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Highly efficient, cost-effective and durable electrocatalysts for water splitting are crucial for energy conversion and storage. Transition-metal phosphides have been proven to be efficient catalysts for water splitting. In this paper, surface phosphation of 3D NiCo₂O₄ nanowires grown on Ni foam (P-NiCo₂O₄/NF) have been prepared to investigate the effect of surface phosphating on catalyst activity. XRD and XPS results demonstrate that P element has been decorated on the surface of the NiCo₂O₄ nanowires. The electrochemical results prove that P-NiCo₂O₄/NF shows better electrochemical performance than pure NiCo₂O₄/NF as an electrode for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of water splitting. It achieves a current density of 10mA cm² at an overpotential of 279mV and 164mV for OER and HER in 1.0M KOH electrolyte, respectively. In addition, the P-NiCo₂O₄/NF$\parallel$P-NiCo₂O₄/NF electrode is constructed by employing P-NiCo₂O₄/NF as both the anode and cathode, it only requires a low 1.68V of cell voltage to reach the current density of 10mA cm${}^{-2}$. Notably, P-NiCo₂O₄/NF$\parallel$P-NiCo₂O₄/NF also exhibits excellent stability for over 30h-long. These results indicate that surface phosphation is an effective approach to improve the electrochemical performance of NiCo₂O₄/NF electrode materials.

The ferrimagnetic mixed spin-1/2 and spin-1 cubic Ising nanowire is studied in the framework of the Monte Carlo simulation. The competition between the bilinear interaction and crystal field of spin-1 atoms as well as the nanowire size effect is highlighted. The corresponding phase diagram is discussed showing compensation points and critical second-order phase transitions. The effect of an external magnetic field and the hysteresis loops behavior are also carried out. Finally, we compare our results with other works in the literature.

The quantum vacuum fluctuation i.e., Casimir attraction can induce mechanical instability in ultra-small devices. Previous researchers have focused on investigating the instability in structures with planar or rectangular cross-section. However, to the best knowledge of the authors, no attention has been paid for modeling this phenomenon in the structures made of nanowires with cylindrical geometry. In this regard, present work is dedicated to simulate the Casimir force-induced instability of freestanding nanoactuator and nanotweezers made of conductive nanowires with circular cross-section. To compute the quantum vacuum fluctuations, two approaches i.e., the proximity force approximation (for small separations) and scattering theory approximation (for large separations), are considered. The Euler-beam model is employed, in conjunction with the size-dependent modified couple stress continuum theory, to derive governing equations of the nanostructures. The governing nonlinear equations are solved via three different approaches, i.e., using lumped parameter model, modified variation iteration method (MVIM) and numerical solution. The deflection of the nanowire from zero to the final stable position is simulated as the Casimir force is increased from zero to its critical value. The detachment length and minimum gap, which prevent the instability, are computed for both nanosystems.

In this paper, buckling of a nanowire column subjected to self-weight and tip load is investigated. One end of the nanowire is free, while the other end is attached to a rotational spring support. Considering the equilibrium equations together with the Euler–Bernoulli beam theory, the governing differential equation describing the behavior of the column can be obtained. Effect of surface stress is also incorporated into the formulations in terms of transverse distributed loading. The differential equation has been solved analytically and the general solution can be presented in the terms of Bessel function of the first kind. Applying the boundary conditions, the characteristic equations influenced by surface stress and stiffness of the rotational spring at the support can be expressed and then the critical load can be determined using the Newton–Raphson iterative scheme. From the results, they reveal that the positive surface stress could strengthen the nanowire against the buckling. Fixity at the base is also influenced to the critical load where the increase of the stiffness of the spring results in the increase of critical load as well.

Nanowires (NWs) play a crucial role across a wide range of disciplines such as nanoelectromechanical systems, nanoelectronics and energy applications. As NWs continue to reduce in dimensions, their mechanical properties are increasingly affected by surface attributes. This study conducts a comprehensive examination of nanomechanical models utilized for interpreting large deformations in the bending response of silicon NWs. Specifically, the Heidelberg, Hudson, Zhan, SimpZP and ExtZP nanomechanical models are explored regarding their capability to predict the elastic properties of silicon NWs with varying critical dimensions and crystal orientations. Molecular dynamics simulations are employed to model silicon NWs with unreconstructed surface states. The calculation of intrinsic stresses and the methodology for quantifying surface properties, including surface stresses and surface elasticity constants, are carried out using atomistic modeling. The findings reveal significant disparities of up to 100 GPa among nanomechanical models in interpreting a singular force-deflection response obtained for a silicon NW. Inadequate consideration of surface and intrinsic effects in nanomechanical modeling of NWs leads to substantial variability in their mechanical properties. This investigation yields valuable insights into the surface characteristics of silicon NWs, thereby enhancing our understanding of the essential role played by nanomechanical models in the intricate interpretation of mechanical properties at the nanoscale.

Supercapacitors are highly attractive energy storage device of the modern world. It can supply peak pulse power and high cycle stability to an electrochemical system. Here, we have explored the formation of copper ferrite (CuFe₂O₄) nanowire formation in presence of carbon nanotubes (CNTs) and enhancement of electrochemical performance on fluorination. All the electrochemical characterization was studied by three electrode system. Fourier transform infrared spectroscopy (FT-IR) was performed to test the functionality present in the composite. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) study had been carried out to observe the change in surface and bulk morphology of the composites which showed that CuFe₂O₄ nanowires are attached with CNTs or fluorinated CNTs. This fluorinated nanocomposite shows the highest specific capacitance of 267 F/g.

Based on the molecular dynamics (MD) method, the single-crystalline copper nanowire with different surface defects is investigated through tension simulation. For comparison, the MD tension simulations of perfect nanowire are first carried out under different temperatures, strain rates, and sizes. It has concluded that the surface–volume ratio significantly affects the mechanical properties of nanowire. The surface defects on nanowires are then systematically studied in considering different defect orientation and distribution. It is found that the Young's modulus is the insensitive of surface defects. However, the yield strength and yield point show a significant decrease due to the different defects. Different defects are observed to serve as a dislocation source.

La-doped and Cu-doped ZnO nanowires have been prepared to compare the substitution effect on the microstructural and magnetic properties. The XRD patterns of both compositions with single diffraction peak (002) show the same wurtzite hexagonal structure. The growth rate of the ZnO nanowires were enhanced by Cu doping, which were different from the suppression of growth rate by La doping. Room temperature ferromagnetism is observed for all ZnO, Cu-doped ZnO and La-doped ZnO nanowires. The saturation magnetizations are 0.102, 0.232 and 0.04 emu/g for ZnO, Cu-doped ZnO and La-doped ZnO nanowires, respectively. The results showed that the ferromagnetism is restrained by Cu doping, but enhanced by the La doping.

In this paper, the effect of incident light intensity, relaxation time, core radius and shell thickness on linear, nonlinear, total optical absorption coefficients and refractive index changes in $GaN/A{l}_{0.1}G{a}_{0.9}N$ core–shell nanowire are theoretically investigated. The presented nanostructure is a cylindrical quantum wire including a shell around the cylinder core. By numerical solution of Schrödinger equation in the cylindrical coordinates with effective mass approximation, the optical absorption coefficients are calculated. The results show that the magnitude of optical absorption coefficients can be adjusted by varying the relaxation time. The positions of resonant peaks of optical absorption coefficients are redshifted by increase of core radius due to decrease of the energy difference between two energy levels. With increase of shell thickness initially, the resonance wavelength of absorption coefficient increases (redshift) and magnitude of absorption coefficient decreases. Then with more increases of the shell thickness, redshifting of resonance wavelength is stopped and magnitude of absorption coefficient is increased. There is a significant increase in the refractive index change with increase of relaxation time.

An optical AND logic device based on chiral surface plasmon polaritons (SPPs) is theoretically proposed. The AND logic device is made up of five Y-shape nanowires with two input ports and one output port. Chiral SPPs excited at the end of input ports propagate along the nanowire. By adding two gold blocks on one side of the AND logic device, the chirality of the device is amplified. By modifying parameters, we find suitable parameters to design the structure with a large chirality at the working wavelength. By setting the threshold, we achieve the AND logic devices. Our structure may provide a significant component in signal transmission and processing devices.

The stability and electronic structure of a single monatomic Al wire has been studied using the ab initio pseudopotential method. The Al wire undergoes two structural rearrangements under compression, i.e., zigzag configurations at angles of 140° and 60°. The evolution of electronic structures of the Al chain as a function of structural phase transition has been investigated. The relationship between electronic structure and geometric stability is also discussed. The 2p bands in the Al nanowire are shown to play a critical role in its stability. The effects of density functionals (GGA and LDA) on cohesive energy and bond length of Al nanostructures (dimer, chains, and monolayers) are also examined. The link between low dimensional 0D structure (dimer) to high dimensional 3D bulk Al is estimated. An example of optimized tip-suspended finite atomic chain is presented to bridge the gap between hypothetical infinite chains and experimental finite chains.

TiO₂ aerogel–10 mol% TiO₂ nanowire composite was prepared by a sol–gel technique with the addition of TiO₂ nanowires to TiO₂ sol, followed by supercritical drying in CO₂. TiO₂ nanowires (anatase with minor rutile phases) as dispersoid were prepared by a hydrothermal process followed by calcination in air at 600°C. The TiO₂ nanowires were dispersed in a 2-propanol/H₂O/HNO₃ solution, and the mixture was added drop by drop to a tetrabutyl orthotitanate [i.e. Ti (IV) n-butoxide] solution in 2-propanol. After gelation, the TiO₂ alcogel–TiO₂ nanowire composite was dried in supercritical CO₂ to obtain the final, TiO₂ aerogel–TiO₂ nanowire composite. TEM analysis revealed that a unique "nanowire network" structure was formed within the mesoporous aerogel matrix. The aerogel–TiO₂ nanowire composite had a relatively large surface area 427 m²/g, with mesopores ~ 16 nm in diameter and a pore of volume of 1.63 cm³/g.

ZrNi metallic glass alloy nanowires (NWs) under torsion are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effect of cooling rate on the deformation mechanism and mechanical properties of ZrNi NWs is evaluated in terms of shear strain, torque, potential energy and radial distribution function. Simulation results show that for slower cooling rates, the NWs have larger packing density, whereas for faster cooling rates, the packing density of atoms decreases. The amount of deformation increases with increasing torsional angle before it reaches a critical torsional angle (${\theta }_c)$. The torque required for deformation and the ${\theta }_c$ value increase with decreasing cooling rate, indicating a larger mechanical strength. Localized shear bands concentrate at regions with high shear strains, leading to the formation of torsional buckling.

Manganese-based oxides are one of the most promising high-performance supercapacitor (SC) electrode materials. In this work, a stable MnO_x nanowires@MnO_x nanosheets core–shell heterostructure electrode material consisting of MnO_x nanosheets grown uniformly on the surface of MnO_x nanowires has been prepared by a simple liquid phase method followed by thermal treatment. The electrode displays a specific capacity of 336 Fg${}^{-1}$ at 1Ag${}^{-1}$ and exhibits a good cycling life of 83% capacitance retention after 5000 cycles. This is mainly due to the synergy effect between the one-dimensional MnO_x nanowires as the backbone structure and the two-dimensional MnO_x nanosheets with large specific surface area provide more active sites and the rapid transmission of electrons.

One-dimensional (1D) nanostructures are of great interest due to the promise of enhanced properties and improved device performance such as increased efficiency in solar cells by improved charge separation. There are many means of producing 1D nanostructures including chemical synthesis, lithography, template assisted growth and gas phase reaction. While all of these have their advantages and disadvantages, growth by gas phase reaction has the benefit of low cost and scalability to be used in mass production. This work outlines several of the more common growth mechanisms which utilize gas phase reactions to produce 1D nanostructures. The similarities and differences between the different mechanisms are discussed with an emphasis on the confinement of growth to 1D.

Currently, nanowires present a type of unique one-dimensional materials showing promising prospects in many fields. The octahedron molecular sieve (OMS-2, with chemical compositions of K${}_{2-}$${}_x$Mn₈O₁₆) materials are utilized extensively as efficient catalysts for numerous critical reactions. In this work, it was found that the evolution from $\gamma$-MnOOH microrod to OMS-2 nanowire can be induced facilely by altering the temperature of hydrothermal treatment. The obtained OMS-2 nanowire exhibited high catalytic activity and high durability in peroxymonosulfate (PMS) activated degradation of rhodamine B (RhB) or methylene blue (MB). Under optimum conditions (OMS-2 catalyst: 0.1 g⋅L${}^{-1}$; RhB or MB: 8 mg⋅L${}^{-1}$, 100 mL), the degradation can be completed within 10 min. The possible reason for OMS-2 nanowire’s high performance was also proposed.

A bottom-up approach for the fabrication of an assembly of electrodeposited nanowires has been combined to single nanowire electrical connection techniques to investigate the spin-transfer-torque and microwave emission of specially designed nanowires containing Co/Cu/Co pseudo spin-valves (SVs). Porous alumina templates are used for the growth by electrodeposition of metallic in-series connected SVs. Under specific magnetic field and injected current conditions, emission of microwave current is detected with frequency in the GHz range and linewidth as low as 1.8MHz. Microwave signals have been obtained even at zero magnetic field and high frequency versus magnetic field tunability was demonstrated. Our findings are in good agreement with micromagnetic simulations. In addition, it appears that in our particular geometry, the microwave emission is generated by the vortex gyrotropic motion which occurs in, at least, one of the two magnetic layers of our SV structures.

We present the possibility of enhancing magnetoresistance (MR) by controlling nanoscale domain wall (DW) width in a planar nanowire array. Results based on micromagnetic calculations show that DW width decreases with increasing exchange bias field and decreases with reducing exchange interaction between neighboring nanowires. Fe/Fe₃O₄ nanowire arrays were grown on $c$-plane sapphire to demonstrate the feasibility of this concept, and an enhanced MR ratio of 3.7% was observed at room temperature. compared with flat and stepped Fe₃O₄ thin films.