NiCl2 Solution Research Articles

Properties of magnetic nickel/porous-silicon composite powders

The magnetic and photoluminescence (PL) properties of nickel/porous-silicon (Ni/PSi) composite powders are investigated. Ni/PSi composite powders are prepared by stain etching of Si powder in a HF/HNO3 solution followed by electroless plating of Ni nanoparticles on the stain-etched PSi powder in a NiCl2 solution. The Ni/PSi powders exhibit hydrophillicity, superparamagnetism caused by the deposited Ni nanoparticles, and orange-red PL owing to the nanostructured PSi surface. The degree of magnetization decreases with increasing Ni plating time, indicating its dependence on the size of the Ni nanoparticles. The Ni/PSi composite powders also show a stronger magnetization as compared to that of the Ni-particle-plated Si powder. The stronger magnetization results from the larger surface area of PSi. The PL intensity, peak wavelength, and lifetime of Ni/PSi are strongly dependent on the NiCl2 concentration. This dependence is due to the different thickness of the oxide overlayer on the PSi surface formed during the Ni plating process. The existence of the oxide overlayer also results in a small change in the PL intensity against excitation time.

Temperature-dependent structure and phase variation of nickel silicide nanowire arrays prepared by in situ silicidation

In this paper, we report an in situ silicidizing method to prepare nickel silicide nanowire arrays with varied structures and phases. The in situ reaction (silicidation) between Si and NiCl2 led to conversion of Si nanowires to nickel silicide nanowires. Structures and phases of the obtained nickel silicides could be varied by changing the reaction temperature. At a relatively lower temperature of 700°C, the products are Si/NiSi core/shell nanowires or NiSi nanowires, depending on the concentration of NiCl2 solution. At a higher temperature (800°C and 900°C), other phases of the nickel silicides, including Ni2Si, Ni31Si12, and NiSi2, were obtained. It is proposed that the different diffusion rates of Ni and Si atoms at different temperatures played a critical role in the formation of nickel silicide nanowires with different phases.

Synthesis and photocatalytic activity of monodisperse single crystalline NiO octahedrons by the selective adsorption of Cl− ions

Monodisperse NiO octahedrons have been synthesized by heating NiCl2 solutions on the Si substrates at 400–500°C for 1h. The NiO octahedrons are single-crystalline with the body-centered cubic structure and have controllable sizes in the range of 166–257nm. Control over the size of NiO octahedrons was achieved by adjusting the heating temperature. The formation of NiO octahedrons results from the selective adsorption of Cl– ions on unsaturated Ni(II) sites of NiO (111) surface. The NiO octahedrons with exposed {111} facets show higher intrinsic photocatalytic activity than Degussa P25 TiO2, and the photocatalytic activity was enhanced with a decrease on the size of NiO octahedrons.

Experimental study on the nickel (II) removal from aqueous solutions using silica fume with/without apocarbonic anhydrase

Abstract The silica fume is a fine-grain, thin and very high surface area silica. Although the silica fume is a waste material of industrial applications, it has become the most valuable by-product among the pozzolanic materials due to its very active and high pozzolanic property. In this study, the potential use of silica fume in the remediation of polluted heavy metal water to remove nickel ions is presented. For studying metal adsorption, 1 g of silica fume has been taken as adsorbent and then it has been suspended in 50 ml of 3 mmol dm−3 NiCl2, at pH between 3 and 9 and contacted batchwise in a thermostatic (t = 25°C ± 0.1°C) water-bath agitator for 1 h to enable equilibration of the sorbent and solution phases. The nickel concentrations in the samples taken from the silica fume treated aqueous solutions of polluted river water with/without apocarbonic anhydrase (apoCA) and NiCl2 solution have been determined by spectrophotometric method using dithizone. The nickel concentration in the samples of sili...

Pyrolysis of a femtoliter drop in a low-temperature aerosol reactor at a lowered pressure

The products of low-temperature pyrolysis of a solute in the rapid evaporation of droplets of an aqueous solution of NiCl2 in an aerosol reactor, were found experimentally. An x-ray spectroscopic analysis has shown that approximately 37% of nickel atoms pass into oxides. The pyrolysis products possess residual magnetization. It is also found that the rate of evaporation of nickel and chlorine compounds depends on the radius of droplets and their mass flow rate.

Synthesis and characterization of L-histidine capped silver nanoparticles

L-histidine capped Ag nanoparticles have been synthesized by a hydrothermal method. Spherical Ag nanoparticles with average diameter ranging from 9 to 21nm can be obtained by tuning the reaction pH and the reactant ratio. The topography, surface and internal structures of the histidine capped Ag nanoparticles have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering, X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), Raman spectroscopy and UV–vis absorption spectroscopy. Surface enhanced Raman scattering (SERS) results revealed that the Ag colloid in present study have a structure that the imidazole moiety of histidine is bound on the Ag surface and COO− group is exposed outward. The as-synthesized Ag colloidal solution was very stable and can be stored at room temperature at least one month. In addition, it was found that the solution color of Ag colloid can change from yellow to reddish-brown by addition of the NiCl2 solution, which may have potential application for Ni2+ detection.

Structure of reverse microemulsion-templated metal hexacyanoferrate nanoparticles.

The droplet phase of a reverse microemulsion formed by the surfactant cetyltrimethylammonium ferrocyanide was used as a matrix to synthesize nanoparticles of nickel hexacyanoferrate by adding just a solution of NiCl2 to the microemulsion media. Dynamic light scattering and small-angle neutron scattering measurements show that the reverse microemulsion droplets employed have a globular structure, with sizes that depend on water content. Transmission electron microscopy and electron diffraction are used to obtain information about the structure of the synthesized nanoparticles. The results show that the size and shape of the coordination compound nanoparticles correspond with the size and shape of the droplets, suggesting that the presented system constitutes an alternative method of the synthesis of metal hexacyanoferrate nanoparticles.

Preparation of graphene supported nickel nanoparticles and their application to methanol electrooxidation in alkaline medium

In this paper, we present the synthesis of Ni nanoparticles supported on graphene (Ni/G) using graphene oxide (GO) and Ni2+ ions as starting materials. GO is mixed with NiCl2 solution and treated by hydrazine. Hydrazine both reduces the GO and forms a complex with nickel(II). A treatment in the tubular furnace allows decomposing the nickel-hydrazine complex into Ni metallic nanoparticles as well as further reducing the GO into graphene. The materials are characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and thermogravimetry–mass spectrometry as well as tested for methanol electrooxidation in alkaline medium.

Structure of a new molecular rhenium cluster complex: trans-{[Ni(NH3)5]2×[Re6Se8(CN)4(OH)2]}·6H2O

Counter-diffusion of the aqueous solution of Cs2.75K1.25[Re6Se8(CN)4(OH)2] and a water-ammonia solution of NiCl2 afforded crystals of a rhenium cluster complex trans-{[Ni(NH3)5]2[Re6Se8(CN)4(OH)2]}·6H2O. The structure of the complex is determined by single crystal X-ray diffraction. In the structure, nickel atoms have an octahedral coordination environment involving nitrogen atoms of five NH3 ligands and one CN ligand of the cluster anion. The anion has two bridging CN ligands in the trans-positions

A 1-D cyano-bridged coordination polymer, [Ni(NH3)6]2[{Ni(NH3)4}{Re12CS17(CN)6}] · 8H2O: reactivity studies of dodecanuclear rhenium cluster anion [Re12CS17(CN)6]6− in Ni(II)-ammonia system

A cyano-bridged coordination polymer, [Ni(NH3)6]2[{Ni(NH3)4}{Re12CS17(CN)6}] · 8H2O, has been synthesized by reaction between concentrated aqueous ammonia solution of NiCl2 and aqueous solution of K6[Re12CS17(CN)6]. The compound has been characterized by single crystal X-ray diffraction, IR-spectroscopy and EDS analysis. The compound adopts 1-D structure, which consists of anionic chains [{Ni(NH3)4}{Re12CS17(CN)6}], discrete cations [Ni(NH3)6]2+ and crystal waters bonded together by hydrogen bonds. The influence of reagent concentrations on composition and structure of the resultant product has also been studied and discussed.

Composition of Ni2+ cation solvation shell in NiCl2–methanol solution by multinuclear NMR

1H-, 2H- and 13C-NMR spectra have been used to test the Ni2+ solvation shell composition in the 1.1 molal methanol solution of NiCl2. It has been confirmed that Cl− anion takes part in the nearest environment of Ni2+ cation at all the temperatures investigated. Using 2H-NMR allowed us to detect for the first time OD-signal of methanol in the primary solvation shell of Ni2+ cation. Both 2H- and 13C-NMR spectra show that the composition of the cation solvation shell becomes more complicated at temperatures lower than 220 K.

Ni–Fe–B catalysts for NaBH4 hydrolysis

A series of Ni–Fe–B catalysts with different Fe/(Fe+Ni) molar ratios, used for the hydrolysis of NaBH4, were prepared by chemical reduction of NiCl2 and FeCl3 mixed solution with NaBH4. The measurements revealed that the catalysts with the molar ratio of Fe/(Fe+Ni) (30%) exhibited the highest catalytic activity, and the optimal reduction temperature is 348K. In addition, the effects of the concentration of NaBH4, NaOH and the hydrolytic temperature of NaBH4 were discussed in detail. The results show that the reaction rate of hydrolysis first rises up and then goes down subsequently with the increase of NaBH4 concentration, as well as the concentration of NaOH. The activation energy of the hydrolysis for Ni–Fe–B catalysts is fitted to 57kJ/mol. The maximum value of hydrogen generation is 2910ml/(ming) at 298K.

Ternary Mutual Diffusion Coefficients of Aqueous NiCl2 + NaCl and NiCl2 + HCl Solutions at 298.15 K

The influence of sodium chloride and hydrochloric acid on the diffusion of aqueous nickel chloride has been investigated by using Taylor dispersion to measure ternary mutual diffusion coefficients for aqueous solutions of NiCl2 + NaCl and NiCl2 + HCl at 298.15 K and carrier concentrations from (0.000 to 0.050) mol·dm–3 for each solute. Mutual diffusion coefficients estimated from limiting ionic conductivities using Nernst equations are used to discuss the composition dependence of the diffusion coefficients and the electrostatic mechanism for the strongly coupled diffusion of the solutes.

Synthesis and Characterization of Nickel-Based Monolithic Aerogel via Sol-Gel Method

The synthesis and characterization of nickel-based aerogel prepared using nickel chloride as the precursor via sol-gel method is described. The addition of the polyacrylic acid as an template to the solution of NiCl2•6H2O can guide the gelation in the reaction to build a three dimensional open structure. The aerogel has been characterized using field emission scanning electron microscopy (FESEM), highresolution transmission electron microscopy (HRTEM), nitrogen adsorption desorption analysis and powder X-ray diffraction (XRD). The results indicate that the nickel-based aerogel has a typical three dimensional structure made up of spherical particles with an open porous network and has high surface area about 192 m2/g, average pore diameter about 40nm. The X-ray diffraction (XRD) patterns show that the aerogel prepared at room temperature belongs to amorphous material. The synthesis of nickel-based aerogel, using polyacrylic acid as an template, is especially unique in our experiment.

Azidoacetone as a complexing agent of transition metals Ni2+/Co2+ promoted dissociation of the CC bond in azidoacetone

The relevance of metal interactions with azides has led us to the study of the complexation of some transition metals, nickel and cobalt, by azidoacetone by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of NiCl(2) and CoCl(2) , in methanol/water. Nickel was electrosprayed with other counter ion, bromide (Br), as well as other solvent (ethanol/water). For nickel and cobalt, the complexes detected were single positively charged, with various stoichiometries, some resulted from the fragmentation of the ligand, the loss of N(2) being quite common. The most abundant species were [Ni(II)Az(2)X](+) where X = Cl, Br and Az = azidoacetone. Some of the complexes showed solvation with the solvent components. Metal reduction was observed in complexes where a radical was lost, resulting from the homolytic cleavage of a metal coordination bond. Collision-induced dissociation (CID) experiments followed by tandem mass spectrometry (MS-MS) analysis were not absolutely conclusive about the coordination site. However, terminal ions of the fragmentation routes were explained by a gas-phase mechanism proposed where a C-C bond was activated and the metal inserted subsequently. Density functional theory calculations provided structures for some complexes. In [Ni(II)Az(2)X](+) species, one azidoacetone ligand is monodentate and the dominant binding location is the alkylated nitrogen and not the carbonyl group. The other azidoacetone ligand is bidentate showing coordination through alkylated nitrogen and the carbonyl group. These are also the preferential binding sites for the most stable isomer of [Ni(II)AzX](+) species.

Multilayered Thin Metal Film Deposition by Sequential Operation of Nanosilicon Electron Emitter in Metal–Salt Solutions

The use of a nanocrystalline silicon (nc-Si) ballistic electron emitter in metal–salt solutions induces the deposition of thin metal films. The nc-Si emitter is composed of a thin Au/Ti film, an anodized polycrystalline Si layer, and an n+-Si substrate. When the emitter is driven in NiCl2, CoSO4, and ZnSO4 solutions without using any counter electrodes, thin Ni, Co, and Zn films are deposited on the emission area, respectively, as well as a thin Cu film in CuSO4 solution. According to cyclic voltammogram measurements under a standard three-electrode configuration, the hot electron injection effect into the solution is clearly observed in all cases at potentials within the electrochemical window, in which no electrolytic reactions occur. Energetic electrons injected into the solutions cause the direct reduction of metal ions. As a possible application, the multilayered deposition of different metals is demonstrated by sequential operation in NiCl2 and CuSO4 solutions.

ChemInform Abstract: Low‐Platinum‐Content Quaternary PtCuCoNi Nanotubes with Markedly Enhanced Oxygen Reduction Activity.

AbstractPt5Cu76Co11Ni8 nanotubes are prepared by a highly efficient template‐assisted one‐step electrodeposition method using a solution of KPtCl6, CuCl2, CoCl2, NiCl2, and H3BO3 as electrolyte.

10.2478/s11814-009-0269-5

Nickel oxide particles were prepared by spray pyrolysis of aqueous solution of NiCl2·6H2O. In the reactor the salt droplets were first converted to hollow particles by drying and then they were collapsed by oxidation to reduce their size. Each oxide particle was composed of many small nuclei with voids among them due to extremely low rate of sintering. The particle size decreased with the temperature as the sintering and crystallization proceeded. The size as well as the crystallinity of the particles increased with the initial salt concentration. When the salt droplets were preliminarily dried in diffusion dryer before entering the reactor, the collapse of the particles was considerably reduced, resulting in lower hollowness and higher sphericity. Numerical simulation on the drying of the droplets provided insight on the initial stage of spray pyrolysis.

Synthesis, characterization and growth mechanism of ZnO nanowires on NiCl2-coated Si substrates

Well-crystallized ZnO nanowires have been successfully synthesized on NiCl2-coated Si substrates via a carbon thermal reduction deposition process. The pre-deposited Ni nanoparticles by dipping the substrates into NiCl2 solution can promote the formation of ZnO nuclei. The as-synthesized nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectrum. The results demonstrate that the as-fabricated nanowires with about 60 nm in diameter and several tens of micrometers in length are preferentially arranged along [0001] direction with (0002) as the dominate surface. Room temperature PL spectrum illustrates that the ZnO nanowires exist a UV emission peak and a green emission peak, and the peak centers locate at 387 and 510 nm. Finally, the growth mechanism of the nanowires is briefly discussed.

Synthesis of AuNi/NiO Nanocables by Porous AAO Template Assisted Galvanic Deposition and Subsequent Oxidation

AbstractA facile and economic approach has been developed for the synthesis of coaxial nanocables with AuNi alloy nanowires as inner solid cores and NiO as outer shells by infiltrating a gold‐coated anodic aluminum oxide (AAO) template, with ring‐shaped Al foil on its outer edge, with a mixed aqueous solution of NiCl2 and HAuCl4 to form AuNi/Ni nanocables, and subsequent immersion in an aqueous NaOH solution to oxidize the Ni sheath during template removal. The formation of the AuNi/Ni nanocables in the channels of the AAO template could be ascribed to the reduction of the Ni2+ ion complexes adhering on the AAO channel walls and the redox reactions of two galvanic cells in which the surrounding Al foil acts as the anode. The approach enables excellent control over the shell thickness and the chemical composition of the AuNi/NiO nanocable by tuning the composition of the mixed solution. The AuNi/NiO nanocables have potentials in nanodevices and nanosystems.