Amount Of Ni2 Research Articles

Looking into how nickel doping affects the structure, morphology, and optical properties of TiO2 nanofibers

In this paper, we have systematically studied the structural, morphological, and optical properties of Ni-doped TiO2, synthesized via a simple, cost-effective electrospinning method followed by calcination at 500 °C. The nanofibers with a core-shell structure were relatively homogeneous, smooth and randomly oriented, and there were no significant differences in fiber diameters due to Ni2+ content. Core loss mapping using electron energy loss spectroscopy confirmed an even distribution of titanium and relatively uniform nickel in the fibers. It was found that doping with 0.5 mol.% Ni2+ decreased the rutile content, while doping with 1 mol.% Ni2+resulted in a pure anatase phase with a significantly increased specific surface area (36.6 m2/g). Further increase in Ni2+ content (3–10 mol.%) not only prolonged the response of TiO2 nanofibers to visible light, but also increased the specific surface area (49.5 m2/g), decreased crystallite size (7 nm), and increased rutile content in TiO2 (33 wt.%). Photoluminescence analysis revealed that doping TiO2 with different amounts of Ni2+ leads to a gradual decrease of emission spectra intensity and red shift in the maxima positions. The XPS results confirmed that as the Ni2+ content enlarged, the Ti2+ and Ti3+ content increased significantly, effectively promoting the formation of oxygen vacancies. Raman analysis showed that an increase in nickel content (3–5 mol.%) led to a decrease and shift in peak intensity due to Ti3+ formation and also the possible presence of NiTiO3 phases. HRTEM analysis showed that Ni was doped into the substitution sites of both the anatase and rutile TiO2 lattice but had a stronger influence on the distortion of the anatase phase. The photocatalytic activity of Ni-doped TiO2 nanofibers was explored by analyzing the degradation of an antibiotic, oxytetracycline, monitored in laboratory conditions under visible light irradiation. After 60 min of irradiation, the degradation of OTC with 1Ni-TiO2 reached 76.4 % and with 10Ni-TiO2 70.5 %.

Effect of air abrasive polishing on nickel release, stainless steel corrosion, and nickel-titanium archwires.

Orthodontic treatment is becoming more and more popular. However, using fixed orthodontic devices for treatment affects oral hygiene and raises the risk of corrosion, plaque-related illnesses, and dental discoloration-related issues. Air abrasive polishing has a superior effect over the conventional method in removing dental deposits. Using fixed orthodontic appliances affects oral hygiene and raises the risk of diseases caused by plaque, tooth discoloration, and corrosion, as well as corrosion by ions. This study evaluated the impact of air polishing on nickel ion release and corrosion from stainless steel, nickel-titanium, coated stainless steel, and coated nickel-titanium. A total of 288 (stainless steel, coated stainless-steel, nickel-titanium, and coated nickel-titanium rectangular archwires) of one brand were subjected to varying air abrasion polishing times (5, 10, and 20 seconds). Then, they were submerged in artificial saliva with a pH of 6.75 and incubated for 28 days at 37 °C. The release of nickel ions (Ni2+) was measured using an atomic absorption spectrophotometer at 7, 14, and 28 days to estimate the cumulative effect. The corrosion of the test-selected samples and surface alterations was evaluated using scanning electron microscopy (SEM). Prolonged polishing significantly increased Ni2+ release and corrosion. Archwires made of coated stainless steel exhibited the least amount of Ni2+ release. The air polishing process increased the Ni2+ release at a subtoxic level and could be used on adult patients with long gaps between visits with a polishing period of 5 seconds.

Boosted Catalytic Performance of Ni2Co2@T-PMo@ZIF-67 for Glucose Oxidation in a Direct-Glucose Fuel Cell

In this study, we report on how to design efficient catalysts for glucose oxidation via the transitional metal doping of nanohybrids of polyoxometalates (POMs) and metal-organic frameworks (MOFs). ZIF-67, a cobalt-based MOF, as well as phosphomolybdic acid (PMo), were used as precursors for the fabrication of pyrolyzed PMo@ZIF-67 (T-PMo@ZIF-67). A different amount of Ni2+ was doped into PMo@ZIF-67 to produce NixCoy@T-PMo@ZIF-67. Among them, Ni2Co2@T-PMo@ZIF-67 had the best performance. The power density of the fuel cell that used Ni2Co2@T-PMo@ZIF-67 as an anode catalyst was 3.76 times that of the cell that used active carbon as an anode catalyst. SEM and EDS mapping results indicate that Ni2Co2@T-PMo@ZIF-67 has a spherical structure and rough surface, and elements such as cobalt, nickel, and molybdenum are evenly distributed. XRD characterization indicates that Co3O4, CoMoO4, CoNiO4, and MoNiO4 co-exist in the composites. It is supposed that Co2+, Mo6+, and Ni2+ in the composites may have synergistic effects on the catalytic oxidation of glucose.

Zeolitic‐Imidazolate Framework Derived Intermetallic Nickel Zinc Carbide Material as a Selective Catalyst for CO2 to CO Reduction at High Pressure

AbstractThe conversion of CO2 into CO is an important step in CO2 utilization to achieve clean fuels and value‐added chemicals. Herein, we explored the pyrolysis of zeolitic imidazolate framework‐8 (ZIF‐8) loaded with different amounts of Ni2+ to obtain Ni−Zn carbide (Ni3ZnC) embedded in N‐doped carbon. Ni is present in the intermetallic compound, while Zn excess remains on the N‐doped carbon. The Ni3ZnC phase catalyzes the selective hydrogenation of CO2 into CO via the reverse water gas shift reaction, reaching 100 % CO selectivity at ∼30 % CO2 conversion at 450 °C and atmosphere pressure (CO2 : H2=1 : 4, GHSV=30000 mL gcat−1 h−1). The methanation reaction of CO2/CO, which is usually favored over Ni catalysts, is suppressed. The selectivity to CO at the expense of CH4 is related to the stability of chemisorbed CO in the Ni3ZnC surface, which is lower compared to Ni surfaces. The Ni3ZnC@NC catalyst is selective towards CO over a wide range of conditions, including high pressure, that is usually required for the conversion of CO to hydrocarbons and alcohols via the Fisher‐Tropsch synthesis (FTS) process. Contrarily, a classical Ni/SiO2 catalyst prepared by impregnation produces CH4 under high pressure.

The effect of addition Ni2+ to Cr2O3 and its potential characterization as anode potassium ion battery

Potassium ion battery (PIB) is an alternative to replace Lithium ion battery (LIB). In this study, amount of Ni2+ is added to substitute of Cr(III) on Cr2O3. The purpose of this study is to determine the effect of adding Ni2+ ions to Cr2O3 and to test its potential as anode of PIB. Synthesis used the coprecipitation method followed by calcination at 700°C for 12 hours. The results showed that the Cr2O3 - NiCr2O4 composites were formed when the addition of Ni2+ was 0.25; 0.50; and 0.75 mole with the most dominant amounts of NiCr2O4 in the addition of 0.50 mole Ni2+. Cyclic voltammetry analysis of addition of 0.50 mole of Ni2+ to the Cr2O3 shows that the material has an a reduction potential of +0.0344 V and an oxidation potential of +0.587 V. NiCr2O4/Cr2O3 material has the potential as anode material for PIB.

Selective synthesis of triacetyl glyceride biofuel additive via acetylation of glycerol over NiO-supported TiO2 catalyst enhanced by non-microwave instant heating

NiO-supported TiO2 (nNiO/TiO2) as highly active and selective catalysts for triacetyl glyceride (TAG) biofuel additive production via acetylation of glycerol is reported. The catalysts are prepared by incorporating various amounts of Ni2+ (n = 10, 30 and 50 wt% Ni added during catalysts preparation) onto the TiO2 support using simple sol-gel approach followed by calcination. The spectroscopy and microscopy analyses reveal that the NiO nanoparticles (ca. 6 nm) are uniformly distributed on the surface of TiO2 support where octahedrally coordinated NiO as active species is formed upon calcination. Among the catalysts prepared, 30NiO/TiO2 with strongest acidity and highest accessible surface area is found to be the most active in the acetylation of glycerol with acetic acid, achieving 90.2% glycerol conversion with 65.9% selective to TAG under non-microwave instant heating conditions (170 °C, 30 min). In addition, 30NiO/TiO2 also shows better catalytic performance than previous reported catalysts. No significant deterioration in catalytic activity is shown by 30NiO/TiO2 after eight successive runs, thus offering a green pathway for synthesizing TAG vehicle fuel additives with high selectivity.

Thermal behavior of Mg−Ni‐phyllosilicate nanoscrolls and performance of the resulting composites in hexene‐1 and acetone hydrogenation

AbstractHere we report on the thermal properties of Mg−Ni‐phyllosilicate nanoscrolls as a promising precursor for production of Ni/silicate composite catalysts. Spontaneous scrolling of the phyllosilicate layer originating from size difference between metal‐oxygen and silica sheets provides high surface area of the catalyst. Metal nanoparticles can be obtained directly from the matrix by H2 reduction. The phyllosilicate structure passed through a number of transformations including partial dehydroxylation with formation of sepiolite‐like phase followed by silicate or oxide crystallization. Temperature ranges of these transitions overlapped with the reduction process sophisticating the H2 consumption profiles. In particular, some amount of Ni2+ got sealed up by the sepiolite structural features, that opened a path for the tuning of Ni0 : Ni2+ ratio of the catalyst. An increase of Ni content in the system yielded a decrease in the metal nanoparticles sizes due to both high intensity of nucleation and type of residual matrix. Ni nanoparticles size distribution and specific surface area of the composite catalysts governed conversion rate of hexene‐1 and acetone hydrogenation. In the view of the turnover frequency MgNi2Si2O5(OH)4 precursors were slightly more preferable than pure Ni3Si2O5(OH)4.

Enhanced Negative Thermal Expansion Induced by Simultaneous Charge Transfer and Polar-Nonpolar Transitions.

Negative thermal expansion (NTE) induced by simultaneous mechanisms, that is, charge transfer and polar-nonpolar transitions, was observed for the first time in BiNi1-xFexO3 (0.25 ≤ x ≤ 0.5). The low-temperature phase was found to have a polar structure (space group of R3c) with a Bi3+0.5(1+x)Bi5+0.5(1-x)Ni2+1-xFe3+xO3 charge distribution and short-range ordering of Bi3+ and Bi5+. The volume reduction upon heating that was induced by charge transfer between Bi5+ and Ni2+ decreased with increasing x because of the reduction in the amount of Ni2+. Simultaneous polar-nonpolar transition also contributed to NTE, and a composition-independent enhanced volume reduction of ∼2% was observed.

Characterization of mixed-ligand shells on gold nanoparticles by transition metal and supramolecular surface probes.

We report herein two methods to characterize the surface of mixed-ligand shell gold nanoparticles, which was explored with gold nanoparticles containing varying molar ratios of 3-mercaptopropionic acid (MPA) and 3-mercapto-1-propanesulfonate (MPS) or 11-mercaptoundecanoic acid (MUA) and triethylene glycol mono-11-mercaptoundecyl ether (TEG) in their ligand shell. Incubation of gold nanoparticles with a solution containing the transition metal cation Ni2+ allows the extraction of Ni2+ depending on the number of negatively charged surface groups and the reaction of surface carboxylic acid groups with an aminomethyladamantane derivative allows the extraction of the supramolecular host molecule cucurbit[7]uril (CB7) depending on the number of reactive surface groups. In both the methods, the remaining surface probes in the supernatant could be conveniently quantified in a homogeneous solution after a simple centrifugation step. An excellent linear correlation between the amount of Ni2+ extracted and the ligand density of MPA and MPS in MPA/MPS gold nanoparticles or MUA in MUA/TEG gold nanoparticles afforded a simple and reliable assay method to determine the number of negatively charged surface groups. The supramolecular CB7 assay enabled the determination of the accessible ligand density of reactive surface carboxylic acid groups and revealed a striking difference in the number of surface groups that can be reacted with MPA/MPS gold nanoparticles or MUA/TEG gold nanoparticles, which suggests a simple method to probe the surface structure of mixed monolayer gold nanoparticles.

Structural, Magnetic, and Catalytic Evaluation of Spinel Co, Ni, and Co-Ni Ferrite Nanoparticles Fabricated by Low-Temperature Solution Combustion Process.

Here, we present the low-temperature (∼600 °C) solution combustion method for the fabrication of CoFe2O4, NiFe2O4, and Co0.5Ni0.5Fe2O4 nanoparticles (NPs) of 12–64 nm range in pure cubic spinel structure, by adjusting the oxidant (nitrate ions)/reductant (glycine) ratio in the reaction mixture. Although nitrate ions/glycine (N/G) ratios of 3 and 6 were used for the synthesis, phase-pure NPs could be obtained only for the N/G ratio of 6. For the N/G ratio 3, certain amount of Ni2+ cations was reduced to metallic nickel. The NH3 gas generated during the thermal decomposition of the amino acid (glycine, H2NCH2COOH) induced the reduction reaction. X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy techniques were utilized to characterize the synthesized materials. XRD analyses of the samples indicate that the Co0.5Ni0.5Fe2O4 NPs have lattice parameter larger than that of NiFe2O4, but smaller than that of CoFe2O4 NPs. Although the saturation magnetization (Ms) of Co0.5Ni0.5Fe2O4 NPs lies in between the saturation magnetization values of CoFe2O4 and NiFe2O4 NPs, high coercivity (Hc, 875 Oe) of the NPs indicate their hard ferromagnetic behavior. Catalytic behavior of the fabricated spinel NPs revealed that the samples containing metallic Ni are active catalysts for the degradation of 4-nitrophenol in aqueous medium.

Photocolorimetric determination of zirconium microcontent in the products of linear alpha-olefins production

Analytical control of the technological process of linear alpha-olefins (LAO) production using a zirconium carboxylate based catalyst according to α-SABLIN technology calls for determination of the residual zirconium in the solvent when washing equipment, in the reaction products and wastewater, the purity of which is strictly regulated. Features of photocolorimetric determination of zirconium impurities with different complexing agents are considered and sensitivity of the determination with iron, aluminum, nickel and chromium present is estimated by comparing the values of the «sensitivity index» (by E. Sendel) and «specific absorption» (by Z. Marchenko). The reaction of complex formation with arsenazo III in 9 – 10 M HCl is used for determination of zirconium in the LAO production related products. The resulting colored complex exhibits the maximum light absorption at a wavelength of 670 nm. The measured content ranges from 0.100 to 100 mg/kg, 103-fold amounts of Ni2+, Fe3+, Al3+ and 400-fold amounts of Cr3+ do not interfere with the determination. The method of additives is used to eliminate the interfering effect of the acidity of the medium. It is shown that the developed technique provides a satisfactory level of the reproducibility and correctness of the results for analytical control of LAO production.

Biosorption of nickel (II) ion from synthetic wastewater on watermelon rind activated carbon using reponse surface methodology (RSM) optimization approach

The introduction of lethal heavy metals into the environment from industrial wastes is a major problem that needs immediate attention. In the present study the adsorption efficiency of nickel ions from a synthetic wastewater using watermelon rind activated carbon as a biosorbent is reported. Four basic process variables – initial Ni2+ concentration (5 – 100mg/l); pH (2 – 7); contact time (20 – 720 minutes) and adsorbent dosage (5 – 25g/l) were used for the investigation. Response surface (Box Behnken design expert 7.0®) methodology based on a design of experiment (DOE) that produced 29 batch experimental runs was used. The amount of Ni2+ adsorbed was optimized numerically to determine the optimum conditions for the adsorption process. The results of the study show that initial Ni2+ concentration of 100 mg/l; pH value of 6.69; 5g adsorbent dosage and 365.89 minutes contact time were the optimum process conditions for the removal of 18.43mg/g of Ni2+ representing 97% of the maximum predicted adsorption rate. It can be concluded therefore, that water melon rind activated carbon has high adsorption capacity and can be used effectively as adsorbent for the removal of nickel from nickel polluted waste and surface water. Keywords : Adsorption, nickel ion, optimization, response surface methodology, water melon rind

Template free synthesize mesoporous manganese dioxides for water treatment

Mesoporous materials present infinite application prospect for their special pore structure and large specific surface area. However, the synthesis process of mesoporous transition metal oxides always needs a template such as mesoporous silica to create the porous structure, thus the synthesis technology became complicated and energy consumption. In this work, 3D mesoporous MnO2 microsphere have been successfully prepared by a facile and simple hydrothermal process through introducing a certain amount of Ni2+. A high specific surface area (426 m2/g) was realized due to the mesoporous and ultrathin nanosheets structure. Owing to the special pore structure and 3D morphology assembled with ultrathin nanosheets (∼4 nm). These 3D mesoporous MnO2 shows a high-efficiency catalytic activity contrast with commercial MnO2 and 1D MnO2 nanorods and displays admirable repeatability as well as structure stability in dye degradation.

Luminescent–electrical–magnetic performances of sol–gel-derived Ni2+-modified Bi0.5Na0.5TiO3

2.5 mol% Ni2+-modified Bi0.5Na0.5TiO3 (BNT–Ni-0.025) ceramic has been fabricated based on the sol–gel method. The BNT–Ni-0.025 ceramic possesses a rhombohedral perovskite structure with denser microstructure than that of pure BNT ceramic. The introduction of certain amount of Ni2+ (e.g. 2.5 mol%) in BNT can reduce the sintering temperature (50 °C lower), effectively suppress the grain growth, greatly decrease the dielectric loss and then produce multifunctionality. The BNT–Ni-0.025 ceramic also exhibits good ferroelectric properties with a large remanent polarization of ~26 μC/cm2. The observed weak ferromagnetism of the ceramic can be ascribed to the exchange interaction between free carriers (oxygen vacancy induced delocalized electrons) and the localized Ni2+ ions. Under the excitation of 370 nm, the BNT–Ni-0.025 ceramic shows broadband NIR luminescence centered at ~1480 nm from Ni2+ with long emission lifetime (28 µs), which can cover the optical communication window and be applied in broadband optical amplifiers. The multifunctional BNT–Ni-0.025 ceramic shows potentials in the application of optical–electrical–magnetic areas.

Synthesis and Characterization of Ni2+-doped TiO2 Nanowires

Abstract: TiO2 nanowires doped with different amounts of Ni2+ ions (from 0 to 18 mol%) were synthesized by hydrothermal technique. The samples were characterized by X-ray diffraction (XRD) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and diffuse reflection spectroscopy. The XRD analysis showed that the doped samples exhibit anatase single phase. The lattice parameters remain unchanged, independent on Ni2+ content. Diameter of TiO2 nanowires increased significantly with increasing concentrations of Ni2+. The investigated results indicate that a greater portion of the Ni2+ ions are well-incorporated into the anatase TiO2 lattice. Indirect and direct band gap energies of Ni2+-doped TiO2 with different doping concentration were found to be in the range from 3.24 to 2.99 eV and 3.54 to 3.35 eV, respectively. 
 Keywords: TiO2:Ni2+ nanowires, hydrothermal, diffuse reflection, band gap energy.

Effects of ZnO and NiO on material properties of microwave absorptive glass-ceramic tile derived from iron ore tailings

Effects of ZnO and NiO on structural, morphological, magnetic properties and microwave absorption behavior of glass-ceramic tiles derived from iron ore tailings (IOTs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetization measurements, fourier transform infrared spectroscopy (FTIR) and complex permittivity and permeability measurements. Gradual replacement of NiO by ZnO was found to lower crystallinity of the glass-ceramic and reduce average grain size of the only crystalline phase indexed as spinel Ni–Zn ferrite. Ni2+ ion oscillations at different coordination environments inside glass network led to several notable dielectric losses in 3.8–15GHz. Ferromagnetic resonance frequency is positively correlated with the amount of Ni2+. These Ni-related effects enhanced the maximum microwave attenuation of the glass-ceramic to reach −34.35dB with its frequency being tunable in 6.70–11.20GHz.

Ni/SnO2复合薄膜的制备与光电性能

Ni / Sn O2 films were prepared by spin coating Ni / Sn O2 gel on the glass substrates. The effects of the doping amount of nickel and calcination temperature on the structure and morphology of Ni / Sn O2 films were discussed. The structure and morphology of Ni / Sn O2 composite film were characterized by using XRD,IR,SEM and other testing methods. The results show that the particles of the film calcined at 500 ℃ have high crystallization,small size,and distribute uniformly. The right amount of Ni2 +doping can improve the absorbance in the near ultraviolet region of Sn O2 film,and the absorbance in the near ultraviolet region of Ni / Sn O2 film decreases with the increasing of Ni2 +mole fraction from 5% to 10%. The conductivity of Ni / Sn O2 film is the best when Ni2 +mole fraction is 6%.

Structure‐Dependent Microwave Dielectric Properties and Middle‐Temperature Sintering of Forsterite (Mg1–xNix)2SiO4 Ceramics

The crystal structure, microstructure, and microwave dielectric properties of forsterite‐based (Mg1–xNix)2SiO4 (x = 0.02–0.20) ceramics were systematically investigated. All samples present a single forsterite phase of an orthorhombic structure with a space group Pbnm except for a little MgSiO3 secondary phase as x > 0.08. Lattice parameters in all axes decrease linearly with increasing Ni content due to the smaller ionic radius of Ni2+ compared to Mg2+. The substitution of an appropriate amount of Ni2+ could greatly improve the sintering behavior and produce a uniform and closely packed microstructure of the Mg2SiO4 ceramics such that a superior Q × f value (152 300 GHz) can be achieved as x = 0.05. The τf value was found to increase with increasing A‐site ionic bond valences. In addition, various additives were used as sintering aids to lower the sintering temperature from 1500°C to the middle sintering temperature range. Excellent microwave dielectric properties of εr~6.9, Q × f~99800 GHz and τf~−50 ppm/°C can be obtained for 12 wt% Li2CO3‐V2O5‐doped (Mg0.95Ni0.05)2SiO4 ceramics sintered at 1150°C for 4 h.

The synthesis of graphene oxide nanostructures for supercapacitors: a simple route

In this work, we report a simple strategy for synthesis of graphene oxide nanostructures with various morphologies including single-, few-layer, and three-dimensional networks. Morphology control is achieved by adding different amounts of Ni2+ into a one-step hydrothermal process. The involved growth mechanisms for the morphology control are discussed. A random arrangement of graphene oxide nanosheets is suggested to induce the networks’ formation. Ni2+ facilitates the formation of graphene oxide’s preferential face-to-face overlapping structure, and high Ni2+ concentrations render adjacent graphene oxide sheets to combine each other tightly to form closely packed, layered structures. Compared with single-, few-layer graphene oxide, the electrode prepared by three-dimensional networks has a mass specific capacitance of 352 F g−1 at v = 5 mV s−1, which is much higher than that of recently reported three-dimensional graphene oxide nanostructures (240 F g−1).

Structure and high rate performance of Ni2+ doped Li4Ti5O12 for lithium ion battery

Li4−2xNi3xTi5−xO12 (0 ≤ x ≤ 0.25) has been synthesized via solid-state reaction. X-ray diffractions (XRD) demonstrate that all doped samples have a spinel structure with Fd3¯m space group without any impurities. Through further Rietveld refinements, it is shown that both lattice parameter and occupancy of non-Li+ ions in the 8a sites negligibly change with the amount of Ni2+ dopants. Scanning electron microscope reveals that Ni2+ doping does not change the morphology of Li4Ti5O12. The best electronic conductivity of Ni2+ doped Li4Ti5O12 is at least one order of magnitude higher than that of the pristine one, while all samples have similar Li+ ion diffusion coefficients. The electrochemical performance of Ni2+ doped Li4Ti5O12 shows good rate capability. The specific capacity of Li3.9Ni0.15Ti4.95O12 at 5 C is as high as 72 mAh g−1, while that of the pristine one can only achieve 33 mAh g−1. This improved rate performance can be ascribed to its enhanced electronic conductivity.