Nickel Nitride Research Articles

Design of cobalt nickel nitrides/carbon nitride composite catalysts for enhanced electrochemical water splitting

Design of efficient non-noble metal electrocatalysts for oxygen evolution reaction (OER) have been considered as a crucial issue in the development of future renewable energy utilization. In this paper, we report a composite structure of cobalt nickel nitrides and carbon nitrides as efficient OER electrocatalysts. A facile hydrothermal method was utilized to synthesize the precursors, then the samples were treated with melamine and heated in an N2 atmosphere. The successful preparation of the cobalt nitride nickel/carbon nitride composite catalysts was confirmed by SEM, XRD, and the OER electrochemical performance characterizations. The Co2NiNx/CN catalyst demonstrate an optimal electrocatalytic performance with an overpotential of 0.62 V to reach the current density of 10 mA/cm2, which is lower than that of Ni3N, Ni3N/CN and Co2NiNx. The Tafel slope of Co2NiNx/CN catalyst is only 83.68 mV/dec. The significantly improved electrocatalytic ability is owing to the synergetic effect of cobalt incorporation and imbedding of carbon nitride. The electrochemical impedance spectroscopy characteristics were further investigated to understand the mechanism of the novel non-noble metal electrocatalysts with high efficiency.

Nickel-Cobalt Hydrogen Phosphate on Nickel Nitride Supported on Nickel Foam for Alkaline Seawater Electrolysis.

Developing high-performance non-noble bifunctional catalysts is pivotal for large-scale seawater electrolysis but remains a challenge. Here we report a sandwichlike NiCo(HPO4)2@Ni3N/NF (denoted by NiCoHPi@Ni3N/NF) catalyst. Vertical Ni3N nanosheet arrays are first grown and supported on nickel foam, and then a bimetallic NiCoHPi coating is decorated on Ni3N nanosheets by one-step electrodeposition. The hierarchical sandwich like structure offers a large surface area and plenty of catalytic active sites, and the coupling of interconnected Ni3N and NiCoHPi accelerates the electron transfer. Moreover, the surficial hydrogen phosphate ions contribute to a proper OH- absorption capacity due to the Lewis acid-base reaction. As a result, the NiCoHPi@Ni3N/NF catalyst exhibits good OER and HER activity, requiring overpotentials of 365 mV (for OER) and 174 mV (for HER) to deliver 100 mA cm-2 in the alkaline simulated seawater electrolyte. When assembled the NiCoHPi@Ni3N/NF catalyst as both the anode and cathode, it only needs 1.86 V to reach 100 mA cm-2 in alkaline simulated seawater electrolyte. This work may inspire the design and exploration of self-supported hierarchical composite electrocatalysts for hydrogen production from the electrolysis of seawater.

Epitaxially Grown Ru Clusters–Nickel Nitride Heterostructure Advances Water Electrolysis Kinetics in Alkaline and Seawater Media

The epitaxial heterostructure can be rationally designed based on the in situ growth of two compatible phases with lattice similarity, in which the modulated electronic states and tuned adsorption behaviors are conducive to the enhancement of electrocatalytic activity. Herein, theoretical simulations first disclose the charge transfer trend and reinforced inherent electron conduction around the epitaxial heterointerface between Ru clusters and Ni3N substrate (cRu‐Ni3N), thus leading to the optimized adsorption behaviors and reduced activation energy barriers. Subsequently, the defect‐rich nanosheets with the epitaxially grown cRu‐Ni3N heterointerface are successfully constructed. Impressively, by virtue of the superiority of intrinsic activity and reaction kinetics, such unique epitaxial heterostructure exhibits remarkable bifunctional catalytic activity toward electrocatalytic OER (226 mV @ 20 mA cm−2) and HER (32 mV @ 10 mA cm−2) in alkaline media. Furthermore, it also shows great application prospect in alkaline freshwater and seawater splitting, as well as solar‐to‐hydrogen integrated system. This work could provide beneficial enlightenment for the establishment of advanced electrocatalysts with epitaxial heterointerfaces.

Interface engineering of in−situ formed nickel hydr(oxy)oxides on nickel nitrides to boost alkaline hydrogen electrocatalysis

Highly efficient platinum−group−metal (PGM) free catalysts for alkaline hydrogen oxidation reaction (HOR) are of vital issues for the development of alkaline hydroxide exchange membrane fuel cells (HEMFCs). Herein, with the help of interface engineering by the in−situ electrochemical surface reconfiguration strategy, the seamless nickel nitrides-nickel hydr(oxy)oxide (denoted as Ni3N−Ni(OH)2) heterostructures were developed. From the systematic electrochemical measurements, the impressive HOR performance such as nearly zero onset overpotential, larger exchange current density, excellent long−term durability, and robust CO tolerance in alkaline media, are obtained by the optimized Ni3N−Ni(OH)2 catalyst, thus rendering it significant potential for applications in HEMFCs. Furthermore, this catalyst also exhibits superior HER activity, approaching to that of Pt/C catalyst. The tailored d band center of Ni and the enhanced hydroxyl adsorption ability at Ni3N−Ni(OH)2 heterojunctions are evidenced by the comprehensive spectroscopy and electrochemical analyses, which are favorable for the accelerated Volmer step toward alkaline hydrogen electrocatalysis.

Interfacial engineering of heterojunction copper-cobalt-nickel nitride as binder-free electrode for efficient water splitting

Good interfacial compatibility is essential to grow intermetallic compound layer on the surface of substrates for the potential application of electrocatalytic reactions. Here, an interface strategy is proposed to prepare a free-standing copper-cobalt-nickel nitride electrode，in which copper-cobalt-nickel nitride is anchored on hydrophilic treated nickel foam. Compared to bi-metal hierarchical catalysts, the as-fabricated epitaxial heterostructure shows excellent oxygen evolution reaction (OER) activity with an ultralow overpotential of 190 mV, as well as an overpotential of 63 mV for hydrogen evolution reaction (HER) at the current density of 10 mA cm–2. Most importantly, the modified tri-metal nitrides exhibit improved interfacial compatibility due to the interfacial defects, which can increase electron transport across the junction during the catalytic reactions. Density functional theory calculations reveal that the synergistic effect between copper, cobalt, and nickel nitride creates a proper electronic structure that lowers the reaction barriers of HER/OER.

Engineering Metallic Heterostructure Based on Ni3 N and 2M-MoS2 for Alkaline Water Electrolysis with Industry-Compatible Current Density and Stability.

Alkaline water electrolysis is commercially desirable to realize large-scale hydrogen production. Although nonprecious catalysts exhibit high electrocatalytic activity at low current density (10-50mAcm-2 ), it is still challenging to achieve industriallyrequired current density over 500mAcm-2 due to inefficient electron transport and competitive adsorption between hydroxyl and water. Herein, the authors design a novel metallic heterostructure based on nickel nitride and monoclinic molybdenum disulfide (Ni3 N@2M-MoS2 ) for extraordinary water electrolysis. The Ni3 N@2M-MoS2 composite with heterointerface provides two kinds of separated reaction sites to overcome the steric hindrance of competitive hydroxyl/water adsorption. The kinetically decoupled hydroxyl/water adsorption/dissociation and metallic conductivity of Ni3 N@2M-MoS2 enable hydrogen production from Ni3 N and oxygen evolution from the heterointerface at large current density. The metallic heterostructure is proved to be imperative for the stabilization and activation of Ni3 N@2M-MoS2 , which can efficiently regulate the active electronic states of Ni/N atoms around the Fermi-level through the charge transfer between the active atoms of Ni3 N and MoMo bonds of 2M-MoS2 to boost overall water splitting. The Ni3 N@2M-MoS2 incorporated water electrolyzer requires ultralow cell voltage of 1.644V@1000mAcm-2 with ≈100% retention over 300h, far exceeding the commercial Pt/C║RuO2 (2.41V@1000mAcm-2 , 100h, 58.2%).

Precious-Group-Metal-Free Energy-Efficient Urea Electrolysis: Membrane Electrode Assembly Cell Using Ni3N Nanoparticles as Catalyst

The sluggish kinetics of the anodic oxygen evolution reaction (OER) limit the overall efficiency of green hydrogen production. The proposed strategy to overcome this is to replace OER with other kinetically favorable anodic reactions like urea oxidation reaction (UOR). Herein, we develop an organometallic synthesis of nickel nitride nanoparticles supported on carbon (Ni3N–C) as the catalyst for both UOR and hydrogen evolution reaction (HER). A precious group metal-free electrolyzer based on Ni3N–C catalyst (as both anode and cathode) is implemented for the first time, and the urea electrolyzer cell has a 200 mV lower overpotential compared to that of the water electrolyzer.

Quantifying the Proportion of Active Sites Following Different Urea Oxidation Reaction Pathways Over Highly Efficient Nickel Nitride

Quantifying the Proportion of Active Sites Following Different Urea Oxidation Reaction Pathways Over Highly Efficient Nickel Nitride

Features of Machining Rotor Shafts of Diesel Engine Turbochargers with a Multilayer-Coated Tool

Introduction. The paper presents the results of experimental studies of power parameters when hard alloy steels are machined with tools, the cutting units of which have multilayer hard, heat-resistant and wear-resistant coatings. The obtained data will make it possible to optimize machining hard-to-machine materials. Materials and Methods. The aim of the study is to measure the power parameters of turning products and to create experimental formulas of power parameters for different technological modes. For this purpose, a special measuring multicomponent complex was used to estimate the influence of the mode parameters on the change in the cutting force components. Results. The numerically controlled machine tool was retooled by combining it with a three-component dynamometer and tooling. The cutting unit of the tool was coated with a multi-layer hard, heat-resistant and wear-resistant coating. The tool was equipped with instruments connected to a personal computer for measuring and processing experimental data. According to the results of the study, there have been obtained graphical dependences and empirical formulas, which take into account the influence of the mode parameters on the cutting force components when machining the units of alloy steels of high hardness, heat resistance and wear resistance. Discussion and Conclusion.The study allowed us to obtain experimental formulas of cutting force components for different mode parameters when machining parts by the tool equipped with cutting plates. The plates are coated with multilayer hard and wear-resistant coatings of titanium carbonitride, aluminum oxide and nickel nitride. The coating increases significantly the hardness, heat and wears resistance of the tool cutting unit and provides quality machining.

Microfabrication of the Ammonia Plasma-Activated Nickel Nitride–Nickel Thin Film for Overall Water Splitting in the Microfluidic Membraneless Electrolyzer

Hydrogen production in the microfluidic alkaline membraneless electrolyzer (μAME) marks a new paradigm in sustainable energy technology. One challenge in this field is implementing a bifunctional catalyst to catalyze hydrogen evolution reaction and oxygen evolution reaction using methods compatible with microfabrication techniques. Herein, the scalable synthesis, micropatterning, and performance of a nickel nitride (Ni3N/Ni) bifunctional catalyst are demonstrated. Microfabrication is used to pattern Ni microelectrodes, and nitridation and N–H grafting of the electrodes—which also act as the catalysts—are achieved by ammonia plasma. These electrodes are incorporated into the μAME device, and the electrolyte flow rate is optimized to maximize gas product separation. The μAME is operated in a two-electrode configuration exhibiting a current density of 263.73 mA cm–2 at 2.5 V and a stable 6 h operation for overall water splitting. The μAME performance efficiency is 99.86%, with a current density of 150 mA cm–2. Gas chromatography of the electrolysis products revealed no gas cross-over across the electrodes. Volumetric collection efficiencies of 97.72% for H2 and 96.14% for O2 are obtained. The performance of the μAME is comparable to a membrane-based electrolyzer operating under stringent conditions of high temperature (60–80 °C) and extreme electrolyte pH (30–40 wt % KOH).

In situ N K-edge XANES study of iron, cobalt and nickel nitride thin films.

A prototype in situ X-ray absorption near-edge structure (XANES) system was developed to explore its sensitivity for ultra-thin films of iron-nitride (Fe-N), cobalt-nitride (Co-N) and nickel-nitride (Ni-N). They were grown using DC-magnetron sputtering in the presence of an N2 plasma atmosphere at the experimental station of the soft XAS beamline BL01 (Indus-2, RRCAT, India). XANES measurements were performed at the N K-edge in all three cases. It was found that the N K-edge spectral shape and intensity are greatly affected by increasing thickness and appear to be highly sensitive, especially in low-thickness regions. From a certain thickness of ∼1000 Å, however, samples exhibit a bulk-like behavior. On the basis of the obtained results, different growth stages were identified. Furthermore, the presence of a molecular N2 component in the ultra-thin regime (<100 Å) was also obtained in all three cases studied in this work. In essence, this prototype insitu system reveals that N K-edge XANES is a powerful technique for studying ultra-thin films, and the development of a dedicated in situ system can be effective in probing several phenomena that remain hitherto unexplored in such types of transition metal nitride thin films.

Theoretical Insights into the Hydrogen Evolution Reaction on the Ni3N Electrocatalyst

Ni-based catalysts are attractive alternatives to noble metal electrocatalysts for the hydrogen evolution reaction (HER). Herein, we present a dispersion-corrected density functional theory (DFT-D3) insight into HER activity on the (111), (110), (001), and (100) surfaces of metallic nickel nitride (Ni3N). A combination of water and hydrogen adsorption was used to model the electrode interactions within the water splitting cell. Surface energies were used to characterise the stabilities of the Ni3N surfaces, along with adsorption energies to determine preferable sites for adsorbate interactions. The surface stability order was found to be (111) &lt; (100) &lt; (001) &lt; (110), with calculated surface energies of 2.10, 2.27, 2.37, and 2.38 Jm−2, respectively. Water adsorption was found to be exothermic at all surfaces, and most favourable on the (111) surface, with Eads = −0.79 eV, followed closely by the (100), (110), and (001) surfaces at −0.66, −0.65, and −0.56 eV, respectively. The water splitting reaction was investigated at each surface to determine the rate determining Volmer step and the activation energies (Ea) for alkaline HER, which has thus far not been studied in detail for Ni3N. The Ea values for water splitting on the Ni3N surfaces were predicted in the order (001) &lt; (111) &lt; (110) &lt; (100), which were 0.17, 0.73, 1.11, and 1.60 eV, respectively, overall showing the (001) surface to be most active for the Volmer step of water dissociation. Active hydrogen adsorption sites are also presented for acidic HER, evaluated through the ΔGH descriptor. The (110) surface was shown to have an extremely active Ni–N bridging site with ΔGH = −0.05 eV.

Hydrogen-Mediated Thin Pt Layer Formation on Ni3N Nanoparticles for the Oxygen Reduction Reaction.

A simple wet-chemical route for the preparation of core-shell-structured catalysts was developed to achieve high oxygen reduction reaction (ORR) activity with a low Pt loading amount. Nickel nitride (Ni3N) nanoparticles were used as earth-abundant metal-based cores to support thin Pt layers. To realize the site-selective formation of Pt layers on the Ni3N core, hydrogen molecules (H2) were used as a mild reducing agent. As H2 oxidation is catalyzed by the surface of Ni3N, the redox reaction between H2 and Pt(IV) in solution was facilitated on the Ni3N surface, which resulted in the selective deposition of Pt on Ni3N. The controlled Pt formation led to a subnanometer (0.5-1 nm)-thick Pt shell on the Ni3N core. By adopting the core-shell structure, higher ORR activity than the commercial Pt/C was achieved. Electrochemical measurements showed that the thin Pt layer on Ni3N nanoparticle exhibits 5 times higher mass activity and specific activity than that of commercial Pt/C. Furthermore, it is expected that the proposed simple wet-chemical method can be utilized to prepare various transition-metal-based core-shell nanocatalysts for a wide range of energy conversion reactions.

Advanced Carbon-Nickel Sulfide Hybrid Nanostructures: Extending the Limits of Battery-Type Electrodes for Redox-Based Supercapacitor Applications.

Transition-metal sulfides combined with conductive carbon nanostructures are considered promising electrode materials for redox-based supercapacitors due to their high specific capacity. However, the low rate capability of these electrodes, still considered “battery-type” electrodes, presents an obstacle for general use. In this work, we demonstrate a successful and fast fabrication process of metal sulfide–carbon nanostructures ideal for charge-storage electrodes with ultra-high capacity and outstanding rate capability. The novel hybrid binder-free electrode material consists of a vertically aligned carbon nanotube (VCN), terminated by a nanosized single-crystal metallic Ni grain; Ni is covered by a nickel nitride (Ni3N) interlayer and topped by trinickel disulfide (Ni3S2, heazlewoodite). Thus, the electrode is formed by a Ni3S2/Ni3N/Ni@NVCN architecture with a unique broccoli-like morphology. Electrochemical measurements show that these hybrid binder-free electrodes exhibit one of the best electrochemical performances compared to the other reported Ni3S2-based electrodes, evidencing an ultra-high specific capacity (856.3 C g–1 at 3 A g–1), outstanding rate capability (77.2% retention at 13 A g–1), and excellent cycling stability (83% retention after 4000 cycles at 13 A g–1). The remarkable electrochemical performance of the binder-free Ni3S2/Ni3N/Ni@NVCN electrodes is a significant step forward, improving rate capability and capacity for redox-based supercapacitor applications.

Tailoring charge and mass transport in cation/anion-codoped Ni3N / N-doped CNT integrated electrode toward rapid oxygen evolution for fast-charging zinc-air batteries

Searching for the highly active and low cost electrocatalysts with fast-charging capability for rechargeable zinc-air batteries are paramount in terms of their commercial-scale application. Here, we propose an innovative cation/anion-codoped nickel nitrides (FC-Ni3N) along with creating 3D architecture by integrating N-doped carbon nanotubes (NCNT), which is found to be an outstanding bifunctional oxygen electrocatalyst for Zn-air batteries with ultrafast charging rate (Potential =2.02V at 50 mA cm−2 with area capacity of 4 mAh cm−2) and long cycling life (700 cycles at 20 mA cm−2). Through varying the cation/anion moiety, the optimal FC-Ni3N/NCNT shows low overpotential of 260 mV at 10 mA cm−2 and Tafel slope of 46 mV dec−1, much outperforming the RuO2 benchmark with overpotential of 337 mV and Tafel slope of 91 mV dec−1. The extraordinary oxygen evolution reaction performance (corresponding to the charge process) stems from the simultaneous regulation of charge- and mass-transport kinetics in air electrodes. The proposed strategy and results may pave the way for promoting commercial application of rechargeable zinc-air batteries or other metal-air batteries.

Pressure-induced disordering of site occupation in iron–nickel nitrides

Controlled disordering of substitutional and interstitial site occupation at high pressure can lead to important changes in the structural and physical properties of iron–nickel nitrides. Despite important progress that has been achieved, structural characterization of ternary Fe–Ni–N compounds remains an open problem owing to the considerable technical challenges faced by current synthetic and structural approaches for fabrication of bulk ternary nitrides. Here, iron–nickel nitride samples are synthesized as spherical-like bulk materials through a novel high-pressure solid-state metathesis reaction. By employing a wide array of techniques, namely, neutron powder diffraction, Rietveld refinement methods combined with synchrotron radiation angle-dispersive x-ray diffraction, scanning electron microscopy/energy dispersive x-ray spectroscopy, and transmission electron microscopy, we demonstrate that high-temperature and high-pressure confinement conditions favor substitutional and interstitial site disordering in ternary iron–nickel nitrides. In addition, the effects of interstitial nitrogen atoms and disorderly substituted nickel atoms on the elastic properties of the materials are discussed.

Current-Driven Domain Wall Dynamics in Ferrimagnetic Nickel-Doped Mn4N Films: Very Large Domain Wall Velocities and Reversal of Motion Direction across the Magnetic Compensation Point.

Spin-transfer torque (STT) and spin-orbit torque (SOT) are spintronic phenomena allowing magnetization manipulation using electrical currents. Beyond their fundamental interest, they allow developing new classes of magnetic memories and logic devices, in particular based on domain wall (DW) motion. In this work, we report the study of STT-driven DW motion in ferrimagnetic manganese nickel nitride (Mn4-xNixN) films, in which magnetization and angular momentum compensation can be obtained by the fine adjustment of the Ni content. Large domain wall velocities, approaching 3000 m/s, are measured for Ni compositions close to the angular momentum compensation point. The reversal of the DW motion direction, observed when the compensation composition is crossed, is related to the change of direction of the angular momentum with respect to that of the spin polarization. This is confirmed by the results of ab initio band structure calculations.

Activity origin and alkalinity effect of electrocatalytic biomass oxidation on nickel nitride

Electro-oxidation of 5-hydroxymethylfurfural (HMFOR) is a promising green approach to realize the conversion of biomass into value-added chemicals. However, considering the complexity of the molecular structure of HMF, an in-depth understanding of the electrocatalytic behavior of HMFOR has rarely been investigated. Herein, the electrocatalytic mechanism of HMFOR on nickel nitride (Ni3N) is elucidated by operando X-ray absorption spectroscopy (XAS), in situ Raman, quasi in situ X-ray photoelectron spectroscopy (XPS), and operando electrochemical impedance spectroscopy (EIS), respectively. The activity origin is proved to be Ni2+δN(OH)ads generated by the adsorbed hydroxyl group. Moreover, HMFOR on Ni3N relates to a two-step reaction: Initially, the applied potential drives Ni atoms to lose electrons and adsorb OH− after 1.35 VRHE, giving rise to Ni2+δN(OH)ads with the electrophilic oxygen; then Ni2+δN(OH)ads seizes protons and electrons from HMF and leaves as H2O spontaneously. Furthermore, the high electrolyte alkalinity favors the HMFOR process due to the increased active species (Ni2+δN(OH)ads) and the enhanced adsorption of HMF on the Ni3N surface. This work could provide an in-depth understanding of the electrocatalytic mechanism of HMFOR on Ni3N and demonstrate the alkalinity effect of the electrolyte on the electrocatalytic performance of HMFOR.

Stable and Highly Efficient Hydrogen Evolution from Seawater Enabled by an Unsaturated Nickel Surface Nitride.

Electrocatalytic production of hydrogen from seawater provides a route to low-cost and clean energy conversion. However, the hydrogen evolution reaction (HER) using seawater is greatly hindered by the lack of active and stable catalysts. Herein, an unsaturated nickel surface nitride (Ni-SN@C) catalyst that is active and stable for the HER in alkaline seawater is prepared. It achieves a low overpotential of 23mV at a current density of 10mA cm-2 in alkaline seawater electrolyte, which is superior to Pt/C. Compared to conventional transition metal nitrides or metal/metal nitride heterostructures, the Ni-SN@C has no detectable bulk nickel nitride phase. Instead, unsaturated NiN bonding on the surface is present. In situ Raman measurements show that the Ni-SN@C performs like Pt with the ability to generate hydronium ions in a high-pH electrolyte. The catalyst operation is then demonstrated in a two-electrode electrolyzer system, coupling with hydrazine oxidation at the anode. Using this system, a cell voltage of only 0.7V is required to achieve a current density of 1 A cm-2 .

Phase relations, and mechanical and electronic properties of nickel borides, carbides, and nitrides from ab initio calculations.

Based on density functional theory and the crystal structure prediction methods, USPEX and AIRSS, stable intermediate compounds in the Ni–X (X = B, C, and N) systems and their structures were determined in the pressure range of 0–400 GPa. It was found that in the Ni–B system, in addition to the known ambient-pressure phases, the new nickel boride, Ni2B3-Immm, stabilizes above 202 GPa. In the Ni–C system, Ni3C-Pnma was shown to be the only stable nickel carbide which stabilizes above 53 GPa. In the Ni–N system, four new phases, Ni6N-R3̄, Ni3N-Cmcm, Ni7N3-Pbca, and NiN2-Pa3̄, were predicted. For the new predicted phases enriched by a light-element, Ni2B3-Immm and NiN2-Pa3̄, mechanical and electronic properties have been studied.