Hexagonal CuS Research Articles

CuS nanostructures prepared by a hydrothermal method

Without using any surfactant or template, novel CuS three-dimensional (3D) structures consisting of nanosheets were successfully synthesized via a convenient one-step hydrothermal approach. X-ray diffraction pattern showed that the as-prepared product was pure hexagonal phase CuS. Scanning electron microscopy and high-resolution transmission electron microscopy images revealed that the as-prepared product comprised 3D microspheres (about 1–3 μm in diameter), which were further constructed with randomly oriented, single-crystalline CuS nanosheets (about 20 nm in thickness). The UV–vis absorption spectrum of the as-synthesized CuS 3D microspheres displayed an optical absorption minimum near 672 nm. Besides, the thermal stability of the as-synthesized CuS 3D microspheres was also studied.

Hydrothermal synthesis of copper selenides with controllable phases and morphologies from an ionic liquid precursor

Cu2−xSe nanocrystals and CuSe nanoflakes are successfully synthesized through a convenient hydrothermal method from an ionic liquid precursor 1-n-butyl-3-ethylimidazolium methylselenite ([BMIm][SeO2(OCH3)]). The phases and morphologies of the copper selenides can be controlled by simply changing the atom ratio of Cu/Se in the reactants and reaction temperature. Furthermore, it is found that the [BMIm][SeO2(OCH3)] not only serves as Se source but also has influence on the shapes of CuSe nanoflakes. The adsorption of alkyl imidazolium rings ([BMIm]+) onto the (0001) facets of covellite CuSe prohibits the growth in the [0001] direction, and CuSe nuclei growth mainly processes along the six symmetric directions (±[011], ±[10], and ±[100]) to form flakelike CuSe. The obtained copper selenides are characterized by XRD, SEM, EDS, XPS, TEM, and HRTEM. The results indicate that the Cu2−xSe nanocrystals are nearly spherical particles with an average diameter of about 20 nm, the hexagonal CuSe nanoflakes are single crystals with an edge length of 100–400 nm and a thickness of 25–50 nm. The potential formation mechanism of the copper selenides is also proposed.

Low-Temperature Synthesis of CuInSe2 Nanotube Array on Conducting Glass Substrates for Solar Cell Application

Highly ordered arrays of Cu-rich and -deficient CuInSe(2) nanotubes as well as ZnO/CuInSe(2) core/sheath nanocables have been synthesized on glass substrates by using ZnO nanorod arrays as sacrificial templates via a low-cost solution method. Chemical conversions from hexagonal ZnO to cubic ZnSe, hexagonal CuSe and tetragonal CuInSe(2) are demonstrated as a novel means for synthesis of I-III-VI nanomaterials. Large differences in their solubility product constant (K(sp)) are crucial for direct exchange in the conversions. In solvothermal reaction of ZnO/CuSe core/shell nanocables with InCl(3), the triethylene glycol solvent serves as a reducing agent for the reduction of cupric (Cu(2+)) to cuprous (Cu(+)) ions and also as an agent for the dissolution of ZnO cores. The absorption coefficient of the CuInSe(2) nanotubes in the visible region is on the order of 10(4) cm(-1). Photoelectrochemical solar cells were fabricated with arrays of ZnO/Cu(1.57±0.10)In(0.68±0.10)Se(2) and ZnO/CuSe nanocables. It was found that power conversion efficiency of the ZnO/Cu(1.57±0.10)In(0.68±0.10)Se(2) cell is about two times higher than that based on ZnO/CuSe.

Effect of weak reductant on properties of electroless copper polyacrylonitrile nanocomposites for electromagnetic interference shielding

AbstractIn this work, the electroless copper method with different reductant compositions (NaHSO3/Na2 S2O3·5H2O and Na2S2O3·5H2O) without sensitizing and activating, was used to deposit copper‐sulfide deposition on the polyacrylonitrile (PAN) surface for electromagnetic interference (EMI) shielding materials. The weak reductant, NaHSO3, in the electroless copper method was used to control the phase of copper‐sulfide deposition. The Cux(x=1–1.8)S was deposited on the PAN (CuxS‐PAN) by reductant composition (NaHSO3/Na2S2O3·5H2O) and the Cux(x=1–1.8)S deposition of CuxS‐PAN possesses three kinds of copper‐sulfide phases (CuS, Cu1.75S and Cu1.8S). However, the electroless copper with reductant was only Na2S2O3·5H2O (without weak reductant, NaHSO3), the hexagonal CuS deposition was plated on the PAN (CuS‐PAN) and increased the EMI shielding effectiveness of CuS‐PAN composites about 10–15 dB. In this study, the best EMI SE of CuS‐PAN and CuxS‐PAN composites were about 27–30 dB and 15–17 dB respectively, as the cupric ion concentration was 0.24 M. The volume resistivity of CuS‐PAN composite was about 1000 times lower than that of CuxS‐PAN composite and lowest volume resistivity of CuS‐PAN composites was 0.012 Ω cm, as the cupric ion concentration was 0.24 M. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Facile synthesis and assembly of CuS nano-flakes to novel hexagonal prism structures

Highly ordered hexagonal prism microstructures of copper sulfide (CuS) by assembling nano-flakes have been synthesized with high yield via a facile one-step route. We synthesized CuS microstructures using low cost beginning materials CuSO 4·5H 2O and Na 2S 2O 3·5H 2O under lower reaction temperature (60 °C). Hexamethylinetetramin (C 6H 12N 4, HMT) was introduced into the reaction system as a capped agent. The influence of reaction time and capping agent (HMT) on the final structure of products was studied systematically. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopes (EDS), and transmission electron microscopy (TEM). The possible mechanism for the formation of the interesting highly ordered hexagonal prism microstructures CuS was also proposed.

Large-Scale Synthesis and Phase Transformation of CuSe, CuInSe2, and CuInSe2/CuInS2 Core/Shell Nanowire Bundles

Facile chemical approaches for the controllable synthesis of CuSe, CuInSe2 nanowire, and CuInSe2/CuInS2 core/shell nanocable bundles were developed. Hexagonal CuSe nanowire bundles with lengths up to hundreds of micrometers, consisting of many aligned nanowires with a diameter of about 10-15 nm, were prepared by reacting cubic Cu(2-x)Se nanowire bundles with a sodium citrate solution at room temperature. The CuSe nanowire bundles were then used as self-sacrificial templates for making bundles of tetragonal chalcopyrite CuInSe2 nanowires by reacting with InCl3 via a solvothermal process. Furthermore, bundles of CuInSe2/CuInS2 core/shell nanocables were obtained by adding sulfur to the reaction system, and the shell thickness of the polycrystalline CuInS2 in the nanocables increased with increasing S/Se molar ratios. It was found that the small radius of copper ions allows their fast outward diffusion from the interior to the surface of nanowires to react with sulfur atoms/anions and indium ions to form a CuInS2 shell. Enhanced optical absorption in the vis-NIR region of CuInSe2/CuInS2 core/shell nanocable bundles is demonstrated, which is considered beneficial for applications in optoelectronic devices and solar energy conversion.

Controlled synthesis of copper sulfide 3D nanoarchitectures through a facile hydrothermal route

CuS three-dimensional nanoarchitectures have been successfully prepared in the presence of surfactant Poly( N -vinyl-2-pyrrolidone) by hydrothermally treating the solution of CuSO 4 ·5H 2 O and CS 2 at 140 °C for 18 h. X-ray diffraction, scanning electron microscope, transmission electron microscope, and ultraviolet–visible spectrophotometer were used to characterize the CuS. The assembled three-dimensional nanoarchitecture, with a diameter of about 100 nm, was composed of hexagonal CuS nanoplates with a thickness of 20 nm. The influences of synthetic parameters, such as Poly( N -vinyl-2-pyrrolidone), reaction temperature and reaction time, on the morphologies of the products have been investigated. The possible mechanism of forming three-dimensional flower-like nanoarchitecture was discussed.

Characterization of copper sulfide nanostructured spheres and nanotubes synthesized by microwave-assisted solvothermal method

Copper sulfide nanostructured spheres and nanotubes were successfully synthesized, using a microwave-assisted solvothermal method, by the decomposition of [Cu(CH 3CSNH 2) 2]Cl 2 complexes, formed by the reaction of CuCl 2·2H 2O and CH 3CSNH 2 in ethylene glycol at different pH values, and identified by CHNS/O and FTIR analyses. The decrease in bonding energy of N–H revealed the coordination of copper ions and thioacetamide molecules. It was specified that nitrogen atoms of thioacetamide molecules were used to form Cu–thioacetamide complexes. XRD, SEM, TEM and SAED analyses show that the products were hexagonal CuS spheres in an extremely low pH solution, and hexagonal CuS nanotubes at a pH 13. Their Raman spectra show sharp peaks at 473 cm − 1 , identified as the S–S stretching mode of S 2 ions at the 4e sites.

P-type CuInSe2 thin films prepared by selenization of one-step electrodeposited precursors

In this study, p-type CuInSe2 (CIS) films were prepared by selenization of one-step electrodeposited Cu-In-2Se (atomic ratio) precursors. To obtain high-quality, dense, and homogeneous CIS films for solar cell application, the effects of substrate temperatures during selenization and precursor compositions on the final microstructures were systematically investigated. The precursor layers evolved in very different ways under different selenization conditions. The final microstructures and phases of the films depended critically on the precursor compositions, selenization temperature, and the selenization thermal process history. Low melting temperature CuxSe phase, which tended to segregate at the film surface, can efficiently assist the CIS grain growth. Large hexagonal CuSe platelets were formed at a temperature as low as 170 °C in Cu-rich precursor, which acted as an element-transport flux agent at higher temperature under high Se vapor and reacted with In-Se selenide to form CIS at temperatures above 500 °C. Good crystalline quality chalcopyrite CIS film was obtained at a selenization temperature of 550 °C.

Self-assembly of CuS nanoflakes into flower-like microspheres: Synthesis and characterization

Using Cu(S 2CNEt 2) 2 as a single-source precursor and ethylamine solution (65–70%) as the reaction medium, large-scale flower-like CuS microspheres have been synthesized via a solvothermal treatment in the presence of a surfactant. The products were characterized by XRD, SEM, TEM, HRTEM, and UV-vis spectrum. The assembled microspheres, with a diameter of about 2–3 μm, were composed of single-crystalline hexagonal CuS nanoflakes with a thickness of several tens of nanometers. It was revealed that the solvent medium, the surfactant, and the reaction time have great influence on the morphology and size of the resulting CuS products.

Selective precipitation of Cu from Zn in a pS controlled continuously stirred tank reactor

Copper was continuously and selectively precipitated with Na 2S to concentrations below 0.3 ppb from water containing around 600 ppm of both Cu and Zn in a Continuously Stirred Tank Reactor. The pH was controlled at 3 and the pS at 25 (pS = −log(S 2−)) by means of an Ag 2S sulfide selective electrode. Copper's recovery and purity were about 100%, whereas the total soluble sulfide concentration was below 0.02 ppm. X-ray diffraction (XRD) analysis showed that copper precipitated as hexagonal CuS (covellite). The mode of the particle size distribution (PSD) of the CuS precipitates was around 36 μm. The PSD increased by high pS values and by the presence of Zn. Depending on the turbulence, the CuS precipitates can grow up to 200 μm or fragment in particles smaller than 3 μm in a few seconds. Zn precipitation with Na 2S at pH 3 and 4, in batch, always lead to Zn concentrations above 1 ppm. Zn precipitated as cubic ZnS (spharelite).

Phase-Selective Synthesis and Self-Assembly of Monodisperse Copper Sulfide Nanocrystals

Single-crystalline, monodisperse copper sulfide nanocrystals with controlled sizes, shapes, and phases were successfully synthesized via a simple, low-cost, and environmentally friendly chemical reaction of CuCl2 and S in oleylamine at 100−180 °C. It was found that the molar ratios of [CuCl2]:[S] played the critical role for the control of the sizes, shapes, and phases of copper sulfide nanocrystals. The hexagonal CuS nanodisks, hexagonal CuS nanoribbons consisting of face-to-face stacked nanodisks, and monoclinic Cu1.75S nanoribbons consisting of face-to-face stacked nanodisks were obtained when the molar ratios of [CuCl2]:[S] were 1:1, 2:3, and 2:1, respectively. It was believed that the van der Waals force and dipole−dipole interaction were responsible for the self-assembly of copper sulfide nanodisks. Finally, the copper sulfide nanocrystals were characterized by transmission electron microscopy, high-resolution transmission electron micrscopy, X-ray diffraction, and Fourier transform infrared, and it...

Water-Induced Thermolytic Formation of Homogeneous Core−Shell CuS Microspheres and Their Shape Retention on Desulfurization

Homogeneous inorganic core−shell microspheres made from hexagonal CuS are synthesized via thermolysis of Cu(R2dtc)2 (R = octyl, dtc = dithiocarbamate) precursor at 130−180 °C under N2 flow, optimally at 180 °C for 0.5 h. Scanning electron microscopy (SEM) analyses indicate that the core−shell microspheres have an average diameter of 1.74 μm (σ = ±12.7%) with a shell thickness of about 225 nm. Their formation is induced by the small amount of water in the precursor. A tentative formation mechanism is speculated. Interestingly, the as-made cupric sulfide CuS microspheres undergo a reduction to tetragonal cuprous sulfide Cu2S microspheres without morphology changes via solid-state annealing at 400 °C under N2 atmosphere. The microspheres made over 400−700 °C are invariably tetragonal Cu2S phase.

A facile electrochemical synthesis of covellite nanomaterials at room temperature

A novel method for the electrochemical synthesis of covellite (CuS) nanoparticles (NPs) in aqueous phase was developed. In this experiment, thioglycerol (TG) is used as the catalyst for the hydrolysis of sodium thiosulfate, the sulfur source for the synthesis of CuS. Cu foil, which acts as the sacrificing anode, is oxidized to Cu2+ by applying a potential of 0.5 V while OH- was produced on the cathode surface at the same time. The production of OH- facilitates the reaction between Cu2+ and thiosulfate under the catalysis of TG. The evolution of hydrogen bubbles effectively prevents the deposition of copper sulfide on the cathode. Copper sulfide sols of “golden-brown”, and “dark-green” forms can be obtained by varying the concentration of TG. The “golden-brown” copper sulfide sols are also observed to convert to the green form with time, and the rate of this conversion process is faster at higher temperatures. X-ray diffraction (XRD) and chemical analysis indicate that the “dark-green” form of product is pure hexagonal phase CuS. The obtained CuS NPs were covered by a layer of TG as suggested by Fourier transform infrared (FTIR) data. The size and morphology of the particles are studied by transmission electron microscope (TEM).

Thermal behaviour of CuS (covellite) obtained from copper–thiosulfate system

Thermal behaviour of CuS (covellite) obtained from the Cu(CH3COO)2·H2O and Na2S2O3·5H2O system, working at different molar ratio (1:6 and 1:4) in presence/absence of NH4VO3, was studied. It was established that the presence of vanadium in the system induces a densification of CuS nodules, but do not change the hexagonal CuS structure. It has an important influence in thermal behaviour of copper sulfide CuS obtained also. The morphological characteristics of CuS play an important role in the thermal stability and the stoichiometry of the thermal decompositions.

A facile solution route to CuS hexagonal nanoplatelets

We report a facile solution route for the synthesis of single-crystalline and hexagonal CuS nanoplatelets by thermolysing single-precursor copper ethylxanthate [Cu(exan) 2] in hexadecylamine (HDA) at moderate temperature. The morphology and structure of CuS nanocrystals (NCs) are characterized by means of XRD, TEM, HRTEM, SAED and UV–vis absorption spectroscopy. Key synthetic parameters, such as reaction temperature, reaction time and precursor concentration, which have a great influence on the size and shape of the products, have been comprehensively investigated. It was found out that the nanoplatelets are self-assembled into one-dimensional ordered string-like structure under appropriate conditions. The solvent used to disperse the nanocrystals can affect the self-assembly of the CuS nanoplatelets, and polar solvent favors the formation of long strings. The possible mechanisms of forming hexagonal nanoplatelets and self-assembled strings are discussed.

Synthesis and Characterization of Hexagonal CuSe Nanotubes by Templating against Trigonal Se Nanotubes

A novel method has been developed for the preparation of crystalline nanotubes of copper selenide (CuSe). The method was based on template-directed synthesis in which the trigonal Se nanotubes were used as a template-directed reagent. Apart from CuSe nanotubes, one-direction (1D) nanocrystallites of Cu3Se2, Cu2-xSe, and Cu2Se were also obtained by changing the atom ratio of Cu and Se in the precursors. The products were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), laser Raman spectrography (LRS), and X-ray photoelectron spectroscopy (XPS). On the basis of a series of experiments and characterizations, the formation mechanism of the CuSe nanotubes is discussed.

Low-temperature synthesis of CuS nanorods by simple wet chemical method

CuS nanorods of length 60–100 nm and 15 nm in diameter have been synthesized by simple wet chemical method at 105 °C using CuCl 2·2H 2O as Cu-precursor, CS 2 as S-source and ethylenediamine as the attacking reagent. The plausible reaction mechanism has been proposed and the effect of reaction temperature on morphology has been discussed. X-ray diffraction (XRD) pattern suggests the formation of hexagonal phase CuS. The morphology of the products has been studied by transmission electron microscope (TEM) analysis. A detailed optical study has also been done.

Controlled synthesis and characterization of covellite (CuS) nanoflakes

Trigonal and hexagonal CuS (covellite) nanoflakes with controlled size (10–200 nm, and thickness of 3.6–5 nm) were synthesized through the reaction between copper acetylacetonate and sulfur in oleylamine. Size and shape of the products could be tuned by reaction parameters and reactant concentration. The as-prepared flakes have smooth surfaces and self-assemble face-to-face each other. High-resolution transmission electron microscopy and electron diffraction show that the nanoscale flakes were single-crystal hexagonal covellite. Formation mechanism of the nanoflakes is discussed. UV–vis spectra reveal that the samples have blue-shift absorbance onsets owning to the quantum size effects.

Hydrothermal fabrication of copper sulfide nanocones and nanobelts

Novel copper sulfide nanocones and nanobelts have been hydrothermally fabricated at 140 °C for 24 h with acrylamide and sodium dodecyl benzene sulfonate (SDBS) as surfactants, respectively. X-ray diffraction (XRD) pattern indicates that the as-prepared samples are the pure hexagonal phase CuS. XPS spectra show that the ratio of Cu/S is about 1:1.084. The morphology was characterized by scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM) techniques. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images reveal that nanocones and nanobelts grow along the [110] axis. The surfactant is found to be critical to the morphologies of the products. The possible formation mechanism is also discussed.