Composition Of Cu Research Articles

Ag-modified CuO-Fe2O3 composite catalysts for low-temperature NH3-SCO

A series of CuFe and Ag-modified CuFe composite catalysts were prepared for low-temperature selective catalytic oxidation of ammonia (NH3-SCO). Significant synergistic effects existed between Cu and Fe oxides in the CuFe(7:12) catalyst for catalyzing NH3 oxidation. Loading 6 wt.% Ag over CuFe(7:12) further enhanced NH3 conversion and N2 selectivity. At 200 °C, NH3 conversion and N2 selectivity reached 97.1 % and 79.3 %, respectively, over 6Ag/CuFe(7:12). Besides the exceptional catalytic effects of Ag species, the increased surface area, formation of CuFe2O4, improved reducibility of Cu and Fe oxides, and increased acid sites due to the composite of Cu and Fe and modification with Ag contributed to the superior performance of the 6Ag/CuFe(7:12) catalyst in NH3-SCO. In-situ DRIFTS results showed that NH3 oxidation might follow the internal selective catalytic reduction mechanism: NH3 was dehydrogenated and oxidized to NOx and nitrate species, and the formed NOx and nitrate species were reduced by the remaining NH3, −NH2 and −NH species to N2 and H2O. Loading Ag over CuFe(7:12) suppressed the formation of NO and NO2 but promoted that of N2O during NH3 oxidation, which could be attributed to the enhanced formation and decomposition of NH4NO3 in the presence of Ag.

Two Step Synthesis of CuS Thin Films via High Vacuum Sulphidation

In this study, synthesis of CuS thin films on soda lime glass (SLG) substrates has been investigated. The synthesis method is based on high vacuum post-sulphidation of Cu thin films deposited by rf. magnetron sputtering. Sputtering conditions have been optimized so as to reduce grain size for better diffusion of S atoms through grain boundaries. XRD pattern of the precursor Cu sample revealed fcc structure with an average crystallite size of 24 nm. Best sulphidation was obtained at 175 oC for 60 min. The crystallite size of CuS calculated from the dominant peak of (110) planes was approximately 48 nm while average grain size observed via SEM was about 400 nm. Raman spectroscopy confirmed CuS structure by scattering peaks at around 467-472 cm-1. Elemental mapping unveiled homogenous distribution of Cu and S atoms over the surface. According to EDS data, at% compositions of Cu and S were 51.6% and 48.4%, respectively. Moreover, SIMS investigation has demonstrated uniformity of S atoms through the thickness of CuS thin film. Although XRD, Raman, and EDS analysis have resulted in predominant formation of CuS structure, existence of Cu2S phase with a strong luminescence peak located at 1.8 eV was determined by PL spectroscopy.

Investigation of the concentration and isotopic composition of Cu, Fe and Zn in human biofluids in the context of Alzheimer’s disease via tandem and multi-collector inductively coupled plasma-mass spectrometry

Studies on essential trace elements in the context of Alzheimer’s disease (AD) concluded that Cu, Fe and Zn interact with amyloid-β, accelerating plaque formation in the brain. Additionally, Cu and Fe in the vicinity of plaques produce reactive oxygen species (ROS) resulting in oxidative stress, whereas Zn plays a role in the antioxidant defence as a co-factor for antioxidants. In this work, the Cu, Fe and Zn concentrations and isotope ratios were determined in whole blood, blood serum and cerebrospinal fluid of 10 patients diagnosed with AD and 8 control individuals, using tandem (ICP-MS/MS) and multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), respectively. In whole blood and blood serum of AD patients, a heavier Cu isotopic composition was observed (significant for whole blood only) compared to controls. Albumin levels in cerebrospinal fluid tend to increase with age, which could indicate an increased leakiness of the blood-brain barrier. In cerebrospinal fluid, a large variability was observed for the Cu and Fe isotope ratios, potentially resulting from that leakiness at the blood-brain barrier. Therefore, potential effects of AD on the concentration and isotopic composition of essential elements in cerebrospinal fluid related to amyloid-β formation could be hidden. Finally, in blood serum, Zn, urea and creatinine concentrations showed an increase with age and showed a significant difference between sexes.

Correlation between phase composition and physicochemical properties in Cu-, Mo-, and W- doped bismuth vanadate

We report a detailed study about the correlation between the physicochemical properties of solvothermally synthesized pristine and 1 %, 2.5 %, and 5 % Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) with its phase composition. The effect of the dopant and the duration of synthesis (8 h and 20 h) on the physicochemical properties of BVO allowed us to tune the ratio of monoclinic scheelite to tetragonal zircon phase in BVO powders. This approach helped us to establish the relationship between the presence of monoclinic scheelite or tetragonal zircon phase with structural, morphological and optical properties of BVO powders, obtained by different physicochemical methods (e.g. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Diffuse Reflectance Spectroscopy (DRS) and Photoluminescence spectroscopy (PL)). The results indicated that, in addition to XRD, Raman, and DRS, several other methods could distinguish between the two phases. For example, SEM analysis revealed that monoclinic scheelite BVO exhibits either elongated assemblies of cube-like particles or prismatic particles with sizes ∼500 nm. In contrast, tetragonal zircon BVO exclusively exhibited porous spherical particles with diameter ∼2 μm. DRS and Raman spectroscopy indicated that there is a possibility of distinguishing between the two phases if their shares are large enough. For instance, monoclinic BVO showed band gap values in the range of 2.35–2.52 eV, while tetragonal zircon BVO exhibited values in the range of 2.80–3.00 eV. XPS showed a correlation between phase composition and surface chemistry of BVO only for Cu-doped samples, revealing the presence of Cu+ in monoclinic BVO and the presence of both Cu+ and Cu2+ in tetragonal zircon BVO. PL showed that monoclinic scheelite BVO displayed decreased charge recombination compared to tetragonal zircon BVO. Deeper insight into the correlation between the physicochemical properties and phase composition of Cu, Mo, and W-doped bismuth vanadate (BiVO4, BVO) was based on water/pentanol medium (2:1 vol%) as a novel synthesis pathway. This may open new avenues for the broader methodological exploration of surface chemistry, particle size, and morphology of BVO particles through the use of diverse functionalization agents. Finally, the established links between phase composition and structural, morphological, and other physicochemical properties provide new and more predictable opportunities for further improvement of BVO properties for various applications.

Cu1.3Mn1.7O4/LaNi0.6Fe0.4O3 composite with prospects for IT-SOFC/SOEC applications

Composite materials with the composition (100-x)Cu1.3Mn1.7O4/xLaNi0.6Fe0.4O3 (CMxLNF, where: x = 5, 10, 15, 20, 30, 40 and 50 wt%) were evaluated as possible coating materials for SOFC/SOEC metallic interconnects. The introduction of LaNi0.6Fe0.4O3 into spinel matrices improved electrical conductivity compared to pure Cu1.3Mn1.7O4. The measured Seebeck coefficient values indicate that carrier concentration increased with LaNi0.6Fe0.4O3 content, yet the activation energy of the carriers' mobility decreased. Extensive structural and microstructural studies of selected CM/LNF systems showed that composite material components exhibited high stability in relation to one another. Additionally, LaNi0.6Fe0.4O3 significantly improved the chemical stability of Cu1.3Mn1.7O4 in the presence of chromia, as tested after 150 h of exposure to air at 800 °C. Finally, coatings based on selected composite powders were deposited electrophoretically on the steel and were oxidized for 1500 h in air at 750 °C, confirming that CM10LNF can be applied as effective protective-conducting coatings on low-chromium ferritic steel.

Corrosion resistance of powder metallurgy fabricated Cu–10Sn/SiC/mica hybrid composite

Abstract For the first time, bronze/SiC/mica hybrid composite has been manufactured using powder metallurgy method. Mixture – process variable design has been applied to design of experiments and optimization of the composite composition, as well as the production process variables (compaction pressure and sintering temperature) to attain superior corrosion resistance. This involved mixing different compositions of bronze, SiC, and mica powders, which were subsequently subjected to varied pressures and temperatures during the pressing and sintering stages, all in accordance with the experimental design plan. The microstructure, chemical composition, and elemental distribution of the samples were examined using scanning electron microscope equipped by energy dispersive X-ray analyzer, and an optical microscope. In order to study the corrosion resistance, potentiodynamic polarization test and electrochemical impedance spectroscopy were performed in 3.5 wt.% NaCl solution. The results revealed that co-incorporation of SiC and mica particles in Cu–10Sn bronze matrix increases the corrosion resistance, with a synergistic effect between these particles. The result of optimization process showed that the highest corrosion resistance could be achieved for the composite with the composition of Cu–10Sn/9.85SiC/0.67mica. This outcome was subsequently validated through experimental procedures.

Optimizing photovoltaic performance: Strategic enhancement of Ag-doped graded CAZTS solar cells achieving 27.3% efficiency

The Ag-doped Cu2ZnSnS4 (CAZTS) based solar cell has been explored, with varying Ag concentrations (x = 0, 0.1, 0.2, 0.3, 0.4) in the composition (Cu1−xAgx)2ZnSnS4. In order to mitigate back surface recombination in CAZTS-based solar cells, a Sn2S3 layer has been incorporated as a back surface field (BSF). Further, the efficiency enhancement employs a bandgap grading approach, elevating efficiency from 15.8 % to 24.7 % compared to devices without the graded structure. Additionally, the thickness and total defect density of the CAZTS layer are optimized. The result demonstrates that the optimized value of the CAZTS layer’s thickness is 1.1 µm, and the defects are 1 × 1012 cm−3. To further enhance the performance, the doping variation of the CAZTS layer has also been investigated. The findings indicate that the maximum efficiency of 27.32 % is attained with a doping value of 1 × 1016 cm−3.

Tuning of Catalytic Dimethyl Adipate Hydrogenation by Changing Composition of Cu–ZnO–TiO2 Catalysts

Tuning of Catalytic Dimethyl Adipate Hydrogenation by Changing Composition of Cu–ZnO–TiO₂ Catalysts

Green Synthesis of CuO Nanoparticles Using Tragopogon porrifolius and Their Antioxidant and Photocatalytic Applications

Copper oxide nanoparticles (CuO NPs) were produced by green synthesis method which is a cheap, easy and effective method using Tragopogon porrifolius extract. The shape, bond and crystal structure of the nanoparticles were determined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffractometer (XRD) analysis methods. SEM analysis showed that the particles were spherical and EDX analysis showed the elemental composition of Cu and O as Cu 58.17 % and O 32.73 %. Cu-O bond structure was identified in FTIR analysis. In XRD analysis, peaks defining CuO NPs were observed. The antioxidant and photocatalytic activity of the synthesized CuO NPs were investigated. Antioxidant capacities were examined in the range of 50-500 μg/mL. The free radical scavenging activity of the nanoparticles was determined as 70.75 % at a concentration of 500 μg/mL. In photocatalytic studies, Reactive Red 120 (RR 120) dye degradation was investigated. The degradation time was calculated as 76 % in 30 min.

The influence of reconstructive transformation from micro-/nanostructured copper(II) hydroxide to copper oxides as electrodes for high-performance supercapacitors

Copper(II) hydroxides, particularly Cu(OH)2 micro/nanostructures, are metastable under normal conditions. Notably, Cu(OH)2 micro-/nanostructures undergo structural restructuring and phase transitions during electrochemical reactions. In this study, the effects of electrolyte concentration, current, and duration of the electrochemical reaction on the crystal morphology, structure, and chemical composition of Cu(OH)2 micro-/nanostructured composite electrodes were investigated by anodic oxidation. The results showed that a Cu(OH)2 nanorod-like structure was formed on the electrode surface in the KOH electrolyte at a concentration of 3 M, while Cu2O crystals were synthesized at electrolyte concentrations of 1 M and 6 M. The growth current of the Cu(OH)2 nanorod-like structures ranged from 30 mA to 70 mA. At a reaction time of 10–80 min, the micro-/nanostructure of the electrode surface changed from an unstable Cu2O to a stable CuO phase through metastable Cu(OH)2. The synthesized Cu(OH)2 composite electrode exhibited an area-specific capacitance of 2777 mF cm–2 at a scanning rate of 10 mV s–1. In particular, the relationships between the surface morphology, structure, and chemical composition of the Cu(OH)2 composite electrode and the electrolyte concentration during cyclic voltammetry were studied. The results showed that in the KOH electrolyte at 1 M concentration, the Cu(OH)2 micro-/nanostructure transformed into Cu2O under electrochemical action, Cu(OH)2 transformed into both the Cu2O and CuO phases at 3 M electrolyte concentration, and Cu(OH)2 transformed into the CuO phase when the electrolyte concentration was increased to 6 M, indicating that the concentration of the alkaline electrolyte had a significant effect on the reconstruction and phase transformation of the Cu(OH)2 micro-/nanostructures. These results are expected to address the pressing issues in the application of metastable Cu(OH)2 micro/nanostructured composite electrodes in high-performance supercapacitors, such as insufficient energy, mass transfer, and structural instability.

Thermal stability of the CuCrSe2

The crystal structure of CuCrSe2 in the temperature range 25 - 1000 °C was studied by synchrotron X-ray diffraction. It was found that heating leads to the decomposition of stoichiometric CuCrSe2 into two phases of composition CuCr2Se4 and Cu1+xCrSe2 with increased Cu content. It was found that copper enrichment of CuCrSe2 during heating occurs up to the temperature of 800 °C and the limiting composition is close to the compound Cu4Cr3Se6. It was found that heating equalizes the copper distribution at the α- and β-tetrahedrally coordinated chalcogen positions, but full equality of their occupancy at temperatures up to 1000 °C was not achieved. The low temperature limit of CuCr2Se4 excretion was established to be approximately 300 °C and the decomposition temperature of CuCr2Se4 to be approximately 1050 °C.

Incommensurately Modulated Cu0.9Pb1.2Sb2.9Se6 in the Lillianite Structure Type.

Samples with the nominal composition Cu0.9Pb1.2Sb2.9Se6 mainly contain a phase with incommensurately modulated lillianite-type structure with the respective composition. Single crystal diffraction with synchrotron radiation enabled a detailed refinement using the superspace group Cmcm(α00)00s with lattice parameters a = 4.16537(5), b = 14.0821(2), c = 19.8234(3) Å, and a modulation vector q = 0.6890(2)a* at room temperature. The structure is built up from tilted and distorted NaCl-type slabs that are interconnected by bicapped trigonal prisms, which mainly host Pb atoms, according to a 4L arrangement. Satellites up to the second order reveal positional and occupational modulation that mainly involves a sequence of Sb and Cu atoms and allows the Se substructure to adapt in a way that Sb and Cu feature predominantly octahedral and tetrahedral coordination, respectively. Above 523 K, satellite reflections disappear, and the crystal structure becomes more disordered with average coordination spheres of both Sb and Cu atoms corresponding to distorted octahedra. This phase transition leads to discontinuities in the evolution of lattice parameters and physical properties as functions of temperature. HRTEM investigations corroborate centrosymmetry and highlight atoms that are strongly affected by the modulation. Measurements of transport properties reveal a p-type semiconductor with a thermoelectric figure of merit up to 0.1 at 623 K. In accordance with B factor analysis, a small amount of substitution could increase zT significantly by optimizing the carrier concentration.

Deposition-controlled phase separation in CuNb metallic alloys

Vapor co-deposited metal nanocomposites with immiscible components have shown to have several superior properties including mechanical performance, radiation tolerance, and enhanced functionalities. The morphology and structural design of these nanocomposites are important in determining the expression of these properties. The conditions used to deposit thin film nanocomposites are the governing factors in determining the final nanostructure. In this work, we link the effects of process gas pressure, substrate temperature, and sputtering target power on resultant Cu/Nb thin film nanostructures. We find that for films with equiatomic phase fractions of Cu and Nb, inhomogeneous precipitate segregation dominated the structure at lower substrate temperature depositions while higher temperatures distributed the Cu and Nb phases more uniformly. Increasing process gas pressure during deposition lead to a spatially homogeneous, nanocrystalline structure of Cu/Nb. In situ annealing of this sample shows that the phase separated morphology of the two immiscible materials depends on the initial composition. Finally, compositions of Cu and Nb that were highly disparate lead to interface segregation of the minority phase. The morphological evolution observed in the Cu/Nb system is compatible with modified structural zone models for immiscible thin film systems.

Crystal Growth and the Structure of a New Quaternary Adamantine Cu□GaGeS4

Single crystals of quaternary adamantine-type Cu□GaGeS4 were grown using the chemical vapor transport technique, with iodine as the transport agent. Dark red transparent crystals were grown in a temperature gradient of DT = 900–750 °C. Chemical characterization by X-ray fluorescence showed the off-stoichiometric composition of Cu□GaGeS4 crystals—in particular, a slight Ge deficiency was observed. By X-ray diffraction, Cu□GaGeS4 was found to adopt the chalcopyrite-type structure with the space group . Cation distribution in this structure was analyzed by multiple energy anomalous synchrotron X-ray diffraction, and it was found that Cu and vacancies occupied the 4a site, whereas Ga and Ge occupied the 4b site. The band gap energies of several off-stoichiometric Cu□GaGeS4 crystals were determined by UV-Vis spectroscopy and ranged from 2.1 to 2.4 eV. A non-linear correlation of the band gap energy with the Ge content of the compound was shown to follow the usual bowing behavior of semiconductor alloys, with a bowing parameter of = −1.45 (0.08).

Investigating the role of film thickness on the physical properties of sol-gel coated CuO thin films: Discussing its potentiality in optoelectronic applications

In the present study, Cupric oxide thin films with varying thicknesses were successfully fabricated on a glass substrate at room temperature via dip coating technique. Highly crystalline CuO films with monoclinic symmetry were examined from XRD which was further confirmed with the help of Raman spectra. FESEM results showed a uniform coating surface with nano-sized grains without any agglomerations. The elemental composition of Cu and O atoms is in a 1:1 stoichiometric ratio for samples having higher thickness values. Strong absorption in the visible and nearby IR region makes the sample a viable choice in the field of photovoltaics. The estimated band gap values from the Tauc plot ranges from 1.10 eV to 1.26 eV. All the samples exhibited a p-type nature and their uniformity of resistance over the film surface was examined by resistance mapping. Hall measurements indicated the direct proportionality of sample resistivity with thickness.

Assessment of the effectiveness of Saba shielding with the composition of Cu–Bi in neck CT imaging: a phantom and patient study

The use of computed tomography (CT) is a very well-established medical diagnostic imaging modality, however, the high radiation dose due to this imaging method is a major concern. Therefore, dose reduction methods are necessary, especially for superficial radiosensitive organs like the thyroid. The aim of this study is to construct and assess a CT shield with composition of 90% Cu and 10% Bi (Saba shield) with regard to dose reduction and image quality. The efficiency of the constructed shields for dose reduction was assessed by measuring entrance skin dose (ESD), using thermoluminescence dosimeters placed on an anthropomorphic phantom. Image quality was assessed quantitatively based on image noise and CT number accuracy by drawing regions of interest on CT images of the anthropomorphic phantom. Image quality was further investigated qualitatively in a patient study. Application of the Saba shield and 100% Bi shield with the thickness of one thickness (1T) reduced ESD by 50.2% and 51.7%, respectively, and using a three-fold thickness reduced ESD by 64.6% and 65.1%, respectively. Saba shield with thickness of 1T had no significant change in image noise in the anterior part, and image noise and mean CT number in the posterior part (P > 0.05). The statistical analysis performed did not find any meaningful difference between the study and control groups in image quality assessment of the patient study (P > 0.05). The 1T Saba shield reduced thyroid dose efficiently during neck CT imaging without causing unwanted effects on image quality.

Optoelectronics characteristics of chemically synthesized Cu(In1-xGax)Se2 based Schottky and heterojunctions

CIGS is an important photovoltaic material in recent years. In this work, we have performed a comparative analysis of various conduction mechanism in CIGSe2 based Schottky and hetero junction nanostructures. Cu(In1-xGax)Se2 nanostructure dispersed in PVP matrix has been synthesized through chemical bath deposition method at a compositional variation x = 0-1. The structural and optical characterization are done and correlated with the In/Ga fraction ratio. The conduction mechanism for both Schottky and hetero structures has been analyses and systematically co-related with compositional variation of In/Ga. By using the thermionic theory, the diode parameters ideality factor, saturation current, barrier height is determined in hetero junction device and co related with composition of Cu(In1-xGax)Se2. Richardson-Schottky(RS) mechanism is found to be dominant in Schottky type junction whereas both Pool-Frenkel(PF) and Richardson-Schottky(RS) mechanism is involved in hetero junction at different range of bias. Our findings points to Cu(In1-xGax)Se2 nanostructures synthesized at x = 0, 0.3,0.5 as promising candidate for solar cell because of their optimum diode parameters and band gap for absorption of maximum solar radiation.

New Data on the Conditions of Localization and Composition of Cu–Ni Sulfide Ores in the Western Part of the Oktyabr’skoe Deposit, Norilsk District

New Data on the Conditions of Localization and Composition of Cu–Ni Sulfide Ores in the Western Part of the Oktyabr’skoe Deposit, Norilsk District

Alzheimer's Disease and Age-Related Changes in the Cu Isotopic Composition of Blood Plasma and Brain Tissues of the APPNL-G-F Murine Model Revealed by Multi-Collector ICP-Mass Spectrometry.

Alzheimer's' disease (AD) is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary tangles of tau protein in the brain. Aβ plaques are formed by the cleavage of the β-amyloid precursor protein (APP). In addition to protein aggregations, the metabolism of the essential mineral element Cu is also altered during the pathogenesis of AD. The concentration and the natural isotopic composition of Cu were investigated in blood plasma and multiple brain regions (brain stem, cerebellum, cortex, and hippocampus) of young (3-4 weeks) and aged (27-30 weeks) APPNL-G-F knock-in mice and wild-type controls to assess potential alterations associated with ageing and AD. Tandem inductively coupled plasma-mass spectrometry (ICP-MS/MS) was used for elemental analysis and multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) for high-precision isotopic analysis. The blood plasma Cu concentration was significantly altered in response to both age- and AD-related effects, whereas the blood plasma Cu isotope ratio was only affected by the development of AD. Changes in the Cu isotopic signature of the cerebellum were significantly correlated with the changes observed in blood plasma. The brain stem showed a significant increase in Cu concentration for both young and aged AD transgenic mice compared with healthy controls, whereas the Cu isotopic signature became lighter as a result of age-related changes. In this work, ICP-MS/MS and MC-ICP-MS provided relevant and complementary information on the potential role of Cu in ageing and AD.

In situ determination of sputtered Ni–Cu film composition from emission intensities

In situ elemental analysis of films comprising multielements deposited by sputtering is necessary to improve the reliability of the films because small changes in the film composition affect the properties of the films. Recently, we developed a method to determine the composition of Cu–Zn films by measuring the intensities of emission lines of Cu and Zn during sputter deposition. However, this method was only applicable to a constant chamber pressure, and only a narrow composition range (65.9–80.6 at. % of Cu in the target) was investigated. In this study, the applicability of this method was investigated for a wide range of film compositions, and the combination of emission lines that can be used to determine the film composition regardless of the chamber pressure was determined. This was achieved using Ni–Cu alloy targets, whose Cu composition ranged from 29.4 to 85.3 at. %, by evaluating the linearity (R2 value) between the emission intensity ratio of Ni/Cu lines and the atomic ratio of Ni/Cu in the films. An R2 value of 0.9870 was obtained for the combination of Ni 338.1 nm and Cu I 296.1 nm lines at chamber pressures from 1 to 5 Pa. This result indicates that the composition of Ni–Cu films can be determined from the intensities of the emission lines of Ni and Cu during sputter deposition regardless of the chamber pressure.