Synthesis and structure of actinide(VII) compounds Rb3NpO4(OH)2·3H2O and Rb3PuO4(OH)2·3H2O

Actinide(VII) salts Rb₃[NpO₄(OH)₂]·3H₂O (I) and Rb₃[PuO₄(OH)₂]·3H₂O (II) were prepared as single crystals and examined by X-ray diffraction. The compounds are isostructural and crystallize in the monoclinic system, space group C2/c, Z = 4; unit cell parameters: a = 12.1544(3), b = 10.9942(2), c = 7.789(2) ?, ?? = 91.0930(11)° for I and a = 12.1254(3), b = 10.9506(2), c = 7.7699(2) ?, ?? = 90.8253(12)° for II. The main structural elements of I and II are centrosymmetrical anions [AnO₄(OH)₂]^3? forming together with water molecules, owing to strong hydrogen bonding, chains oriented along [101]. In [AnO₄(OH)₂]^3? anions, the central An(VII) atom has a tetragonal-bipyramidal oxygen surrounding. The An-O(OH) interatomic distances decrease in going from I to II owing to actinide contraction by a factor of ??2 more strongly than the An-O bond lengths in the equatorial planes of the bipyramids. The previously studied structure of Cs₃[NpO₄(OH)₂]·3H₂O (III) was refined.     

Zn3V2O7(OH)2·2H2O and Zn3(VO4)2 3D microspheres as anode materials for lithium-ion batteries

Three-dimensional Zn₃V₂O₇(OH)₂·2H₂O microspheres have been successfully synthesized by a simple and facile liquid phase precipitation method without using any surfactants or additives. The as-prepared microspheres were constructed by two-dimensional nanosheets, which interconnected with each other through self-assembly. The influences of the aging time, reaction temperature, and pH value on the morphologies of the products were systematically investigated. Moreover, three-dimensional Zn₃(VO₄)₂ microspheres could be formed through calcination of the Zn₃V₂O₇(OH)₂·2H₂O precursor. The obtained Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ microspheres were further investigated as the anode materials of lithium-ion batteries. Electrochemical measurements showed that the Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ microspheres exhibited high discharge capacity and good cycle stability, indicating potential anode candidates in advanced rechargeable lithium-ion batteries. It should be noted that this is the first report on the Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ three-dimensional microspheres as anode materials in lithium-ion batteries. The present work will greatly expand the range of anode choices and could assist long-term endeavors in developing high capacity anode materials for lithium-ion batteries.     

3D hierarchical Zn3(OH)2V2O7·2H2O and Zn3(VO4)2 microspheres: Synthesis,characterization and photoluminescence

Via a simple glycine-assisted hydrothermal route, large-scale 3D hierarchical Zn₃(OH)₂V₂O₇·2H₂O microspheres have been fabricated. Their purity, crystalline phase, morphologies and thermal stability were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform IR (FTIR), scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The SEM results indicate that the microspheres are self-assembled by numerous nanoflakes with mean thickness of 100 nm. Some factors influencing the morphologies of the Zn₃(OH)₂V₂O₇·2H₂O micro-/nanostructures have been systematically investigated, as well as quantity of glycine and the reaction time. The possible mechanism of the crystal growth and assembled procedure were also proposed. The as-prepared Zn₃(OH)₂V₂O₇·2H₂O can be transformed into Zn₃(VO₄)₂ with the similar morphologies by calcination in air at 600 °C. Furthermore, the photoluminescent properties of both Zn₃(OH)₂V₂O₇·2H₂O and Zn₃(VO₄)₂ were studied and exhibited different spectra.     

Synthesis of hexagonal Zn3(OH)2V2O7·2H2O nanoplates by a hydrothermal approach: Magnetic and photocatalytic properties

Hexagonal Zn₃(OH)₂V₂O₇·2H₂O nanoplates have been successfully synthesized via a facile and template-free hydrothermal method. The nanocrystals have a hexagonal shape with 650–750 nm in diameter and 120–140 nm in thickness. The possible mechanism of forming such hexagonal Zn₃(OH)₂V₂O₇·2H₂O nanoplates may be due to its inherent anisotropic crystal structure. Magnetic hysteresis measurement indicates that the as-synthesized hexagonal Zn₃(OH)₂V₂O₇·2H₂O nanoplates have weak ferromagnetic property at room temperature. Compared to the floriated-like nanostructured Zn₃V₂O₇(OH)₂(H₂O)₂ synthesized by a hydrothermal route, the as-prepared hexagonal Zn₃(OH)₂V₂O₇·2H₂O nanoplates exhibited a significant increase in the methylene blue (MB) photodegradation rate under UV irradiation.     

Synthesis and crystal structure of americium(V) dichromate, Cs3AmO2(Cr2O7)2·H2O

A new Am(V) chromate complex with outer-sphere cesium cation, Cs₃AmO₂(Cr₂O₇)₂·H₂O, was prepared from aqueous solution. Its composition and structure were determined by single crystal X-ray diffraction. The Am(V) atom has coordination surrounding in the form of a distorted pentagonal bipyramid with the O atoms of the AmO ₂ ⁺ group in apical positions. The equator of the bipyramid is formed by the O atoms of four dichromate groups and of the water molecule. The mean bond lengths (Å) are as follows: Am=O 1.802(5), Am-O(Cr₂O₇) 2.443(6), and Am-O_w 2.519(6). The Am(V) pentagonal bipyramids are combined via bidentate bridging Cr₂O ₇ ^2? anions into infinite chains [AmO₂(Cr₂O₇)₂H₂O] _n ^3? arranged in layers parallel to the series of diagonal planes (111). A system of hydrogen bonds links the chains in a layer and the layers with each other. The Cs cations are arranged between the layers, forming cationic interlayers.     

Synthesis and electrochemical properties of Ag0.333V2O5–V2O5 core–shell nanobelts for rechargeable lithium batteries

Ag_0.333V₂O₅–V₂O₅ core–shell nanobelts have been synthesized by a facile homogeneous reaction between peroxovanadic acid and AgNO₃ under hydrothermal conditions. The formation of Ag_0.333V₂O₅–V₂O₅ core–shell nanobelts is time dependent: Ag_0.333V₂O₅ nanobelts are formed firstly, and then V₂O₅ grows on the Ag_0.333V₂O₅ surfaces. The core–shell nanobelts exhibit stable lithium-ion intercalation/deintercalation reversibility and deliver specific discharge capacities of around 276.4 mAhg^?1 after 50 cycles at a rate of 0.25 Ag^?1. The value is lowered to 228 mAhg^?1 at 0.5 Ag^?1, and 147.2 mAhg^?1 at 0.75 Ag^?1. The good electrochemical properties of Ag_0.333V₂O₅–V₂O₅ core–shell nanobelts make them a promising candidate as a cathode material for rechargeable lithium batteries.     

Ordered mesoporous α-Fe2O3 (hematite) thin-film electrodes for application in high rate rechargeable lithium batteries

Herein is reported the synthesis of ordered mesoporous α-Fe(2)O(3) thin films produced through coassembly strategies using a poly(ethylene-co-butylene)-block-poly(ethylene oxide) diblock copolymer as the structure-directing agent and hydrated ferric nitrate as the molecular precursor. The sol-gel derived α-Fe(2)O(3) materials are highly crystalline after removal of the organic template and the nanoscale porosity can be retained up to annealing temperatures of 600 °C. While this paper focuses on the characterization of these materials using various state-of-the-art techniques, including grazing-incidence small-angle X-ray scattering, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and UV-vis and Raman spectroscopy, the electrochemical properties are also examined and it is demonstrated that mesoporous α-Fe(2)O(3) thin-film electrodes not only exhibit enhanced lithium-ion storage capabilities compared to bulk materials but also show excellent cycling stabilities by suppressing the irreversible phase transformations that are observed in microcrystalline α-Fe(2)O(3).     

Synthesis and Characteristics of Double Np(VI) Potassium and Pu(VI) Potassium Silicates K[(NpO2)(SiO3OH)]·H2O and K[(PuO2)(SiO3OH)]·H2O

K[(NpO₂)(SiO₃OH)]·H₂O (I) and K[(PuO₂)(SiO₃OH)]·H₂O (II) were prepared by hydrothermal synthesis at 120°C, and their IR and near-IR spectra were measured. The unit cell parameters of the compounds were determined from powder X-ray patterns [a = 7.068(1), b = 7.064(2), c = 6.640(1) Å. = 106.68(1)°, V = 317.6 ų (I); a = 7.102(1), b = 7.100(2), c = 6.637(1) Å, = 107.62(1)°, V = 318.9 ų (II)]. These compounds are isostructural with potassium boltwoodite K[(UO₂)(SiO₃OH)]·H₂O.     

Synthesis and structure of Cs3[UO2(CH3COO)3]2(NCS)·H2O

The compound Cs₃[UO₂(CH₃COO)₃]₂(NCS)·H₂O (I) was synthesized and studied by IR spectroscopy and single crystal X-ray diffraction. Compound I crystallizes in the monoclinic system with the following unit cell parameters: a = 7.8286(9), b = 19.892(2), c = 20.050(2) Å, β = 94.527(2)°, space group P2₁/c, Z = 4, R = 0.0387. The uranium-containing structural units in crystals of I are mononuclear complexes [UO₂(CH₃COO)₃]^? belonging to crystal-chemical group AB ₃ ⁰¹ (A = UO ₂ ²⁺ , B⁰¹ = CH₃COO^?) of uranyl complexes.     

Novel self-assembled decavanadate clusters forming 1D molecular chains and 2D molecular arrays: [HMTA-H···H2O][HMTA-CH2OH][H3V10O28{Na(H2O)4}]·4H2O and [Na2(H2O)10] [H3V10O28 {Na(H2O)2}]·3H2O

Two novel materials, [HMTA-H··H₂O] [HMTA-CH₂OH] [H₃V₁₀O₂₈[Na(H₂O)₄}]·4H₂O, 1 and [Na₂(H₂O)₁₀][H₃V₁₀O₂₈[Na(H₂O)₂}]·3H₂O, 2 containing decavanadate clusters interconnected through hydrated sodium cations forming 1D molecular chains and 2D molecular arrays have been self-assembled from acidified, aqueous vanadate solution in the presence of organic bases, hexamethylenetetramine and 1,3,5-triazine respectively.     

Synthesis and crystal structure of a new Np(V) oxalate, Na4(NpO2)2(C2O4)3·6H2O

A new oxalate complex, Na₄(NpO₂)₂(C₂O₄)₃·6H₂O, with the Np:C₂O₄ ratio of 2:3 was synthesized and studied by single crystal X-ray diffraction. In the crystal, the NpO ₂ ⁺ cations and oxalate anions are bound in open networks [(NpO₂)₂(C₂O₄)₃] _n ^4n- parallel to the bc plane. The Na(1) cations are accommodated in large voids of the neptunyl oxalate networks with the formation of crimped mixed-cation layers of the composition [Na₂(NpO₂)₂(C₂O₄)₃] _n ^2n- . The negative charge of the layers is compensated by the Na(2) cations arranged between the layers. The Np atoms have a pentagonal bipyramidal coordination surrounding with the equatorial plane formed by the oxygen atoms of three oxalate anions. The structure contains tridentate-bridging and tetradentate-bridging oxalate anions.     

Facile one-step synthesis of Fe5(PO4)4(OH)3 · 2H2O hollow octahedra and their application for DNA separation

A simple one-step process has been used to synthesize novel Fe₅(PO₄)₄(OH)₃?·?2H₂O hollow octahedra in a mixed solvent of diethylene glycol (DEG) and H₂O. The x-¹ray diffraction (XRD) and scanning electron microscopy (SEM) have been provided for the characterizations of the nanostructures. The shape of the as-obtained products could be controlled by adjusting the volume ratio of DEG and H₂O in the solvothermal process. The possible formation mechanism was proposed based² on nucleation and the Ostwald ripening process as well as the soft-template function of DEG. In addition, the study herein demonstrated that the hollow octahedra exhibit excellent capability for the adsorption of salmon sperm DNA and would have great application potentials in DNA separation.     

Morphological and topotactical aspects of the reactions Co(OH)2 → CoOOH and CoOOH → Co3O4

Studies of the thermal decomposition to Co₃O₄ of particles of CoOOH with different textures and porosities were carried out by electron microscopy and diffraction. A comparison of topotactical relationships, crystallite misorientation and porosity between these results and those previously obtained for the reaction Co(OH)₂ CoOOH has permitted significant conclusions to be drawn about the interaction of these parameters. In particular, a reaction can be topotactical even without a good fit between the lattices of the starting and final products provided that an easy texture reordering is observed in the reaction conditions.     

Fabrication and application of MFe2O4 (M = Zn,Cu) nanoparticles as anodes for Li ion batteries

In this work, MFe₂O₄ (M?=?Zn, Cu) nanoparticles were successfully prepared by a hydrothermal method. The structure, morphology, microstructure, specific surface area and electrochemical properties of the resultant particles were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen physical adsorption, charge–discharge test and cyclic voltammetry (CV) method, respectively. The resulting ZnFe₂O₄ and CuFe₂O₄ products were sphere-like and cubic-shaped particles and their average size was about 30–40?nm and 60–70?nm, respectively. The initial discharge capacities of ZnFe₂O₄ and CuFe₂O₄ electrodes reached 1287.5?mAh?g^?1 and 1412.3?mAh?g^?1, respectively, at a current density of 0.2?mA?cm^?2 in a potential range of 0.0–3.0?V. This indicated that Cu is a better counter ion than Zn. The resulting MFe₂O₄ nanoparticles are expected to be a promising candidate of anode materials for Li ion batteries. The reaction mechanism of MFe₂O₄ nanoparticles in Li ion batteries was also discussed based on the CV of Li/MFe₂O₄ cell.     

Hydrothermal synthesis of mesoporous VO2·½(H2O) nanosheets and study of their electrical properties

Layered sheet-like nanocrystalline VO₂·½(H₂O) has been synthesized by hydrothermal process using V₂O₅ as vanadium source and 2-phenylethylamine as a reducing agent and a structure-directing template. Techniques X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption/desorption isotherms have been used to characterize the structure, morphology and composition of the materials. Electrical conductivity measurements showed that the as synthesized VO₂·½(H₂O) nanosheets has a conductivity value which goes from 75 × 10^?6 Ω^?1 cm^?1 at 298 K, to 68 10^?5 Ω^?1 cm^?1 at 386 K with activation energy of 0.24 eV.     

Synthesis of a novel layered double hydroxides [MgAl(4)(OH)(12)](Cl)(2)·2.4H(2)O and its anion-exchange properties

A novel layered double hydroxide of Mg and Al with composition [Mg(0.96)Al(4.00)(OH)(12)]Cl(1.86)(CO(3))(0.03)·2.4H(2)O, designated as MgAl(4)-Cl, was synthesized by mixing crystalline gibbsite (γ-Al(OH)(3)) and solid MgCl(2)·6H(2)O with subsequent hydrothermal treatment at 160 °C for 72h. The MgAl(4)-Cl exhibited a crystalline material of a layered structure, as evidenced from X-ray diffraction. Anion uptake experiments with the MgAl(4)-Cl showed that Cl(-) in the interlayer space can be exchanged with anions such as Br(-), H(2)PO(4)(-), CO(3)(2-) or dodecyl sulfate (DS(-)) from aqueous solutions with preservation of the layered structure. Uptake of NO(3)(-), BrO(3)(-) or SO(4)(2-) on the MgAl(4)-Cl showed different behavior; these anions can be exchanged within 1h maintaining the layered structure, but a release of Mg(2+) cations from the sample was observed with increased reaction time, resulting in collapse of the layered structure and formation of the gibbsite phase, as determined from chemical analyses and X-ray diffraction.     

Crystal Structure and Electronic Absorption Spectrum of Double Neptunium(V) Phthalate Co(NH3)6NpO2[(OOC)2C6H4]2·2H2O

Single crystals of Co(NH₃)₆NpO₂[(OOC)₂C₆H₄]₂·2H₂O were grown. The crystal structure of this compound [monoclinic cell: a = 7.748(2), b = 23.051(5), c = 14.608(3) Å, = 96.21(3)°, space group P2₁/c, Z = 4, V = 2593.7(9) ų, d _calc = 2.034 g cm^{- 3}, CAD4 automatic diffractometer, MoK , graphite monochromator, R ₁ = 0.041 for all 3567 reflections observed, wR ₂ = 0.1344 for all 4445 unique reflections, 325 refined parameters] was studied. The structure consists of infinite anionic chains {NpO₂[(OOC)₂C₆H₄]₂} _n ^{3 n -}, [Co(NH₃)₆]^{3 +} cations, and molecules of crystallization water. Neptunium(V) atom is in pentagonal-bipyramidal oxygen surrounding (CN 7); the neptunyl(V) group is linear and symmetrical; the Np = O bond lengths are 1.830(6) and 1.833(5)Å, the O = Np = O angle is 176.4(2)°. The equatorial plane of the bipyramid is formed by five oxygen atoms of phthalate anions. The Np-Oeq bond length correlates with the denticity of the phthalate anions. Two types of phthalate anions are localized in the structure. The first tridentate ligand is a bridge between Np(V) atoms in the chains. The second ligand is coordinated to Np in the bidentate fashion to form NpOCCCCO seven-membered chelate ring. The cation [Co(NH₃)₆]^{3 +} has an octahedral structure. The average Co-N distance in the octahedron is 1.961 Å the N-Co-N bond angles are close to 90°. Two water molecules along with [Co(NH₃)₆]^{3 +} cations are located between the anionic chains {NpO₂[(OOC)₂C₆H₄]₂} _n ^{3 n -}. The chains are additionally bonded along the Z-axis of the crystal by O_w-H···O hydrogen bonds.     

Reaction of Cd(NO3)2·4H2O with 4,4'–bipyridine (bpy) in MeOH solvent: synthesis and characterization of T-shaped [Cd(bpy)1.5(NO3)2]·3H2O,square grid [Cd(bpy)2(H2O)2](NO3)2·4H2O and linear polymeric [Cd(bpy)(H2O)2(NO3)2]

The influence of concentration of water and metal salt in the reaction between Cd(NO₃)₂·4H₂O and 4,4′–bipyridine in MeOH has been studied and three compounds namely, T-shaped [Cd(bpy)_1.5(NO₃)₂]·3H₂O, 1 square grid [Cd(bpy)₂(H₂O)₂](NO₃)₂ 4H₂O, 2 and one dimensional linear polymer, [Cd(bpy)(H₂O)₂(NO₃)₂], 3 were isolated quantitatively in this process. Compound 1 forms in MeOH at high dilution of the metal salt (5.0 mg/mL or less) and for the metal-to-ligand ratio 1:(1.5–2.0). Compound 2 forms exclusively in the concentration range, 17–33% for water in MeOH by volume and 12–28 mg/mL for the metal salt of the solution. Outside these limits, mixtures of 2 and 3 were isolated. For 1:1 ratio of metal salt to bpy, the linear polymer, 3 was obtained in major quantity and its formation was found to be independent of concentration of water or the metal salt. Compounds 1 and 2 have been characterized by X-ray crystallography. On heating all the compounds decompose through a common intermediate [Cd(bpy)(NO₃)₂] and finally to CdO as monitored by TG.     

Synthesis, Physicochemical Properties, and Electrode Behavior of Ni2[Ni(OH)6W6O18 ] · 8H2O

Nickel(II) hexatungstonickelate(II) was synthesized and characterized by elemental analysis, x-ray diffraction, thermal analysis, IR spectroscopy, and ¹H nuclear magnetic resonance. The results demonstrate that constitutional water is present in the form of OH groups, which can be removed by heating to 230–370°C. The chemical formula of the compound is Ni₂[Ni(OH)₆W₆O₁₈] · 8H₂O. Nickel(II) hexatungstonickelate(II), a poorly soluble compound, was tested as an electrode for Ni(II) determination in solution. Its electrode properties and selectivity for other ions suggest that it is a promising material for such applications. At pH 5, the ion-selective electrode we fabricated has a Nernstian response to Ni(II) (10^–5 to 10^–1 mol/l) which is close to that predicted theoretically.