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The use of eco-friendly biomass as a resource is an efficient way to address the problems of fossil fuel depletion and climate change. In biomass conversion, versatile γ-valerolactone (GVL) is generally obtained from levulinic acid (LA) hydrogenation via a multimetallic catalyst system. Despite conversion efficiency being enhanced in mild conditions due to metal interactions, maintaining high catalyst stability is still a challenge. In this study, we synthesized a surrounded Co0.52Ni0.48@Al2O3-IE catalyst that exhibited excellent alloying and synergistic interaction between the metal constituents. Under relatively mild reaction conditions, the GVL yield over the catalyst exceeded 99% in LA hydrogenation. The catalyst showed no deactivation in a test of five cycles, displaying superiority in stability, possibly due to reasons of the physical isolation of the shell and the alumina retention on the Co-Ni alloys surface caused by the reversibility of exchange equilibrium. The present work demonstrated that a surrounded structured catalyst fabricated by ion exchange (IE) with active metals physically enclosed can lead to high catalytic activity and superior stability. [ABSTRACT FROM AUTHOR]

Monometallic (Ni, Co, Cu) and bimetallic (Ni-Co, Ni-Cu) 10–20 wt.% metal containing catalysts supported on fly ash zeolite were prepared by post-synthesis impregnation method. The catalysts were characterized by X-ray powder diffraction, N2 physisorption, XPS and H2-TPR methods. Finely dispersed metal oxides and mixed oxides were detected after the decomposition of the impregnating salt on the relevant zeolite support. Via reduction intermetallic, NiCo and NiCu phases were identified in the bimetallic catalysts. The catalysts were studied in hydrodeoxygenation of lignocellulosic biomass-derived levulinic acid to γ-valerolactone (GVL) in a batch system by water as a solvent. Bimetallic, 10 wt.% Ni, and 10 wt.% Cu or Co containing fly ash zeolite catalysts showed higher catalytic activity than monometallic ones. Their selectivity to GVL reached 70–85% at about 100% conversion. The hydrogenation activity of catalysts was found to be stronger compared to their hydration ability; therefore, the reaction proceeds through formation of 4-hydroxy pentanoic acid as the only intermediate compound. [ABSTRACT FROM AUTHOR]

The great challenge in the aldol condensation of tailored fermentation products (acetone–butanol–ethanol, ABE) into energy intensive fuels is to develop a suitable catalyst with high activity and low–cost. In this study, Co, Ni, and Co–Ni supported on Mg–Al oxide catalysts were prepared and their pore diameters were enlarged via adding active carbon as a hard template into Mg–Al hydrotalcite. During the aldol condensation reaction, the catalyst activity was enhanced after enlarging the pore diameter and Co–Ni bimetal supported catalyst presented the highest activity, which was resulted from that the electron transfer between Co and Ni in Co–Ni alloy enhanced the dehydrogenation activity and large pore lowered the mass transfer resistance. After optimizing the reaction conditions, acetone conversion and the total selectivity of C5–C11 desired products in the aldol condensation of ABE reached up to 76% and 90%, respectively. The stability study showed that the activity was decreased with the increase of reaction number because of the oxidation of metallic Co and Ni, but this could be solved via a simple hydrogen reduction method.

Monometallic (Ni, Co, Cu) and bimetallic (Ni-Co, Ni-Cu) 10–20 wt.% metal containing catalysts supported on fly ash zeolite were prepared by post-synthesis impregnation method. The catalysts were characterized by X-ray powder diffraction, N2 physisorption, XPS and H2-TPR methods. Finely dispersed metal oxides and mixed oxides were detected after the decomposition of the impregnating salt on the relevant zeolite support. Via reduction intermetallic, NiCo and NiCu phases were identified in the bimetallic catalysts. The catalysts were studied in hydrodeoxygenation of lignocellulosic biomass-derived levulinic acid to γ-valerolactone (GVL) in a batch system by water as a solvent. Bimetallic, 10 wt.% Ni, and 10 wt.% Cu or Co containing fly ash zeolite catalysts showed higher catalytic activity than monometallic ones. Their selectivity to GVL reached 70–85% at about 100% conversion. The hydrogenation activity of catalysts was found to be stronger compared to their hydration ability; therefore, the reaction proceeds through formation of 4-hydroxy pentanoic acid as the only intermediate compound.

Mixed Co-Ni bimetallic systems with the structure of a solid substitution solution have been synthesized using the supercritical antisolvent precipitation (SAS) method, which uses supercritical CO2 as an antisolvent. The systems obtained have been characterized in detail using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared (FTIR) spectroscopy, and magnetostatic measurements. It has been found that Co-enriched systems have a defective hexagonal close-packed (hcp) structure, which was described by a model which embedded cubic fragments of packaging into a hexagonal close-packed (hcp) structure. It has been shown that an increase in water content at the precipitation stage leads to a decrease in the size of cubic fragments and a more uniform distribution of them in Co-enriched systems. It has also been shown that mixed systems have the greatest coercivity in the line of samples. Ni-enriched bimetallic systems have a cubic close-packed (ccp) structure with modified crystal lattice parameters. [ABSTRACT FROM AUTHOR]

Mixed Co-Ni bimetallic systems with the structure of a solid substitution solution have been synthesized using the supercritical antisolvent precipitation (SAS) method, which uses supercritical CO2 as an antisolvent. The systems obtained have been characterized in detail using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared (FTIR) spectroscopy, and magnetostatic measurements. It has been found that Co-enriched systems have a defective hexagonal close-packed (hcp) structure, which was described by a model which embedded cubic fragments of packaging into a hexagonal close-packed (hcp) structure. It has been shown that an increase in water content at the precipitation stage leads to a decrease in the size of cubic fragments and a more uniform distribution of them in Co-enriched systems. It has also been shown that mixed systems have the greatest coercivity in the line of samples. Ni-enriched bimetallic systems have a cubic close-packed (ccp) structure with modified crystal lattice parameters.

Dry reforming of methane (DRM) is an effective route to convert two major greenhouse gas (CH 4 and CO 2) to syngas (H 2 and CO). Herein, in this work, monometallic Ni/CeO 2 and a series of bimetallic Co–Ni/CeO 2 catalysts with Co/Ni ratios between 0 and 1.0 have been tested for DRM process at 600–850 °C, atmospheric pressure and a CH 4 /CO 2 ratio of 1. The catalysts were characterized by X-ray diffraction, hydrogen-temperature programmed reduction, CO 2 -Temperature programmed desorption, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The catalyst with a Co/Ni ratio of 0.8 (labeled as 0.8 Co–Ni/CeO 2) exhibited the highest catalytic activity (CH 4 and CO 2 initial conversion for 80% and 85% at 800 °C, respectively) and the highest stability (less carbon deposition after 600min). This improved activity can be attributed to the Co–Ni alloy, which formed after reduction. Its weak chemisorption with hydrogen results in inhibition of reverse water gas shift reaction. In addition, Co-promoted the adsorption of surface oxygen enhances carbon removal, making it more stable. Image 1 • CeO 2 supported Ni and Co–Ni catalysts were tested for dry reforming of methane. • A molar Co/Ni ratio of 0.8 provides the most active and least deactivated catalyst. • Co–Ni alloy was formed after reduction, which was responsible for its superior performance. [ABSTRACT FROM AUTHOR]

Monometallic (Ni, Co, Cu) and bimetallic (Ni-Co, Ni-Cu) 10-20 wt.% metal containing catalysts supported on fly ash zeolite were prepared by post-synthesis impregnation method. The catalysts were characterized by X-ray powder diffraction, N 2 physisorption, XPS and H 2 -TPR methods. Finely dispersed metal oxides and mixed oxides were detected after the decomposition of the impregnating salt on the relevant zeolite support. Via reduction intermetallic, NiCo and NiCu phases were identified in the bimetallic catalysts. The catalysts were studied in hydrodeoxygenation of lignocellulosic biomass-derived levulinic acid to γ-valerolactone (GVL) in a batch system by water as a solvent. Bimetallic, 10 wt.% Ni, and 10 wt.% Cu or Co containing fly ash zeolite catalysts showed higher catalytic activity than monometallic ones. Their selectivity to GVL reached 70-85% at about 100% conversion. The hydrogenation activity of catalysts was found to be stronger compared to their hydration ability; therefore, the reaction proceeds through formation of 4-hydroxy pentanoic acid as the only intermediate compound.

In this work, electrodeposition of Co-Ni alloy nanostructures was performed on copper foam and directly applied as an electrocatalyst for the electrooxidation of acetaminophen (Paracetamol) and its detection. The surface morphology and the elemental composition were investigated using SEM and EDX analyses respectively. The observed morphology was similar to nano cones that are uniformly grown on the electrode surface. EDX analysis also confirmed the presence of both cobalt and nickel in the electrodeposit. The preferred orientation lies in (002) and (110) planes of cobalt and nickel respectively that confirmed the formation of alloy. Electrooxidation of acetaminophen was carried out using cyclic voltammetric method in 0.1 M NaOH solution. On addition of acetaminophen, an apparent anodic oxidation current enhancement was observed with lesser overpotential than cobalt and nickel electrodes which revealed the excellent electrocatalytic activity of the material. Interference studies also revealed the good selectivity for acetaminophen even in the presence of some interfering species. The reproducibility and stability was checked for the proposed Co-Ni alloy modified electrode. The analytical applicability was examined using the commercial paracetamol tablets and the recovery results were also good. The above results revealed that Co-Ni modified electrode on copper foam is a suitable candidate for electrochemical detection of acetaminophen. [ABSTRACT FROM AUTHOR]

A comparison was performed between Co-Ni thin films and template-assisted nanowires arrays obtained by electrochemical co-deposition. To reduce the effects of anomalous deposition and increase the Ni content in the deposit, an electrolyte with three times more Ni than Co in atomic ratio was chosen. Electrochemical deposition was performed at constant potentials chosen in the range from E = −0.8 to −1.2 V vs. Ag/AgCl. Cyclic voltammetry, chronoamperometry, and charge stripping techniques were used to characterize and compare the electrochemical behavior of Co-Ni films and nanowires. Morphological and compositional characterization was performed by scanning electron microscopy (SEM/EDAX) to assess the influence of the deposition potential on the growth of film and nanowires. A comprehensive analysis of the deposit growth rates for thin films and nanowires is presented taking into consideration the hydrogen evolution and anomalous deposition. The comparative study of the composition of film and nanowires obtained at different deposition potentials has shown that deposition of nanowires with a film-like composition takes place at more positive potential than thin film.

The performance of La 0.9 Sr 0.1 Co 1−x Ni x O 3 perovskite catalysts with different Ni substitution levels was evaluated in the Fischer-Tropsch (F-T) synthesis for higher alcohol production. It was found that Ni substitution improved the catalyst’s reducibility and had a positive effect on higher alcohol synthesis (HAS) from syngas. Only a limited amount of Ni ions can enter into the perovskite structure and then form Co-Ni alloy after reduction. Catalyst characterisation and activity test results indicate that the synergistic effects of the two metal species in the Co-Ni are responsible for the catalytic activity improvement. For high Ni-substituted perovskite catalysts (x ≥ 0.5), the extra-lattice Ni segregates on the catalyst surface and promotes CO methanation during the F-T reaction. A significant deviation of methanol selectivity from the Anderson-Schulz-Flory (ASF) linear distribution was detected for catalysts containing both Ni and Co, suggesting that the alcohol formation mechanism is altered with nickel substitution in La 0.9 Sr 0.1 Co 1−x Ni x O 3 perovskite catalysts. The La 0.9 Sr 0.1 Co 0.9 Ni 0.1 O 3 perovskite catalyst exhibited the highest selectivity towards higher alcohols. The effect of reaction temperature on the catalytic activity is also discussed. [ABSTRACT FROM AUTHOR]

In this paper, the interdiffusivities in fcc Co-Ni alloys at 1373 K due to different types of diffusion couple experiments were firstly re-calculated via the unifiedWagner method based on the measured composition profiles. Their maximum difference due to different approaches for diffusion couple preparation was found to be larger than one order of magnitude. Then, a comprehensive analysis on the effect of different preparation methods was performed. After that, a two-step diffusion couple technique in combination with the pragmatic numerical inverse method was proposed to determine the accurate interdiffusivities by eliminating the effect of external stress. Such a novel approach was successfully applied in the binary fcc Co-Ni alloys for demonstration purposes. Moreover, it is anticipated that such novel approach can be utilized as the standard method for accurate interdiffusivity measurement, and the resultant accurate interdiffusivities in different alloys may serve as a benchmark for the later experimental and theoretical studies. [ABSTRACT FROM AUTHOR]

Highly ordered Co x Ni 1− x nanowire (NW) arrays were electrodeposited inside nanoporous anodic aluminum oxide membranes. The control of the applied potential during the electrodeposition process allowed us to easily tune the Co% in the alloy. Systematic studies on the morphological and crystallographic properties together with static and dynamic magnetic characterizations were performed. In this work we focus on the study of the dynamic magnetic properties of CoNi NW arrays using the ferromagnetic resonance method at both room (RT) and low (LT) temperatures. The careful comparison analysis performed between the magnetic anisotropy fields obtained at RT and LT, allowed us to extract for the first time the magnetocrystalline anisotropy effect of the Co component and, most importantly, the magnetoelastic anisotropy effect of Ni. [ABSTRACT FROM AUTHOR]

This study continues previous work which showed that the anomalous behavior of Co-Ni deposition could be alleviated or eliminated through use of cyclic voltammetry (CV) or pulse reverse (PR) plating. The research focuses on aspects not considered in this previous work: the effects of the anion and agitation in the plating bath. A comparison is made of Co-Ni electrodeposition using the CV and PR techniques in sulfate and chloride baths at pH 3 containing equimolar Co(II) and Ni(II) concentrations under both stirred and unstirred conditions. The anomalous behavior can be significantly suppressed and even eliminated with current efficiencies above 90 % through use of PR plating, in particular, but only if carried out in a chloride solution under quiescent conditions. Both metal ion reduction during the cathodic portion and oxidation of the coating during anodic polarization are accelerated in the chloride solution relative to that in the sulfate solution. Electrolyte agitation exacerbates anomalous deposition and reduces the current efficiency by enhancing mass transport of Co(II) and H to and from the electrode. The origin of anomalous deposition and effects of the chloride ion are examined in terms of coordination chemistry and ligand field theory. This analysis suggests that oxidation of the Co-Ni coating in the chloride solution during anodic polarization of the PR and CV cycles when cobalt preferentially dissolves is crucial to suppressing the anomalous behavior. Examination of the coatings shows that the anion type, degree of agitation of the electrolyte, and electroplating technique significantly affects their microstructure and roughness. [ABSTRACT FROM AUTHOR]

The surface morphology and magnetic properties of Co-Ni-N thin films electrodeposited under an external magnetic field were investigated. The films were electroplated on Al substrates using the same electrodeposition parameters (temperature and pH) for all experiments, with an external magnetic field of 107 Oe applied to the cathode surface. The films were compared with similar samples obtained in the absences of magnetic field. The magneto-induced modifications in the Co-Ni-N morphology can be explained by the specific local convection of ions at the interface cathode-electrolyte, which promotes changes both in the electrical charge of the double layer and in the thickness of the diffusion layer. From the magnetic measurements, we found that the coercivity varied between H=(14÷27) kA/m depending on the direction of the applied magnetic field and on the sodium nitrate content in the plating bath. It was observed that an induced anisotropy appeared in the Co-Ni-N films due to the preferential orientation of the easy axis of magnetization in the magnetic field direction. In addition, the Co-Ni-N alloy films showed good magnetic property, which is considered that not only the smaller grain size of the films, but also more uniform surface of the films than that deposited in absence of applied magnetic field. [ABSTRACT FROM AUTHOR]

Abstract: Linear sweep voltammetry and cathodic polarization experiments were conducted to investigate the effects of electrolyte composition and current/overpotential on Co–Ni alloy co-deposition in sulphate solutions and its anomalous behavior whereby Co is preferentially deposited over Ni. Ni deposition was shown to be inhibited in the presence of CoSO4 in solution, whereas the rate of Co deposition was not accelerated and, in fact, completely unaffected by the presence of NiSO4. The extent of anomalous behavior was found to be affected strongly by the CoSO4 concentration, but was less pronounced when Co(II) reduction became mass transfer-controlled or the NiSO4 concentration exceeded the CoSO4 concentration by at least one order of magnitude. Analysis of the linear scans and measurement of the deposition current efficiencies indicated that the onset of reactions occurred in the following order with increasing cathodic overpotential: H+ reduction, Ni(II) reduction, Co(II) reduction and H2O reduction. Boric acid was found to have little effect on alloy composition whenever deposition occurred to any significant extent. On the other hand, the presence of boric acid was required to attain acceptably high current efficiencies over a wide range of current densities. Moreover, effective Co–Ni deposition was not possible in the absence of boric acid. [Copyright &y& Elsevier]

Abstract: We present in this paper several results concerning the preparation by means of electrolysis and characterization of Co–Ni–Mo thin films. Co–Ni–Mo thin films with different molybdenum content in the range 0–25at% Mo were prepared from a complex solution containing ions of Co, Ni and Mo, using galvanostatic control, on aluminum substrates. The effects of applied current density on the morphology, magnetic, magnetoresistance, and optical properties of the electrodeposited Co–Ni–Mo films were investigated. The applied current density significantly influenced the film composition and their magnetic properties. The increase of molybdenum content in Co–Ni films (up to 25at% Mo) enhances the resistivity, but it reduces the magnetoresistance effect. We report the first observation of magnetoresistance as high as 8% in Co–Ni–Mo thin films. [Copyright &y& Elsevier]

Ni-Co-Fe2O3 composite coatings were electrodeposited using cetyltrimethylammonium bromide (CTAB)-modified Watt’s nickel bath with Fe2O3 particles dispersed in it. The effects of the plating parameters on the chemical composition, structural and morphological characteristics of the electrodeposited Ni-Co-Fe2O3 composite coatings were investigated by energy dispersive X-ray (EDS) spectroscopy, X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results reveal that Fe2O3 particles can be codeposited in the Ni-Co matrix. The codeposition of Fe2O3 particles with Ni-Co is favoured at high Fe2O3 particle concentration and medium stirring, and the deposition of Co is favoured at high concentration of CTAB. Moreover, the study of the textural perfection of the deposits reveals that the presence of particles leads to the worsening of the quality of the observed 〈220〉 preferred orientation. Composites with high concentration of embedded particles exhibit a preferred crystal orientation of 〈111〉. The more the embedded Fe2O3 particles in the metallic matrix, the smaller the sizes of the crystallite for the composite deposits. [ABSTRACT FROM AUTHOR]

Using the electrochemical cyclic voltammetry, the Co, Ni, and Co66Ni34 alloy films were electrodeposited on GaAs(001) surface. XRR and XRD have been used to characterize the structure of the films. We especially measure the L-edge X-ray absorption spectroscopy (XAS), which is element specific and sensitive to chemical valence, and the X-ray magnetic circular dichrosim (XMCD) spectra, which is sensitive to magnetic moments of the atoms. The orbital and spin magnetic moments of the Co and Ni atoms from the monocomponent Co, Ni and binary Co66Ni34 alloy films are obtained from the XAS and XMCD spectra by using the sum rules. [ABSTRACT FROM AUTHOR]

Abstract: The electrodeposition of cobalt, nickel and Ni–Co alloys was studied by electrochemical techniques. Cyclic voltammetry and current transient measurements were used to characterize the Co–Ni system in other to obtain the nucleation and growth mechanism. The cyclic voltammetry results clearly showed that electrodeposition of cobalt, nickel and Co–Ni alloy is diffusion-controlled process with a typical nucleation mechanism. The redox potentials of the Co and Ni are shifted to more cathodic potentials in the Co–Ni alloy system. In addition, the current transients revealed that nucleation mechanism is instantaneous with a typical three-dimensional (3D) nucleation and growth process. The number of nucleation sites is increased with the overpotential and nickel or cobalt concentration. It was found that addition of nickel sulfate to cobalt solution, resulted in increasing the number of nucleation sites and therefore the nucleation rate of the Co–Ni alloy system is increased. However, AFM analysis showed that alloying cobalt thin films with nickel changed the microstructure. In this condition, a large number of equally sized spherical grains are observed in single cobalt deposits, while the rectangular particles are deposited in the Co–Ni alloy system as layer-by-layer deposition. [Copyright &y& Elsevier]

Abstract: A monolayer of Co nanoparticles was fabricated on a polyimide (PI) film by successively depositing a 3.5-nm-thick Co thin film on top of a pre-existing nano-sized Ni particle template. Each Co deposition was followed by thermal annealing to induce coalescence of the Co film onto the pre-existing Ni seed particles. The Co deposition/thermal annealing step was repeated up to three times to grow 7–10-nm-sized Co nanoparticles on a polyimide film. We demonstrate that the average particle size can be controlled by the number of Co depositions. Thus-produced Co nanoparticles exhibited saturation magnetization comparable to its bulk value with coercivity reaching up to 120Oe. Such a nanoparticle template process presented here can be easily extended to a ternary alloy particle and multi-functional nanoparticle system for potential applications in nanomagnet arrays, nanophotonic arrays or nanocatalyst arrays. [Copyright &y& Elsevier]

The use of cobalt based alloys in micro-electromechanical systems (MEMS) applications seems feasible and promising as these materials are compatible with both planar and bulk technologies involved in MEMS processing. Co–Ni, Co–Mo and Co–Ni–Mo alloys can fulfil the demand for new materials in the MEMS sector especially in the magnetic actuation field. The route to obtain these alloys must take into consideration the plating bath design, the deposition parameters and the ex situ characterisation of the deposits. A continuous feedback study based on these items allows tailoring the deposit properties until deposit optimisation is achieved. This optimisation is not only focused on finding out the more appropriate mechanical and magnetic properties, but on achieving adherent, uniform, low stressed electrodeposited layers. [ABSTRACT FROM AUTHOR]

The damping capacity of Co–32 wt.% Ni alloy was investigated as a function of the amount of thermal and strain-induced ϵ martensite under non-magnetic and 900 Oe magnetic fields, respectively. The damping capacity of the Co–32 wt.% Ni alloy containing ϵ martensite without magnetic field consists of the magneto-mechanical damping capacity of mainly α phase, damping capacities of α and ϵ phases without magneto-mechanical damping effect. Under a magnetic field of 900 Oe, the more the thermal ϵ martensite mass fraction the higher the damping capacity. However, the damping capacity of the deformed Co–32 wt.% Ni alloy with the strain-induced ϵ martensite decreases with increasing deformation degree despite the increase in total ϵ martensite fraction, because the lattice defects like dislocations introduced during deformation act as barriers to movement of damping sources such as magnetic domain walls, stacking faults boundaries in both α and ϵ phases, and α/ϵ interfaces. [Copyright &y& Elsevier]

N-doped rich-defect carbon nanotubes coated CoNi alloy nanocomposites with abundant cavities exhibit efficient trifunctional electrocatalyst performance and excellent stability. • N-doped carbon nanotubes coated CoNi alloy was prepared by one-pot process on MOFs. • N-doped rich-defect nanotube facilitates to accelerate mass and electron transfer. • Abundant cavity structure enables active centers more widely uniformly distributed. • CoNi alloy, N-doped carbon and CoNi-Nx jointly promoted electrocatalytic activity. This paper introduces a facile strategy to fabricate trifunctional electocatalysts through one pool treatment on MOFs to obtain carbon nanotube coated ultrafine CoNi alloy (CoNi@NCNTs) nanocomposites with N-doped rich-defect and abundant cavity structure. During the pyrolysis process, volatile CNx species from dicyandiamide were trapped by ZIF-67@Ni-ZIF nanosheets, simultaneously introducing nitrogen atom into carbon matrix to achieve the rich-defect porous nanotubes and abundant cavity structure. The as-prepared nanomaterials can simultaneously boost the ORR, OER and HER catalytic activity with strong durability. Significantly, the CoNi@NCNTs-700 exhibits excellent electrocatalytic activity including half-wave potential (E ORR, 1/2) of 0.80 V, lower operating voltage (E OER, 10) of 1.60 V at 10 mA cm−2 and potential difference (ΔE) of 0.80 V between E OER, 10 to E ORR, 1/2 in 0.1 M KOH, and low overpotential (E HER, 10) of −0.130 V reaching 10 mA cm−2 in acidic medium. The remarkable activity is ascribed to defect-rich porous carbon nanotubes structure and the synergistic effect between CoNi alloy nanoparticles, N-dope carbon and CoNi-Nx. And hollow structure facilitates to improve conductivity and stability. This work offers a useful archetypical template to design and construct efficient and stable trifunctional electrocatalysts, illustrating its viability for practical applications of energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

A comparison was performed between Co-Ni thin films and template-assisted nanowires arrays obtained by electrochemical co-deposition. To reduce the effects of anomalous deposition and increase the Ni content in the deposit, an electrolyte with three times more Ni than Co in atomic ratio was chosen. Electrochemical deposition was performed at constant potentials chosen in the range from E = −0.8 to −1.2 V vs. Ag/AgCl. Cyclic voltammetry, chronoamperometry, and charge stripping techniques were used to characterize and compare the electrochemical behavior of Co-Ni films and nanowires. Morphological and compositional characterization was performed by scanning electron microscopy (SEM/EDAX) to assess the influence of the deposition potential on the growth of film and nanowires. A comprehensive analysis of the deposit growth rates for thin films and nanowires is presented taking into consideration the hydrogen evolution and anomalous deposition. The comparative study of the composition of film and nanowires obtained at different deposition potentials has shown that deposition of nanowires with a film-like composition takes place at more positive potential than thin film. [ABSTRACT FROM AUTHOR]

In this paper, the interdiffusivities in fcc Co-Ni alloys at 1373 K due to different types of diffusion couple experiments were firstly re-calculated via the unified Wagner method based on the measured composition profiles. Their maximum difference due to different approaches for diffusion couple preparation was found to be larger than one order of magnitude. Then, a comprehensive analysis on the effect of different preparation methods was performed. After that, a two-step diffusion couple technique in combination with the pragmatic numerical inverse method was proposed to determine the accurate interdiffusivities by eliminating the effect of external stress. Such a novel approach was successfully applied in the binary fcc Co-Ni alloys for demonstration purposes. Moreover, it is anticipated that such novel approach can be utilized as the standard method for accurate interdiffusivity measurement, and the resultant accurate interdiffusivities in different alloys may serve as a benchmark for the later experimental and theoretical studies., Competing Interests: The authors declare no conflict of interest.