Showing papers on "Copper published in 2014"
1,256 citations
TL;DR: Online mass spectroscopy studies combined with X-ray diffraction data suggest the reduction of the Cu2O films in the presence of CO2, generating a nanoparticulate Cu morphology, prior to the production of hydrogen, CO, and hydrocarbons.
Abstract: The catalytic activity and hydrocarbon selectivity in electrochemical carbon dioxide (CO2) reduction on cuprous oxide (Cu2O) derived copper nanoparticles is discussed. Cuprous oxide films with [100], [110] and [111] orientation and variable thickness were electrodeposited by reduction of copper(II) lactate on commercially available copper plates. After initiation of the electrochemical CO2 reduction by these oxide structures, the selectivity of the process was found to largely depend on the parent Cu2O film thickness, rather than on the initial crystal orientation. Starting with thin Cu2O films, besides CO and hydrogen, selective formation of ethylene is observed with very high ethylene-to-methane ratios (8 to 12). In addition to these products, thicker Cu2O films yield a remarkably large amount of ethane. Long term Faradaic efficiency analysis of hydrocarbons shows no sign of deactivation of the electrodes after 5 hours of continuous experiment. Online mass spectroscopy studies combined with X-ray diffraction data suggest the reduction of the Cu2O films in the presence of CO2, generating a nanoparticulate Cu morphology, prior to the production of hydrogen, CO, and hydrocarbons. Optimizing coverage, number density and size of the copper nanoparticles, as well as local surface pH, may allow highly selective formation of the industrially important product ethylene
447 citations
TL;DR: It is demonstrated that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes, which represents a first step toward the preparation of practical meethanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers.
Abstract: Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO2. The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic con...
431 citations
TL;DR: A simple and scalable technique for the deposition of amorphous molybdenum sulphide films as hydrogen evolution catalyst onto protected copper(I) oxide films, which demonstrates the potential of earth-abundant light-harvesting material and catalysts for solar hydrogen production.
Abstract: Photoelectrochemical water splitting may be used to produce hydrogen using abundant solar energy. Here, the authors fabricate layered films of amorphous molybdenum sulphide on copper(I) oxide and demonstrate the catalytic activity and enhanced stability of these devices made from earth-abundant materials.
426 citations
TL;DR: Copper oxide nanoparticles synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight.
397 citations
TL;DR: It is reported that a porous coordination polymer containing Cu2+ ions can selectivity bind CO through serial structural changes reminiscent of allosteric effects in proteins, and crystallographic evidence that CO molecules can coordinate with copper(II) ions is presented.
Abstract: Carbon monoxide (CO) produced in many large-scale industrial oxidation processes is difficult to separate from nitrogen (N2), and afterward, CO is further oxidized to carbon dioxide. Here, we report a soft nanoporous crystalline material that selectively adsorbs CO with adaptable pores, and we present crystallographic evidence that CO molecules can coordinate with copper(II) ions. The unprecedented high selectivity was achieved by the synergetic effect of the local interaction between CO and accessible metal sites and a global transformation of the framework. This transformable crystalline material realized the separation of CO from mixtures with N2, a gas that is the most competitive to CO. The dynamic and efficient molecular trapping and releasing system is reminiscent of sophisticated biological systems such as heme proteins.
383 citations
TL;DR: In this article, a catalytic coper was selected from the group comprising copper nanofoam, copper aerogel, and copper nanoparticles, and a method for the reduction of CO 2 by the steps of (i) providing a membrane divided electrochemical cell comprising an anode in a first cell compartment, a catalysttic-copper electrode in a second cell compartment containing an aqueous electrolyte in contact with the anode and cathode.
Abstract: This invention includes a catalytic copper electrode is selected from the group comprising copper nanofoam, copper aerogel, and copper nanoparticles. Particular note is made of the catalytic copper electrode having at least about 5 times and preferably about 10 times the electrochemically accessible surface area as determined by the Randles-Sevcik equation at 50 mV/s. particular note is made of the catalytic coper electrode being a copper nanofoam electrode. This invention further includes a method for the reduction of CO 2 by the steps of (i) providing a membrane divided electrochemical cell comprising an anode in a first cell compartment, a catalytic-copper electrode in a second cell compartment containing an aqueous electrolyte in contact with the anode and cathode; (ii) introducing CO 2 to said second cell compartment (iii) exposing said CO 2 to said catalytic-copper electrode at a step potential between about −0.8 and preferably about −1.0 and about −1.8 V versus the reference electrode; (iv) electrochemically reducing said CO 2 and solution by the catalytic-copper electrode in the second cell compartment; (v) thereby producing propylene and (vi) extracting said propylene from said second compartment.
363 citations
TL;DR: The biological functions of copper in the brain are summarized and the current knowledge on the mechanisms involved in copper transport, storage and export of brain cells are described.
339 citations
TL;DR: In this paper, the authors reported antifungal activity of copper nanoparticles against selected crop pathogenic fungi, which were synthesized by chemical reduction of Cu 2+ in the presence of Cetyl trimethyl ammonium Bromide and isopropyl alcohol.
316 citations
TL;DR: The observed characteristics and results obtained in in vitro assays suggest that the copper nanoparticles might be a potential anticancer agent.
308 citations
TL;DR: This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.
Abstract: Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm−2) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.
TL;DR: Silver and copper nanoparticles were produced by chemical reduction of their respective nitrates by ascorbic acid in the presence of chitosan using microwave heating and particle size was shown to increase by increasing the concentration of nitrate and reducing the chitOSan concentration.
Journal Article•
TL;DR: In this paper, a review of nanostructured CuxO focusing on their material properties, methods of synthesis and an overview of various applications that have been associated with the nanostructure of the oxides of copper is presented.
Abstract: The oxides of copper (CuxO) are fascinating materials due to their remarkable optical, electrical, thermal and magnetic properties. Nanostructuring of CuxO can further enhance the performance of this important functional material and provide it with unique properties that do not exist in its bulk form. Three distinctly different phases of CuxO, mainly CuO, Cu2O and Cu4O3, can be prepared by numerous synthesis techniques including, vapour deposition and liquid phase chemical methods. In this article, we present a review of nanostructured CuxO focusing on their material properties, methods of synthesis and an overview of various applications that have been associated with nanostructured CuxO.
TL;DR: In this paper, a holographic duality was proposed to reproduce the linear resistivity of the normal state of the copper oxides, in addition to the linear specific heat, which requires only quenched disorder and a strongly interacting, locally quantum critical state.
Abstract: We present a strange metal, described by a holographic duality, which reproduces the famous linear resistivity of the normal state of the copper oxides, in addition to the linear specific heat. This holographic metal reveals a simple and general mechanism for producing such a resistivity, which requires only quenched disorder and a strongly interacting, locally quantum critical state. The key is the minimal viscosity of the latter: unlike in a Fermi liquid, the viscosity is very small and therefore is important for the electrical transport. This mechanism produces a resistivity proportional to the electronic entropy.
TL;DR: In this paper, the tensile strength of steel/Cu SLM parts was evaluated using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques.
TL;DR: In this article, the results of quantum-chemical calculations concerning the formation of oxygen vacancies in monoclinic and tetragonal ZrO2 have been also presented, and it was found that selection of the appropriate conditions of the catalyst preparation influences the degree of copper dispersion, its electronic state, and contents of the zirconia polymorphic phases (tetragonal and monocliic).
Abstract: Cu/ZrO2 catalysts obtained by impregnation of ZrO2 and complexation with citric acid were studied for CO2 hydrogenation to methanol. The catalyst structure, texture, and active copper surface were determined using XRD, BET, and reactive adsorption of N2O, respectively. The XPS and Auger spectroscopies were used to determine the surface structure and copper electronic state. FT-IR pyridine adsorption was studied to determine acidity of the catalysts. The results of quantum-chemical calculations concerning the formation of oxygen vacancies in monoclinic and tetragonal ZrO2 have been also presented. It was found that selection of the appropriate conditions of the catalyst preparation influences the degree of copper dispersion, its electronic state, and contents of the zirconia polymorphic phases (tetragonal and monoclinic). The presence of oxygen vacancies stabilizes both the thermodynamically unstable t-ZrO2 phase and Cu1+ cations, which are present in the vicinity of oxygen vacancies. Complexes formed pref...
TL;DR: Copper oxide nanoparticles showed efficient antibacterial and antifungal effect against Escherichia coli, Pseudomonas fluorescens and Candida albicans and confirmed that copper oxide nanoparticle have cytotoxicity activity.
TL;DR: Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst and a combination of chemisorption, reaction, and spectroscopic techniques provides a consistent picture of surface alloying between copper and zinc.
Abstract: Methanol has recently attracted renewed interest because of its potential importance as a solar fuel.1 Methanol is also an important bulk chemical that is most efficiently formed over the industrial Cu/ZnO/Al2O3 catalyst. The identity of the active site and, in particular, the role of ZnO as a promoter for this type of catalyst is still under intense debate.2 Structural changes that are strongly dependent on the pretreatment method have now been observed for an industrial-type methanol synthesis catalyst. A combination of chemisorption, reaction, and spectroscopic techniques provides a consistent picture of surface alloying between copper and zinc. This analysis enables a reinterpretation of the methods that have been used for the determination of the Cu surface area and provides an opportunity to independently quantify the specific Cu and Zn areas. This method may also be applied to other systems where metal–support interactions are important, and this work generally addresses the role of the carrier and the nature of the interactions between carrier and metal in heterogeneous catalysts.
TL;DR: Single crystalline copper nanowires with large aspect ratio were used as filling materials for the first time and obtained excellent thermal conductivity at an ultralow loading fraction, which makes copper Nanowires attractive fillers for high-performance TIMs.
Abstract: Thermal interface materials (TIMs) are of ever-rising importance with the development of modern microelectronic devices. However, traditional TIMs exhibit low thermal conductivity even at high loading fractions. The use of high-aspect-ratio material is beneficial to achieve low percolation threshold for nanocomposites. In this work, single crystalline copper nanowires with large aspect ratio were used as filling materials for the first time. A thermal conductivity of 2.46 W/mK was obtained at an ultralow loading fraction, ∼0.9 vol %, which was enhanced by 1350% compared with plain matrix. Such an excellent performance makes copper nanowires attractive fillers for high-performance TIMs.
TL;DR: In this article, the photophysical properties of photocatalysts based on copper and on synthetic transformations mediated by them are discussed, including [2+2]-cycloadditions, cross-coupling reactions or atom transfer radical additions.
Abstract: Light-induced electron transfer (CuI to CuII), oxidative addition (CuI to CuIII), or the activation of copper alkene or alkyne complexes are possible key steps that offer unique possibilities for organic synthesis, including [2+2]-cycloadditions, cross-coupling reactions or atom transfer radical additions. This Minireview provides an overview on the photophysical properties of photocatalysts based on copper and on synthetic transformations mediated by them.
TL;DR: It was concluded that the Cu content affects the Cu existence and the Cu ion release behavior, which in turn influences the antibacterial property.
TL;DR: In this article, the degradation capacity and mechanism of Fe/Cu bimetallic system with different theoretical copper mass loadings were characterized by SEM, EDS, XRD and laser particle size analyzer.
Abstract: In this study, in order to further investigate the degradation capacity and mechanism of Fe/Cu bimetallic system, the prepared Fe/Cu bimetallic particles with different theoretical copper mass loadings (0.05, 0.11, 0.24, 0.41, 0.62, 0.89, 1.26 and 1.81 g Cu/g Fe) were characterized by SEM, EDS, XRD and laser particle size analyzer. Also, the effect of theoretical Cu mass loading and five key operating parameters on the PNP removal efficiency was investigated thoroughly. Furthermore, the mineralization process of PNP was studied by using COD, TOC, UV–vis spectra, FTIR spectra and GC/MS. The results show that a large number of fine Cu particles were produced from the excessive theoretical Cu mass loading, and they facilitated the catalytic reactivity of the Fe/Cu bimetallic particles at Cu loading
TL;DR: ICP-OES results showed that nano-Cu/CuO treatments produced significant accumulation of Cu in roots compared to the CuSO(4)·5H(2)O treatment, and in roots, all Cu treatments increased CAT activity but decreased APX activity.
TL;DR: An active copper nanocomposite is reported, inspired by natural coordination environments of catalytic sites in an enzyme, which catalyzes oxygen reduction/evolution at potentials closely approaching standard potential.
Abstract: In many green electrochemical energy devices, the conversion between oxygen and water suffers from high potential loss due to the difficulty in decreasing activation energy. Overcoming this issue requires full understanding of global reactions and development of strategies in efficient catalyst design. Here we report an active copper nanocomposite, inspired by natural coordination environments of catalytic sites in an enzyme, which catalyzes oxygen reduction/evolution at potentials closely approaching standard potential. Such performances are related to the imperfect coordination configuration of the copper(II) active site whose electron density is tuned by neighbouring copper(0) and nitrogen ligands incorporated in graphene. The electron transfer number of oxygen reduction is estimated by monitoring the redox of hydrogen peroxide, which is determined by the overpotential and electrolyte pH. An in situ fluorescence spectroelectrochemistry reveals that hydroxyl radical is the common intermediate for the electrochemical conversion between oxygen and water.
TL;DR: It is concluded that TEMPO oxidized biobased nanofibers from waste resources represent an inexpensive and efficient alternative to classical sorbents for heavy metal ions removal from contaminated water.
Abstract: Biobased nanofibers are increasingly considered in purification technologies due to their high mechanical properties, high specific surface area, versatile surface chemistry and natural abundance In this work, cellulose and chitin nanofibers functionalized with carboxylate entities have been prepared from pulp residue (ie, a waste product from the pulp and paper production) and crab shells, respectively, by chemically modifying the initial raw materials with the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediated oxidation reaction followed by mechanical disintegration A thorough investigation has first been carried out in order to evaluate the copper(II) adsorption capacity of the oxidized nanofibers UV spectrophotometry, X-ray photoelectron spectroscopy and wavelength dispersive X-rays analysis have been employed as characterization tools for this purpose Pristine nanofibers presented a relatively low content of negative charges on their surface thus adsorbing a low amount of copper(II) The copper adsorption capacity of the nanofibers was enhanced due to the oxidation treatment since the carboxylate groups introduced on the nanofibers surface constituted negative sites for electrostatic attraction of copper ions (Cu2+) The increase in copper adsorption on the nanofibers correlated both with the pH and carboxylate content and reached maximum values of 135 and 55 mg g−1 for highly oxidized cellulose and chitin nanofibers, respectively Furthermore, the metal ions could be easily removed from the contaminated nanofibers through a washing procedure in acidic water Finally, the adsorption capacity of oxidized cellulose nanofibers for other metal ions, such as nickel(II), chromium(III) and zinc(II), was also demonstrated We conclude that TEMPO oxidized biobased nanofibers from waste resources represent an inexpensive and efficient alternative to classical sorbents for heavy metal ions removal from contaminated water
TL;DR: The fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu are studied to suggest that B is taken up in the Cu catalyst while N is not, indicating element-specific feeding mechanisms including the bulk of the catalyst.
Abstract: Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxid...
TL;DR: On the basis of the inhibitory effect of ascorbic acid on oxidation of TMB, this system serves as a colorimetric method for the detection of AA, suggesting that the present work would expand the potential applications of MOF-derived nanocomposites in biomedical fields.
Abstract: Metal-organic frameworks (MOFs) have emerged as very fascinating functional materials due to their diversity nature. A nanocomposite consisting of copper nanoparticles dispersed within a carbon matrix (Cu NPs@C) is prepared through a one-pot thermolysis of copper-based metal-organic framework precursors. Cu NPs@C can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to form a colored product in the presence of H2 O2 . As a peroxidase mimic, Cu NPs@C not only has the advantages of low cost, high stability, and easy preparation, but also follows Michaelis-Menten behaviors and shows strong affinity to H2 O2 . As the Cu NPs' surfaces are free from stabilizing agent, Cu NPs@C exhibited a higher affinity to H2 O2 than horseradish peroxidase. On the basis of the inhibitory effect of ascorbic acid (AA) on oxidation of TMB, this system serves as a colorimetric method for the detection of AA, suggesting that the present work would expand the potential applications of MOF-derived nanocomposites in biomedical fields.
TL;DR: In this article, chitosan beads were produced from chitosa flakes and grafted with polyaniline to enhance the adsorption properties of chitoshan-based material for copper (II) ions.
Abstract: In this study, chitosan beads were produced from chitosan flakes and grafted with polyaniline to enhance the adsorption properties of chitosan based material for copper (II) ions. Chitosan and polyaniline graft chitosan beads (PGCB) were characterized by FTIR and SEM to provide evidence of successful grafting. The effect of pH, pHpzc, contact time and initial concentration was investigated in a batch system. Equilibrium data were obtained from the adsorption experiment carried out at different initial ion concentration. The data were fitted to the Langmuir and Freundlich isotherm at temperatures of 25 °C, 35 °C and 45 °C. The Langmuir model gave the best fit for both adsorbent. The maximum adsorption capacity for chitosan and PGCB at a temperature of 45 °C was found to be 52.6 mg/g and 100 mg/g, respectively and at a solution pH of 5. Thermodynamic parameters of the adsorption process such as the standard Gibb's free energy change (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°) were calculated, and the result showed that adsorption of copper onto PGCB is spontaneous and endodermic in nature. The pseudo-first-order and pseudo-second-order were used to analyze kinetic data. The data fit well with the second-order kinetic model. Desorption of copper ions from loaded PGCB was efficient, 0.5 M HCl was successfully used in desorbing the beads loaded with copper ions and a percentage desorption of 97.1% was achieved at contact time of 180 min.
TL;DR: This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing, which exhibited efficiencies of 4.9%.
Abstract: This work describes a process to make anodes for organic solar cells from copper–nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper–nickel nanowire films exhibited efficiencies of 4.9%.
TL;DR: In this article, a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces was reported.
Abstract: The authors report a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces. Instead of using common atomic layer deposition (ALD) oxygen sources such as water, oxygen, or ozone, the authors use ethanol, which serves as oxygen source for the ALD on the silicon side and as effective reducing agent on the copper side, thereby selectively depositing ZrO2 film on the silicon surface of the substrate without any deposition on copper up to at least 70 ALD cycles. The resulting ZrO2 nanofilm is found to be an effective copper diffusion barrier at temperatures at least up to 700 °C.