Cadmium Hydroxide Research Articles

Shape control of cadmium hydroxides(Cd(OH)2) sensitive to pH quenching depth and massive production of CdSe nanocrystals by theirchemical transformation

This study demonstrates that the structure of cadmium hydroxides(Cd(OH)2) precipitated from a basic cadmium nitrate solution can be finely controlled by adjusting the pHof the precursor solution. The synthesis process involves only pouring the saturated solutioninto pure water to quench the pH and the total process is finished within 30 s. At a shallowpH quenching, the unstable nanoparticles turned into microparticles via a ripening process.Cd(OH)2 was precipitated in the form of one-dimensional nanowires and then two-dimensional platesas the pH quenching was increased. At a large pH quenching, porous aggregates ofCd(OH)2 were obtained due to the too fast precipitation. The ultrafineCd(OH)2 nanowires were readily transformed into CdSe chain-like nanocrystals. The transformation was quickand gave 100% yield, facilitating massive production of CdSe nanocrystals in an aqueous condition.The Cd(OH)2 nanowires were directly grown on Si nanowires and transformed into CdSe chain-likenanocrystals, decorating the surface of each Si nanowire.

Synthesis and characterization of cadmium hydroxide nanowires by arc discharge method in de-ionized water

In this study, Cd(OH)2 nanowires have been synthesized by using arc discharge method in de-ionized water. The morphology and properties of the Cd(OH)2 nanowires were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and UV–Vis spectroscopy. TEM observations revealed that Cd(OH)2 nanowires were abundant morphology in synthesized nanostructures, and the diameter of the Cd(OH)2 nanowires ranges from 5 to 40 nm with several micrometers of length. In addition, the width of nanowires is not uniform and varies throughout the nanowire. XRD analysis revealed that the Cd(OH)2 nanowires grow along [001] direction. Furthermore, hexagonal- and irregular-shaped Cd(OH)2 nanoplates were synthesized during arc discharge. It was obtained that required arc current is 50 A for the effective and large scale production of Cd(OH)2 nanowires. Furthermore, the optical properties of the nanowires have been characterized by UV–Vis spectra. By the means of the optical studies, the direct band gap of Cd(OH)2 nanowires was found to be 4.0 eV with strong quantum size effect. It is also shown that a simple and cheap method which does not require relatively expensive vacuum and laser equipment stipulates an economical alternative for the synthesis of Cd(OH)2 nanowires.

Flexible ultrathin free-standing fluorescent films of CdSexS1−x/ZnS nanocrystalline and protein

The integration of fluorescent inorganic nanocrystals into hybrid thin films with desirable optoelectronic properties is strongly demanded for their applications. We prepared flexible free-standing ultrathin protein films containing fluorescent nanocrystals by means of a filtration technique assisted by metal hydroxide nanostrands with high aspect ratio and extremely high positive charges on the surfaces. First, negatively charged proteins (apoferritin), CdSxSe1−x/ZnS nanocrystals (and/or fluorescent dye) were assembled on the surfaces of cadmium hydroxide nanostrands in water through electrostatic interaction. The resultant dispersion of nanocomposite fibers was filtered on a porous membrane to give a thin filter cake. After cross-linking apoferritin, the nanostrands were removed, and the remaining protein/nanocrystal composite layer was peeled off from the substrate in ethanol as a free-standing fluorescent film. The film thickness could be as thin as 40 nm, without limitation in the diameter. The free-standing fluorescent films are robust enough to be transferred onto any solid substrate without rupturing. The fluorescent films with different colors were obtainable by choosing fluorescent nanocrystals (and/or fluorescent dye) to be immobilized into the protein matrix. The optical properties of these films were changed with the combination of the nanocrystals and fluorescent dye, and the fluorescent resonance energy transfer quenching (or enhancement) was clearly observed in certain conditions. The amount of CdSxSe1−x/ZnS nanocrystals in the film was as high as 41% in weight, and 13% in volume. The fluorescent film was transparent and without obvious segregation of the nanocrystals, as confirmed by high-resolution transmission electron microscope (HR-TEM). The fluorescent emission was bright, uniform, and as narrow as that in the original solution of the nanocrystals. This is remarkable for the application of fluorescent inorganic nanocrystals to flexible solid optical devices.

Formation of cadmium sulfide (CdS) nanofilm on a Cd(OH)2/SiO2 precursor layer

Dense thin nanostructured films of cadmium sulfide CdS obtained by chemical deposition from aqueous solutions are strongly bound to a substrate due to the formation of cadmium hydroxide Cd(OH)2 in the system. By X-ray reflectometry and grazing incidence diffraction it is found that at the beginning of the deposition a dense Cd(OH)2/SiO2 layer is produced on the surface of a silicon or glass substrate. This layer is formed through the atomic-layer adsorption of crystalline 1–3 nm thick Cd(OH)2 film by the oxygencontaining substrate surface. During sulfidation of this cadmium-containing substrate layer, a surface nucleation layer of CdS/Cd(OH)2/SiO2 forms, which provides the growth, denseness, and strong adhesion to the substrate of nanostructured CdS film with a disordered structure. According to the obtained experimental data, a “hydroxide scheme” of film deposition is confirmed and refined, and the stages of CdS nanofilm formation are determined.

Na 2Cd 2I 6L 2(H 2O) 6 [L = Urotropine]: An interesting precursor for synthesizing CdO particles

A coordination polymer, Na 2Cd 2I 6L 2(H 2O) 6 [L = Urotropine] has been employed as sole precursor to synthesize CdO particles. Two different preparation methods viz (i) pyrolysis of the title compound at 700 °C for 2 h and (ii) forming cadmium hydroxide from the title compound followed by pyrolysis at 700 °C for 2 h have been used for the synthesis of nano sized CdO-I and CdO-II, respectively. From powder XRD data the lattice parameters (0.4701 and 0.4696 nm respectively for the two samples) and particle size (~ 77 and 30 nm for CdO-I and CdO-II) have been evaluated. Morphology of the two varieties of CdO is widely different as is evident from their SEM images. The estimated values of the band gap of 2.53 eV and 2.59 eV for CdO-I and CdO-II respectively are obtained from the optical spectral analysis.

ENVIRONMENTAL BIOLOGY AND PATHOPHYSIOLOGY OF CADMIUM

Cadmium (Cd) is a soft, silver-white metal being together with zinc and mercury in group II b in the periodic table. It's melting and boiling point are 320.9 0 C and 765 0 C, respectively. Cd is rapidly oxidized into cadmium oxide in the air. When reactive gases such as carbon dioxide, sulphur dioxide, sulphur trioxide and hydrogen chloride or water vapour are present in the air, cadmium vapour reacts to produce cadmium carbonate, cadmium sulphite, cadmium sulphate, cadmium chloride or cadmium hydroxide. These compounds may be formed in chimneys and emitted into the environment. It is indicated that zinc-bearing coals of the central United States and carboniferous age coals of other countries contain large sub economic resources of cadmium. Although some cadmium compounds such as acetate, chloride and sulphate are soluble in water; cadmium oxide, carbonate and sulphide are insoluble.

Zn1.86Cd0.14(OH)VO4

The title compound, dizinc cadmium hydroxide tetraoxido­vanadate, Zn1.86Cd0.14(OH)VO4, was prepared under low-temperature hydro­thermal conditions. It is isostructural with Zn2(OH)VO4 and Cu2(OH)VO4. In the crystal structure, chains of edge-sharing [ZnO6] octahedra are inter­connected by VO4 tetra­hedra (site symmetries of both V atoms and their coordination polyhedra are .m.) to form a three-dimensional [Zn(OH)VO4]2− framework with channels occupied by Zn and Zn/Cd cations adopting trigonal–bipyramidal and distorted octa­hedral coordinations, respectively. Zn1.86Cd0.14(OH)VO4 is topologically related to adamite-type phases, and descloizite- and tsumcorite-type structures.

Bio-template route for facile fabrication of Cd(OH) 2@yeast hybrid microspheres and their subsequent conversion to mesoporous CdO hollow microspheres

Cadmium oxide (CdO) microspheres with a porous hollow microstructure were prepared by a facile yeast mediated bio-template route. The yeast provides a solid scaffold for the deposition of cadmium hydroxide (Cd(OH) 2) from cadmium acetate and sodium hydroxide solutions to form the hybrid Cd(OH) 2@yeast precursor. Thermal conversions of this at above 500 °C in air have produced hollow CdO microspheres. The products were characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), thermal gravimetric and differential thermal analysis (TGA–DTA), and Brunauer–Emmett–Teller (BET) surface analysis respectively. The obtained CdO microspheres have uniform size (length = 2.6 ± 0.4 μm; width = 2.0 ± 0.2 μm) and a well defined, continuous, mesoporous hollow microstructure. The shell is about 250–280 nm in thickness. The mechanism of formation of Cd(OH) 2@yeast precursor and its conversion to CdO hollow microspheres is discussed. In comparison with traditional template-directed method, the present strategy represents a general, economical and environmentally benign route for the formation of metal oxide hollow microspheres. These materials have potential applications in different fields such as encapsulation, drug delivery, efficient catalysis, battery materials and photonic crystals. The method presented can be extended to the synthesis of other inorganic hollow microstructures of different sizes and shapes by pre-selecting suitable bio-templates.

Formation and Self-Assembly of Cadmium Hydroxide Nanoplates in Molten Composite-Hydroxide Solution

In this article, we report a novel molten hydroxide strategy to prepare bulk-sized complexes of three-dimensional (3D) nanostructures at a large scale. Taking cadmium hydroxide as an example, we re...

ChemInform Abstract: Investigation on the Charge-Discharge Properties of the Pressed-Type Nickel-Cadmium Alkaline Cells Using Polyethylene as a Binder.

The electrodes were produced by pressing the mixtures of nickel or cadmium hydroxide as active materials, an appropriate addition agent, and polyethylene as a binder on a nickel net. The cycle test of the cells assembled by these electrodes was carried out by charging and discharging under the condition of a constant current density of 12 mA cm−2 until the 300th cycle. The cell capacities and the availabilities of the active materials obtained at the initial cycle were held even after 300 cycles.

Nanoarchitectural Evolution from Laser-Produced Colloidal Solution: Growth of Various Complex Cadmium Hydroxide Architectures from Simple Particles

Complex nanostructures and nanoassemblies have exhibited their potential application in the fabrication of future molecular machines and molecular devices. Liquid phase pulsed laser ablation (LP-PLA) is an easy, versatile, environmentally friendly, and rapidly growing method for the synthesis of nanostructured materials. Several experimental laser and liquid media parameters have been developed, but others are under development. The interaction of an anionic surfactant with the nanomaterials having a positive surface charge density is a key parameter, but an unanswered question until now, in the field of LP-PLA. Nanosecond pulsed laser ablation of a cadmium rod placed on the bottom of a glass vessel containing aqueous media of sodium dodecyl sulfate at different concentrations is used to produce a variety of cadmium hydroxide nanostructures from nanoparticles to nanorods, nanotetrapods, nanoflower buds, and 2D and 3D nanoflowers in order to investigate the above liquid media parameter. It is suggested tha...

Controllabe growth of cadmium hydroxide nanostructures by hydrothermal method

We proposed a general hydrothermal strategy for the fabrication of one-dimensional cadmium hydroxide nanostructures.Through controlled experimental conditions, such as solvent properties, salt concentration and alkaline concentration, the different morphologies and dimensions of the final products have been controlled. With this method, Cd(OH) 2 nanowires were prepared readily. XRD, TEM, FESEM and UV-vis absorption spectroscopy were used to characterize the nanowires product, which revealed that the Cd(OH) 2 nanowires consisted of about 30 nm in diameter and length up to several hundreds of nanometers. The optical absorption spectrum indicates that the Cd(OH) 2 nanowires have a indirect band gap of ∼2.56 eV. In addition, the as-prepared Cd(OH) 2 nanowires acting as a precursor was converted into porous cadmium oxide through dehydration.

Laser ablative approach for the synthesis of cadmium hydroxide–oxide nanocomposite

Cadmium hydroxide/oxide nanocomposite material is synthesized by pulsed laser ablation of cadmium metal in double distilled water. As-synthesized cadmium hydroxide/oxide particles transforms into pure oxide after annealing at 350 °C for 9 h. As-obtained particles are spherical in shape with 15 nm average diameter, while spherical as well as rod shaped nanostructures are formed after annealing. PL spectrum of annealed powder has peaks corresponding to the defect levels rather than the band gap transitions.

Ultralong Cadmium Chalcogenide Nanotubes from One-Dimensional Cadmium Hydroxide Nanowire Bundles by Soft Solution Chemistry

Herein, we report a soft solution method for CdX (X = S, Se, Te) nanotubes (NTs) with a high aspect ratio directly onto the substrate of a large area using one-dimensional (1D) Cd(OH)2 nanowire bundles (NBs) which were grown by a low-temperature soft chemical approach. A simple anion exchange route was designed to synthesize CdX NTs using the Cd(OH)2 NBs as a Cd source as well as a template. By the reaction of Cd(OH)2 NBs on the substrates with an aqueous solution of X2−, the anion exchange reaction takes place, and due to the difference in the solubility products, as well as the diffusion rates, the nanocrystalline CdX NTs are formed. The CdX NTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD). On the basis of a series of experiments and characterizations, the formation mechanism of the CdX NTs from Cd(OH)2 NBs is proposed. This work demonstrates a cost effective method ...

Morphology controlled solvothermal synthesis of Cd(OH) 2 and CdO micro/nanocrystals on Cd foil

Cadmium hydroxide (Cd(OH) 2) and cadmium oxide (CdO) nano and micro crystals were synthesized in ethanol–water medium using cadmium foil both as a source and substrate under solvothermal condition. Different concentrations of ammonium hydroxide, hydrazine hydrate, sodium hydroxide and potassium hydroxide were added to study the structural and morphological variations in the products. Synthesis was carried out at different temperatures to study the growth stages of the nano/microstructures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The as-prepared Cd(OH) 2 products were transformed to CdO by thermal treatment in air. The possible growth mechanism for the formation of different morphologies at different basic medium has been proposed. The optical absorption measurement was carried out to determine the values of the band gap of CdO.

Synthesis of cadmium(II) hydroxide, cadmium(II) carbonate and cadmium(II) oxide nanoparticles; investigation of intermediate products

Sonochemical and hydrothermal routes have been used in different conditions for preparation of CdCO 3 and Cd(OH) 2 nanoparticles at air and inert atmospheres, respectively. The CdO nanoparticles were obtained by heating of CdCO 3 and Cd(OH) 2 nanoparticles at 400 °C. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) microscopy have been used to characterize the nanoparticles. The XRD results of intermediate products showed that the origin of CdCO 3 is CO 2 from air atmosphere.

Ultrathin Nanofibrous Films Prepared from Cadmium Hydroxide Nanostrands and Anionic Surfactants

We developed a simple fabrication method of ultrathin nanofibrous films from the dispersion of cadmium hydroxide nanostrands and anionic surfactants. The nanostrands were prepared in a dilute aqueous solution of cadmium chloride by using 2-aminoethanol. They were highly positively charged and gave bundlelike fibers upon mixing an aqueous solution of anionic surfactant. The nanostrand/surfactant composite fibers were filtered on an inorganic membrane filter. The resultant nanofibrous film was very uniform in the area of a few centimeters square when the thickness was not less than 60 nm. The films obtained with sodium tetradecyl sulfate (STS) had a composition close to the electroneutral complex, [Cd37(OH)68(H2O)n] x 6(STS), as confirmed by energy dispersive X-ray analysis. They were water-repellent with a contact angle of 117 degrees, and the value slightly decreased with the alkyl chain length of anionic surfactants. Ultrathin nanofibrous films were stable enough to be used for ultrafiltration at pressure difference of 90 kPa. We could effectively separate Au nanoparticles of 40 nm at an extremely high filtration rate of 14000 L/(h m2 bar).

Preparation and stability of strongly luminescent CdSe/Cd(OH)2/SiO2 nanocomposite particles in aqueous solution

Cadmium hydroxide-deposited cadmium selenide nanoparticles were prepared by the addition of cadmium sulfate solution to cadmium selenide nanoparticles in a weak alkaline solution at room temperature. The photoluminescence measurements displayed that the luminescence intensity was greatly increased by the addition of cadmium ions due to the formation of cadmium hydroxide on the surfaces of the cadmium selenide nanoparticles. Then, CdSe/Cd(OH)2/SiO2 nanocomposite particles were synthesized using 3-mercatopropyl trimethoxysilane by Stober method. After the formation of CdSe/Cd(OH)2/SiO2 nanocomposite particles, the emission ability was mostly stabilized. Additionally, the stabilization of the composite particles against dilution with the physiological saline was checked. The results showed that the photoluminescence stability was promoted after the deposition of silica on the surfaces of the CdSe/Cd(OH)2 nanoparticles. Comparison of the stability of CdSe/SiO2 nanoparticles with that of CdSe/Cd(OH)2/SiO2 ones showed that Cd(OH)2 shell could enhance the photoluminescence effectively.

On-line precipitation–dissolution in knotted reactor for thermospray flame furnace AAS for determination of ultratrace cadmium

A simple, environmentally friendly, cost-effective and sensitive method was developed for the determination of trace cadmium in rice and water by using flow injection (FI) on-line precipitation–dissolution in a knotted reactor (KR) as a preconcentration scheme for thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). The preconcentration was achieved by online merging the sample solution and the precipitating reagent in a KR and subsequently eluting the resultant precipitate of cadmium hydroxide with 1 mol/L HNO 3. The eluant was then introduced into TS-FF-AAS for the determination. A self-assembled FI system was employed to hyphenate the KR system with TS-FF-AAS. Under optimal chemical and instrumental conditions, a limit of detection of 0.04 μg/L and a sensitivity enrichment factor of 34 for cadmium was obtained with a total initial sample volume of 4 mL. The proposed method was applied to the determination of cadmium in certified reference rice and water samples with analytical results in good agreement with their certified values. Real rice samples and real water samples were also determined by the proposed method, with analytical results confirmed by inductively coupled plasma mass spectroscopy (ICP-MS).

Use of cadmium hydroxide gel for isolation of extracellular catalases from Penicillium piceum and characterization of purified enzymes

We optimized the conditions for isolation of extracellular catalases from Penicillium piceum F-648 and P. piceum A3 by means of volume chromatography with cadmium hydroxide gel. Our study showed that 55-57 mg wet gel are sufficient for the maximum sorption of catalase from 1 ml of culture fluid. This gel was formed in 1 ml 70 mM Cd(NO3)2 after addition of NaOH (Cd(NO3)2/NaOH molar ratio 1:2.2). The eluting solution contained 50 mM NaH2PO4 (pH 7.0), 5.0 mM dithiothreitol, and 0.3% sodium cholate and was potent in desorbing catalase from the gel. Subsequent ultrafiltration of the eluate on the membrane with a retention limit of 50 kDa allowed us to concentrate and purify the sample from low-molecular-weight protein impurities. NH4Cl (1.0 M) containing 0.3% sodium cholate was used to wash the sample from low-molecular-weight aromatic metabolites. Purified catalases included 33-34% antiparallel beta-structures and 9% alpha-spirals. Under optimal conditions in the medium of 10 mM phosphate buffered saline (pH 7.0) at 30 degrees C, catalases from P. piceum F-648 were characterized by the following parameters: K(M), 158.8 mM; catalytic constant, 2.83 x 10(6) s(-1); enzyme inactivation rate constant in H2O2 decomposition, 3.5 x 10(-2) s(-1); and constant of the interaction between catalase complex I and second molecule of H2O2, 1.8 x 10(7) M(-1) s(-1).