而快速减小(6~7 MPa/K),显著制约了其在宽温域中的应用。本文通过熔炼、锻造及拔丝获得纳米晶NiTi/Nb丝材,然后采用透射电子显微镜、差示扫描量热仪及拉伸试验机分别研究丝材的显微组织、相变行为及超弹性能。结果表明:纳米晶NiTi/Nb丝材中NiTi合金的平均晶粒尺寸为14 nm,丝材在降温和升温过程中分别发生热诱发B2→R相变和R→B2相变。在328~376 K温度范围内,纳米晶NiTi/Nb丝材应力诱发B2→B19′相变超弹应力的平均值为1002 MPa,超弹应力的温度依赖性为4.1 MPa/K。

Ultrathin ternary PtNiGa nanowires for enhanced oxygen reduction reaction

Achieving high activity and durability for the oxygen reduction reaction(ORR)with an ultra-low amount of platinum is significant to promote the widespread application of proton exchange membrane fuel cells(PEMFCs).Here we report a new ultrathin(∼1 nm)ternary PtNiGa alloy nanowires(PtNiGa NWs)electrocatalyst,in which the presence of gallium(Ga)enhances the oxidation resistance of platinum(Pt)and nickel(Ni)and suppresses the dissolution of Ni.The mass and specific activities of PtNiGa NWs are about 11.2 and 7.6 times higher than those of commercial Pt/C catalysts for ORR.Moreover,the mass activity of PtNiGa/C NWs nanocatalyst decreased only by 12.8%and largely retained its electrochemical surface area(ECSA)after 10,000 potential cycles,compared with 38%loss of ECSA for commercial Pt/C catalyst.Therefore,this work provides a general guideline for preparing ternary alloy electrocatalysts and enhancing the activity and stability of the cathode ORR reaction of PEMFCs.

Pt3Ag alloy wavy nanowires as highly effective electrocatalysts for ethanol oxidation reaction

Direct ethanol fuel cell(DEFC)has received tremendous research interests because of the more convenient storage and transportation of ethanol vs.compressed hydrogen.However,the electrocatalytic ethanol oxidation reaction typically requires precious metal catalysts and is plagued with relatively high over potential and low mass activity.Here we report the synthesis of Pt3Ag alloy wavy nanowires via a particle attachment mechanism in a facile solvothermal process.Transmission microscopy studies and elemental analyses show highly wavy nanowire structures with an average diameter of 4.6±1.0 nm and uniform Pt3Ag alloy formation.Electrocatalytic studies demonstrate that the resulting alloy nanowires can function as highly effective electrocatalysts for ethanol oxidation reactions(EOR)with ultrahigh specific activity of 28.0 mA/cm^2 and mass activity of 6.1 A/mg,far exceeding that of the commercial Pt/carbon samples(1.10 A/mg).The improved electrocatalytic activity may be partly attributed to partial electron transfer from Ag to Pt in the Pt3Ag alloy,which weakens CO binding and the CO poisoning effect.The one-dimensional nanowire morphology also contributes to favorable charge transport properties that are critical for extracting charge from catalytic active sites to external circuits.The chronoamperometry studies demonstrate considerably improved stability for long term operation compared with the commercial Pt/C samples,making the Pt3Ag wavy nanowires an attractive electrocatalyst for EOR.

Low-temperature fusion fabrication of Li-Cu alloy anode with in situ formed 3D framework of inert LiCu_x nanowires for excellent Li storage performance

The commercialization of rechargeable Li metal batteries is hindered by dendrite growth and volumetric variation. Herein, we report a Li-rich dual-phase Li-Cu alloy with built-in 3 D conductive skeleton to replace conventional planar Li anode. The Li-Cu alloy is simply prepared by fusion of Li and Cu metals at a relatively low-temperature of 500 °C, followed by a cooling process where phase-segregation leads to metallic Li phase distributed in the network of LiCu_x solid solution phase. Different from the common Li alloy, the electrochemical alloying reaction between Li and Cu metals is not observed. Therefore, the lithiophilic LiCu_x nanowires guides conformal plating of Li and the porous framework provides superior dimensional stability for the anode. This unique ferroconcrete-like structure of Li-Cu alloy enables dendrite-free Li plating for an expanded cycling lifetime. Constructing a new type of Li alloy with in situ formed electrochemically inactive framework is a promising and easily scaled-up strategy toward practical application of Li metal anodes.