Ni Phase Research Articles

High temperature (up to 1200 °C) thermal-mechanical stability of Si and Ni doped CrN framework coatings

High temperature thermal-mechanical stability of tribological thin coatings is extremely important to a large number of applications in modern industries. DC magnetron sputtering of single metallic element (Cr, Si) and alloy (Ni:Cr) targets formed transition metal nitrides film coatings, CrSiN and CrNiN onto M2 steel. High temperature in-situ synchrotron X-ray diffraction, in the range 25 °C–700 °C, obtained experimental data for a range of structural and mechanical properties. Furthermore, experimental room temperature Nanoindentation measurements, made before and after the in-situ heating cycle, provided corresponding hardness and shear modulus results. The structural results identified microstructure and phase transformation changes, while the mechanical results identified microstrain, hardness, elastic modulus and deformation resistance properties of the coatings. Density functional theory (DFT) and quasi-harmonic approximation (QHA) modelled the high temperature thermal and mechanical properties such as: Young's modulus, shear modulus and thermal expansion coefficients (populated up to 1200 °C). Estimates of hardness are made by correlating the bulk phase hardness and shear modulus, of the CrN and Ni phases, as a function of temperature. Results indicate that Si doping enhances the hardness of the CrN framework, increasing from 29 to 36 GPa and improves the coatings elastic modulus, and resistance to deformation. However the addition of Ni reduced these properties. Furthermore, formation of (Cr,Si)N and Ni(Cr) solid solutions is inferred from DFT, Rietveld and lattice constant analysis.

Effect of interface orientation on the adhesion strength and fracture toughness of Ni/CrN interfaces by first-principles study

The brittleness and relatively poor adhesion properties of CrN materials have been extensively addressed by developing Ni/CrN composites with a separate Ni phase. However, conditions at the Ni/CrN interfaces, which are the key features leading to the enhanced toughness, remain poorly understood. The present work addresses this issue by investigating the effect of interface orientation on adhesion strength and fracture toughness of Ni/CrN interfaces using first-principles calculations. To this end, we build seven Ni/CrN interface models, including Ni(100)/CrN(100), Ni(110)/CrN(110), Ni(110)/CrN(111), and Ni(111)/CrN(111), with different interface orientation and stacking orders. The results demonstrate that the interface orientation plays a predominant role in determining the mechanical properties of the Ni/CrN interfaces, while the effect of stacking order can be neglected. The Ni(111)/CrN(111) interface is demonstrated to provide the greatest adhesion strength, interfacial stability, and fracture toughness among the Ni/CrN interfaces considered, and is therefore the preferred orientation for Ni/CrN composite applications.

Excellent glass former Ni[formula omitted]Nb[formula omitted] crystallizing under combined shear and ultra-high pressure

Study of condensed matter in certain extreme conditions allows one to better understand the mechanisms of microscopic structural transformations and to develop materials with completely new mechanical properties. In the present work, we study the structure and crystallization kinetics of bulk metallic glass (BMG) Ni62Nb38. We show that this BMG is rapidly crystallized under the combined effect of shear deformation and ultrahigh pressure. A threshold pressure required to initiate the formation of a stable crystalline phase is revealed. Shear deformation and pressure lead to the phase separation: two high-density inhomogeneous crystal structures are formed. We find that the crystallization of this BMG occurs in two stages due to the significant difference in the growth rates of Ni and Nb crystalline phases. The results of the present study make a significant contribution to understanding the crystallization and amorphization features of Ni-based BMG’s.

Microstructure and mechanical properties in TLP joint of FeCoNiTiAl alloy and IC10 superalloy using Mn-Ni-Cr filler

A filler metal of Mn-Ni-Cr was used to transient liquid phase (TLP) bonding high-entropy alloy (HEA) of FeCoNiTiAl and Ni3Al base IC10 superalloy for 10 min ~ 120 min at 1150 °C and a pressure of 2 MPa. There was no diffusion affected zone (DAZ) existed in the bonded zone as the filler material Mn-Ni-Cr contained no conventional melting-point depressants (MDPs) of Si/B. Hence, the TLP joint was composed of two isothermally solidified zones (ISZs) and an athermally solidified zone (ASZ). The ISZ beside IC10 consisted of strip Ni(Al, Mn) phases, resulted from the diffusion of Al atoms, and only γ-(Ni, Mn) phases formed in another ISZ adjacent to HEA base metal (BM). Moreover, sluggish diffusion of HEA can prevent the BM from dissolving and formed a straight bond line consisting of “(Hf, Ta)C + Al0.89Mn1.1” compound in the interface between HEA and bonded zone. Furthermore, increase of bonding time can lead to enrichment of Al in the bonded zone and induce composition segregation during solidification. A compound of “Ni(Al, Mn) + Ni3Ta” formed in ASZ of joint bonded for 30 min ~ 120 min. Hardness results revealed that formations of Ni(Al, Mn) phases and the compounds in ASZ can cause the alternant hardness distribution of valley and peak across the joint and lead to the generation of stress concentration. Therefore, the maximum shear strength, 269.9 MPa, was achieved in the joint dwelled for a period of 10 min.

In-Operando Observations of Ni-YSZ Patterned Fuel Electrodes Under SOFC and SOEC Operations

Solid oxide cells (SOCs), both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC), have being attracting more and more attention due to its high energy conversion efficiency and fuel flexibility. However, degradation of fuel electrodes after long-term operation remains as one of the main challenges for their commercial application. In particular, migration and coarsening of nickel (Ni) in Ni - yttria-stabilized zirconia (Ni-YSZ) fuel electrodes have strong impacts on the decreases in both active three-phase boundary (TPB) and Ni network connectivity, which result in performance deterioration. One of the mechanisms proposed as an explanation of Ni migration is Ni transport via volatile Ni(OH)x species, so-called evaporation-condensation mechanism [1]. On the other hand, Jiao and Shikazono [2] proposed a model to explain Ni spreading on YSZ surface based on the variation of Ni-YSZ wettability which is modified by the oxygen adsorption. Nevertheless, further investigations are required to understand the mechanisms of Ni migration. In the present study, Ni-film patterned electrodes which can provide well defined TPB configurations are used to investigate the Ni-YSZ degradation under SOFC, SOEC and sequential SOFC and SOEC operations, i.e. reversible operation (RSOC). The edge of sputtered Ni-film contacting with open YSZ surface can be treated as active TPB during operation. Confocal laser scanning microscopy (CLSM, Keyence, VK-X 1000) is used, which enabled in-operando observation of the real-time local morphological change at active TPB [3]. The in-operando potentiostatic experiment was carried out inside a high temperature chamber which was kept at 800oC with 4% H2O-4% H2-92% N2 as fuel gas and 30% O2-70% N2 as oxidant as shown in Fig. 1(a). The correlations between the Ni morphological changes and cells’ electrochemical performances were investigated. The Ni phase dynamically spread and de-percolated only under the SOFC operation, while such a phenomenon was not observed during the SOEC operation, as shown in Figs. 1(c), (d) and (e). Ni coarsening occurred regardless of the operation modes. The competition between Ni-film spreading and breaking-up finally determined the complicated local morphological change and corresponding cell performance variation. The time variations of active TPB and current density showed good correlation as shown in Fig. 1(b). Real-time in-operando observations revealed different Ni migration under SOFC, SOEC and RSOC operations, which may provide new insights for the understanding of Ni-YSZ fuel electrode degradation.Fig. 1. (a) Schematic illustration of in-operando setup. (b) Correlation between current density and Ni morphological evolution. (c)-(e) CLSM images and 3D surface height contour maps of the yellow-frame-enclosed areas after SOFC, SOEC and RSOC modes, respectively.

Structural, morphological and magnetic properties of Ni/NiO systems produced by a sorbitol-assisted wet chemical method

In this work, we show the sorbitol-assisted synthesis method to produce polycrystalline Ni/NiO systems with different phase proportions. The samples were prepared from heat treatment of an aqueous solution of nickel chloride and sorbitol by using a simple wet chemical approach. The produced samples were calcined at 500 °C and the characterization of the as-produced samples was performed by X-ray diffraction (XRD), Rietveld analysis and scanning electron microscopy (SEM). Magnetic properties of Ni/NiO samples were investigated by DC magnetometry technique. XRD data reveal an increase in the proportion of metallic Ni phase in the synthesis products as the quantity of sorbitol in the starting solution is increased. Multi-phase Rietveld analysis showed that the phase fractions in the samples varied from 5.9 wt% (94.1 wt%) to 22.5 wt% (77.5 wt%) for Ni (NiO) phase. SEM analyses show changes in particle shape and size when sorbitol increases. The increase in the magnetization with increasing of Ni phase content up to at 65 kOe is assigned to the increase of the ferromagnetic (FM) phase.

Anodic polarization creates an electrocatalytically active Ni anode/electrolyte interface and mitigates the coarsening of Ni phase in SOFC

An intimate Ni anode/electrolyte interface is vital for the performance and operating stability of solid oxide fuel cells, while the interface is greatly influenced under anodic polarization conditions. Here for the first time Ni anodes are directly assembled on 8 mol% Y2O3-stabilized ZrO2 (YSZ) electrolyte without high temperature sintering process, and the interface formation between Ni anode and YSZ electrolyte is studied at varied anodic polarization currents at 800 °C. The results show that an intimate anode/electrolyte interface can be created by applying anodic polarization current, leading to remarkably enhanced electrocatalytic activity and operating stability. The major reason of enhanced stability is ascribed to the mitigated microstructure coarsening of Ni anodes due to the strong interfacial bonding induced by the anodic polarization. The present findings shed lights on rational design of Ni based anode/electrolyte interface by tuning the anodic polarization.

Effect of CeO2 addition on microstructure and tribological characteristics of laser cladded Cu10Al–MoS2 coating under oil lubrication

In order to improve the friction and wear properties of Cu10Al–MoS2 coating, the addition of CeO2 is one of the present research hot spots. In this work, Cu10Al–MoS2 coatings with different CeO2 mass fractions were successfully fabricated on Q235 steel using a laser cladding. The microstructure and phase compositions of obtained coatings were analyzed using an ultra-depth of field microscope and X-ray diffraction, respectively. The friction-wear test was carried out under oil lubrication using a ball-on-disk wear tester, and the effects of CeO2 mass fraction on the microstructure, hardness, and friction-wear properties were studied, and the wear mechanism was also discussed. The results show that the laser cladded Cu10Al–MoS2 coatings with the different CeO2 mass fractions were mainly composed of Cu9Al4, Cu, AlFe3, Ni, MoS2, and CeO2 phases. The Vickers-hardness (HV) of Cu10Al–8MoS2–3CeO2, Cu10Al–8MoS2–6CeO2, and Cu10Al–8MoS2–9CeO2 coatings was 418, 445, and 457 HV0.3, respectively, which indicates an increase in hardness with the increase of CeO2 mass fraction. The average coefficients of friction (COF) and wear rates decrease with the increase of CeO2 mass fraction, presenting the outstanding friction reduction and wear resistance performances. The wear mechanism of Cu10Al–MoS2 coatings is changed from abrasive wear with slight fatigue wear to abrasive wear with the increase of CeO2 mass fraction.

Stability of Nickel/Scandia-Doped-Stabilized-Zirconia Composite Anode Under High Fuel Utilization Conditions

Stability of nickel/scandia-doped-stabilized-zirconia (Ni/ScSZ) composite anode under high pH2O condition was investigated. Electrolyte supported cell with ScSZ electrolyte and Ni/ScSZ anode was operated at 700oC for 500 h by feeding mixture of H2/H2O/N2 as a fuel. Under 10%H2-40%H2O-50%N2, Sc diffused out of the ScSZ grain and dissolved into the adjacent Ni phase. Condensation of Sc in the Ni grain was enhanced by the application of current density of 0.5 A/cm2.

PROPERTIES OF ALUMINIUM/ELECTROLESS Ni-COATED SiC COMPOSITES - A REVIEW

The combination of properties of Al/SiC composites make them very attractive materials for applications in automotive and aerospace industries. Several techniques are used in developing Al/SiC composites but stir casting process is most commonly used because it is the simplest and cost effective technique. However, composites produced via stir casting suffer from limitations such as low wettability and inadequate bonding between the molten Al & SiC particulates and the formation of degrading interfacial products like aluminum carbide (Al4C3) which degrades the mechanical properties of the composite. Some of the techniques to improve Al-SiC wettability include addition of surface active elements such as magnesium, heat treatment of particles and application of metallic coating on the reinforcements before addition to the melt. Wetting agents alter the composition of the matrix alloy, while heat treatment of the reinforcement does not completely prevent the formation of Al4C3 when utilized. To reduce the direct interaction and promote wetting between reinforcements and molten aluminum during processing, the surface of SiC particulates can be modified by coating via oxidation, sol-gel and electroless processes. Of all these methods, electroless nickel deposition produces the best coatings with uniform thickness and adequate strength. In the present study, influence of electroless nickel-coating of SiC on the mechanical, corrosion and microstructural properties of Al/SiC composite has been evaluated. Finally, it can be concluded that the Ni and Ni3P intermetallic phases produced via electroless coating improves the wettability between the SiC and molten aluminium leading to enhanced properties of the composite.

Pengaruh Waktu Milling Terhadap Sifat Desorpsi Material Penyimpan Hidrogen MgH2-Ni Melalui Teknik Mechanical Alloying

Hydrogen is a renewable energy source that can be used as a fuel and as an alternative to fossil fuels. Solid storage media in solid form are safer to use than liquid (-253 oC) or gaseous media (700 bar) media. To store hydrogen in a solid medium, it requires a metal able to interact with hydrogen . Magnesium is one of the metals which can form metal hybrids based on MgH2 which is capable of absorbing hydrogen up to (7.6wt%). However, the reaction kinetics for magnesium are very slow, it takes at least 60 minutes to absorb hydrogen and the operating temperature is always very high (300 oC). Several attempts have been made to add the catalytic converter and milling time. Hydrogen storage material based on MgH2 with a 10wt%Ni catalyst was successfully synthesized using a mechanical alloy technique with time variations of 2 hours, 5 hours, and 10 hours. From the results of the X-ray diffraction schema at a diffraction angle of 2θ=37.87o, it shows the presence of a MgH2 phase, Ni phase is at a diffraction angle of 61.85o, the diffraction peak also shows that there was a widening of the diffraction peak with increasing milling time, this explains that there was a reduction in the size of the crystal. When calculating with the Schereer method, the crystal size of the material reaches 10 nm. The results of the DSC test indicated a decrease in temperature of 383 oC in 41 minutes with a milling time of 10 hours.

The ‘Green’ Ni-UGSO Catalyst for Hydrogen Production under Various Reforming Regimes

A new spinelized Ni catalyst (Ni-UGSO) using Ni(NO3)2·6H2O as the Ni precursor was prepared according to a less material intensive protocol. The support of this catalyst is a negative-value mining residue, UpGraded Slag Oxide (UGSO), produced from a TiO2 slag production unit. Applied to dry reforming of methane (DRM) at atmospheric pressure, T = 810 °C, space velocity of 3400 mL/(h·g) and molar CO2/CH4 = 1.2, Ni-UGSO gives a stable over 168 h time-on-stream methane conversion of 92%. In this DRM reaction optimization study: (1) the best performance is obtained with the 10–13 wt% Ni load; (2) the Ni-UGSO catalysts obtained from two different batches of UGSO demonstrated equivalent performances despite their slight differences in composition; (3) the sulfur-poisoning resistance study shows that at up to 5.5 ppm no Ni-UGSO deactivation is observed. In steam reforming of methane (SRM), Ni-UGSO was tested at 900 °C and a molar ratio of H2O/CH4 = 1.7. In this experimental range, CH4 conversion rapidly reached 98% and remained stable over 168 h time-on-stream (TOS). The same stability is observed for H2 and CO yields, at around 92% and 91%, respectively, while H2/CO was close to 3. In mixed (dry and steam) methane reforming using a ratio of H2O/CH4 = 0.15 and CO2/CH4 = 0.97 for 74 h and three reaction temperature levels (828 °C, 847 °C and 896 °C), CH4 conversion remains stable; 80% at 828 °C (26 h), 85% at 847 °C (24 h) and 95% at 896 °C (24 h). All gaseous streams have been analyzed by gas chromatography. Both fresh and used catalysts are analyzed by scanning electron microscopy-electron dispersive X-ray spectroscopy (SEM-EDXS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) coupled with mass spectroscopy (MS) and BET Specific surface. In the reducing environment of reforming, such catalytic activity is mainly attributed to (a) alloys such as FeNi, FeNi3 and Fe3Ni2 (reduction of NiFe2O4, FeNiAlO4) and (b) to the solid solution NiO-MgO. The latter is characterized by a molecular distribution of the catalytically active Ni phase while offering an environment that prevents C deposition due to its alkalinity.

Time-resolved dynamics of laser-induced cavitation bubbles during production of Ni nanoparticles via pulsed laser ablation in different solvents and their electrocatalytic activity for determination of toxic nitroaromatics

In this study, the dynamics of laser-induced cavitation bubbles (LICBs) during pulsed laser ablation (PLA) of a nickel (Ni) target in different solvents was investigated by measuring the time-resolved formation of LICBs utilizing an intensified charge-coupled device (ICCD) camera. Intriguingly, it was found that the lifetime of LICBs depended on the liquid environment (i.e., methanol, deionized water, hexane, and acetonitrile). It was also determined that the phases of the Ni nanoparticles (NPs) were strongly defined by the lifetime of the LICBs during PLA. Specifically, a face-centered cubic (fcc)/hexagonal closest packed (hcp) mixed Ni phase and pure fcc Ni NPs were formed in the presence of LICBs exhibiting short and long lifetimes, respectively. The prepared Ni NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HRTEM). Following fabrication on a glassy carbon electrode (GCE), the obtained Ni NPs were employed as electrochemical sensors for toxic 4-nitrophenol (4-NP) detection. The electrocatalytic behavior was examined by cyclic voltammetry (CV). The CV profiles showed a linear increase in the peak current with increasing concentration of 4-NP from 20 to 150 μM. The fcc/hcp Ni structure displayed enhanced sensitivity, electrochemical performance (0.4040 μA μM−1 cm−2), and limit of detection (LOD) (0.66 μM) compared to the pure fcc Ni phase (0.2956 μA μM−1 cm−2 and 1.72 μM, respectively). This was predominantly attributed to the presence of more electrocatalytically active surface sites in the multiphase structure. The current study provides a concise explanation of the selective formation of Ni NPs with specific crystal phases during PLA in various solvents. Notably, the fabricated fcc/hcp Ni structure demonstrated potential for application as an electrochemical sensor.

An experimental study of Ni-Mo adsorbent for reactive adsorption desulfurization of spent tire pyrolysis oil modelled using n-hexane and thiophene

The reactive adsorption desulfurization (RADS) of a model spent tire pyrolysis oil, using n-hexane as the hydrocarbon fuel and thiophene as the sulfur-bearing compound, over a co-precipitated nickel-molybdenum (Ni-Mo) adsorbent was examined. The percentage of sulfur removal, indicating the efficacy of the adsorbent, was evaluated in a continuous fixed-bed reactor operating over a range of conditions including reaction time (1–10 h), temperature (250–300 °C), pressure (0.2–1 MPa), and hydrogen to sulfur (H:S) molar ratio (14–108). The fresh, reduced, and spent adsorbents were characterized by elemental analyzer and ICP-OES for the element contents, BET for the surface area and pore properties, SEM for the morphology, STEM-EDS for the element distributions, and XRD for the change of Ni, Mo, and S mineral phases in the adsorbent with the change of reaction time. The Ni-Mo adsorbent achieved a high percentage of sulfur removal of 99.9 wt% under mild reaction conditions of 300 °C, 1 MPa, and 108 H:S molar ratio. The corresponding breakthrough sulfur capacity of the adsorbent was 288 mg g−1. Increasing reaction temperature, pressure, or H:S molar ratio led to a greater percentage of sulfur removal. Ni and Mo played cooperative and multifunctional roles in the RADS process, firstly as sulfur acceptors, then as active centers for hydrodesulfurization (HDS). The Ni and MoS2 phases formed during the RADS process functioned as highly effective HDS catalyst cycles, which improved the sulfur transfer rate and facilitated the continuation of sulfur removal.

Synchrotron X-ray diffraction studies of the phase-specific deformation in additively manufactured Ni–CrC composites

Cold spray is a promising solid-state additive manufacturing process for the fabrication of metal matrix composites in the forms of coatings, and more recently, bulk materials, particularly when deposition of two phases is needed with minimal alterations of the chemistry and phase composition. While prior studies have reported improved mechanical performance in cold sprayed composites, a fundamental understanding of the response and contribution of individual constituent phases to the collective mechanical properties of the composite is yet to be developed. In this work, we use in-situ synchrotron X-ray diffraction to study the strain partitioning between the soft and hard phases in cold sprayed Ni–CrC bulk composites. We conduct stepwise uniaxial tensile loading experiments and use high energy X-ray diffraction at multiple load steps to measure phase-specific strains and stresses upon loading. We find neither plasticity in the Ni phase nor a significant load transfer or redistribution between Ni and CrC phases during the loading process and attribute them to a premature failure governed by the presence of defects.

Effects of hyper-high-temperature solid-solution treatment on microstructure evolution and nanoprecipitation of the Al-Ni-Cu-Fe-Zr-Sc alloy manufactured by selective laser melting

The novel selective laser melting (SLM) Al-Ni-Cu-Fe-Zr-Sc alloy has high temperature stability, but the segregation of the melting pool boundary limits its potential applications. Because conventional heat treatment with a solid solution at 530 °C is inappropriate for the SLM Al-Ni-Cu-Fe-Zr-Sc alloy, this study used hyper-high-temperature solid-solution treatment at three temperatures (560, 570, and 580 °C for 1 h) to investigate the evolution of the melting pool structure. An artificial aging treatment was applied at 175 °C for 6 h to investigate the precipitation mechanism. The results indicated that as-printed presented a bimodal microstructure consisting of a coarse-grained (CG) region and a fine-grained (FG) region. The hyper-high-temperature solid-solution treatment promoted the decomposition of the melting pool boundary and expansion of FG region. The FG region was composed of Ni-, Cu-, and Fe-rich equiaxed grains. After aging treatment, Al9Fe(Cu)Ni and Al3(Sc, Zr) nano-scale strengthening phases could be found in the FG region. The decomposition of the melting pool boundary, bimodal microstructure, and nano-scale phases can strengthen the matrix and increase hardness. In addition, the mechanism of element diffusion in melting pool was also explored to confirm that heat treatment can reduce material deterioration caused by boundary precipitation. These characteristics mitigate the disadvantages of the SLM Al-Ni-Cu-Fe-Zr-Sc alloy in terms of its strength directionality and establish its potential for use in aerospace applications.

Dopant Redistribution, Phase Propagation, and Electrochemical Properties of Co-Free Layered Cathodes

With the increasing demand for higher energy density in Li-ion battery applications, the development of Ni-based layered oxide cathodes has been focused on increasing the Ni content. However, higher Ni content gives rise to structural and thermal instability of the cathodes and potential safety concerns in applications. The battery community has made great efforts to achieve better battery performance, with manipulating the doping chemistry and engineering the microstructure being two of the most popular yet not well-understood methods.[1–6] Recent studies suggest that manipulating the dopant distribution is effective to improve cathode stability and battery performance.[1,7] However, the prediction of dopant distribution patterns primarily relies on thermodynamics-based theoretical calculations. Therefore, there is strong research need to understand the kinetic factors by experimentally investigating the dopant distribution, local chemical and structural changes and their interplay in the practical synthesis. In this presentation, we will first discuss our recent progress in probing dopant redistribution, phase propagation, and local chemical changes in the synthesis of layered oxide battery cathodes. Then we will show that these multiscale doping strategies enhance the electrochemical performance of Co-free layered cathodes by improving the cycling stability, rate capability, thermal stability, and self-discharge resistance.We investigated the dopant distribution, phase propagation and local chemical changes in the synthesis of layered oxide cathodes at multiple length scales using multielement-doped LiNiO2 as a platform. We observed that dopants Mg and Ti diffuse dynamically from the surface to the bulk of cathode particles below 300 °C long before the formation of layered phase. After calcination, Ti is still enriched at the cathode particle surface while Mg has a relatively uniform distribution throughout cathode particles. We also observed that Ni oxidation completes earlier at the particle surface than in the bulk. Ni oxidation and phase propagation are heterogeneous at the mesoscale and exhibit in two forms- radial heterogeneity and mosaic-like heterogeneity, which vary with calcination conditions. Globally, phase transformation takes place from the initial mixed hydroxide phase to the layered phase through a metal oxide-liked intermediate phase. We probed the layered cathode synthesis at multiple length scales in single particle, as well as at ensemble-averaged electrode scale, which connects the local materials properties with the global electrochemical behavior. These findings enrich the understanding of multiscale layered cathode formation and can potentially inform the cathode design, such as dopant distribution and 3D chemical homogeneity.Ultimately, the resulting materials deliver a material-level specific energy of ∼780 W h/kg at C/10 with 96% retention after 50 cycles, and ~680 Wh/kg with 77% retention after 300 cycles. The dopants reduce the Li/vacancy ordering and mitigate the irreversible phase transformations. Ni dissolution is suppressed due to enhanced interfacial stability. The multielement-doped LiNiO2 also shows higher thermal stability, increased self-discharge resistance, and enhanced Li+ kinetics. Our promising battery performance suggests that there is a large space to manipulate the three-dimensional distribution of dopants to improve the stability of LiNiO2.

SiC nanoparticles incorporation in electroless NiP-Graphene oxide nanocomposite coatings

The presence of SiC nanoparticles within the Graphene oxide (GO) incorporated electroless deposited NiP layers (NiP-GO) on carbon steel substrate was studied in this work. The effect of co-deposition of GO nanoplatelets and/or SiC nanoparticles on the morphology and structure of the heat-treated NiP coatings were investigated by scanning electron microscope and X-ray diffraction, respectively. The results revealed that the heat-treated NiP and NiP–SiC coatings consisted of Ni and Ni3P phases, whereas the NiP-GO also contains the intermediated Ni2P and Ni12P5 metastable phases due to the incomplete precipitation of Ni3P. Such metastable phases are significantly decreased by the incorporation of SiC nanoparticles in NiP-GO coatings. The mechanical properties of the coatings were characterized by microhardness measurement and “pin on disk” wear test. The corrosion tests were conducted in aqueous 3.5 %wt NaCl using electrochemical measurement for Ni–P, NiP-GO, NiP–SiC, and NiP-GO-xSiC coatings. By co-deposition of SiC nanoparticles, the hardness of NiP-GO is significantly increased and the wear loss is reduced, especially at a high sliding distance during the wear test. The corrosion behavior of the NiP-GO coatings containing different amounts of SiC nanoparticles has been investigated.

Effect of Synthesis Method of Nickel–Samarium-Doped Ceria Anode on Distribution of Triple-Phase Boundary and Electrochemical Performance

Two-dimensional (2D) electron back scattered diffraction (EBSD) is a powerful tool for microstructural characterization of crystalline materials. EBSD enables visualization and quantification of the effect of synthesis methods on the microstructure of individual grains, thus correlating the microstructure to mechanical and electrical efficiency. Therefore, this work was designed to investigate the microstructural changes that take place in the Ni-SDC cermet anode under different synthesis methods, such as the glycine–nitrate process (GNP) and ball-milling. EBSD results revealed that different grain size and distribution of Ni and SDC phases considerably influenced the performance of the Ni–SDC cermet anodes. The performance of the Ni–SDC cermet anode from GNP was considerably higher than that of Ni-SDC from ball-milling, which is attributed to the triple-phase boundary (TPB) density and phase connectivity. Due to the poor connectivity between the Ni and SDC phases and the development of large Ni and SDC clusters, the Ni-SDC cermet anode formed by ball milling had a lower mechanical and electrical conductivity. Moreover, the Ni–SDC cermet anode sample obtained via GNP possessed sufficient porosity and did not require a pore former. The length and distribution of the active TPB associated with phase connectivity are crucial factors in optimizing the performance of Ni-SDC cermet anode materials. The single cell based on the Ni–SDC composite anode prepared through GNP exhibited a maximum power density of 227 mW/cm2 and 121 mW/cm2 at 800 °C in H2 and CH4, respectively.

Three-dimensional Nanoporous Cu-Doped Ni Coating as Bifunctional Electrocatalyst for Hydrazine Sensing and Hydrogen Evolution Reaction

Developing a cost-effective and efficient bifunctional electrocatalyst with simple synthesis strategy for hydrazine sensing and H evolution reaction (HER) is of utmost importance. Herein, a three-dimensional porous Cu-doped metallic Ni coating on Ti mesh (Ni(Cu) coating/TM) was successfully electrodeposited by a facile electrochemical method. Electrochemical etching of the electrodeposited Ni(Cu) coating with metallic Ni and Cu mixed phase on a Ti mesh contributed to the formation of a three-dimensional porous Cu-doped metallic Ni coating. Owing to the large specific surface area and enhanced electroconductivity caused by the porous structure and Cu doping, respectively, the developed Ni(Cu) coating/TM exhibited superior hydrazine sensing performance and electrocatalytic activity toward hydrogen evolution reaction (HER). The Ni(Cu) coating/TM electrode presented a good sensitivity of 3909 μA mM−1 cm−2 and two relatively broad linear ranges from 0.004 mM to 2.915 mM and from 2.915 mM to 5.691 mM as well as a low detection limit of 1.90 μM. In addition, the Ni(Cu) coating/TM required a relatively low HER overpotential of 140 mV to reach −10 mA cm−2 and exhibited robust durability in alkaline solution. The excellent hydrazine electrooxidation and HER performance guarantee its promising application in hydrazine detection and energy conversion.