Ni 3s Research Articles

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. III. LiNi0.6Co0.2Mn0.2O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated LiNi0.6Co0.2Mn0.2O2 powder obtained from Ecopro Company, Ltd. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with Ni 2p, Co 2p, Mn 2p, Ni LMM, O 1s, C 1s, Ni 3s, Co 3s, Mn 3s, Ni 3p, Co 3p, Li 1s, and Mn 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals. Making use of the O 1s, Ni 3p, Co 3p, Mn 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surface of LiNi0.2Co0.05Mn0.1O0.7.

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. IV. LiNi0.5Co0.2Mn0.3O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy (XAES) were used to analyze two lots of untreated LiNi0.5Co0.2Mn0.3O2 powder and one of the two lots of LiNi0.5Co0.2Mn0.3O2 powder recalcined in air at 750 °C obtained from TODA America. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with Ni 2p, Co 2p, Mn 2p, Ni LMM, O 1s, C 1s, Ni 3s, Co 3s, Mn 3s, Ni 3p, Co 3p, Li 1s, and Mn 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals and show only minor sulfur contamination. Making use of the O 1s, Ni 3p, Co 3p, Mn 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surfaces for the first lot, the first lot recalcined, and the second lot of LiNi0.3Co0.1Mn0.2O1.2, LiNi0.4Co0.1Mn0.3O1.5, and LiNi0.4Co0.1Mn0.2O1.3, respectively.

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. VI. LiNi0.4Co0.2Mn0.4O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated LiNi0.4Co0.2Mn0.4O2 powder obtained from TODA America. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with Ni 2p, Co 2p, Mn 2p, Ni LMM, O 1s, C 1s, Ni 3s, Co 3s, Mn 3s, Ni 3p, Co 3p, Li 1s, and Mn 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals. Making use of the O 1s, Ni 3p, Co 3p, Mn 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surface of LiNi0.5Co0.2Mn0.5O1.9.

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. V. LiNi0.4Co0.3Mn0.3O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated LiNi0.4Co0.3Mn0.3O2 powder obtained from TODA America. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with Ni 2p, Co 2p, Mn 2p, Ni LMM, O 1s, C 1s, Ni 3s, Co 3s, Mn 3s, Ni 3p, Co 3p, Li 1s, and Mn 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals. Making use of the O 1s, Ni 3p, Co 3p, Mn 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surface of LiNi0.4Co0.2Mn0.3O1.6.

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. VII. LiNi0.33Co0.33Mn0.33O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze fresh LiNi0.33Co0.33Mn0.33O2 powder obtained from TODA America. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with Ni 2p, Co 2p, Mn 2p, Ni LMM, O 1s, C 1s, Ni 3s, Co 3s, Mn 3s, Ni 3p, Co 3p, Li 1s, and Mn 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals and show carbon with only minor fluorine contamination. Making use of the O 1s, Ni 3p, Co 3p, Mn 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surface of LiNi0.4Co0.1Mn0.7O2.0.

Lithium-based transition-metal oxides for battery electrodes analyzed by x-ray photoelectron spectroscopy. I. LiNi0.8Co0.15Al0.05O2

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated LiNi0.8Co0.15Al0.05O2 powder obtained from TODA America. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.83401 nm. A survey spectrum together with Ni 2p, Co 2p, Ni LMM, O 1s, C 1s, Al 2s, Ni 3s, Co 3s, Al 2p, Ni 3p, Co 3p, and Li 1s are presented. The spectra indicate the principal core level photoelectron and Auger electron signals and show carbon with only minor sulfur contamination. Making use of the O 1s, Al 2s, Ni 3p, Co 3p, and Li 1s lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surface of LiNi0.2Co0.03Al0.1O0.7.

Hierarchical NiO@N-Doped Carbon Microspheres with Ultrathin Nanosheet Subunits as Excellent Photocatalysts for Hydrogen Evolution.

Achieving highly efficient hierarchical photocatalysts for hydrogen evolution is always challenging. Herein, hierarchical mesoporous NiO@N-doped carbon microspheres (HNINC) are successfully fabricated with ultrathin nanosheet subunits as high-performance photocatalysts for hydrogen evolution. The unique architecture of N-doped carbon layers and hierarchical mesoporous structures from HNINC could effectively facilitate the separation and transfer of photo-induced electron-hole pairs and afford rich active sites for photocatalytic reactions, leading to a significantly higher H2 production rate than NiO deposited with platinum. Density functional theory calculations reveal that the migration path of the photo-generated electron transfer is from Ni 3d and O 2p hybrid states of NiO to the C 2p state of graphite, while the photo-generated holes locate at Ni 4s and Ni 4p hybrid states of NiO, which is beneficial to improve the separation of photo-generated electron-hole pairs. Gibbs free energy of the intermediate state for hydrogen evolution reaction is calculated to provide a fundamental understanding of the high H2 production rate of HNINC. This research sheds light on developing novel photocatalysts for efficient hydrogen evolution.

Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

AbstractFlexible, chelating bis(NHC) ligand 2, able to accommodate both cis‐ and trans‐coordination modes, was used to synthesize (2)Ni(η2‐cod), 3. In reaction with GeCl2, it produced (2)NiGeCl2, 4, featuring a T‐shaped Ni0 and a pyramidal Ge center. Complex 4 could also be prepared from [(2)GeCl]Cl, 5, and Ni(cod)2, in a reaction that formally involved Ni–Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ‐donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2Ni(cod) complexes 9 and 10, as well as (NHC)2GeCl2 derivative 11, incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni–Ge complexes. The isolation of (2)Ni(η2‐Py), 12, provides further evidence for the reluctance of the (2)Ni0 fragment to act as a σ‐Lewis acid.

Nickel as a Lewis Base in a T-Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand.

Flexible, chelating bis(NHC) ligand 2, able to accommodate both cis- and trans-coordination modes, was used to synthesize (2)Ni(η2 -cod), 3. In reaction with GeCl2 , it produced (2)NiGeCl2 , 4, featuring a T-shaped Ni0 and a pyramidal Ge center. Complex 4 could also be prepared from [(2)GeCl]Cl, 5, and Ni(cod)2 , in a reaction that formally involved Ni-Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ-donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2 Ni(cod) complexes 9 and 10, as well as (NHC)2 GeCl2 derivative 11, incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni-Ge complexes. The isolation of (2)Ni(η2 -Py), 12, provides further evidence for the reluctance of the (2)Ni0 fragment to act as a σ-Lewis acid.

Optical constants and band structure of trigonal NiO

Using spectroscopic ellipsometry and transmission measurements, the authors determined the optical constants (absorption coefficient, complex refractive index, and dielectric function) of bulk trigonal NiO from 0.08 to 6.5 eV. By careful discussion of the data, elastic scattering by oxygen bubbles was ruled out and the effects of surface roughness were removed numerically to obtain an accurate dielectric function of NiO. A direct band gap of 0.85 eV was found from transmission and assigned to direct interband transitions from the Ni-O hybrid valence band states to the Ni 4s conduction band at the center of the Brillouin zone. At 4 eV, the authors find the well-known charge transfer gap from the lower to the upper Hubbard band. Several intermediate sharp peaks were also found. The temperature dependence of the NiO charge transfer gap is similar to the E1 gap of Si between 100 and 700 K. At higher temperatures, heating NiO in vacuum leads to sublimation, which has drastic irreversible consequences for the pseudodielectric function of the sample, including a strong Ni nanoparticle plasmon peak at 2 eV.

Early stage oxidation of Ni–Cr binary alloy (1 1 1), (1 1 0) and (1 0 0) surfaces: A combined density functional and quantum chemical molecular dynamics study

First-principles and tight-binding quantum chemical molecular dynamics were used in this study. The chemisorption energies of O and OH on the Ni–Cr (110) surface are lower than those of other surfaces. The oxygen 2p orbitals hybridise with Ni 3d, 4s and small amounts of p orbitals for the (100) surface while Ni p orbitals have no contribution for the (110) surface, which might reduce the adsorption energy. Additionally, oxygen acquires the maximum depth into the Ni–Cr (110) surface. Applied strain increases the oxygen diffusivity. This study reveals that the Ni–Cr (110) surface is easier for oxygen diffusion accordingly oxidation accelerates.

Effects of ascorbic acid on carcinogenicity and acute toxicity of nickel subsulfide, and on tumor transplants growth in gulonolactone oxidase knock-out mice and wild-type C57BL mice

The aim of this study was to test a hypothesis that ascorbate depletion could enhance carcinogenicity and acute toxicity of nickel. Homozygous l - gulono- < gamma > - lactone oxidase gene knock-out mice (Gulo−/− mice) unable to produce ascorbate and wild-type C57BL mice (WT mice) were injected intramuscularly with carcinogenic nickel subsulfide (Ni 3S 2), and observed for the development of injection site tumors for 57 weeks. Small pieces of one of the induced tumors were transplanted subcutaneously into separate groups of Gulo−/− and WT mice and the growth of these tumors was measured for up to 3 months. The two strains of mice differed significantly with regard to (1) Ni 3S 2 carcinogenesis: Gulo−/− mice were 40% more susceptible than WT mice; and (2) transplanted tumors development: Gulo−/− mice were more receptive to tumor growth than WT mice, but only in terms of a much shorter tumor latency; later in the exponential phase of growth, the growth rates were the same. And, with adequate ascorbate supplementation, the two strains were equally susceptible to acute toxicity of Ni 3S 2. Statistically significant effects of dietary ascorbate dosing levels were the following: (1) reduction in ascorbate supplementation increased acute toxicity of Ni 3S 2 in Gulo−/− mice; (2) ascorbate supplementation extended the latency of transplanted tumors in WT mice. In conclusion, the lack of endogenous ascorbate synthesis makes Gulo−/− mice more susceptible to Ni 3S 2 carcinogenesis. Dietary ascorbate tends to attenuate acute toxicity of Ni 3S 2 and to extend the latency of transplanted tumors. The latter effects may be of practical importance to humans and thus deserve further studies.

Methylation of RAR-β2, RASSF1A, and CDKN2A Genes Induced by Nickel Subsulfide and Nickel-carcinogenesis in Rats

Objective To investigate the expression variation of RAR-β2, RASSF1A, and CDKN2A gene in the process of nickel-induced carcinogenesis. Methods Nickel subsulfide (Ni 3S 2) at dose of 10 mg was given to Wistar rats by intramuscular injection. The mRNA expression of the three genes in induced tumors and their lung metastasis were examined by Real-time PCR. The methylation status of the 5' region of these genes were detected by Quantitative Real-time methylation specific PCR. Results The mRNA expressions of the three genes both in muscle and lung tumor were decreased distinctly in comparison with normal tissue. But hypermethylation was found only in muscle tumor. Conclusion These findings suggest that loss of function or decrease of RAR-β2, RASSF1A, and CDKN2A, as well as the hypermethylation of 5' region of these genes, are related with nickel exposure.

In situ XAS study on the mechanism of reactive adsorption desulfurization of oil product over Ni/ZnO

Reactive adsorption desulfurization (RADS) of a model oil n-nonane containing dibenzothiophene (DBT) was conducted over a Ni/ZnO adsorbent; the evolution of Ni/ZnO adsorbent structure during desulfurization was monitored by in situ X-ray absorption spectroscopy (XAS). The reaction mechanism under different atmospheres and the role of hydrogen in the desulfurization were investigated. The results indicated that the desulfurization processes under nitrogen and hydrogen are different in the reaction mechanism. In nitrogen, the desulfurization over Ni/ZnO is achieved through physical and chemical adsorption; a severe decrease in the desulfurization activity of Ni/ZnO is observed with the time on stream and the desulfurization capacity is very low. In hydrogen, the desulfurization turns to be a reactive adsorption process and Ni/ZnO exhibits a high desulfurization activity and capacity. Hydrogen plays an important role in the RADS; it facilitates the decomposition of DBT on active Ni species, the formation of Ni3S2, and thereafter the transfer of sulfur to ZnO. Metallic Ni as the active nickel species is preserved until most of ZnO is converted to ZnS. On the basis of these observations, a possible sulfur transfer mechanism for the RADS is then proposed.

The addition of iron to Ni 3S 2 electrode for sodium secondary battery

In order to investigate the role of iron additive in the Ni 3S 2 electrode, the Ni 3S 2 electrode was prepared by addition of iron. The discharge properties of Na/Ni 3S 2 cells using 1 M NaCF 3SO 3 in tetra(ethylene glycol)dimethyl ether liquid electrolyte were investigated at room temperature. The Na/Ni 3S 2 cell had an initial discharge capacity of 400 mAh g −1 with a plateau potential at 0.84 V versus Na/Na +. The discharge capacity decreased to 255 mAh g −1 after 15 cycles. Iron additive in Ni 3S 2 electrode played a role as a conductive agent and did not form iron sulfide during charging.

Sulfur behavior in chemical looping combustion with NiO/Al 2O 3 oxygen carrier

Chemical looping combustion (CLC) is a novel technology where CO 2 is inherently separated during combustion. Due to the existence of sulfur contaminants in the fossil fuels, the gaseous products of sulfur species and the interaction of sulfur contaminants with oxygen carrier are a big concern in the CLC practice. The reactivity of NiO/Al 2O 3 oxygen carrier reduction with a gas mixture of CO/H 2 and H 2S is investigated by means of a thermogravimetric analyzer (TGA) and Fourier Transform Infrared spectrum analyzer in this study. An X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to evaluate the phase characterization of reacted oxygen carrier, and the formation mechanisms of the gaseous products of sulfur species are elucidated in the process of chemical looping combustion with a gaseous fuel containing hydrogen sulfide. The results show that the rate of NiO reduction with H 2S is higher than the one with CO. There are only Ni and Ni 3S 2 phases of nickel species in the fully reduced oxygen carrier, and no evidence for the existence of NiS or NiS 2. The formation of Ni 3S 2 is completely reversible during the process of oxygen carrier redox. A liquid phase sintering on the external surface of reduced oxygen carriers is mainly attributed to the production of the low melting of Ni 3S 2 in the nickel-based oxygen carrier reduction with a gaseous fuel containing H 2S. Due to the sintering of metallic nickel grains on the external surface of the reduced oxygen carrier, further reaction of the oxygen carrier with H 2S is constrained, and there is no increase of the sulfidation index of the reduced oxygen carrier with the cyclical reduction number. Also, a continuous operation with a syngas of carbon monoxide and hydrogen containing H 2S is carried out in a 1 kW th CLC prototype based on the nickel-based oxygen carrier, and the effect of the fuel reactor temperature on the release of gaseous products of sulfur species is investigated.

Structures and magnetic properties of Si nNi ( n = 1–17) clusters

The structure, electronic and magnetic properties of Si n Ni clusters up to n = 17 are systematically investigated using the density-functional theory (DFT) within the generalized gradient approximation (GGA). In the ground configurations of Si n Ni clusters, the equilibrium site of Ni atom gradually moves from convex, to a surface, and to a concave site as the number of Si atoms varying from 1 to 17. Starting from n = 8, the Ni atom completely falls into the center of the Si outer frame, forming Ni-encapsulated Si cages. Maximum peaks of second-order energy difference are found at n = 5, 7, 10, 12 and 14, indicating that these clusters possess relatively higher stability. Especially, Si 10Ni cluster is more stable. The electronic structures and magnetic properties of Si n Ni clusters are discussed. The strong hybridization between Ni 4s, 3d, 4p and Si 3s, 3p states leads to the decrease of the gaps between highest-occupied and lowest-unoccupied molecular orbitals of Si n Ni clusters compared with corresponding those of Si n clusters and may be one of important factors which result in Si n Ni clusters magnetic moment quenched except for Si 2 Ni cluster.

Structural characterization of Ni–W hydrocracking catalysts using in situ EXAFS and HRTEM

The detailed structural characterization of the metal function of two fully formulated Ni–W hydrocracking catalysts was investigated by time resolved in situ X-ray absorption spectroscopy (EXAFS and XANES) at both the Ni K-edge and W L 3-edge, and by high resolution transmission electron microscopy. These two hydrocracking catalysts (designated as HCA and HCB) contained the same wt% of Ni and W, the same wt% of the other constituents ( γ-Al 2O 3/silico-aluminate), and were calcined at the same temperature, but were prepared by different methods in order to highlight the sensitivity of the characterization techniques to the structural differences. The morphology of the WS 2 particles in the sulfided catalyst is substantially different between the two catalysts: in the HCA catalyst there are many more particles with multiple WS 2 layers whereas in HCB there are more single layers. The average diameter of the WS 2 plates is similar in both. The catalysts show a difference in the amount of W sulfidation after the 410 °C sulfidation treatment in 10% H 2S/H 2. The W of HCA catalyst was completely sulfided whereas 16% W of HCB catalyst was unsulfided. Similarly there is a difference in the amount of sulfided Ni: 16% Ni in HCA and 60% Ni in HCB remain unsulfided. In the sulfided form of both catalysts the Ni exists in three different morphologies: oxidized Ni (six-fold coordinate as a nickel aluminate), nanoparticulate Ni 3S 2, and Ni decorating the edge sites of the WS 2. In both the Ni 3S 2, and Ni decorating the edge sites of the WS 2, the Ni is in a tetrahedral coordination with sulfur. In both catalysts the sulfidation of the Ni and W occurs essentially simultaneously over most of the temperature range and the sulfidation of the W proceeds through the same tungsten oxysulfide in both samples. The characterization methodology presented here is a powerful one for elucidating the structural differences of complex heterogeneous catalysts.

Preparation of .ALPHA.-nickel hydroxide/carbon composite by the liquid phase deposition method

High purity α-nickel hydroxide/carbon composite has been synthesized by the liquid phase deposition (LPD) method. The purity of the as-prepared samples was confirmed by X-ray photon electron (XPS) survey spectra, which showed no other peak than that of the core levels Ni 2p, O 1s, C1s, Ni 3s and Ni 3p involved in the process. Scanning electron microscope (SEM) images showed carbon particles randomly embedded within the Ni(OH)2 network. The amount of deposited nickel hydroxide can be controlled by the ratio between carbon and the quantity of the treatment solution, and the reaction time.

Interaction of Ni/SiO 2 with thiophene

The interaction between Ni/SiO 2 (18 wt%) and thiophene was studied by thermal gravimetric analysis (TGA) and in a fixed-bed reactor. The samples were prepared by incipient wetness impregnation and reaction was realized in hydrogen flow at 280–360 °C in the presence of 10–40 mbar of thiophene. It is found that sulfidation of Ni is not complete in TGA experiments and the maximum achievable transformation degree depends not only on the temperature and thiophene pressure, but also on the sample weight and the gas flow rate. The maximum transformation degree is shown to vary reversibly when conditions are changed. Analysis of the reaction products during sulfidation in a fixed-bed reactor showed that H 2S is present in the gas phase from the beginning of the reaction and that catalytic activity of the solid decreases strongly when going from Ni 0 to Ni 3S 2. All these observations suggest that, except at the surface, the interaction between thiophene and Ni/SiO 2 is not direct: thiophene is first desulfurized and then H 2S reacts with Ni. As Ni sulfidation progresses the amount of produced H 2S decreases (because of a lowering catalytic activity of the solid) and after certain time H 2S partial pressure can drop to the equilibrium value for Ni/Ni 3S 2 system. In such conditions Ni sulfidation cannot be completed and the system achieves a steady state corresponding to the maximum transformation degree observed in TGA experiments. The present study shows that due to involvement of a catalytic reaction, the stability of metallic particles in the presence of complex sulfur-containing molecules can be determined by the desulfurization activity of the metal and operation conditions rather than by the thermodynamics of the metal-sulfur system.