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The technique of X-ray photoelectron spectroscopy has been used to investigate the chemical reactivity at the metal/CuO interfaces. Thin films of the metallic overlayer (0.5 nm, 1.0 nm and 2.0 nm thickness) were deposited on copper oxide substrates at room temperature. In situ characterization of the interfaces has been performed. The 2p core level regions of the metals have been investigated. The spectral features show considerable reactivity at the interfaces. The core level peaks of the metal are observed to be shifted to the high BE energy side with the appearance of satellites. The spectral data confirm the formation of the metallic oxide at the interface. The satellite structure in the copper region is observed to disappear and the spectral features are found to approach those of elemental copper. The room temperature deposition of the metal on copper oxide therefore results in the reduction of copper oxide to elemental copper followed by the oxidation of the metal. The interface is found to consist of a mixture of metal oxide and elemental copper. The 2.0 nm samples were annealed. These samples show the diffusion of copper oxide through the overlayer. The metal reacts with this diffusing oxide to form metallic oxide. The interface is found to consist of a mixture of unreacted metal, the metal oxide, and elemental copper. The amount of the unreacted metal varied between 0% and 40% and can be controlled by the processing conditions. The investigation shows room temperature chemical reactivity at the metal/CuO interface and provides a new method of preparing sub-nano-oxide films.

Copper oxide is a semiconducting compound with a narrow band gap and is used for photoconductive and photothermal applications. Most of the synthesis methods for the preparation of copper oxide composite materials either are unsuitable for mass fabrication or inevitably introduce unwanted impurities. In this work, we report on the synthesis of copper oxide composite materials by the arc discharge method with a pure copper rod as the anode and graphite as the cathode. Ion beam analysis techniques, particle-induced X-ray emission and Rutherford backscattering spectrometry were used to probe the impurities in the copper oxide composites. Ion beam analysis results revealed copper and oxygen as constituent elements with no impurities. X-ray diffraction results discovered the presence of CuO, Cu₂O and Cu phases in the composite materials. The morphology of the as-synthesized copper oxide was studied by scanning electron microscopy. Results clearly demonstrated that spherical particles were obtained with an average diameter of 14 $\mu$m (range 2–85 $\mu$m), 35 $\mu$m (range 20–100 $\mu$m) and 50 $\mu$m (range 30–120 $\mu$m) for the arc current of 60 A, 80 A and 95 A, respectively. It was found that the morphology can be controlled by the arc discharge parameters, e.g. a lower arc discharge current contributed to a smaller particle size. This is because the electric arc current influences the nucleation and the growth of the spherical structures. Due to its simplicity of synthesis, the proposed arc discharge is a promising technique for the fabrication of copper oxide composite materials for optical and electrical applications.

The effect of substrate temperature on growth of pulsed laser deposited copper oxide thin films has been investigated by employing Nd: YAG laser (532nm, 6ns, 10Hz) irradiation at a fluence of 8.2J/cm². XRD analysis reveals that copper oxide films deposited at room temperature are amorphous in nature, whereas films deposited at higher substrate temperatures are polycrystalline in nature. SEM and AFM analyses revealed that films deposited at substrate temperatures, ranging from room temperature to 300${}^{\circ }$C are comprised of large sized clusters, islands and particulates, whereas uniform films with an appearance of granular morphology and distinct bump formation are grown at higher substrate temperatures of 400${}^{\circ }$C and 500${}^{\circ }$C. The optical bandgap of deposited films is evaluated by UV-VIS spectroscopy and shows a decreasing trend with increasing substrate temperature. Four point probe analysis reveals that electrical conductivity of the deposited films increases with increase in the substrate temperature, and is maximum for highest growth temperature of 500${}^{\circ }$C. It is revealed that growth temperature plays a significant role for structure, texture, optical and electrical behavior of copper oxide thin films. The surface and structural properties of the deposited films are well correlated with their electrical and optical response.

Nano-crystalline copper oxide films were deposited on quartz substrates by RF-magnetron sputtering in argon gas environment. The XRD patterns show Cu₄O₃ phase for films deposited at 50 and 60W of RF power. The film deposited at 70W shows existence of Cu₄O₃ and CuO phases, whereas film deposited at 100W of RF power consists of only CuO phase. Raman spectra and transmission electron microscopy (TEM) also confirm these results. Field emission scanning electron microscopy (FESEM) shows morphological changes in the film as a function of RF power. The optical band gap estimated from the transmission spectra of the films are 2.3 and 1.7eV for Cu₄O₃ and CuO phase, respectively. The hydrothermal heat treatment of the film leads to transformation of Cu₄O₃ to CuO phase in the film.

Properties of nanodispersed powder copper oxide, synthesized during arc sputtering of copper in a gas mixture of low pressure oxygen, were studied. It was shown that the particles possess nanometer size and narrow size distribution. The issue of reduction, recrystallization and sintering of nanodispersed powder were discussed.

A simple green one-step method for the synthesis of highly active palladium nanoparticles embedded on copper oxide as an efficient catalyst for ligand-free Heck and Sonogashira cross-coupling reactions has been developed. The synthetic approach is based on Microwave (MW)-assisted simultaneous chemical reduction of an aqueous solution of palladium and copper salts using hydrazine hydrate as the reducing agent. Selected characterization of the catalyst with transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectroscopy (XRD) reveal a size range of 25$\pm$2nm for the generated catalyst nanoparticles with the highest catalytic activity. The use of the generated Pd/CuO nanoparticles is highly advantageous due to the use of ethanol/water as an environmentally green solvent under mild reaction conditions. Furthermore, the synthesized Pd/CuO nanoparticles catalyst can be recycled and re-used up to five times with negligible effect on the efficiency having turnover number up to 6000 and turnover frequency reaching 72000h${}^{-1}$ for 20wt.% Pd loaded catalyst at 150^∘C.

Plasma-chemical synthesis of nanopowders based on copper oxide and metal-organic framework structures was carried out using low-pressure arc discharge plasma. The study of the obtained material was carried out by several methods (XRD, FTIR, TEM, TGA and EIS). TEM showed that the obtained powder is highly agglomerated particles with an average particle size of 13 nm, and the crystalline ordering of nanoparticles with a large (about 2 nm) lattice parameter is clearly visible. XRD showed the presence of four crystalline phases corresponding to [Cu₃ (BTC)₂], Cu, Cu₂O and CuO. XRD results are in good agreement with FTIR studies. The DTA curve demonstrates a continuous exothermic process associated with a number of features of plasma-chemical synthesis and the morphology of the obtained nanoparticles. The study of the electrochemical properties of the materials obtained by the method of impedance spectroscopy revealed an anomalous accumulation of electrical charges around the electrodes due to electrochemical reactions for [Cu₃ (BTC)₂], which are associated with various reactions involving copper species in the organic framework.

Nanostructured CuO has been successfully synthesized via Thermal decomposition method at 700^∘C. Prepared CuO was characterized using IR spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM). IR spectra confirm the metal–oxygen bonding in these nanoparticles. The XRD pattern confirms a single-phase crystalline nature of the nanoparticles. The synthesized CuO was demonstrated as an efficient catalyst in degradation of Rhodamine B in the presence of light through oxidation. More than 93% of the Rhodamine B dye was degraded after 150min. It was observed that photocatalytic degradation of dyes follows pseudo-first-order kinetics. A tentative mechanism has also been proposed for the photocatalytic degradation of dyes in the presence of copper oxide semiconductor.

In this work, novel sisal-like hollow CuO micro-flowers were synthesized via a facile solvothermal reaction followed by calcination. The flower-like shells of hollow CuO are constructed by irregular petals interweaving each other, which are composed of aggregated nanoparticles with sizes of ca. 18nm. It was found that the flower-like morphology of the as-synthesized CuO products can be controlled via finely tuning the solvothermal reaction time. When used as catalysts for the synthesis of organosilane, the obtained hollow CuO micro-flowers exhibit better catalytic performances than the commercial CuO powders. Superior catalytic performances are due to the hollow and flower-like structures of the as-synthesized CuO products, which can promote the synthetic reaction for the organosilane, that is, the gas–solid contacting reaction occurred among the reaction gas, solid silicon powders and CuO catalysts. Our work will be helpful to design and develop the novel Cu-based nanocatalysts for the synthesis of organosilane.

In this study, the development of a graphite paste electrode (GPE) modified by copper oxide nanoparticles (CuO@GP) to be used as a practical and economical sensor for the electrochemical sensing of malachite green (MG) has been elucidated. The sol–gel technique was applied for the synthesis of CuO nanoparticles (NPS) from copper chloride (CuCl${}_2)$, where the surfactant cetylpyridinium chloride (C${}_{21}$H${}_{38}$NCl) played the role of a capping agent. The synthesized CuO NPS were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). A bare GPE was modified using these CuO NPS and thus developed; the new electrode was used as a working electrode (WE) in a 3-electrode system for studying the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) responses of MG. Phosphate buffered saline (PBS) with a pH value of 6 was used as the optimum buffer. Using DPV, a widely linear operational range of 1–1000 $\mu$M was obtained with a detection limit of 0.18 $\mu$M. This CuO@GP provided excellent repeatability, reproducibility and prolonged stability for the MG molecule. For the selectivity study, various common interfering agents were used to observe MG’s corresponding peak current variation. Moreover, this electrode demonstrated a successful application for detecting MG in pond water and fish flesh. This method is effective for similar other applications.

The influence of different shapes of nanoparticles on peristaltic flow of Casson fluid in an asymmetric channel is studied in this paper. The suspension of Copper oxide nanoparticles of needle, platelet and lamina shapes is taken into account. The problem is modeled in partial differential equations with suitable slip boundary conditions. The standard nonlinear equations are solved by the Homotopy Analysis Method in Mathematica Software. The influences of different shapes of nanoparticles on concentration, velocity profile and temperature profile are analyzed through the graphs. It is observed that the different shape of nanoparticles has different thermal conductivity, but the lamina shaped nanoparticles have high thermal conductivity as compared to needle and platelet shaped nanoparticles.