Fe-Ni Alloys Research Articles

Tuning Ce-doping La0.7Sr0.3Fe0.9Ni0.1O3-δ internal reforming catalyst to enhanced conversion efficiency and coking tolerance of solid oxide fuel cells fueled by oxygen-bearing low concentration coal mine methane

Solid oxide fuel cells (SOFCs) possess the potential to directly utilize abundant low concentration coal mine methane for power generation, which is crucial for energy conservation and reducing greenhouse gas emissions. Herein, Ce-doped La0.55Ce0.15Sr0.3Fe0.9Ni0.1O3-δ (LCSFN) perovskite is firstly employed as an anode internal reforming catalyst to enhance the electrochemical performance, stability, and resistance against carbon deposition in SOFCs. The results demonstrate that Ni-Fe alloy nanoparticles can be effectively precipitated from LCSFN under reducing atmosphere, thereby significantly promoting the partial oxidation reaction of methane while preventing direct contact between methane and Ni particles for the anode. The anode-supported single cells demonstrated exceptional electrochemical performance using a composite catalytic layer consisting of LCSFN-Ce0.9Gd0.1O2-δ (LCSFN-GDC). At 800℃, the utilization of both H2 and 16 %CH4-1 %O2-N2 resulted in the attainment of maximum power densities (MPD) measuring 881.66 mW·cm−2 and 824.69 mW·cm−2, respectively, with the recorded values for polarization resistance were 0.32 and 1.16 Ω·cm2. Additionally, the single cells equipped with LCSFN-GDC internal reforming catalytic exhibit remarkable resistance to carbon deposition, maintaining stable performance for a duration of 100 h using 16 %CH4-1 %O2-N2. These findings underscore the efficacy of methane catalysts in SOFCs, as it not only enhances power generation efficiency through using internal reforming catalyst but also ensures long-term stability by mitigating carbon-related issues.

In-situ construction of Ni–Fe alloy nanoparticles on perovskite surface for CO2 direct electrolysis

Perovskite (ABO3) materials are commonly used as cathodes for solid oxide electrolysis cells (SOECs), but their electrochemical performance is poor due to the low CO2 adsorption and conductivity. Herein, we design an A-site deficient (La0.5Sr0.5)0.95Fe0.85Mn0.1Ni0.05O3-δ (95LSFMNi) perovskite cathode with rich oxygen vacancy and Ni–Fe alloy to enhance the CO2 adsorption. The surface precipitated Ni–Fe alloy nanoparticles introduce more oxygen vacancies into the matrix and increase the active sites for CO2 adsorption, enhancing the electrochemical reduction reaction for CO2 (CO2RR). Fe element exsolution was stimulated after the Ni reduction, and Fe content in the nanoparticles increased with the reduced time. The 95LSFMNi with in-situ dissolved Ni–Fe particles exhibits a doubled conductivity than the parent La0.5Sr0.5Fe0.9Mn0.1O3-δ (LSFM) at 800 °C and 5%H2/Ar. In addition, the electrolysis current density at 1.6 V and 800 °C reaches 1.09 A cm−2, representing a 28.2% increase compared to the LSFM. These findings demonstrate that the in-situ precipitated nano Ni–Fe particles are highly effective in enhancing the catalytic ability of CO2RR.

The importance of long range Fe–Fe interactions in magnetically ordered 2D Fe0.2Ni0.8/Ni(001) and Fe0.3Ni0.7/Ni(001) alloy systems

We develop a theoretical approach to study the magnonic properties of the 2D ordered surface Fe–Ni alloys with 20% and 30% Fe on a face-centered cubic Ni(001) surface substrate. The surface alloy nanostructures in stable equilibrium are determined by computing the lowest energy configurations of constitutive supercells of the ordered alloys. The magnetic exchange constants of the ground state of the stable systems are calculated to define their Heisenberg Hamiltonians using the DFT Spin-Polarized Relativistic Korringa–Kohn–Rostoker (SPRKKR) method and considering Fe–Fe interactions up to third nearest neighbors. To determine the propagating exchange spin-wave modes, evanescent modes, and the consequent magnonic properties, the spin dynamics of the magnetic surface alloy nanostructures are solved using the phase field matching theory (PFMT). Our results indicate that the Fe–Fe exchange interactions up to third nearest neighbors are vital for accurately describing their magnonics. In particular, the exchange interactions influence the form of dispersion branches for the high-energy spin-wave modes of the Fe–Ni surface alloys considered. Appropriate Green’s functions are also derived from the PFMT method to compute the local densities of states (LDOS) for the atomic sites at the surface boundary. For the case of 20% Fe surface alloy, the Fe–Fe exchange interactions shift the Fe LDOS peaks to lower frequency intervals. We also distinguish the emergence of remarkable LDOS peaks for the he case of the 30% Fe surface alloy at specific Ni sites. These peaks change positions under second and third nearest neighbor Fe–Fe interactions, heralding new accessible spin-wave channels. Our results contribute to establishing a systematic understanding of the magnonics of the magnetic surface alloys of transition metal (TM) materials. This new knowledge will enable the study of the quantum transport of spin waves at interfacial alloy nanojunctions composed of such materials. The present DFT-PFMT theoretical approach is general and can be applied to other surface TM alloy magnetic nanostructures.

Uniformly Dispersed Ultrasmall Fe(Co)Ni Alloy Nanoparticles Embedded in Thin‐Walled Carbon Nanotubes as High‐Performance Anode Materials for Lithium‐Ion Battery

Uniformly Dispersed Ultrasmall Fe(Co)Ni Alloy Nanoparticles Embedded in Thin‐Walled Carbon Nanotubes as High‐Performance Anode Materials for Lithium‐Ion Battery

NiAlFe catalysts based on hydrotalcite-like precursors for low temperature CO2 methanation: Electronic effects among components and intrinsic activity of Ni site

NiAlFe catalysts based on the hydrotalcite-like precursor were prepared and the catalysts exhibit excellent low temperature catalytic activity for CO2 methanation. CO2 conversion over the NiAlFe0.3 catalyst is nearly 80 % under the condition of T = 225 °C, P = 1 atm, and WHSV = 24000 mL/(g∙h). With the increase in the substitution of Fe for Al, the hydrotalcite-like structure of the catalyst precursor is gradually destroyed; the reducibility of NiO component is promoted; the amount of surface basic site decreases. There is a strong electronic push–pull effect between NiO and Al2O3 in the calcined catalyst, and the electronic effect is weakened with the introduction of Fe because Fe3+ shares the responsibility of Ni2+ for donating electron to Al3+. In the reduced catalysts, the Ni3Fe alloy was formed and the electrons are pushed from Ni0 to Fe0. With the increase in the Fe amount, the number of surface Ni atom decreases, while the intrinsic activity of Ni active site enhances. The number and intrinsic activity of Ni site are the main two factors determining the CO2 methanation activity at low temperature. Moreover, the substitution of Al3+ by Fe3+ is beneficial for the stability of the catalysts by inhibiting the agglomeration of catalyst particle.

Novel FeNiP–FeNi–C nanofiber as an outstanding electrocatalyst for oxygen evolution reaction

Developing stable, highly active, and economical non-precious metal catalysts for the oxygen evolution reaction (OER) has been highly demanded in the new energy field since it can meet the industrial demands of large-scale electrocatalytic water splitting. A novel FeP/Ni2P/Fe0.64Ni0.36/C (FeNiP–FeNi–C) nanofiber was prepared by electrospinning and high-temperature phosphating. Notably, the good dispersion of FeP, Ni2P, and FeNi alloy nanoparticles in the nanocarbon fiber greatly increased the number of electroactive sites, and the synergistic effect between the FeP/Ni2P heterogeneous interface and FeNi alloy significantly improved the inherent activity of each site. Moreover, the carbon nanofibers enhanced the long-term durability of the catalyst by preventing the corrosion of the FeP, Ni2P, and FeNi alloy particles. Therefore, the optimal FeNiP–FeNi–C catalyst revealed exceptionally high OER activity, with overpotentials of 364 mV and 236 mV at 50 mA cm−2 and 10 mA cm−2 respectively, and the slope of Tafel of 61.00 mV·dec−1. This catalyst performs significantly better than commercial RuO2 catalysts in alkaline electrolytes. The results of this study offer a novel perspective for the mass production of non-precious metal OER high-efficiency electrocatalysts.

Microstructure and Mechanical Properties of Al–Zn–Mg–Ni–Fe Alloy Processed by Hot Extrusion and Subsequent Radial Shear Rolling

Microstructure and Mechanical Properties of Al–Zn–Mg–Ni–Fe Alloy Processed by Hot Extrusion and Subsequent Radial Shear Rolling

Facile synthesis of Ni-doped zeolite-based catalysts from waste coal gasification fine slag for steam reforming of toluene

The preparation of efficient and stable catalysts for biomass tar reforming using low-cost solid waste is of great value for achieving green biomass gasification. In this work, new porous Ni-doped zeolite catalysts were formed by an ion exchange method making use of the waste CGFS as the precursor. At a proper NiO loading content, the catalyst (Na@Air-0.2Ni) exhibits a uniform spherical particle-linked porous structure with NaAlSiO4 as the supporting matrix and NiO particles anchoring on the surface as active sites. The catalytic performance of the catalysts was investigated in toluene reforming experiments to evaluate their potential for biomass tar conversion. Under optimized conditions (720 °C, S/C = 1.5, and N2 flow 25 mL/min), toluene conversion reached 92 % using Na@Air-0.2Ni as a catalyst, yielding 2500 μmol/min CO and 2800 μmol/min H2. Continuous steam reforming of toluene formed to FeNi3 alloy, which in turn strengthens the stability of the catalyst, and a high toluene conversion of 81 % can be achieved in 450 min continuous experiment, indicating the excellent stability of the catalyst. This work has confirmed that coal gasification slag rich in silicon and aluminum has the potential to prepare new zeolite-based catalysts, which is an important exploration for promoting high-value conversion of solid waste.

Experimental study on Finding stable catalytic methane decomposition for hydrogen production

This study attempts to find active and stable catalysts for H2 production from catalytic methane decomposition (CMD). Experimental results show that metal-based (Ni, Fe, and Ni–Fe alloy) and carbon-based (biochar and activated carbon) catalysts are gradually deactivated due to carbon deposition during the CMD reaction. Although the CMD performance can be enhanced using bimetallic catalysts supported by either metal oxide (Al2O3) or activated carbon, deactivation due to carbon deposition is still inevitable. It was also found the carbon-based carbon catalyst has lower activity as compared with the metal-based catalysts. When using commercially available nickel foams with pore per inch (PPI) higher than 90 as the catalysts, stable H2 production can be obtained. The reasons for obtaining the stable CMD are attributed to high surface area and catalyst active sites, better heat transfer characteristics, and enhanced Ni dispersion of Ni. For the reaction temperature of 900 °C and the nickel foam with a PPI of 110, the stable methane conversion of 90% can be obtained without COx production.

The transition of strain rate sensitivity induced by Fe solutes in electrodeposited nanocrystalline Ni–Fe alloy

A face-centered cubic nanocrystalline (NC) Ni–Fe alloy was fabricated by adjusting electrodeposition parameter. By evaluating the hardness of NC Ni–Fe via nanoindentation at the selected strain rates from 0.005 s−1 to 0.2 s−1, a transitional point of strain rate sensitivity index (m) was exhibited, contrary to the constant value that reported in other works. Based on X-ray diffraction and transmission electron microscopy analysis, which evidenced the apparent lattice expansion as much more Fe solutes dissolved in intragrain rather than grain boundary (GB), we attributed the unexpected enhancement of m value at lower strain rates to pronounced GB-mediated plasticity facilitated by residual dislocations near GBs, whilst the lower m value at higher strain rates mainly to the intragranular dislocation motions. This work contributes directly to understanding the profound effect of alloying on the mechanical behaviors of NC materials.

Ultrastrong and ductile FeNi-based alloys through Pd-containing multicomponent L12-type precipitates

Precipitation strengthening stands as a paramount strategy for enhancing the mechanical properties of FeNi-based alloys. Conventional precipitates used for strengthening typically contain only two major constituent elements selected from Ni, Al, and Ti. However, knowledge about the intrinsic properties and strengthening mechanisms of multicomponent precipitates remains limited. Here, we propose introducing novel multicomponent L12-type precipitates containing palladium (Pd) to strengthen FeNi-based alloys. The strengthened FeNi alloy achieves an eightfold increase in strength compared to the FeNi matrix while maintaining good ductility. Using meticulous micro-characterization and energy-dispersive X-ray spectroscopy (EDS) techniques, in conjunction with first-principles calculations, this study investigated the effects of Pd addition on the thermodynamic stability, morphology, coherency, and strengthening mechanisms of the precipitates. Results indicate that the addition of Pd induces the nucleation of L12-type precipitates, increases their ductility, and eliminates anisotropy in the shear modulus of the precipitates. Excessive Pd content can alter the shape of precipitates from spherical to acicular due to increased interfacial mismatch between the precipitates and the FeNi matrix. These insights shed light on the impact of Pd addition on the intrinsic properties of L12-type precipitates, offering a promising pathway for the design of advanced FeNi-based alloys with optimized mechanical performance.

The mechanism of enhanced electrocatalytic water splitting on S-doped NiFe2O4/Ni–Fe alloy@copper foams

The development of bifunctional catalysts with subtle structures, high efficiencies, and good durabilities for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial for overall water splitting. In this work, a multicomponent S-doped NiFe2O4/Ni–Fe micro nano flower electrocatalyst was synthesized rapidly on foam copper using a simple one-step constant current electrodeposition method. The introduction of S leads to the transformation of the microsphere structure of the Ni–Fe alloy into a cauliflower-like morphology and induces changes in the surface electronic structure, significantly enhancing the catalytic performance for the HER and OER. The S-NiFe2O4/Ni–Fe alloy/CF showed low overpotentials of 220 and 66 mV at 10 mA cm−2 in 1.0 M KOH for the OER and HER, respectively. High durability OER and HER performances were demonstrated through 60 h of chronopotentiometry and 6000 CV cycles test. Excellent overall water splitting electrocatalytic activity was observed in the S-NiFe2O4/Ni–Fe alloy/CF‖S-NiFe2O4/Ni–Fe alloy/CF two-electrode system. In particular, active-phase NiOOH, a highly active substance for OER, can be controllably formed in the reaction process owing to the nanoflower structure of multi-layer sulfur which slows down the dissolution of NiFe2O4/Ni–Fe alloy. These results suggest that this composite structure is a promising bifunctional electrocatalyst.

Facile Fabrication of Melamine/MXene/FeNi‐PBA Composite Derived Multi‐Interface Magnetic Carbon Foam for High‐Efficiency Microwave Absorption

AbstractThe development of novel materials with high‐efficiency microwave absorption is crucial for mitigating the adverse impacts of electromagnetic pollution. In this study, MXene and FeNi Prussian blue analogs (PBA) are assembled onto a melamine foam using self‐assembly and in situ growth technique. Subsequently, magnetic carbon foam, comprising FeNi alloys, TiN and carbon with various morphologies, is synthesized via carbothermal reduction reaction. The surface morphology electromagnetic properties are significantly influenced by the pyrolysis temperature. The results revealed that the magnetic carbon foam composite demonstrated an effective microwave absorption bandwidth of 4.72 GHz at a thickness of only 1.5 mm, with a minimum reflection loss of −24.83 dB at 1.3 mm. The outstanding microwave absorption performance can be attributed to the 3D conductive network formed by N‐doped carbon, as well as the contributions from polarization loss, magnetic loss, and suitable impedance matching. Furthermore, the corresponding absorber coating demonstrated a maximum reduction value of radar cross‐section (RCS) by 13.16 dB m2. This research offers novel insights for the development of lightweight and efficient low‐filled electromagnetic composite for broadband microwave absorption.

Effect of tetragonality on the magnetic preference, elasticity and magnetocrystalline anisotropy of L10-FeM(M = Ni, Pd, Pt) alloys

The effect of tetragonality on the magnetocrystalline anisotropy of L10-FeM(M = Ni, Pd and Pt) ordered alloys is widely concerned, but its effect on other physical properties is not well understood. In this paper, the impact of tetragonality on the magnetic preference, lattice dynamics and elasticity, as well as magnetocrystalline anisotropy of these L10 ordered alloys are systematically investigated based on the first-principles methods. The antiferromagnetic FeNi and FePd alloys are metastable within appropriate axial ratio c/a range, although the ferromagnetic state is ground-state stable. The reduced axial ratio c/a favors the antiferromagnetic state over the ferromagnetic state for the FePt alloy. The tetragonality has a non-monotonic effect on the Young’s modulus and shear modulus, while the bulk modulus is almost tetragonality independent for all L10 ordered alloys. The uniaxial magnetocrystalline anisotropy increases with tetragonality in the fe rromagnetic state, while it shows different trends in the antiferromagnetic state. Interestingly, the antiferromagnetic FePt exhibits planar magnetocrystalline anisotropy in a wide axial ratio c/a range, and a transition between hard magnetic and semi-hard magnetic at c/a = 1.45 is discovered for the FePd alloy. These intriguing properties induced by tetragonality provide us a deeper understanding of the potential rare-earth-free permanent magnet L10 alloys.

Applying high efficiency internal reforming catalyst for direct low concentration coal mine methane solid oxide fuel cells

Solid oxide fuel cells (SOFCs) are green and efficient power generation devices, which can efficiently utilize the abundant low concentration coal mine methane (LC-CMM), and play an important role in energy saving and emission reduction. However, there are still challenges need to be addressed, such as low conversion efficiency and deposit carbon. In this work, a Sr2Fe1.4Ni0.1Mo0.5O6-δ-Gd0.1Ce0.9O2-δ (SFNM-GDC) internal reforming catalyst is prepared, generating abundant oxygen vacancies with in situ precipitates Fe–Ni alloys in the reducing atmosphere, leading to improved methane reforming efficiency and carbon deposition resistance. The results show that the cell exhibits excellent electrochemical performance with the internal reforming catalyst, with the maximum power density (Pmax) of 1212 mW cm−2 and 980 mW cm−2 at 800 °C with H2 and LC-CMM, respectively, corresponding to polarization impedances of 0.16 Ω cm2 and 0.47 Ω cm2. More importantly, the single cell combining SFNM-GDC reformed layer can maintain stable performance for 100 h at 700 °C under the atmosphere of LC-CMM. These results highlight that the reformed layer enhances CH4 reforming, optimizes electrochemistry and increases resistance to carbon deposition.

FeNi alloys with controllable composition for tunable magnetic properties and broadband absorption

For the further enhancement to the microwave absorbing capabilities of magnetic dendritic materials, this work has successfully prepared dendritic FexNi1-x (x = 0.5, 0.33, 0.25, 0.2) alloys through a facile electrodeposition method. FexNi1-x alloy composition can be easily tuned by changing iron ion concentration in the electrolyte. We investigate the effects of alloy composition on the crystal structure and morphology whereby we intrinsically analyzes the magnetic characteristics and microwave absorbing performance of FexNi1-x alloys. Particularly, Fe0.25Ni0.75 alloy demonstrates the strongest microwave absorption intensity, achieving the minimum reflection loss (RLmin) of −59.02 dB at 4.96 GHz. Comprehensively, Fe0.33Ni0.67 alloy (RLmin = −49.42 dB, d = 1.68 mm) attains optimal microwave absorption performance when combining the perspectives of absorber thickness, RLmin and effective bandwidth (RL<-20 dB). RL values of Fe0.33Ni0.67 alloy at the thickness of 1.4–2.5 mm, exceed −20 dB over a wide frequency range, covering almost the whole X and Ku band (8–18 GHz). Such exceptional microwave absorption performance is attributed to the unique dendritic structure which conduces to the multiple scattering of electromagnetic microwave, hence improving impedance matching and promoting energy dissipation. In addition, the practicability of FexNi1-x alloys is further confirmed by simulating the RCS value in the far field environment.

Redistribution and activation of inert N-configuration in metallic electron donor towards boosted oxygen reaction kinetics for zinc-air batteries

The utilization of metallic nitrides as air–cathode electrocatalysts is promising for sparking fresh vitality to rechargeable zinc-air batteries, but successful case is rare due to their limitation to catalyze one specific reaction. Here, mild topochemical evolution coupled with assembly self-templating is presented to achieve electrocatalytic furnishing on the 2D metallic VN nanosheet. Density functional theory (DFT) calculations predict that lowered energy barriers for potential limiting steps can be achieved by hybridization VN with cost-effective active species. Metallic VN hybrid architecture buffered with flocculent carbon matrix is constructed, featuring decoration of active FeNi alloy nanoparticles (VN-FeNiA@FC). Particularly, prominent interfacial electron delocalization owing to the electron donating from VN boosts the oxygen reaction kinetics. As a stride forward, the redistribution and activation of inert N-configuration from host VN to the formation of Fe/Ni–Nx are revealed, contributing to promoted exposure of active sites. As a proof of concept, a rechargeable zinc-air battery based on bifunctional VN-FeNiA@FC catalyst exhibits desired galvanostatic charge/discharge stability for over 200 h, surpassing the noble metal-based benchmarks (Pt/C + Ir/C). This study is expected to open new avenues for designing hybrid materials with modulated electronic environment and interface chemistry for electrocatalytic applications and beyond.

Improving the Magnetic Properties of Electrodeposited Fe-55wt%Ni Alloy via Abnormal Grain Growth Induced by Second-Phase Particles

In this study, pulse reverse current electrodeposition was employed to fabricate Fe-55 wt%Ni alloy. Abnormal grain growth induced by the precipitation of second-phase particles during annealing resulted in a coarse-grained electrodeposited Fe-55 wt%Ni alloy. The grain evolution process during annealing was investigated, and the temperature for abnormal grain growth was determined through the high-temperature confocal microscopy technique. Subsequently, the mechanism of abnormal grain growth was investigated. The results suggest that abnormal grain growth occurs at approximately 1003 K, attributed to the preferential growth of (110) oriented grains due to local strain energy changes caused by the precipitation and coarsening of the second-phase particles (MnS). The preferred orientation of the grains transitioned from (111) to (110). Annealing at 1073 K for 2 h resulted in an average grain size increase to approximately 200 μm. Under these conditions, the magnetic properties of the alloy reached optimal levels, with a magnetization saturation strength of 186.7 emu g−1 and a coercivity of less than 1 Oe. This research presents a novel approach to preparing coarse-grained electrodeposited Fe-Ni alloys, significantly enhancing their magnetic properties.

The role of phase fraction on the deformation behavior and tensile properties of dual-phase polycrystalline Fe–Ni alloy: A molecular dynamics simulation study

An alloy containing two or more phases with significantly distinct properties may produce a unique combination of high strength and ductility. Fe–Ni alloys processed through the powder metallurgy route form dual-phase structures containing both body- and face-centered cubic phases. The detailed atomic scale microstructural evolution and deformation mechanism of such alloys have not been performed as dual-phase structure materials generate more complex deformation mechanisms than single-phase structure materials. The present study utilizes molecular dynamics simulation to compute the mechanical properties and investigate the deformation mechanism in a dual-phase Fe–Ni alloy with a variable phase fraction of body-centered cubic during a uniaxial tensile test. The results show that phase fraction affects the mechanical properties as well as the deformation behavior. Shear strain distribution and dislocation density provided an explanation for the change in the average flow stress and strengthening mechanism of the dual-phase Fe–Ni alloys. Additionally, the influence of temperature on deformation behavior is investigated. The deformation mechanism at higher temperatures is found to be dislocation slip and grain boundary sliding.

Electrochemical development and characterisation of nanostructured Ni–Fe alloy coatings for corrosion protection

ABSTRACT Nanostructured Ni–Fe alloy coatings were developed galvanostatically using a new low-concentration bath. The composition and operating parameters of the bath were optimised by taking the benefit of the conventional Hull cell method. Ni–Fe alloy coatings were developed at different current densities (2.0 to 5.0 A dm−2), keeping pH = 2.5. The corrosion behaviour of electrodeposited alloy coatings was evaluated in 3.5% NaCl solution, using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarisation methods. Ni–Fe alloy coating, deposited at 2.0 A dm−2 exhibited a lesser corrosion rate (14.71 × 10−2 mm y−1) than those at higher current densities. The lowest corrosion rate was attributed to its least crystallite size (10.4 nm), evidenced by an X-Ray Diffraction (XRD) study. The corrosion performance of Ni–Fe alloy coatings was discussed in the light of their surface morphology and composition, evidenced by SEM and Energy-Dispersive X-ray spectroscopy (EDS) analysis, respectively.