Incorporation Of Nickel Ions Research Articles

Environmental Remediation via Solution Combustion Route Synthesis of Single-Phase Ferromagnetic Nickel Doped Zinc Oxide (Ni-ZnO) Nanostructure for Enhanced Photocatalytic Activity

To flourish new applications at a low cost to the environment, it is important to develop non-toxic eco-friendly ferromagnetic single-phase zinc oxide (ZnO) nanoparticles with nickel (Ni2+) doping. The titled materials were prepared using an easy and rapid solution combustion synthesis method. XRD, SEM, and TEM were used to figure out the structure and morphology of as-synthesized materials, which confirmed the nanoscale ZnO structure in a single phase. The sample shows a single phase with nickel metal incorporated into the Wurtzite crystal structure of ZnO by replacing the Zn2+. The ferromagnetic behavior of the as synthesized samples was observed at room temperature. The ferromagnetic exchange coupling between the doped Ni2+ ions facilitate the ferromagnetic behavior, and the magnetic saturation is increased with the Ni2+ doping. As-synthesized samples were shown to have photocatalytic activity. The incorporation of nickel ions in the ZnO structure facilitated the enhancement of the catalytic activity. The improved catalytic activity is attributed to the band gap tuning of the ZnO, which favors the improved degradation of the Methylene Blue dye under a UV light source. The prepared samples pave the way for recyclable photo-catalysis applications of ZnO, which can be easily separated using a permanent magnet.

Novel ultra-wideband fluorescence material: Defect state control based on nickel-doped semiconductor QDs embedded in inorganic glasses

In recent years, the development of an environmentally friendly quantum dots (QDs) embedded luminous solid by a simple method has attracted considerable attention. In this study, semiconductor ZnS QDs were successfully prepared in an inorganic matrix of amorphous glass, which yielded beneficial broad-band emission in the long-wavelength region of the visible range. The strong red emission belonged to the defect state energy level of the ZnS QDs, which could be enhanced by incorporation of nickel ions into the fixed matrix to regulate the defects state. The novel material had a small self-absorption, wide excitation and emission ranges, and thus potential applications in light-conversion devices, luminescent solar concentrators, and solar cell cover glasses.

Hydrodemethoxylation/Dealkylation on Bifunctional Nanosized Zeolite Beta

Mono-, and bimetallic Ni-, Ru-, and Pt-modified nanosized Beta zeolite catalysts were prepared by the post synthesis method and characterized by powder X-ray diffraction (XRD), nitrogen physisorption, HRTEM microscopy, temperature-programmed reduction (TPR-TGA), ATR FT-IR spectroscopy, and by solid-state MAS-NMR spectroscopy. The presence of nanosized nickel-oxide, ruthenium-oxide, and platinum species was detected on the catalysts. The presence of Brønsted and Lewis acid sites, and incorporation of nickel ions into zeolite lattice was proven by FT-IR of adsorbed pyridine. The structural changes in the catalyst matrix were investigated by solid state NMR spectroscopy. The catalysts were used in a gas-phase hydrodemethoxylation and dealkylation of 2-methoxy-4-propylphenol as a lignin derivative molecule for phenol synthesis.

Enhancement of the OER Kinetics of the Less-Explored α-MnO2 via Nickel Doping Approaches in Alkaline Medium.

Development of a low-cost transition metal-based catalyst for water splitting is of prime importance for generating green hydrogen on an industrial scale. Recently, various transition metal-based oxides, hydroxides, sulfides, and other chalcogenide-based materials have been synthesized for developing a suitable anode material for the oxygen evolution reaction (OER). Among the various transition metal-based catalysts, their oxides have received much consideration for OER, especially in lower pH condition, and MnO2 is one of the oxides that have widely been used for the same. The large variation in the structural disorder of MnO2 and internal resistance at the electrode-electrolyte interfaces have limited its large-scale application. By considering the above limitations of MnO2, here in this work, we have designed Ni-doped MnO2 via a simple wet-chemical synthetic route, which has been successfully applied for OER application in 0.1 M KOH solution. Doping of various quantities of Ni into the MnO2 lattices improved the OER properties, and for achieving 10 mA/cm2 current density, the Ni-doped MnO2 containing 0.02 M of Ni2+ ions (coined as MnO2-Ni0.002(M)) demands only 445 mV overpotential, whereas the bare MnO2 required 610 mV overpotential. It has been proposed that the incorporation of nickel ions into the MnO2 lattices leads to an electron transfer from the Ni3+ ions to Mn4+, which in turn facilitates the Jahn-Teller distortion in the Mn-O octahedral unit. This electron transfer and the creation of a structural disorder in the Mn sites result in the improvization of the OER properties of the MnO2 materials.

Electrochemical behavior of nickel containing passive oxide films on carbon steel in alkaline medium

The passive oxide film formed on the carbon steel surface in lithiated water was modified by the incorporation of nickel ions by hydrothermal deposition at 250°C. The aim was to verify to what extent the in-situ oxide films grown in presence of nickel ions improved the corrosion resistance of the carbon steel substrate in comparison to the films formed in the absence of nickel ions at different exposure times. Grazing incidence-X-ray diffraction studies confirmed the formation of the spinel phase in the passive oxide film. X-ray photoelectron spectroscopy revealed the presence of the nickel ions in the oxide lattice. The electrochemical behavior of the oxide films formed on the carbon steel surface was studied using electrochemical impedance spectroscopy and potentiodynamic anodic polarization methods. Tafel plot extrapolations from the potentiodynamic anodic polarization plots revealed a substantial difference in the corrosion resistance of the films formed on carbon steel substrate in the presence of nickel ions. The oxides grown in the absence and in the presence of nickel ions exhibited similar corrosion current densities but showed a higher polarization resistance value in the presence of nickel ions. The semiconductor properties of these oxides were characterized by Mott Schottky measurements and the results are presented in detail in this paper.

Improving Corrosion Resistance of a Nickel-Aluminum Bronze Alloy via Nickel Ion Implantation

An as-cast nickel-aluminum bronze alloy was subjected to nickel ion implantation, modifying its surface structure. A nickel-rich layer was formed on the surface of the alloy and its corrosion resistance in salt spray environment was improved gradually with the increasing implantation fluence. The corrosion resistance enhancement after ion implantation is believed to stem from the more compact Cu2O film with the incorporation of nickel ions. Under the protection of this more compact film, selective phase corrosion was inhibited effectively.

Active Sites of a NiSO4/γ-Al2O3 Catalyst for the Oligomerization of Isobutene

Structural characterization, the mechanism of catalytic activity generation and the nature of active sites of a NiSO4/γ-Al2O3 catalyst for isobutene oligomerization were studied by temperature programmed reduction (TPR), X-ray diffraction (XRD), diffuse reflectance infrared fourier transformed (DRIFTS) and X-ray photoelectron spectroscopy (XPS) techniques. The TPR measurements together with the XRD data indicated that calcination of the catalyst at 500 °C did not form either nickel oxide or nickel aluminate. The presence of only one type of surface nickel species formed by the incorporation of nickel ions into the surface vacant sites of γ-alumina lattice was indicated by XPS with Ar+ ions sputtering and TPR measurements. XPS analysis of the calcined catalyst suggested that the oxidation state of nickel ions in the calcined catalyst was (+2) and after calcination the nickel ions were coordinated to relatively more basic ligands. The surface acid centers of the catalyst were found to be only Lewis type. SO4 2− ions were found to be present as a chelating bidentate ligand and enhanced the acidity of metal ( $$ {\text{Al}}^{3 + } $$ and/or $$ {\text{Ni}}^{2 + } $$ ) Lewis acid centers. The results suggested that the combined effects of the presence of the bidentate SO4 2− ligand and dehydroxylation generate coordinatively unsaturated $$ {\text{Ni}}^{2 + } $$ that interact with isobutene during the oligomerization reaction. The formation of lower-valent nickel ions ( $$ {\text{Ni}}^{x + } ,x\; \le\; 1 $$ ) was demonstrated by in situ DRIFTS using CO as a probe molecule and by XPS measurements. Formation of a binuclear bridging carbonyl complex, $$ [{\text{Ni}}({\text{CO}})^{ + } ]_{2} $$ suggested that some lower-valent nickel species were formed via in situ reduction by isobutene. Analysis of Ni 2p photolines indicated the appearance of a new lower-valent nickel species ( $$ {\text{Ni}}^{x + } ,x \;\le\; 1 $$ ) during the course of isobutene oligomerization. Hence it is plausible that lower-valent nickel species might act as the active center for the oligomerization reaction, while the SO4 2− ions enhance the acidity of the Lewis acid sites on the surface and assist in the adsorption of reactant molecules on the surface.

Polypyrrole films polymerised on a nickel substrate

A polypyrrole (Ppy) film has been deposited on a Ni electrode by anodic polymerisation from acetonitrile solutions. X-ray photoelectron spectroscopy (XPS) analysis shows nickel Ni 2+ chemically bound to the polymer chain. Impedance spectroscopy has been employed to characterise this new material in a system of metal/film/electrolyte in a frequency range 10 5/10 −2 Hz. The ac response of the film consists of four or three separable elements depending on the film’s thickness. Incorporation of nickel ions into electronically conducting polymer causes, (i) negligible changes in a polymer redox resistance (high frequency response); (ii) considerable decrease of conductivity responding to ac signal at medium frequency; (iii) linear dependence between resistance measured at medium frequency of ac signal and electrode potential appeared to be caused by nickel presence in the film. Effective diffusion coefficient established for Ppy layers on Ni, Pt and stainless steel at OCV potentials are 1.2×10 −10, 1.0×10 −8, and 2.2×10 −9 cm 2 s −1, respectively.

Temperature-programmed reduction of NiO [sbnd]WO 3/Al 2O 3 Hydrodesulphurization catalysts

Temperature-programmed reduction patterns are reported of NiO/Al 2O 3, WO 3/Al 2O 3, and NiO WO 3/Al 2O 3 catalysts, and of bulk oxides relevant to these catalysts. At loadings below 10% NiO and 19% WO3 nickel and tungsten are present as disperse species and no bulk oxides are found on the support. Tungsten forms a stable monolayer species which is extremely difficult to reduce. At high temperatures of reduction tungsten metal is formed without the intermediate formation of WO 2. Several nickel species were detected in the supported catalysts, and their characters and amounts depend on the loading and the temperature of calcination. After calcination at low temperatures and at low loadings (2% NiO) nickel is incorporated in the surface layers of the support; at higher loadings a NiO like species is formed which is more difficult to reduce than bulk NiO because of the interaction with the aluminium ions of the support. A high temperature of calcination favours the formation of a diluted spinel phase at the expense of the surface phases. In NiO WO 3/Al 2O 3 catalysts a fraction of nickel is present in a mixed NiWOAl phase which is formed by incorporation of nickel in a tungsten containing surface layer. At high temperatures of calcination some disperse NiWO 4 is formed. It is shown that there are two causes for a strong interaction between nickel species and the support: incorporation of nickel ions in the surface layers of the support during impregnation, and solid-state diffusion during calcination of the catalysts. The nickel containing species which are the precursor to the active phases in sulfided HDS catalysts are identified as the nickel species in the surface layers of the support in NiO/Al 2O 3 samples, and the NiWOAl phase in NiO WO 3/Al 2O 3 catalysts.