Ribbon- and boardlike nanostructures of nickel hydroxide: synthesis, characterization, and electrochemical properties

We report the synthesis, characterization, and electrochemistry properties of ribbon- and boardlike nanostructures of nickel hydroxide, which crystallize in different phases. The ribbonlike nanostructures (nanoribbons) of nickel hydroxide were synthesized by treating amorphous alpha-Ni(OH)2 with high concentrations of nickel sulfate. These nanoribbons crystallized in a new phase had typical widths of 5-25 nm, thicknesses of 3-9 nm, and lengths of up to a few micrometers. After further treatment in alkali at 60 degrees C, the nanoribbons converted to boardlike nanostructures (nanoboards), which crystallized in the beta-phase with the average length-width-thickness ratio of 20:6:1. The crystal structures, Raman spectra, and electrochemical properties of these nanostructures of nickel hydroxide are described in this paper. For comparison, the amorphous alpha-Ni(OH)2 has also been investigated. Moreover, the intermediate product between the nanoribbons and the nanoboards displays a unique structure, which implied an interesting transformation process. The nanoribbons with the new phase show some unique features in Raman spectra, two new peaks located at 3534 and 3592 cm(-1) in the OH stretching region, indicating the new chemical environment of the hydroxyl groups. The nanoboards exhibit the highest specific capacity, which is close to the theoretical capacity of beta-Ni(OH)2. It suggests that the boardlike nanostructure is helpful in improving the electrochemical performance of nickel hydroxide. Because of their unique structures and properties, the nanoribbons and nanoboards of nickel hydroxide may give a new perspective for applications in the areas of catalysts and rechargeable batteries.     

Synthesis, characterization and electronic spectra of cefadroxil complexes of d-block elements

Cefadroxil (CD) is an essential pharmaceutical drug used in curing many diseases. Due to its popular use in many pharmaceutical forms, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug both in solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 and 1:2 ratios of metal (M) to ligand (L). The calculated stability constants (Kf) of these complexes (1.5x10(7) to 5x10(13)) and the change in free energy of formation (deltaGf=2.5-12.5 kcal mol(-1) degree(-1)) are indicative of their high stability. The stereo chemical structure of the solid complexes was studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of M-N and M-O bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structure. The prepared complexes were found to have the general formulae [ML(OH)x(H2O)y](H2O)z-M: Fe(II), x=0, y=2, z=1; M: Fe(III) and Co(III), x=1, y=2, z=1; M: Co(II) and Zn(II), x=0, y=1, z=0; M: Ni(II) and Cu(II), x=1, y=0, z=1; L: CD. Octahedral and tetrahedral structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.     

Synthesis of hexagonal nickel hydroxide nanosheets by exfoliation of layered nickel hydroxide intercalated with dodecyl sulfate ions

One-nanometer-thick nickel hydroxide nanosheets were prepared by exfoliation of layered nickel hydroxides intercalated with dodecyl sulfate (DS) ions. The shape of the nanosheets was hexagonal, as was that of the layered nickel hydroxides intercalated with DS ions. The nickel hydroxide nanosheets exhibited charge-discharge properties in strong alkaline electrolyte. The morphology of the nanosheet changed during the electrochemical reaction.     

The use of IR, magnetism, reflectance, and mass spectra together with thermal analyses in structure investigation of codeine phosphate complexes of d-block elements

Codeine is an analgesic with uses similar to morphines, but it is of much less effect, i.e., it had a mild sedative effect; codeine is usually used as the phosphate form (Cod.P) and is often administrated by mouth with aspirin of paracetamol. Due to its serious use, if it is in large dose, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug in both solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 ratio of metal (M) to ligand (L). The steriochemical structures of the solid complexes were studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of MO bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structures. The prepared complexes were found to have the general formulae [ML(OH)(x)(H2O)(y)](H2O)(z)H3PO4, M: Co(II), Ni(II), and Cu(II), x = 1, y = 0, z = 0; M: Fe(II), x = 1, y = 2, z = 1; Fe(III), x = 2, y = 1, z = 0; Co(III), x = 0, y = 2, z = 1; Zn(II), x = 1, y = 0, z = 3; and L: (Cod.P) of the general formula C18H24NO7P (anhydrate). Octahedral, tetrahedral, and square planer structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.     

Magnetic properties of nickel and zinc double hydroxides

Magnetic properties of nickel and zinc double hydroxides were studied using an axial extraction apparatus and a Faraday balance. Measurements were taken mainly between 4.2 and 40 K for applied fields 50-45 000 Oe.The results confirm the existence of two types of structure α and β, which were previously determined by X-ray analysis.The β solids, i.e., with a low zinc concentration, are essentially antiferromagnetic at 4.2 K for fields smaller than 45 kOe. They are compared with the hydroxide β-Ni(OH)₂. The α solids are metamagnetic with a low threshold field. The magnetization isotherms obtained for the α solids at 4.2 K show magnetic viscosity phenomena.This difference in magnetic behaviour is useful for attributing the α or β structure to samples in which the phase containing the double hydroxide is not detected by X-ray analysis.     

新型氢氧化镍正极材料的制备和表征

选取Co、Zn、Ca、Mg、Cu等元素与Ni元素按照一定的化学计量比"合金化",实行修饰或掺杂,制备出新型氢氧化镍(New Type Nickel Hyclroxide,NTNH).利用X射线衍射、扫描电镜和恒电流充放电技术测试其相结构、表面微观形貌和充放电性能.研究结果表明:和商业产品相比,新型氢氧化镍具有良好的高温大电流充放电性能和循环稳定性.实现多种元素共沉积,利用元素之间的协同效应,是改善氢氧化镍正极材料高温大电流充放电性能的一条有效途径.     

Hexamethylenetetramine directed synthesis and properties of a new family of alpha-nickel hydroxide organic-inorganic hybrid materials with high chemical stability

A new family of organic-inorganic hybrid material of alpha-nickel hydroxide formulated as Ni(OH)2-x(An-)x/n-(C6H12N4)y.zH2O (A=Cl-, CH3COO-, SO4(2-), NO3-; x=0.05-0.18, y=0.09-0.11, z=0.36-0.43) with high stability and adjustable interlayer spacing ranging from 7.21 to 15.12 A has been successfully prepared by a simple hydrothermal method. The effects of various anions and hexamethylenetetramine (HMT) on the d values of alpha-nickel hydroxide have been systematically investigated. This family of hybrid materials is of such high stability that they can stand more than 40 days in 6 M KOH. The product with a formula Ni(OH)1.95(C6H12N4)0.11(Cl-)0.05(H2O)0.36 has a high surface area of about 299.26 m2/g and an average pore diameter of about 45.1 A. The coercivity (Hc) value is ca. 2000 Oe for the sample with a d spacing of 13.14 A. Moreover, the prepared alpha-Ni(OH)2 in our experiment is of high stability in strong alkali solution. Such high stability could be derived from strong chelating interactions between the Ni ions and HMT molecules with the interlayers. This high chemical stability could make this material more suitable for the applications.     

R?ntgenfluorescenzspektrometrische Untersuchung der Mitf?llung von Kobalt und Nickel bei der Eisenhydroxidf?llung mit Urotropin

Zusammenfassung Es wurde die Adsorption (Mitfällung) von Kobalt und Nickel an mit der Urotropinmethode gefälltem Eisenhydroxid untersucht. Die Mengen an Kobalt und Nickel im Eisenhydroxid wurden durch Röntgenfluorescenzmessungen an Boratschmelzen der Hydroxide bestimmt. Dabei wurde festgestellt, daß bei gleichen Konzentrationsverhältnissen fünfmal soviel Nickel wie Kobalt adsorbiert wird und daß die Fällung von Eisenhydroxid mit der Urotropinmethode für eine Abtrennung des Eisens vor einer Nickelbestimmung nicht und vor einer Kobaltbestimmung nur bedingt geeignet ist, wenn nicht das Eisenhydroxid durch eine Umfällung, z.B. mit Ammoniak, gereinigt wird.

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X-ray fluorimetric study of the coprecipitation of cobalt and nickel with ferric hydroxide in the precipitation with urotropine

Summary The adsorption (coprecipitation) of cobalt and nickel on ferric hydroxide, precipitated by urotropine, was studied. The quantities of cobalt and nickel in the ferric hydroxide were determined by X-ray fluorimetric measurements of borate fusions of the hydroxides. It has been found, that fivefold more nickel than cobalt is adsorbed with equal ratios of concentration. Therefore the separation of ferric hydroxide with urotropine is not suitable for a following determination of nickel and only conditionally suitable for a following determination of cobalt, if the ferric hydroxide is not purified by reprecipitation with ammonia.

     

Tuning the band gaps and work functions via topology and carbon concentration: a first-principles investigation of C(x)(BN)(y) compounds

The electronic properties, stabilities, and work functions of C(x)(BN)(y) monolayers were systematically investigated by first-principle techniques. The results indicated that the band gaps of the systems are rather sensitive to the topology and symmetry. However, the formation energies clearly suggested that the BN dimers tend to be grouped to one side and the carbon atoms are grouped to the other side. Such an atomic arrangement has the lowest formation energy and is thermodynamically highly stable, and furthermore their band gaps decrease gradually with an increasing of carbon content. Further analysis revealed that the band gap narrowing of G(I) structures depends on the nature of the C-2p(z) and N-2p(z) states. In contrast to the electronic properties, the variation of work functions as functions of carbon content exhibits an opposite trend. The strong correlation between the positive charge (Q(pos.)(tot.))?:work function (W(C(x)(BN)(y))) ratio and carbon content indicated that the ionicity of C(x)(BN)(y) compounds can be controlled by the carbon content and therefore determine the work functions of the systems.     

A general electrochemical approach to deposition of metal hydroxide/oxide nanostructures onto carbon nanotubes

This communication describes a new and relatively general electrochemical approach to the deposition of transition metal hydroxide/oxide nanostructures onto multi-walled carbon nanotubes (MWNTs) based on the precipitation of metal hydroxide/oxide nanostructures onto MWNTs by increasing the local pH values at the electrode/electrolyte interface induced by the proton-consuming electrochemical reduction of hydrogen peroxide (H₂O₂). The results obtained with cyclic voltammetry, scanning electron microscopy, and X-ray photoelectron spectroscopy of the synthetic nanocomposites substantially suggest the deposition of the metal hydroxides/oxides onto MWNTs induced by the electrochemical reduction of H₂O₂. This study essentially offers a facile but effective and relatively general electrochemical approach to the synthesis of the nanocomposites consisting of metal hydroxides/oxides and MWNTs.     

Ni–Al composite hydroxides fabricated by cation–anion double hydrolysis method for high-performance supercapacitor

Chemical doping of nickel hydroxide with other cations(e.g. Al~(3+)) is an efficient way to enhance its electrochemical capacitive performances. Herein, a simple cation–anion(Ni~(2+)and AlO_2) double hydrolysis method was developed toward the synthesis of nickel–aluminum(Ni–Al) composite hydroxides. The obtained composite hydroxides possesses a porous structure, large surface area(121 m~2/g) and homogeneous element distribution. The electrochemical test shows that the obtained composite hydroxides exhibits a superior supercapacitive performances(specific capacitance of 1670F/g and rate capability of 87% from 0.5 A/g to 20 A/g) to doping-free nickel hydroxide(specific capacitance of 1227 F/g and rate capability of 47% from 0.5 A/g to 20 A/g). Moreover, the galvanostatic charge/discharge test displays that after 2000 cycles at large current density of 10 A/g, the composite hydroxides achieves a high capacitance retention of 98%, indicative of an excellent electrochemical cycleability.     

Hydroxy double salt anion exchange kinetics: effects of precursor structure and anion size

(1)H NMR spectroscopy and powder X-ray diffraction have been used to explore the details of anion exchange reactions of two layered hydroxy double salts (HDSs), zinc copper hydroxy acetate (ZCA), nickel zinc hydroxy acetate (NZA), and a related layered material, zinc hydroxy acetate (ZHA), at room temperature (21-22 degrees C). Reactions that followed Avrami-Erofe'ev kinetics with respect to temporal profiles for acetate release, ZCA with butyrate (k = 1.7 x 10(-3) s(-1)), and octanoate (k = 0.79 x 10(-3) s(-1)) anions, as well as ZHA with octanoate (k = 2.6 x 10(-3) s(-1)), demonstrate that rate constants for acetate release are influenced by the exchange anion relative size as well as by the solid precursor structure/composition. The reaction of NZA with octanoate deviated from expected Avrami-Erofe'ev behavior, with evidence for an intermediate species in the solid phase that may influence the rate of acetate release into solution. The reaction of ZCA with formate anions exhibited a unique zeroth-order kinetics release of acetate, providing the possibility of developing tunable nanostructured anion release sources by use of variations in the size of the exchange species.     

Inelastic neutron scattering on three mixed-valence dodecanuclear polyoxovanadate clusters

The magnetic exchange interactions in the mixed-valence dodecanuclear polyoxovanadate compounds Na(4)[V(IV)(8)V(V)(4)As(III)(8)O(40)(H(2)O)].23H(2)O, Na(4)[V(IV)(8)V(V)(4)As(III)(8)O(40)(D(2)O)].16.5D(2)O, and (NHEt(3))(4)[V(IV)(8)V(V)(4)As(III)(8)O(40)(H(2)O)].H(2)O were investigated by an inelastic neutron scattering (INS) study using cold neutrons. In addition, the synthesis procedures and the single-crystal X-ray structures of these compounds have been investigated together with the temperature dependence of their magnetic susceptibilities. The magnetic properties below 100 K can be described by simply taking into account an antiferromagnetically exchange coupled tetramer, consisting of four vanadium(IV) ions. Up to four magnetic transitions between the cluster S = 0 ground state and excited states could be observed by INS. The transition energies and the relative INS intensities could be modeled on the basis of the following exchange Hamiltonian: H(ex) = -2J(12)(xy)[S(1x)S(2x)+ S(3x)S(4x)+ S(1y)S(2y)+ S(3y)S(4y)] - 2J(12)(z)[(S(1z)S(2z)+ S(3z)S(4z)] - 2J(23)(xy)[(S(2x)S(3x)+ S(1x)S(4x)+ S(2y)S(3y)+ S(1y)S(4y)] - 2J(23)(z)[(S(2z)S(3z)+ S(1z)S(4z)]. The following sets of parameters were derived: for Na(4)[V(12)As(8)O(40)(H(2)O)].23H(2)O, J(12)(xy)() = J(12)(z)= -0.80 meV, J(23)(xy) = J(23)(z) = -0.72 meV; for Na(4)[V(12)As(8)O(40)(D(2)O)].16.5D(2)O, J(12)(xy) = J(12)(z) = J(23)(xy) = J(23)(z = -0.78 meV; for (NHEt(3))(4)[V(12)As(8)O(40)(H(2)O)].H(2)O, J(12)(xy) = -0.80 meV, J(12)(z) = -0.82 meV, J(23)(xy)() = -0.67 meV, J(23)(z) = -0.69 meV. This study of the same [V(12)As(8)]-type cluster in three different crystal environments allows us to draw some conclusions concerning the applicability on INS in the area of nondeuterated molecular spin clusters. In addition, the effects of using nondeuterated samples and different sample container shapes for INS were evaluated.     

Length‐Dependent Charge Generation from Vertical Arrays of High‐Aspect‐Ratio ZnO Nanowires

Aqueous chemical growth of zinc oxide nanowires is a flexible and effective approach to obtain dense arrays of vertically oriented nanostructures with high aspect ratio. Herein we present a systematic study of the different synthesis parameters that influence the ZnO seed layer and thus the resulting morphological features of the free‐standing vertically oriented ZnO nanowires. We obtained a homogeneous coverage of transparent conductive substrates with high‐aspect‐ratio nanowire arrays (length/diameter ratio of up to 52). Such nanostructured vertical arrays were examined to assess their electric and piezoelectric properties, and showed an electric charge generation upon mechanical compressive stress. The principle of energy harvesting with these nanostructured ZnO arrays was demonstrated by connecting them to an electronic charge amplifier and storing the generated charge in a series of capacitors. We found that the generated charge and the electrical behavior of the ZnO nanowires are strictly dependent on the nanowire length. We have shown the importance of controlling the morphological properties of such ZnO nanostructures for optimizing a nanogenerator device.     

On the nature of decrease in the particles size of nanostructured nickel oxide obtained by the sol-gel method in the presence of surfactants

A processes of formation of nanostructured powders of nickel oxide by annealing in the temperature range of 200–700°C of the nickel hydroxide obtained by the sol-gel method at 80°C from solutions of nickel nitrate by precipitation with alkali in the presence of surfactant AF-12 (polyethylene oxide alkylphenyl ether) was investigated. The formation of nanostructured powders of nickel oxide in the presence of a surfactant reduces the size of nanoparticles to 20–25 nm, which is 1.5 times smaller than the particles obtained without a surfactant. The effective influence of surfactant on the particle size begins in the temperature range of its decomposition and evaporation equal 350–400°C.     

Deposition precipitation for the preparation of carbon nanofiber supported nickel catalysts

Deposition precipitation of nickel hydroxide onto modified carbon nanofibers has been studied and compared to deposition onto silica. The carbon nanofiber support materials consisted of graphite-like material of the fishbone-type with a diameter of 20-50 nm and a specific surface area of 150 m2/g. Modification involved surface oxidation (CNF-O) optionally followed by partial reduction (CNF-OR) or thermal treatment (CNF-OT). Titration of the support materials showed the presence of 0.17 and 0.03 mmol/g carboxylic acid groups for CNF-O and CNF-OR, respectively. For the CNF-OT only basic groups were present. The deposition precipitation of 20 wt % nickel onto these supports has been studied by time dependent pH and nickel loading studies. With silica, nickel ion adsorption did not occur prior to nucleation of the nickel hydroxide phase at pH = 5.6. With CNF-O, nickel ion adsorption took place right from the start of the deposition process at pH = 3.5, and at pH = 5.6 already 4 wt % nickel was adsorbed. Nucleation of nickel hydroxide onto adsorbed nickel ion clusters proceeded subsequently. Characterization of the dried Ni/CNF-O samples with TEM and XRD showed well dispersed and thin (5 nm) platelets of nickel hydroxide adhering to the carbon nanofibers. After reduction at 773 K in hydrogen the Ni/CNF-O contained metallic nickel particles of 8 nm homogeneously distributed over the fibers. With CNF-OR and CNF-OT, precipitation of large platelets (> 500 nm) separate from the support took place. Clearly, the presence of carboxylic acid groups is essential to successfully deposit nickel hydroxide onto modified carbon nanofibers.     

A Facile Room Temperature Synthesis of Zinc Oxide Nanostructure and Its Influence on the Flame Retardancy of Poly Vinyl Alcohol

In this work, poly vinyl alcohol–ZnO nanocomposites were synthesized via two different in situ and ex-situ methods. In ex-situ, at first zinc oxide nanostructures were synthesized by one-step precipitation reaction between zinc acetate and sodium hydroxide. The effect of different surfactants such as poly vinyl pyrrolidone, poly vinyl alcohol and poly ethylene glycol on the morphology of ZnO nanostructures was investigated. Nanostructures were characterized by X-ray diffraction, scanning electron microscopy. The influence of ZnO nanostructures on the flame retardancy of the poly vinyl alcohol matrix was studied using underwriter laboratories UL-94 analysis.     

Formation of a nickel catalyst on the surface of aluminosilicate supports for the synthesis of catalytic fibrous carbon

Conditions for the homogeneous precipitation of nickel hydroxide in the presence of urea onto the surface of aluminosilicate honeycomb monoliths, which were prepared based on clay, talc, and amorphous aluminum hydroxide, were examined. Factors affecting the concentration of supported nickel (synthesis time, starting solution concentrations, loaded amount of the support, and support calcination temperature) were studied. The possibility of supporting nickel hydroxide onto the surface of cellular ceramic foam, glass foam, and haydite was demonstrated. The morphology of nickel hydroxide particles, nickel metal particles on support surfaces, and carbon coatings synthesized in the course of the catalytic pyrolysis of a propane-butane mixture was studied by scanning electron microscopy.     

双金属复合氧化物的结构与紫外阻隔性能

双金属复合氧化物（ＣＬＤＨ）是一类发展迅速的无机层状材料的煅烧产物,在催化、吸附等领域已获长足进展［１］,但作为紫外阻隔材料的性能研究尚鲜见报道．本文研究了不同双金属复合氧化物的紫外阻隔性能,结果发现二价金属离子为锌离子的ＣＬＤＨ具有良好的紫外阻隔性能．实验所用试剂均为分析纯．ＣＬＤＨ由ＮａＯＨ,Ｎａ２ＣＯ３,ＭｇＳＯ４·７Ｈ２Ｏ,ＺｎＳＯ４·７Ｈ２Ｏ,Ａｌ２（ＳＯ４）３·１８Ｈ２Ｏ为原料,按文献［２］方法制备．ＺｎＯ＋Ａｌ２Ｏ３复配物是按一定比例机械混合后,研磨,并在与ＣＬＤＨ相同的条件下煅烧…     

Multi‐Anion Intercalated Layered Double Hydroxide Nanosheet‐Assembled Hollow Nanoprisms with Improved Pseudocapacitive and Electrocatalytic Properties

Electrochemically active hollow nanostructured materials hold great promise in diverse energy conversion and storage applications, however, intricate synthesis steps and poor control over compositions and morphologies have limited the realization of delicate hollow structures with advanced functional properties. In this study, we demonstrate a one‐step wet‐chemical strategy for co‐engineering the hollow nanostructure and anion intercalation of nickel cobalt layered double hydroxide (NiCo‐LDH) to attain highly electrochemical active energy conversion and storage functionalities. Self‐templated pseudomorphic transformation of cobalt acetate hydroxide solid nanoprisms using nickel nitrate leads to the construction of well‐defined NiCo‐LDH hollow nanoprisms (HNPs) with multi‐anion intercalation. The unique hierarchical nanosheet‐assembled hollow structure and efficiently expanded interlayer spacing offer an increased surface area and exposure of active sites, reduced mass and charge transfer resistance, and enhanced stability of the materials. This leads to a significant improvement in the pseudocapacitive and electrocatalytic properties of NiCo‐LDH HNP with respect to specific capacitance, rate and cycling performance, and OER overpotential, outperforming most of the recently reported NiCo‐based materials. This work establishes the potential of manipulating sacrificial template transformation for the design and fabrication of novel classes of functional materials with well‐defined nanostructures for electrochemical applications and beyond.