Preparation and characterization of nanocrystallite size cuprous oxide

Uniform spheres of nanocrystallite size cuprous oxide particles have been prepared by a simple polyol process using cupric nitrate as a precursor in ethylene glycol. As synthesized compound was dried at 333 K in a vacuum oven and characterized by XRD, FT-IR and SEM techniques. The crystallite size of the cuprous oxide calculated from Scherer's formula was found to be ∼11 nm.     

Synthesis and photocatalytic characterization of porous cuprous oxide octahedra

Porous cuprous oxide octahedra with a mean diameter of 1 μm have been successfully prepared with high yield via a hydrothermal reduction process at a low temperature. The growth mechanism and the influences of the poly(vinylpyrrolidone) (PVP) and citric acid have been discussed. And then, the samples were used as photocatalytic in the degradation of methyl red (MR). Thanks to the 3D architecture of the product, the photocatalytic performance has been significantly improved. We believe that the present work will open up to systematically explore ways to fabricate porous nanostructures and thus find use in a variety of applications.     

Preparation and characterization of zeolite framework stabilized cuprous oxide nanoparticles

Zeolite framework stabilized copper(I) oxide nanoparticles (4.8 ± 2.6 nm) were prepared for the first time by using a four step procedure: the ion exchange of Cu²⁺ ions with the extra framework Na⁺ ions in Zeolite-Y, the reduction of the Cu²⁺ ions within the cavities of zeolite with sodium borohydride in aqueous solution, the dehydration of Zeolite-Y with the copper(0) nanoclusters, and the oxidation of intrazeolite copper(0) nanoclusters by O₂ at room temperature. Zeolite stabilized copper(I) oxide nanoparticles were thoroughly characterized by ICP-OES, XRD, HR-TEM, Raman, XPS, UV-vis spectroscopy and N₂ adsorption-desorption technique.     

Electrodeposition of cuprous oxide on a porous copper framework for an improved photoelectrochemical performance

Journal of Materials Science - Photoelectrochemical (PEC) water splitting can be an efficient and economically feasible alternative for hydrogen production if easily processed photoelectrodes made...     

The mechanical behaviour of cuprous oxide

The stress-strain behaviour under compresion at constant strain rate of single crystals (051 and 122) compression axis) and polycrystalline samples of cuprous oxide have been examined at room temperature and hydrostatic pressure up to 12 kb and at atmospheric pressure and high temperature up to 600° C. At high environmental pressure, plastic flow occurs at 6 kb. At high temperatures and one atmosphere, extensive plastic deformation was observed after 500° C. The resultant slip planes were of the {110} and {100} types. Transmission electron microscopy of thin foils prepared from deformed specimens shows that the Burgers' vectors of the glide dislocations are of the 111, 110 and 100 types.     

Biologically formed hollow cuprous oxide microspheres

Hollow cuprous oxide (Cu₂O) microspheres with a diameter of ca. 1.8 μm are prepared by using yeast as template. The possible mechanism for the formation of the hollow Cu₂O spheres is revealed. The biotemplated sample is investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet–visible (UV–vis) absorption spectra. The sample consists of the crystalline Cu₂O microspheres with diameters of about 59.5 nm and lattice parameter of 4.264 Å. The observed optical band gap of the product indicates that the blue–shift effect occurs, which is attributed to the hollow Cu₂O microspheres.     

Preparation and characterization of cuprous iodide nanoparticles

A new technique for the preparation of CuI nanoparticles from CuSO₄ and KI ethanol solutions has been developed. Preparation conditions were optimized through a series of experiments. Under these conditions, the yield of CuI reached 95.39%. The product was characterized and the reaction kinetics was studied. The results show that the product takes a roughly spherical shape with an average particle size of less then 50 nm. The activation energy of the formation of CuI is found to be E _a = 0.58 × 10² kJ/mol, and the preexponential factor in the Arrhenius equation is k ₀ = 7.43 × 10¹⁶ mol/(l s). The text was submitted by the authors in English.     

On the growth of cuprous oxide films

{lcub;001}rcub; cuprous oxide (Cu₂O) films were epitaxially grown. From the two methods which were used (the oxidation of copper films and the direct evaporation of bulk Cu₂O) only the oxidation of copper yielded good single-crystal films. It was found that the optimum conditions were an oxidation temperature of 450°C with a partial pressure of oxygen of 2×10^-5 Torr and, after oxidation, a further annealing at a pressure of 10^-8 Torr.     

Solution-phase synthesis of smaller cuprous oxide nanocubes

Smaller cuprous oxides (Cu₂O) nanocubes were synthesized by solution-phase method at 160 °C, using ethylene glycol reducing Cu(NO₃)₂·3H₂O with poly(vinylypyrrolidone) (pvp) as capping agent. The Cu₂O nanocubes were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray powder diffraction (XRD). SEM showed that most of Cu₂O nanocubes were uniform and monodisperse, with the average edge length about 130 nm. The TEM results were consistent with the SEM results. Selected area electron diffraction (SAED) suggested that as-prepared Cu₂O nanocubes were single crystalline. The geometric shape and size of Cu₂O nanoparticles were greatly affected by the presence of PVP and its molar ratio (in repeating unit) relative to copper nitrate, temperature and the concentration of Cu(NO₃)₂·3H₂O. The mechanism of Cu₂O nanocubes formation was also discussed.     

Template-assisted electrochemical synthesis of cuprous oxide nanowires

Nanowires of Cu₂O as well as Cu were synthesized within the anodic aluminum oxide templates in an aqueous acidic electrochemical cell. The content of Cu₂O in the copper nanowires was controlled by varying the anodic potential of the pulse-reverse electrolysis and the pH of the electrolyte within a range of 2.0–3.9. For the pH of 2.0, pure Cu nanowires were deposited regardless of the anodic potential. When the anodic potential became higher than the cathodic one, pure Cu₂O nanowires were produced at a pH of 3.9. The growth of Cu₂O nanowires in the acidic electrolyte was ascribed to the local increase of the pH at the pore base, as well as the capacitive barrier layer of the template.     

Combined reduction and sintering of preformed cuprous oxide strip

Abstract

A new method of making thin copper strip direct from cuprous oxide powder by an integrated powder technology route has been outlined. The proposed route consists of making, by a slurry method, a green cuprous oxide strip which is subsequently reduced with hydrogen to produce a porous copper strip. The strip is densified by hot rolling to produce a fully dense structure. The combined reduction and sintering behaviour of the green cuprous oxide strip is reported. The mechanism of reduction of the cuprous oxide with hydrogen at various temperatures is discussed, and the geometry of the reaction zone in the green oxide strip is described.

MST/183     

Electrochemical synthesis and photocatalytic property of cuprous oxide nanoparticles

Cuprous oxide (Cu₂O) nanoparticles of 35 nm in crystal size have been successfully synthesized via electrochemical method in alkali NaCl solutions with copper as electrodes and K₂Cr₂O₇ as additive. Photocatalytic degradation of methyl orange (MeO) in aqueous Cu₂O solution was investigated under either ultraviolet (UV) light or sunlight. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformation infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis) and X-ray photoelectron spectroscopy (XPS) were introduced to characterize the samples. The results indicate that electric current shows no obvious effect on the growth of Cu₂O nanocrystals and that 97% of MeO can be decolorized under UV irradiation for 2 h or under sunlight for 3 h when amount of Cu₂O is 2 g/L. Recycling use of the catalyst revealed that Cu₂O still has a high photocatalytic efficiency when repeatedly used for four times. Cu₂O nanoparticles still kept its cubic crystal phase, but fractionally oxidized to be CuO after the photocatalysis. Compared with the original Cu₂O nanoparticles, there has 1 eV shift of Cu 2p electron and 1.6 eV shift of Cu Auger signals for the Cu₂O powders after four times photocatalysis. Some new peaks can also be observed at 401.1, 237.4 and 170.2 eV in the Cu₂O powders after photocatalysis.     

Surface texture in electrodeposited films of cuprous oxide

The polycrystalline films of Cu₂O, prepared by electrodeposition, consist of grains with well-defined geometrical shapes. The size and the orientation of grains which define the surface texture can be controlled by controlling the deposition parameters. Grains with a size ranging from a few tenths of a micrometer to about 10m and with a preferential orientation of the (1 0 0) or (1 1 1) planes parallel to substrates can be obtained under certain deposition conditions. The effect of pH, bath temperature and the rate of deposition on the orientation and the size of grains is discussed.     

Electrochromism of the electroless deposited cuprous oxide films

Thin cuprous oxide films were prepared by a low cost, chemical deposition (electroless) method onto glass substrates pre-coated with fluorine doped tin oxide. The X-ray diffraction pattern confirmed the Cu₂O composition of the films. Visible transmittance spectra of the cuprous oxide films were studied for the as-prepared, colored and bleached films. The cyclic voltammetry study showed that those films exhibited cathode coloring electrochromism, i.e. the films showed change of color from yellowish to black upon application of an electric field. The transmittance across the films for laser light of 670 nm was found to change due to the voltage change for about 50%. The coloration memory of those films was also studied during 6 h, ex-situ. The coloration efficiency at 670 nm was calculated to be 37 cm²/C.     

溶剂热法制备不同微米结构的氧化亚铜

以乙酸铜为原料,采用溶剂热法合成了球形直径约为2~3μm和八面体粒径大小约为4μm的氧化亚铜颗粒。通过选用不同的还原剂如三乙醇胺和乙二醇,系统研究了不同反应体系中如反应温度、溶剂、原料配比和添加表面活性剂十六烷基三甲基溴化铵(CTAB)对微米结构氧化亚铜晶型与形貌的影响,选出制备氧化亚铜八面体和球形的最佳条件,并初步探讨了氧化亚铜微米颗粒的生长机理。     

A simple solvothermal reduction route to copper and cuprous oxide

Pure copper nanocrystallites and cuprous oxide nanorods have been synthesized via solvothermal treatment of CuSO₄ or CuSO₄·5H₂O and NaOH in pure ethanol and mixed solution of ethanol and deionized water at 140 °C for 10 h, respectively. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were used to investigate the different morphologies of the as-synthesized products. X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) were applied to characterize the composition and crystal phases of the products. It was proposed that the reducibility of ethanol was influenced by temperature and the addition of deionized water in the formation of different phases, which were realized by carefully controlling the experimental conditions.     

Electrodeposition and characterization of nanocrystalline CoNiFe films

Nanocrystalline Co₄₅Ni₁₀Fe₂₄ films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co₄₅Ni₁₀Fe₂₄ films. The results show that, the obtained Co₄₅Ni₁₀Fe₂₄ film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 × 10⁵ A/m. Under the experimental conditions, the nucleation/growth process of Co₄₅Ni₁₀Fe₂₄ films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially.     

Electrodeposition and characterization of CdSe semiconducting nanowires

In this paper, we present our work on the electrodeposited CdSe semiconducting nanowires. Using a low cost and low temperature approach by electrochemistry, CdSe nanowires were successfully grown using polycarbonate template. Depending on the host pore dimension of the substrate, wire diameter can be varied from 400 nm down to 30 nm and wire length from a few microns to tens microns. The as-deposited nanowires exhibit predominantly metastable zinc blende (ZB) structure but after the heat treatment they become wurtzite (W) structure. A combination of different characterization techniques, such as X-ray diffraction, SEM, TEM-HRTEM and EDXS, was used to investigate the growth morphology, crystalline structure and defects in the nanowires. The luminescent properties of CdSe nanowires have also been studied by means of photoluminescence.     

Synthesis and characterization of cuprous sulfide crystals with novel morphology

Cuprous sulfide (Cu_2−xS) crystals in different stoichiometries were synthesized by hydro- and solvo-thermal methods at 125 °C using Na₂S₂O₃ as sulfur source in pure water, mixed solvents of ethylenediamine (en) and water, and pure en, respectively. The products were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersion spectrometer (EDS), transmission electron microscope (TEM) and selected area electronic diffraction (SAED). Owing to different sulfur sources, crystal structures and morphologies of cuprous sulfides were different from those developed by some former researchers. Novel twelve-fold symmetrical Cu₇S₄ single crystals were synthesized at an en/water volume ratio of 3:1, and they were built up by two layers of about 80-100 nm in thickness. Moreover, the possible growth process had been discussed based on the analyses of detailed configuration of the products.     

Cupric oxide inclusions in cuprous oxide crystals grown by the floating zone method

Abstract

Phase-pure cuprous oxide (Cu₂O) crystals are difficult to grow since cupric oxide can form within the crystal as the crystal is cooled to ambient conditions. Vacancies are the solute which causes precipitation of macroscopic defects. Therefore, even when a mostly phase-pure single crystal is used as a feed rod, cupric oxide inclusions persist in the recrystallized solid. Control of the thermal profile during crystal growth, however, can improve phase-purity; a slow counter-rotation rate of the feed and seed rods results in fewer inclusions. Cupric oxide can be removed by annealing, which produces a factor of 540 ± 70 increase in phase-purity.