Nickel Molybdenum Research Articles

Nickel-nitride composite: An eco-friendly and efficient alternative to platinum for electrocatalytic hydrogen production

Water electrolysis using the hydrogen evolution reaction (HER) is a promising method for sustainable hydrogen production. Platinum-based catalysts have traditionally been the most efficient HER catalysts, but their scarcity and sluggish water dissociation limit their practical applications. Here we report on a novel superhydrophilic catalyst of nickel supported on nickel molybdenum nitride (Ni/Ni0.8Mo4.2N6) that outperforms platinum-based nanomaterials. Despite the low catalytic activity of Ni or Ni0.8Mo4.2N6 alone, their optimized composite exhibits exceptional HER activity, with respective 500% and 150% increases in the exchange current and turnover frequency compared to commercial Pt/C. Density of states calculations reveal a decrease in electron density of the supported nickel in Ni/Ni0.8Mo4.2N6, leading to a lower free energy of the HER. These findings demonstrate a powerful electron-engineering strategy for designing supported electrocatalysts with outstanding performance for the HER and related processes.

Anchoring cobalt molybdenum nickel alloy nanoparticles on molybdenum dioxide nanosheets as efficient and stable self-supported catalyst for overall water splitting at high current density

Developing bifunctional electrocatalysts with efficient and stable catalytic performance at high current density to improve the productivity of water splitting is important for relieving the environmental pollution and energy crisis. Herein, the Ni4Mo and Co3Mo alloy nanoparticles were anchored on MoO2 nanosheets (H-NMO/CMO/CF-450) by annealing the NiMoO4/CoMoO4/CF (CF: self-made cobalt foam) under Ar/H2 atmosphere. Benefitting from the nanosheets structure, synergistic effect of the alloys, existence of oxygen vacancy and the cobalt foam with smaller pore sizes as conductive substrate, the self-supported H-NMO/CMO/CF-450 catalyst demonstrates outstanding electrocatalytic performance, which delivers small overpotential of 87 (270) mV at 100 (1000) mA·cm−2 for HER and 281 (336) mV at 100 (500) mA·cm−2 for OER in 1 M KOH. Meanwhile, the H-NMO/CMO/CF-450 catalyst is used as working electrodes for overall water splitting, which just require 1.46 V @ 10 mA·cm−2 and 1.71 V @ 100 mA·cm−2, respectively. More importantly, the H-NMO/CMO/CF-450 catalyst can stabilize for 300 h at 100 mA·cm−2 in both HER and OER. This research provides an idea for the preparation of stable and efficient catalysts at high current density.

Ultrafast Thermal Synthesis of Non-Noble Metal-Based Electrocatalysts for Overall Water Splitting

Non-noble metal-based electrocatalysts have attracted extensive interest due to their low-cost, earth-abundance, and highly efficient catalytic performance as alternatives to noble metal counterparts. However, conventional approaches to synthesize electrocatalysts can endure overlong synthesis time with throughput degradation. Here, we demonstrate an ultrafast thermal method to synthesize non-noble metal-based electrocatalysts for overall water splitting. The method can be extensively used for metal-based catalysts, including metal oxides, metal carbides, alloys, and their composites. Among them, we select two outstanding electrocatalysts as examples for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hybrid structure of nickel oxides and molybdenum carbides on activated carbon felt (Ni–Mo@ACF) for HER shows remarkable catalytic activity with a low overpotential of 87 mV and an excellent durability for 48 h at a current density of 10 mA cm–2. The NiFe alloy nanosheets on activated carbon felt (NiFe@ACF) for OER show superb catalytic activity with a low overpotential of 270 mV and great durability for 48 h at a current density of 10 mA cm–2. Consequently, an overall water splitter assembled with Ni–Mo@ACF as the cathode and NiFe@ACF as the anode only requires a low cell voltage of 1.60 V to drive a current density of 10 mA cm–2 with excellent durability for 36 h, which is the best among non-noble metal-based electrocatalysts reported so far. This work offers an approach for the ultrafast and facile synthesis of non-noble metal-based electrocatalysts for water splitting and other applications.

A Low‐Cost Ni–Mo Electrocatalyst for Highly Efficient Hydrogen and Oxygen Evolution Reaction

Electrocatalytic water splitting provides an effective way to store electrical energy (i.e., solar and wind energy) intermittently. It is believed that developing electrocatalysts with excellent stability, high catalytic efficiency, and abundant natural reserves is the key to the industrialization of electrochemical water splitting. Herein, nickel–molybdenum electrocatalyst formed on the surface of a low‐cost etched stainless‐steel mesh via a one‐step electrodeposition method exhibits a low hydrogen evolution overpotential of 53 mV and oxygen evolution overpotential of 261 mV at a current density of 10 mA cm−2 due to the synergistic effect of nickel and molybdenum. Moreover, the as‐prepared catalyst demonstrates superior hydrogen evolution reaction (HER) catalytic performance than commercial Pt/C at current density exceed 200 mA cm−2. The electrocatalyst also shows excellent HER and oxygen evolution reaction stabilities at high current density attribute to the tightly bond between electrocatalyst and the etched stainless‐steel mesh, as well as the surface reconstruction of catalyst during the cycle test. The facile electrodeposition method has lower requirements on production equipment, using stainless steel mesh as the basement reduces the production cost, the nickel–molybdenum alloy possesses excellent electrolytic water splitting performance and stability. These results indicate that this work can provide an idea for the industrialization of electrochemical water splitting.

Biowax Production from the Hydrotreatment of Refined Palm Oil (RPO)

In this study, conditions were determined to obtain a solid wax with a waxy ester content of more than 25% from the hydrotreating of palm oil. The experiments were conducted in a pilot-scale fixed-bed reactor. The influence of temperature, liquid hourly space velocity (LHSV), and pressure on the conversion of triglycerides were evaluated using a nickel molybdenum catalyst (NiMo/Al2O3). The variables were evaluated between 240 and 260 °C, 1 and 2 h−1 and 41 and 55 bar, respectively. Based on these results, the best conditions were T:240–260 °C; P: 90 bar; LHSV: 1.5 h−1; hydrogen/oil ratio 472 LN/L with a conversion around 60 wt%; and a selectivity towards waxy esters of 40 wt%. These conditions were then validated with a second catalyst (NiMoB/Al2O3), yielding a triglyceride conversion of about 60 wt% and a waxy ester concentration of around 30 wt%.

Nickel Molybdenum Bimetallic Nitrides as Efficient Catalysts for the Hydrodeoxygenation of Methyl Palmitate

AbstractHighly efficient catalysts play an important role in the effective use of biomass oil to produce clean fuel. In this work, pure‐phase Ni−Mo bimetallic nitrides (Ni2Mo3N and Ni3Mo3N) with different stoichiometric ratios are prepared by temperature‐programmed nitridation of the metal oxide precursors in ammonia, which are investigated in the hydrodeoxygenation of methyl palmitate in the fixed‐bed reactor at moderate conditions. The physical and chemical properties of catalysts were evaluated by H2‐TPR, XRD, SEM, TEM, XPS, and CO chemisorption. The Ni2Mo3N catalyst presents the best methyl palmitate hydrogenation activity (con.%=95.4 %) and the maximum hexadecane selectivity (95.0 %), which is obviously higher than those of Ni3Mo3N and Mo2N catalysts. By introducing transition metal Ni into the Mo2N lattice to form nickel‐molybdenum bimetallic nitride, the lattice structure and electronic structure of the Mo active center have been changed, which greatly enhances the hydrodeoxygenation performances for the transformation of biomass oil to clean fuel.

Search for the Optimal Soaking Temperature for Hyperquenching of the Gx2crnimocun 25-6-3-3 Duplex Cast Steel

The paper presents the research results on duplex corrosion-resistant chromium–nickel–molybdenum cast steel of the GX2CrNiMoCuN 25-6-3-3 grade. The aim was to determine the effect of the soaking temperature for the hyperquenching process Tp, that is, 950 to 1200 °C, on the microstructure and mechanical properties, that is UTS tensile strength, the yield strength, HB Brinell hardness, the elongation EL and impact strength KV of the steel, cast under industrial conditions with the minimum content of Cr, Ni, Mo and Cu according to the PN-EN 10283 standard. On the basis of the results, it was confirmed that the hyperquenching guarantees the elimination of the brittle intermetallic phase in the steel microstructure. In addition, the most favorable strength-to-ductility ratio of the steel with an almost equal amount of austenite γ and ferrite α in its microstructure was obtained using the soak temperature of 1080 °C, which was considered optimal for the above-mentioned duplex cast steel.

Phase-controllable NixMoyPz dual-cocatalyst regulates electron transfer for enhanced photocatalytic hydrogen evolution

The rational design and construction of low-cost nickel molybdenum phosphides (NixMoyPz) cocatalysts for hydrogen evolution have aroused wide concern in recent years. However, NixMoyPz involves so many stoichiometric compositions with various crystal phase, thus, fabricating NixMoyPz with excellent hydrogen evolution activity and revealing their intrinsic mechanism at atomic level become crucial problems. Herein, a novel phase-controllable phosphating method by reasonably introducing various amounts of PH3 deriving from red phosphorus is firstly proposed to synthesize NiMoP/ZnxCd1-xS (NMP/ZCS), NiMoP/NiMoP2/ZnxCd1-xS (NMPP2/ZCS) and NiMoP2/ZnxCd1-xS (NMP2/ZCS) photocatalysts. The experimental and theoretical results reveal that this novel NMPP2 dual-cocatalyst maximumly accelerates photoelectrons transfer into the outmost layer of NMP2 component, meanwhile, under the intense synergy among NiMoP and NiMoP2 components, NMPP2 dual-cocatalyst further promotes the dissociation of H2O and the desorption of hydrogen proton. Accordingly, the optimized NMPP2/ZCS heterojunction reveals the best photocatalytic hydrogen evolution (PHE) efficiency of 83.54 mmol h−1 g−1 without an evident decrease after 6 cycles of photocatalytic tests in the Na2S-Na2SO3 solution, which is 25.55, 1.6 and 1.24 times higher than these of Pt/ZCS, NMP/ZCS and NMP2/ZCS, respectively. This tactic hews out a new way for optimizing photocatalysis by the construction of dual-cocatalyst to enhance the activity of PHE.

Boosting flame retardancy of thermoplastic polyurethane: Synergistic effect of nickel phosphide nanoparticles and molybdenum disulfide nanosheets

AbstractFor the first time, a novel nanohybrid based on nickel phosphide (Ni2P) nanoparticles and molybdenum disulfide (MoS2) nanosheets was facilely synthesized for enhancing flame retardancy and smoke suppression of thermoplastic polyurethane (TPU). The synergistic effect on flame retardancy is proposed. TPU composite with 2 wt% Ni2P/MoS2 hybrid exhibits the best overall flame retardancy, while TPU composites with the same amount of individual Ni2P nanoparticles and MoS2 nanosheets are average in performance. Specifically, the 41.2% reduction of peak heat release rate (PHRR) is achieved for TPU/Ni2P/MoS2 composite, which is only 16.8% and 26.4% for TPU/Ni2P and TPU/MoS2 composites, respectively. In addition, a more intact protective char layer of TPU/Ni2P/MoS2 composite can be observed. These results clearly suggest the synergistic effect between Ni2P nanoparticles and MoS2 nanosheets. It is hypothesized that physical barrier effect and chemical catalytic ability of Ni2P/MoS2 hybrid contribute to the dramatic reduction of heat release and smoke production. The strategy proposed here is a simple yet efficient approach to fabricate high‐performance MoS2‐based flame retardants.

Facile one-step hydrothermal route to MSe/Mo3Se4 (M: Zn, Mn, and Ni)-based electrode materials for ultralong-life hybrid supercapacitors

Transition metal selenides have attracted great interest in electrochemical energy storage applications because of their good electrochemical activity and conductivity properties. Herein, we reported the metal molybdenum selenide (MSe/Mo3Se4 (M: Zn, Mn, and Ni)) electrode materials on their morphological and electrochemical properties by varying the metal ions via a facile hydrothermal technique. The effects of the structural, morphological, and surface area properties of the prepared powder materials on their electrochemical performance were studied. Owing to the hierarchical porous and unique interconnected structure, the nickel molybdenum selenide nanosheet spheres (NMS NSSs)-based electrode material delivered an excellent specific capacity value of 252 mAh g–1 at a current density of 1 A g–1. Moreover, the optimized NMS NSSs electrode exhibited outstanding cycling stability with a capacity retention of 80% and a corresponding coulombic efficiency of 99% after 80,000 cycles. Additionally, a pouch-type hybrid supercapacitor (HSC) device was assembled using NMS NSSs material as a positive electrode and activated carbon as a negative electrode in 1 M aqueous KOH electrolyte. Furthermore, the assembled HSC device exhibited superior energy and power density values as well as magnificent cycling stability. For real-time practical applications, light-emitting diodes and a digital display were powered using two series-connected HSC devices. Therefore, the obtained tremendous results strongly suggest that the NiSe/Mo3Se4 NSSs-based materials could be a promising electrode for ultralong-life energy storage applications.

Nitrogen-Doped Porous Nickel Molybdenum Phosphide Sheets for Efficient Seawater Splitting.

Hydrogen is emerging as an alternative clean fuel; however, its dependency on freshwater will be a threat to a sustainable environment. Seawater, an unlimited source, can be an alternative, but its salt-rich nature causes corrosion and introduces several competing reactions, hindering its use. To overcome these, a unique catalyst composed of porous sheets of nitrogen-doped NiMo3 P (N-NiMo3 P) having a sheet size of several microns is designed. The presence of large homogenous pores in the basal plane of these sheets makes them catalytically more active and ensures faster mass transfer. The introduction of N and Ni into MoP significantly tunes the electronic density of Mo, surface chemistry, and metal-non-metal bond lengths, optimizing surface energies, creating new active sites, and increasing electrical conductivity. The presence of metal-nitrogen bonds and surface polyanions increases the stability and improves anti-corrosive properties against chlorine chemistry. Ultimately, the N-NiMo3 P sheets show remarkable performance as it only requires overpotentials of 23 and 35mV for hydrogen evolution reaction, and it catalyzes full water splitting at 1.52 and 1.55V to achieve 10mA cm-2 in 1m KOH and seawater, respectively. Hence, structural and compositional control can make catalysts effective in realizing low-cost hydrogen directly from seawater.

Photovoltaics literature survey (No. 181)

Photovoltaics literature survey (No. 181)

In Situ Growth of Nickel-Cobalt Metal Organic Frameworks Guided by a Nickel-Molybdenum Layered Double Hydroxide with Two-Dimensional Nanosheets Forming Flower-Like Struc-Tures for High-Performance Supercapacitors.

Metal organic frameworks (MOFs) are a kind of porous coordination polymer supported by organic ligands with metal ions as connection points. They have a controlled structure and porosity and a significant specific surface area, and can be used as functional linkers or sacrificial templates. However, long diffusion pathways, low conductivity, low cycling stability, and the presence of few exposed active sites limit the direct application of MOFs in energy storage applications. The targeted design of MOFs has the potential to overcome these limitations. This study proposes a facile method to grow and immobilize MOFs on layered double hydroxides through an in situ design. The proposed method imparts not only enhanced conductivity and cycling stability, but also provides additional active sites with excellent specific capacitance properties due to the interconnectivity of MOF nanoparticles and layered double hydroxide (LDH) nanosheets. Due to this favorable heterojunction hook, the NiMo-LDH@NiCo-MOF composite exhibits a large specific capacitance of 1536 F·g-1 at 1 A·g-1. In addition, the assembled NiMo-LDH@NiCo-MOF//AC asymmetric supercapacitor can achieve a high-energy density value of 60.2 Wh·kg-1 at a power density of 797 W·kg-1, indicating promising applications.

In Situ Synthesis of Nanorod Arrays of Nickel–Molybdenum Nitrides as Stable Electrocatalysts for Hydrogen Evolution Reactions

The development of cheap and highly active electrocatalysts for efficient water splitting is crucial for the production of green hydrogen at a low cost. In this work, we proposed a two-step method including hydrothermal and nitridation reactions to in situ synthesize NiMoN nanorod arrays with abundant active sites and a fast electron transfer rate on nickel foam substrate. The optimal tailoring of the Ni/Mo ratio leads to a high concentration of active Mo3+ species and suitable Ni doping content in the NiMoN catalyst, which shows superior hydrogen evolution reaction performance. The overpotentials at the current densities of 10 and 100 mA/cm2 are only 20 and 46 mV, which are better than those of the most reported NiMoN-based catalysts and even the commercial benchmark material of Pt/C. Additionally, the electrocatalyst also shows excellent long-term stability after 24 h tests at densities of 10 and 100 mA/cm2, possessing great potential for industrial applications for water splitting to produce hydrogen.

Исследование фазовых превращений в двухслойном жаростойком покрытии Ti–Al–C+Y–Al–O на жаропрочном никелевом сплаве

Currently, an active increase in requirements for fuel efficiency and specific gravity of aircraft turbojet engines is observed. Existing coatings based on zirconium dioxide intended for protecting engine parts are largely outdated and have exhausted their development potential, so new ceramic systems for the production of protective coatings based on them are an area of research. The authors carried out a study of a heat-resistant two-layer coating based on the Y–Al–O system (outer layer) and the Ti2AlC MAX phase of the Ti–Al–C system (sublayer) produced using vacuum-arc deposition on the Inconel 738 heat-resistant nickel alloy and molybdenum by alternate deposition of layers based on Ti–Al–C and a Y–Al–O layer. Using synchrotron radiation, phase transformations in the coating were examined when samples were heated to 1400 °C in a vacuum and to 1100 °C in the atmosphere to study the process of oxidation and coating formation in the presence of oxygen. Using scanning electron microscopy, the authors studied the microstructure and chemical composition of the coating. The study identified that heating the coating in a vacuum and in the atmosphere causes various phase transformations in it, but in both cases, the formation of a mixture of oxides of the Y–Al–O group and destabilization of the Ti–Al–C-based sublayer are observed. After heating the coating in the atmosphere without preliminary heat treatment, the coating was destroyed upon cooling, which was not observed when the coating was heated in a vacuum.

Rational construction of porous marigold flower-like nickel molybdenum phosphates via ion exchange for high-performance long-lasting hybrid supercapacitors

The assembled hybrid supercapacitor device using the urea-based nickel molybdenum phosphate nanopetals embedded microspheres electrode exhibits outstanding long-term cycling stability, demonstrating its practical applications.

Rational nitrogen alloying in nickel–molybdenum nitride can mediate efficient and durable alkaline hydrogen evolution

A controlled amount of nitrogen is introduced into the NiMo alloy to obtain a bimetallic nitride with improved activity and stability, resulting in a stability of over 50 h at a current density of 1.0 A cm−2 under 2.17 V in an anion membrane flow cell.

Inverse 'intra-lattice' charge transfer in nickel-molybdenum dual electrocatalysts regulated by under-coordinating the molybdenum center.

The prevalence of intermetallic charge transfer is a marvel for fine-tuning the electronic structure of active centers in electrocatalysts. Although Pauling electronegativity is the primary deciding factor for the direction of charge transfer, we report an unorthodox intra-lattice 'inverse' charge transfer from Mo to Ni in two systems, Ni73Mo alloy electrodeposited on Cu nanowires and NiMo-hydroxide (Ni : Mo = 5 : 1) on Ni foam. The inverse charge transfer deciphered by X-ray absorption fine structure studies and X-ray photoelectron spectroscopy has been understood by the Bader charge and projected density of state analyses. The undercoordinated Mo-center pushes the Mo 4d-orbitals close to the Fermi energy in the valence band region while Ni 3d-orbitals lie in the conduction band. Since electrons are donated from the electron-rich Mo-center to the electron-poor Ni-center, the inverse charge transfer effect navigates the Mo-center to become positively charged and vice versa. The reverse charge distribution in Ni73Mo accelerates the electrochemical hydrogen evolution reaction in alkaline and acidic media with 0.35 and 0.07 s-1 turnover frequency at -33 ± 10 and -54 ± 8 mV versus the reversible hydrogen electrode, respectively. The corresponding mass activities are 10.5 ± 2 and 2.9 ± 0.3 A g-1 at 100, and 54 mV overpotential, respectively. Anodic potential oxidizes the Ni-center of NiMo-hydroxide for alkaline water oxidation with 0.43 O2 s-1 turnover frequency at 290 mV overpotential. This extremely durable homologous couple achieves water and urea splitting with cell voltages of 1.48 ± 0.02 and 1.32 ± 0.02 V, respectively, at 10 mA cm-2.

The Combination of Nickel Oxide (NiO) and Molybdenum Trioxide (MoO3) for Pollutant Gas Detection

The Combination of Nickel Oxide (NiO) and Molybdenum Trioxide (MoO3) for Pollutant Gas Detection

Self-supported molybdenum nickel oxide catalytic electrode designed via molecular cluster-mediated electroplating and electrochemical activation for an efficient and durable oxygen evolution reaction.

Efficient and durable nonprecious catalysts for the oxygen evolution reaction (OER) are crucial for practical water electrolysis for hydrogen production. A self-supported OER catalytic electrode with sufficient exposure of the catalyst and tight anchoring onto the current collector is vital for the catalytic activity and stability, and is therefore deemed to be a preferable tactic to enhance water electrolysis performance. Herein, a polyoxometalate (POM) molecular cluster-mediated electroplating and activation tactics are proposed to design a self-supported molybdenum nickel oxide (MoNiOx) catalytic electrode for the OER. The MoNiOx active layer can anchor tightly onto the Ni foam current collector with sufficient surface exposure and high structural stability, therefore enabling high alkali OER catalytic efficiency (222mV at 10mAcm-2) and robust durability (only slight decay in catalytic efficiency upon 12days of chronopotentiometry (V-t) test). Moreover, the easily processable electroplating and active protocol can serve as a general approach to prepare other OER catalytic electrodes by altering the reactants and current collectors. The current work paves a facile and universal way to design a highly active and durable molybdenum (Mo) based hybrid catalytic electrode for OER via molecular cluster-assisted electroplating and activation treatment.