Sample records for cuprous oxide cu2o

  1. Enhancement of convective heat transfer coefficient of ethylene glycol base cuprous oxide (Cu2O) nanofluids (United States)

    Hassan, Ali; Ramzan, Naveed; Umer, Asim; Ahmad, Ayyaz; Muryam, Hina


    The enhancement in the convective heat transfer coefficient of the ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids were investigated. The nanofluids of different volume concentrations i-e 1%, 2.5% and 4.5% were prepared by the two step method. Cuprous oxide (Cu2O) nanoparticles were ultrasonically stirred for four hours in the ethylene glycol (EG). The experimental study has been performed through circular tube geometry in laminar flow regime at average Reynolds numbers 36, 71 and 116. The constant heat flux Q = 4000 (W/m2) was maintained during this work. Substantial enhancement was observed in the convective heat transfer coefficient of ethylene glycol (EG) base cuprous oxide (Cu2O) nanofluids than the base fluid. The maximum 74% enhancement was observed in convective heat transfer coefficient at 4.5 vol% concentration and Re = 116.

  2. Novel Facile Technique for Synthesis of Stable Cuprous Oxide (Cu2O Nanoparticles – an Ageing Effect

    Directory of Open Access Journals (Sweden)

    Sachin S. Sawant


    Full Text Available A novel facile method to synthesize stable phase of Cuprous Oxide (Cu2O nanoparticles at room temperature is demonstrated. The structural and optical properties of (Cu2O nanoparticles were investigated by using X-ray diffraction (XRD, UV-VIS Spectroscopy. XRD analysis has indexed nanocrystalline nature of cubical phase Cu2O with an average edge length of about 20 nm. The Scanning Electron Microscopy (SEM measurements also ascertain the cubical morphology. The Fourier Transform Infrared Spectroscopy (FTIR affirms the presence of characteristic functional group of Cu2O. The absorbance peak at 485 nm in UV-VIS spectra also confirms the Cu2O synthesis. Furthermore, UV-VIS absorbance spectra at different ageing time substantiate the phase stability of Cu2O nanoparticles. The ageing leads to blue shift of absorbance peak mainly due to decrease in Cu2O particle size with no additional absorbance peak in UV-VIS spectra indicating the formation of secondary phase. The reduction in particle size may be attributed to tiny conversion Cu2O to CuO. The energy band gap measurements from Tauc plots for Cu2O nanoparticles shows the increasing trend (2.5 eV to 2.8 eV with ageing time (2 months, owing to quantum confinement effects.

  3. Effects of lithium (Li) on lithium-cuprous-oxide (Li-Cu2O) composite films grown by using electrochemical deposition for a PEC photoelectrode (United States)

    Kim, Tae Gyoum; Ryu, Hyukhyun; Lee, Won-Jae


    In this study, Li-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates by using the electrochemical deposition method. Various amounts of lithium (Li) were added to grow the Li-Cu2O composite films. We analyzed the morphology, structure, photocurrent density and photo-stability of the Li-Cu2O composite films by using various measurements such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and potentiostat/galvanostat measurements, respectively. As a result, the highest XRD Cu2O (111)/ LiO (011) peak intensity ratio was obtained for the 10-wt% sample, which also had the highest photocurrent density value of -5.00 mA/cm2. The highest photocurrent density value for the 10-wt% sample was approximately 5 times greater than that of the 0-wt% sample. As shown by this result, we found that adding Li could improve the photocurrent values of Li-Cu2O composite films.

  4. Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films



    Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

  5. Resistance switching of electrodeposited cuprous oxide (United States)

    Yazdanparast, Sanaz

    In this work, the resistance switching behavior of electrodeposited cuprous oxide (Cu2O) thin films in Au/Cu2O/top electrode (Pt, Au-Pd, Al) cells was studied. After an initial FORMING process, the fabricated cells show reversible switching between a low resistance state (16.6 O) and a high resistance state (0.4 x 106 O). Changing the resistance states in cuprous oxide films depends on the magnitude of the applied voltage which corresponds to unipolar resistance switching behavior of this material. The endurance and retention tests indicate a potential application of the fabricated cells for nonvolatile resistance switching random access memory (RRAM). The results suggest formation and rupture of one or several nanoscale copper filaments as the resistance switching mechanism in the cuprous oxide films. At high electric voltage in the as-deposited state of Au/Cu 2O/Au-Pd cell structure, the conduction behavior follows Poole-Frenkel emission. Various parameters, such as the compliance current, the cuprous oxide microstructure, the cuprous oxide thickness, top electrode area, and top electrode material, affect the resistance switching characteristics. The required FORMING voltage is higher for Au/Cu2O/Al cell compared with the Au/Cu2O/Pt which is related to the Schottky behavior of Al contact with Cu2O. Cu2O nanowires in Au-Pt/ Cu 2O/Au-Pt cell also show resistance switching behavior, indicating scalable potential of this cell for usage as RRAM. After an initial FORMING process under an electric field of 3 x 106 V/m, the Cu2O nanowire is switched to the LRS. During the FORMING process physical damages are observed in the cell, which may be caused by Joule heating and gas evolution.

  6. Electrocatalytic activity of Cu2O nanocubes-based electrode for glucose oxidation

    Indian Academy of Sciences (India)

    Sathiyanathan Felix; Pratap Kollu; Bala P C Raghupathy; Soon Kwan Jeong; Andrews Nirmala Grace


    A direct electrocatalytic activity of glucose oxidation on cuprous oxide modified glassy carbon electrode is reported. Cu2O nanocubes were synthesized by a simple wet chemical route in the absence of surfactants. Purity, shape and morphology of Cu2O are characterized by XRD, SEM, XPS and DRS-UV. The Cu2O nanocubes-modified glassy carbon electrode (GCE) exhibited high electrocatalytic activity towards glucose oxidation compared with bare GCE electrode. At an applied potential of +0.60V, the Cu2O electrode presented a high sensitivity of 121.7 A/mM. A linear response was obtained from 0 to 500 M, a response time less than 5 s and a detection limit of 38 M (signal/noise=3). The Cu2O nanocubes-modified electrode was stable towards interfering molecules like uric acid (UA), ascorbic acid (AA) and dopamine (DA). In short, a facile chemical preparation process of cuprous oxide nanocubes, and the fabricated modified electrode allow highly sensitive, selective, and fast amperometric sensing of glucose, which is promising for the future development of non-enzymatic glucose sensors.

  7. Magnetoexcitons in cuprous oxide (United States)

    Schweiner, Frank; Main, Jörg; Wunner, Günter; Freitag, Marcel; Heckötter, Julian; Uihlein, Christoph; Aßmann, Marc; Fröhlich, Dietmar; Bayer, Manfred


    Two of the most striking experimental findings when investigating exciton spectra in cuprous oxide using high-resolution spectroscopy are the observability and the fine structure splitting of F excitons reported by J. Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015), 10.1103/PhysRevLett.115.027402]. These findings show that it is indispensable to account for the complex valence band structure and the cubic symmetry of the solid in the theory of excitons. This is all the more important for magnetoexcitons, where the external magnetic field reduces the symmetry of the system even further. We present the theory of excitons in Cu2O in an external magnetic field and especially discuss the dependence of the spectra on the direction of the external magnetic field, which cannot be understood from a simple hydrogenlike model. Using high-resolution spectroscopy, we also present the corresponding experimental spectra for cuprous oxide in Faraday configuration. The theoretical results and experimental spectra are in excellent agreement as regards not only the energies but also the relative oscillator strengths. Furthermore, this comparison allows for the determination of the fourth Luttinger parameter κ of this semiconductor.

  8. Tailoring oxides of copper-Cu2O and CuO nanoparticles and evaluation of organic dyes degradation (United States)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha


    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu2O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu2O and CuO nanoparticles.

  9. Growth and characterization of single phase Cu2O by thermal oxidation of thin copper films (United States)

    Choudhary, Sumita; Sarma, J. V. N.; Gangopadhyay, Subhashis


    We report a simple and efficient technique to form high quality single phase cuprous oxide films on glass substrate using thermal evaporation of thin copper films followed by controlled thermal oxidation in air ambient. Crystallographic analysis and oxide phase determination, as well as grain size distribution have been studied using X-ray diffraction (XRD) method, while scanning electron microscopy (SEM) has been utilized to investigate the surface morphology of the as grown oxide films. The formation of various copper oxide phases is found to be highly sensitive to the oxidation temperature and a crystalline, single phase cuprous oxide film can be achieved for oxidation temperatures between 250°C to 320°C. Cu2O film surface appeared in a faceted morphology in SEM imaging and a direct band gap of about 2.1 eV has been observed in UV-visible spectroscopy. X-ray photoelectron spectroscopy (XPS) confirmed a single oxide phase formation. Finally, a growth mechanism of the oxide film has also been discussed.

  10. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer. (United States)

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun


    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  11. Synthesis, characterization and application of semiconducting oxide (Cu2O and ZnO) nanostructures

    Indian Academy of Sciences (India)

    D P Singh; Jai Singh; P R Mishra; R S Tiwari; O N Srivastava


    In the present study, we report the synthesis, characterization and application of nanostructured oxide materials. The oxide materials (Cu2O and ZnO) have been synthesized by electrolysis based oxidation and thermal oxidation methods. Cuprous oxide (Cu2O) nanostructures have been synthesized by anodic oxidation of copper through a simple electrolysis process employing plain water (with ionic conductivity, ∼ 6 S/m) as electrolyte. In this method no special electrolytes, chemicals and surfactants are needed. The method is based on anodization pursuant to the simple electrolysis of water at different voltages. Two different types of Cu2O nanostructures have been found. One type got delaminated from copper anode and was collected from the bottom of the electrochemical cell and the other was located on the copper anode itself. The nanostructures collected from the bottom of the cell are either nanothreads embodying beads of different diameters, ∼ 10–40 nm or nanowires (length, ∼ 600–1000 nm and diameter, ∼ 10–25 nm). Those present on the copper anode were nanoblocks with preponderance of nanocubes (nanocube edge, ∼ 400 nm). The copper electrode served as a sacrificial anode for the synthesis of different nanostructures. Aligned ZnO nanorod array has been successfully synthesized by simple thermal evaporation catalyst free method. Detailed structural characterizations revealed that the as synthesized aligned ZnO nanorods are single crystalline, with a hexagonal phase, and with growth along the [0001] direction. The room-temperature photoluminescence spectra showed a weak ultraviolet emission at 380 nm, a broad blue band at 435 nm and a strong orange–red emission at 630 nm. Structural/microstructural characterization of these nanomaterials have been carried out employing scanning (XL-20) and transmission electron microscopic (Philips EM, CM-12 and Technai 20G2) techniques and X-ray diffraction techniques having graphite monochromater with CuK radiation

  12. Green chemistry synthesis of nano-cuprous oxide. (United States)

    Ceja-Romero, L R; Ortega-Arroyo, L; Ortega Rueda de León, J M; López-Andrade, X; Narayanan, J; Aguilar-Méndez, M A; Castaño, V M


    Green chemistry and a central composite design, to evaluate the effect of reducing agent, temperature and pH of the reaction, were employed to produce controlled cuprous oxide (Cu2O) nanoparticles. Response surface method of the ultraviolet-visible spectroscopy is allowed to determine the most relevant factors for the size distribution of the nanoCu2O. X-ray diffraction reflections correspond to a cubic structure, with sizes from 31.9 to 104.3 nm. High-resolution transmission electron microscopy reveals that the different shapes depend strongly on the conditions of the green synthesis.


    African Journals Online (AJOL)


    ABSTRACT. Copper (I) oxide (Cu2O) is a potential material for the fabrication of low cost solar cells for ... problems of the above energy sources make the international ..... results of their study on ZnO/Cu2O junction solar cells. The best values ...

  14. Preparation of cuprous oxides with different sizes and their behaviors of adsorption, visible-light driven photocatalysis and photocorrosion (United States)

    Huang, Lei; Peng, Feng; Yu, Hao; Wang, Hongjuan


    Cuprous oxide (Cu 2O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu 2O nanoparticles are substantially stable in ambient atmosphere and the Cu + as main state exists on the surface of Cu 2O nanoparticles. As-prepared Cu 2O microparticles can exist stably as a Cu 2O/CuO core/shell structure; and the Cu 2+ as main state exists on the surface of Cu 2O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu 2O particles with different sizes were investigated in detail. The results show that Cu 2O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu 2O nanoparticles exhibit special property of adsorption. Cu 2O microparticles have a higher photocatalytic activity than Cu 2O nanoparticles because of its slower photocorrosion rate, although Cu 2O microparticles have much lower adsorption capacity than Cu 2O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu 2O under visible light were also discussed.

  15. Epitaxially aligned cuprous oxide nanowires for all-oxide, single-wire solar cells. (United States)

    Brittman, Sarah; Yoo, Youngdong; Dasgupta, Neil P; Kim, Si-in; Kim, Bongsoo; Yang, Peidong


    As a p-type semiconducting oxide that can absorb visible light, cuprous oxide (Cu2O) is an attractive material for solar energy conversion. This work introduces a high-temperature, vapor-phase synthesis that produces faceted Cu2O nanowires that grow epitaxially along the surface of a lattice-matched, single-crystal MgO substrate. Individual wires were then fabricated into single-wire, all-oxide diodes and solar cells using low-temperature atomic layer deposition (ALD) of TiO2 and ZnO films to form the heterojunction. The performance of devices made from pristine Cu2O wires and chlorine-exposed Cu2O wires was investigated under one-sun and laser illumination. These faceted wires allow the fabrication of well-controlled heterojunctions that can be used to investigate the interfacial properties of all-oxide solar cells.

  16. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.


    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square-root relati......-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide....

  17. Attenuated total reflectance spectroscopy of simultaneous processes: Corrosion inhibition of cuprous oxide by benzotriazole (United States)

    Bratescu, Maria Antoaneta; Allred, Daniel B.; Saito, Nagahiro; Sarikaya, Mehmet; Takai, Osamu


    Attenuated total reflectance (ATR) spectroscopy was used to perform in situ studies of the corrosion inhibition of cuprous oxide (Cu 2O) by benzotriazole (BTA) in aqueous solution at concentrations from 1 to 20 μM. Because two separate processes occur simultaneously, that of Cu 2O corrosion and corrosion inhibition by BTA adsorption, the spectral information was subjected to deconvolution by a conjugate gradient minimization algorithm. Under these conditions, a solution phase concentration of 7-10 μM BTA nearly completely inhibited the corrosion of Cu 2O in deionized water. Using a Langmuir adsorption model, this represented only 25% of the maximally covered surface area.

  18. Optical characterization of gold-cuprous oxide interfaces for terahertz emission applications

    NARCIS (Netherlands)

    Ramanandan, G.K.P.; Adam, A.J.L.; Ramakrishnan, G.; Petrik, P.; Hendrikx, R.; Planken, P.C.M.


    We show that the interface between gold and thermally formed cuprous oxide, which emits terahertz radiation when illuminated with ultrafast femtosecond lasers, is in fact an AuCu/Cu2O interface due to the formation of the thermal diffusion alloy AuCu. The alloy enables the formation of a Schottky-ba

  19. Fabrication and Optoelectrical Properties of IZO/Cu2O Heterostructure Solar Cells by Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    Cheng-Chiang Chen


    Full Text Available Indium zinc oxide (IZO/cupper oxide (Cu2O is a nontoxic nature and an attractive all-oxide candidate for low-cost photovoltaic (PV applications. The present paper reports on the fabrication of IZO/Cu2O heterostructure solar cells which the Cu2O layers were prepared by oxidation of Cu thin films deposited on glass substrate. The measured parameters of cells were the short-circuit current (Isc, the open-circuit voltage (Voc, the maximum output power (Pm, the fill factor (FF, and the efficiency (η, which had values of 0.11 mA, 0.136 V, 5.05 μW, 0.338, and 0.56%, respectively, under AM 1.5 illumination.


    African Journals Online (AJOL)

    thickness of copper oxides solar ce[[s prepared 63/ thermaf oxidation method The sampfes were oxidized at di_';§'erent oxidation temperatures and time. The diflerent oxidation ... observed that the later was relatively high. Adrianus (1978).

  1. Parameters controlling microstructures and resistance switching of electrodeposited cuprous oxide thin films (United States)

    Yazdanparast, Sanaz


    Cuprous oxide (Cu2O) thin films were electrodeposited cathodically from a highly alkaline bath using tartrate as complexing agent. Different microstructures for Cu2O thin films were achieved by varying the applied potential from -0.285 to -0.395 V versus a reference electrode of Ag/AgCl at 50 °C in potentiostatic mode, and separately by changing the bath temperature from 25 to 50 °C in galvanostatic mode. Characterization experiments showed that both grain size and orientation of Cu2O can be controlled by changing the applied potential. Applying a high negative potential of -0.395 V resulted in smaller grain size of Cu2O thin films with a preferred orientation in [111] direction. An increase in the bath temperature in galvanostatic electrodeposition increased the grain size of Cu2O thin films. All the films in Au/Cu2O/Au-Pd cell showed unipolar resistance switching behavior after an initial FORMING process. Increasing the grain size of Cu2O thin films and decreasing the top electrode area increased the FORMING voltage and decreased the current level of high resistance state (HRS). The current in low resistance state (LRS) was independent of the top electrode area and the grain size of deposited films, suggesting a filamentary conduction mechanism in unipolar resistance switching of Cu2O.

  2. Annealing Effects of Sputtered Cu2O Nanocolumns on ZnO-Coated Glass Substrate for Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen


    Full Text Available Cuprous oxide (Cu2O films were prepared on an indium tin oxide glass substrate by radiofrequency magnetron sputtering using a high-purity Cu target. The temperature of annealing was varied to obtain Cu2O thin films with various elements, compositions, and surface structures. The p-Cu2O thin films thus formed were characterized by FESEM and XRD. After annealing at 500∘C, the bilayer structure which consisted of Cu nanoclusters on the surface of a film of Cu2O nanocolumns was observed. The Cu2O solar cell with the bilayered structure exhibited poor power conversion efficiency.

  3. Electrochemical CO2 reduction on Cu2O-derived copper nanoparticles: Controlling the catalytic selectivity of hydrocarbons

    NARCIS (Netherlands)

    Kas, Recep; Kortlever, R.; Milbrat, Alexander; Koper, M.T.M.; Mul, Guido; Baltrusaitis, Jonas


    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)

  4. Synthesis of p-Cu2O/rGO composite films for enhancing photocurrent of p-Cu2O and H2 generation (United States)

    Samarakoon, S. P. A. U. K.; Karunarathna, P. G. D. C. K.; Hemachandra, K. A. S. K.; Fernando, C. A. N.


    Composites of p type cuprous oxide (p-Cu2O) and reduced graphene oxide (rGO) were prepared by depositing an rGO layer on top of nano-sized Cu2O particles prepared on a Cu substrate. These synthesized composites help to enhance the photocurrent over that of bare Cu2O, which means rGO acts as an excellent electron acceptor to separate electrons from Cu2O particles. Here the p-Cu2O layer was fabricated using thermal oxidation and the rGO layer was fabricated using electrophoretic deposition (EPD). The samples thus fabricated were characterized using diffuse reflectance spectra, Fourier transmission infrared (FTIR) spectra, scanning electron microscopy (SEM) images, time development of the photocurrent of photoelectrochemical cells, and electrochemical impedance spectroscopy (EIS) measurements. H2 evolution was observed using a gas chromatograph system.

  5. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)

    SHEN ChengLing; LI YuanFang; QI WenJing; HUANG ChengZhi


    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylammonium bromide (CTAB).By taking Staphylococcus aureus (S.a),which always causes a variety of suppurative infections and toxinoses in humans,as a model bioparticle,the negative bioeffect of nano-Cu2O on S.a cells was evaluated,and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics.Cellularity and bactericidal effect were measured by flow cytometry (FCM),dark field light scattering imaging and SEM photography.The results showed that nano-Cu2O particles may,by absorbing on the cell surface,impair the cell wall,damage the cell membrane,and finally increase permeability of the cell membrane,thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  6. Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

    Institute of Scientific and Technical Information of China (English)


    Cuprous oxide nanoparticles of 30-50 nm in size were prepared in the presence of cetyltrimethylam-monium bromide (CTAB). By taking Staphylococcus aureus (S.a), which always causes a variety of suppurative infections and toxinoses in humans, as a model bioparticle, the negative bioeffect of nano-Cu2O on S.a cells was evaluated, and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics. Cellularity and bactericidal effect were measured by flow cytometry (FCM), dark field light scattering imaging and SEM photography. The results showed that nano-Cu2O particles may, by absorbing on the cell surface, impair the cell wall, damage the cell membrane, and finally increase permeability of the cell membrane, thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

  7. RF Magnetron Sputtering Grown Cu2O Film Structural, Morphological, and Electrical Property Dependencies on Substrate Type. (United States)

    Ahn, Heejin; Um, Youngho


    We investigated the structural, morphological, and electrical properties of cuprous oxide (Cu2O) film dependency on substrate type. Thin films grown using RF magnetron sputtering were characterized by scanning electron microscopy, X-ray diffraction (XRD), and Hall effect measurements. Cu2O thin films were deposited onto sapphire (0001), Si (100), and MgO (110) substrates, and showed Cu2O single phase only, which was confirmed by XRD measurement. Relatively larger compressive strain existed in Cu2O film grown on sapphire and Si, while a smaller tensile strain appeared in Cu2O film grown on MgO. Cu2O thin film crystallite sizes showed a linear dependence on strain. Moreover, film carrier concentration and mobility increased with increasing strain, while resistivity decreased with decreasing strain. Cu2O film strain due to induced strain opens the possibility of controlling structural and electrical properties in device applications.

  8. Towards printed perovskite solar cells with cuprous oxide hole transporting layers: a theoretical design (United States)

    Wang, Yan; Xia, Zhonggao; Liang, Jun; Wang, Xinwei; Liu, Yiming; Liu, Chuan; Zhang, Shengdong; Zhou, Hang


    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous oxide (Cu2O) hole transporting layers (HTLs) by using a solar cell simulation program, wxAMPS. The performance of a Cu2O/perovskite solar cell was correlated to the material properties of the Cu2O HTL, such as thickness, carrier mobility, mid-gap defect, and doping concentrations. The effect of interfacial defect densities on the solar cell performance was also investigated. Our simulation indicates that, with an optimized Cu2O HTL, high performance perovskite solar cells with efficiencies above 13% could be achieved, which shows the potential of using Cu2O as an alternative HTL over other inorganic materials, such as NiOx and MoOx. This study provides theoretical guidance for developing perovskite solar cells with inorganic hole transporting materials via a printing process.

  9. Improvement in structural and electrical properties of cuprous oxide-coated multiwalled carbon nanotubes

    Indian Academy of Sciences (India)

    Shivani Dhall; Neena Jaggi


    In the present work, cuprous oxide (Cu2O) nanoparticles are coated on multi-walled carbon nanotubes (MWCNTs) using Fehling’s reaction. The coating of Cu2O nanoparticles on the nanotubes was confirmed by SEM and X-ray diffraction (XRD) spectra. The calculated D/G ratio of Cu2O (using 3% CuSO4 by wt)-coated MWCNTs by Raman spectra is found to decrease to 0.94 as compared to 1.14 for pristine MWCNTs. It shows that the presence of Cu2O nanoparticles on nanotubes decreases the inherent defects present in the form of some pentagons/heptagons in the honeycomb hexagonal carbon atoms in the structure of graphene sheets of MWCNTs and increases the crystalline nature of MWCNTs, which is also confirmed by the XRD peaks. Whereas the value of D/G ratio increases to 1.39 for sample 2 (using 5% CuSO4 by wt), which represents the structural deformation. Moreover, the electrical conductivity of MWCNTs was increased by 3 times after coating the nanotubes with Cu2O (using 3% CuSO4 by wt).

  10. Synthesis and Investigation of Antimicrobial Activity of Cu2O Nanoparticles/Zeolite

    Directory of Open Access Journals (Sweden)

    Bui Duy Du


    Full Text Available Cuprous oxide (Cu2O nanoparticles in zeolite A were synthesized by two steps: (i ion-exchange of copper ions into the zeolite and (ii reduction of copper ions in cages of the zeolite by hydrazine hydrate in base medium. The Cu2O nanoparticles/zeolite product was characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and energy-dispersive X-ray spectroscopy (EDX. The particle size of Cu2O nanoparticles was of 40 nm. The antibacterial activity of the as-synthesized Cu2O nanoparticles/zeolite against Escherichia coli was also investigated. Cu2O NPs/zeolite product can be favorably produced on large scale for water treatment and agricultural application as antimicrobial agent.

  11. Reaction Kinetic Parameters and Surface Thermodynamic Properties of Cu2O Nanocubes

    Directory of Open Access Journals (Sweden)

    Xingxing Li


    Full Text Available Cuprous oxide (Cu2O nanocubes were synthesized by reducing Cu(OH2 in the presence of sodium citrate at room temperature. The samples were characterized in detail by field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, and N2 absorption (BET specific surface area. The equations for acquiring reaction kinetic parameters and surface thermodynamic properties of Cu2O nanocubes were deduced by establishment of the relations between thermodynamic functions of Cu2O nanocubes and these of the bulk Cu2O. Combined with thermochemical cycle, transition state theory, basic theory of chemical thermodynamics, and in situ microcalorimetry, reaction kinetic parameters, specific surface enthalpy, specific surface Gibbs free energy, and specific surface entropy of Cu2O nanocubes were successfully determined. We also introduced a universal route for gaining reaction kinetic parameters and surface thermodynamic properties of nanomaterials.

  12. Oxide p-n Heterojunction of Cu2O/ZnO Nanowires and Their Photovoltaic Performance

    Directory of Open Access Journals (Sweden)

    Seung Ki Baek


    Full Text Available Oxide p-n heterojunction devices consisting of p-Cu2O/n-ZnO nanowires were fabricated on ITO/glass substrates and their photovoltaic performances were investigated. The vertically arrayed ZnO nanowires were grown by metal organic chemical vapor deposition, which was followed by the electrodeposition of the p-type Cu2O layer. Prior to the fabrication of solar cells, the effect of bath pH on properties of the absorber layers was studied to determine the optimal condition of the Cu2O electrodeposition process. With the constant pH 11 solution, the Cu2O layer preferred the (111 orientation, which gave low electrical resistivity and high optical absorption. The Cu2O (pH 11/ZnO nanowire-based solar cell exhibited a higher conversion efficiency of 0.27% than the planar structure solar cell (0.13%, because of the effective charge collection in the long wavelength region and because of the enhanced junction area.

  13. In situ preparation of cubic Cu2O-RGO nanocomposites for enhanced visible-light degradation of methyl orange (United States)

    Zhang, Wei; Li, Xiaolin; Yang, Zhi; Tang, Xuehui; Ma, Yujie; Li, Ming; Hu, Nantao; Wei, Hao; Zhang, Yafei


    There has been a growing interest in gathering together photocatalysis of semiconductors, like cuprous oxide (Cu2O), and the excellent electron transmittability of graphene to produce a graphene-based semiconductor for photocatalytic degradation. In this paper, a mild one-pot in situ synthesis of cubic cuprous oxide-reduced graphene oxide (Cu2O-RGO) nanocomposites has been proposed for the removal of methyl orange. In contrast to pure cubic Cu2O particles under similar preparation conditions, the cubic Cu2O-RGO nanocomposites demonstrate enhanced visible-light-driven photocatalytic activity for methyl orange dye with a 100% degradation rate in 100 min. The enhanced photocatalytic performance is mainly attributed to the increased charge transportation, effective separation of photoelectrons from vacancies, and the improved contact area.

  14. Reduced graphene oxide wrapped Cu2O supported on C3N4: An efficient visible light responsive semiconductor photocatalyst

    Directory of Open Access Journals (Sweden)

    S. Ganesh Babu


    Full Text Available Herein, Cu2O spheres were prepared and encapsulated with reduced graphene oxide (rGO. The Cu2O–rGO–C3N4 composite covered the whole solar spectrum with significant absorption intensity. rGO wrapped Cu2O loading caused a red shift in the absorption with respect to considering the absorption of bare C3N4. The photoluminescence study confirms that rGO exploited as an electron transport layer at the interface of Cu2O and C3N4 heterojunction. Utmost, ∼2 fold synergistic effect was achieved with Cu2O–rGO–C3N4 for the photocatalytic reduction of 4-nitrophenol to 4-aminophenol in comparison with Cu2O–rGO and C3N4. The Cu2O–rGO–C3N4 photocatalyst was reused for four times without loss in its activity.

  15. Controlling the Performance of P-type Cu2O/SnO Bilayer Thin-Film Transistors by Adjusting the Thickness of the Copper Oxide Layer

    KAUST Repository

    Al-Jawhari, Hala A.


    The effect of copper oxide layer thickness on the performance of Cu2O/SnO bilayer thin-film transistors was investigated. By using sputtered Cu2O films produced at an oxygen partial pressure, Opp, of 10% as the upper layer and 3% Opp SnO films as the lower layer we built a matrix of bottom-gate Cu2O/SnO bilayer thin-film transistors of different thickness. We found that the thickness of the Cu2O layer is of major importance in oxidation of the SnO layer underneath. The thicker the Cu2O layer, the more the underlying SnO layer is oxidized, and, hence, the more transistor mobility is enhanced at a specific temperature. Both device performance and the annealing temperature required could be adjusted by controlling the thickness of each layer of Cu2O/SnO bilayer thin-film transistors.

  16. A photoemission study of benzotriazole on clean copper and cuprous oxide (United States)

    Fang, Bo-Shung; Olson, Clifford G.; Lynch, David W.


    Photoemission spectra of benzotriazole (BTA) chemisorbed on clean Cu and on cuprous oxide were compared with the spectra of condensed- and gas-phase BTA. Chemisorbed BTA bonds to both Cu and Cu 2O via lone-pair orbitais on the nitrogen ring. The lack of a chemical shift for the π- orbitais indicates that BTA does not lie flat on the surface. We propose a model for the geometry and bonding of chemisorbed BTA which accounts for its corrosion inhibition on Cu, and for the corrosion inhibition, or lack of inhibition, by molecules similar to BTA.

  17. p-Cu2O-shell/n-TiO2-nanowire-core heterostucture photodiodes

    Directory of Open Access Journals (Sweden)

    Hsueh Ting-Jen


    Full Text Available Abstract This study reports the deposition of cuprous oxide [Cu2O] onto titanium dioxide [TiO2] nanowires [NWs] prepared on TiO2/glass templates. The average length and average diameter of these thermally oxidized and evaporated TiO2 NWs are 0.1 to 0.4 μm and 30 to 100 nm, respectively. The deposited Cu2O fills gaps between the TiO2 NWs with good step coverage to form nanoshells surrounding the TiO2 cores. The p-Cu2O/n-TiO2 NW heterostructure exhibits a rectifying behavior with a sharp turn-on at approximately 0.9 V. Furthermore, the fabricated p-Cu2O-shell/n-TiO2-nanowire-core photodiodes exhibit reasonably large photocurrent-to-dark-current contrast ratios and fast responses.

  18. Electrochemical preparation of uniform CuO/Cu2O heterojunction on β-cyclodextrin-modified carbon fibers

    KAUST Repository

    Chen, Fang-Ping


    Abstract: In this work, a uniform heterojunction of cupric oxide/cuprous oxide was decorated on the surface of carbon fibers by electrochemical method (CuO/Cu2O/CDs/CFs). Methyl-β-cyclodextrin was first grafted on the surface of carbon fibers (CDs/CFs). Cubic cuprous oxide was electrodeposited on the surface of (Cu2O/CDs/CFs) in 0.1 M KNO3, the cuprous oxide was then partly anodized to cupric oxide to form a heterojunction of cupric oxide/cuprous oxide with a burr shape (CuO/Cu2O/CDs/CFs). The obtained materials were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. The potential application in pollution treatment was further investigated, and the prepared CuO/Cu2O/CDs/CFs could be a promising adsorbent/photocatalyst toward the uptake and degradation of 2, 6-dichlorophenol (2, 6-DCP). Graphical Abstract: [Figure not available: see fulltext.] © 2016 Springer Science+Business Media Dordrecht

  19. One-pot synthesis of cuprous oxide-reduced graphene oxide nanocomposite with enhanced photocatalytic and electrocatalytic performance (United States)

    Han, Fugui; Li, Heping; Yang, Jun; Cai, Xiaodong; Fu, Li


    We report on the facile one-step synthesis of porous cuprous oxide nanoparticles on reduced graphene oxide (Cu2O-RGO) by synchronously reducing Cu2+ ions and GO with ethylene glycol. The basic chemical components, crystal structure and surface morphology of prepared nanocomposite was carefully characterized. The photocatalytic activities of the as-prepared nanocomposite was investigated by photodegrading methylene blue (MB) under visible light. The electrocatalytic property of the nanocomposite was investigated by electrocatalytic determination of acetaminophen. The results indicate that the corporation of RGO with Cu2O nanoparticles could high enhance the both photocatalytic and electrocatalytic properties. Moreover, we found that the content of RGO introduced into nanocomposite could highly affect the product properties.

  20. Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

    KAUST Repository

    Zhang, Zhonghai


    In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

  1. Measurement of Photoluminescence of Cu2O at 2 K

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yu; ZHANG Gui-Zhong; XIANG Wang-Hua; KETTERSON J. B.


    @@ We present our measured photoluminescence of the quadrupolar transitions of the yellow series excitons of cuprous oxide at 2 K. By tuning the excitation energy in the two-photon quadrupolar absorption scheme of Cu2O, it is found that the band-gap value associated with this optical process can be characterized by a sharp resonance at 2.036eV at cryogenic temperature. This energy value is helpful to guide a proper excitation for creating cold excitonic gas in this crystal.

  2. Structural, Optical and Electrical Properties of Nanocrystalline Cuprous Oxide Thin Film Deposited By Chemical Method

    Directory of Open Access Journals (Sweden)

    Prakash Bansilal Ahirrao


    Full Text Available Cuprous oxide (Cu2O is an interesting p-type semiconductor material used in solar cell applications.  The Modified Chemical Bath Deposition (M-CBD method is suitable for growing thin multilayer structure due to low deposition temperature. This method does not require any sophisticated instrument and substrate need not to be conductive. The nanocrystalline Cu2O thin films were deposited on glass substrates by M-CBD method. The deposited films were characterized by different characterization techniques to study structural, surface morphological, optical and electrical properties. The structural studies show that, the formation of Cu2O thin films with an average crystallite size of 14 nm. Optical studies show a direct band gap 2.48 eV. The room temperature electrical resistivity is of the order of 1.3 kW-cm and activation energy 0.33 eV. The films exhibit p-type electrical conductivity as seen by thermo-emf measurements.

  3. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor. (United States)

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun


    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors.

  4. Picosecond nonlinear optical properties of cuprous oxide with different nano-morphologies

    Indian Academy of Sciences (India)

    P Harshavardhan Reddy; H Sekhar; D Narayana Rao


    Cuprous oxide nanoclusters, microcubes and microparticles were successfully synthesized by a simple co-precipitation method. Phase purity and crystallinity of the samples were studied by using X-ray powder diffraction. Transmission electron microscopy (TEM) images show different morphologies like nanoclusters, microcubes and microparticles. For linear and nonlinear optical measurements, the as-synthesized Cu2O with different morphologies were dispersed in isopropanol solution. The absorption spectrum recorded in the visible regions shows peaks that depend on the morphology of the particles and the peak shifts towards red region as one goes from nanoclusters to microparticles. Simple open-aperture Z-scan technique is used to measure nonlinear optical properties of cuprous oxide at 532 nm, 30 ps excitation at 10 Hz repetition rate. Cuprous oxide nanoclusters show reverse saturable absorption (RSA) behaviour, the microcubes and microparticles at a similar concentration exhibit saturable absorption (SA) type of behaviour at lower peak intensities and exhibit RSA within SA at higher peak intensities. The results show that the transition from SA to RSA can be ascribed to the two-photon absorption (TPA) process.

  5. Characterizations of Cuprous Oxide Thin Films Prepared by Sol-Gel Spin Coating Technique with Different Additives for the Photoelectrochemical Solar Cell

    Directory of Open Access Journals (Sweden)

    D. S. C. Halin


    Full Text Available Cuprous oxide (Cu2O thin films were deposited onto indium tin oxide (ITO coated glass substrate by sol-gel spin coating technique using different additives, namely, polyethylene glycol and ethylene glycol. It was found that the organic additives added had a significant influence on the formation of Cu2O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and ultraviolet-visible spectroscopy (UV-Vis. Based on the FESEM micrographs, the grain size of film prepared using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC.

  6. Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho2Cu2O5 nanoplates prepared with a coordination-complex method (United States)

    Guo, Rui; You, Junhua; Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng; Liu, Xuanwen


    Ho2Cu2O5 nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc)2(OAc)(H2O)3]·8H2O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N2 environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho2Cu2O5 formed through the diffusion of CuO into Ho2O3 particles. Cu2+ diffused faster than Ho3+ during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N2 atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho2Cu2O5 particles. The final Ho2Cu2O5 particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N2 played important roles in determining the morphology of the resulting Ho2Cu2O5. The catalytic oxidation activity of Ho2Cu2O5 samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.

  7. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Sayed M. Badawy


    Full Text Available Copper/Copper oxide (Cu/Cu2O nanoparticles were synthesized by modified chemical reduction method in an aqueous medium using hydrazine as reducing agent and copper sulfate pentahydrate as precursor. The Cu/Cu2O nanoparticles were characterized by X-ray Diffraction (XRD, Energy Dispersive X-ray Fluorescence (EDXRF, Scanning Electron Microscope (SEM, and Transmission Electron Microscope (TEM. The analysis revealed the pattern of face-centered cubic (fcc crystal structure of copper Cu metal and cubic cuprites structure for Cu2O. The SEM result showed monodispersed and agglomerated particles with two micron sizes of about 180 nm and 800 nm, respectively. The TEM result showed few single crystal particles of face-centered cubic structures with average particle size about 11-14 nm. The catalytic activity of Cu/Cu2O nanoparticles for the decomposition of hydrogen peroxide was investigated and compared with manganese oxide MnO2. The results showed that the second-order equation provides the best correlation for the catalytic decomposition of H2O2 on Cu/Cu2O. The catalytic activity of hydrogen peroxide by Cu/Cu2O is less than the catalytic activity of MnO2 due to the presence of copper metal Cu with cuprous oxide Cu2O. © 2015 BCREC UNDIP. All rights reservedReceived: 6th January 2015; Revised: 14th March 2015; Accepted: 15th March 2015How to Cite: Badawy, S.M., El-Khashab, R.A., Nayl, A.A. (2015. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 169-174. (doi:10.9767/bcrec.10.2.7984.169-174 Permalink/DOI:  

  8. Non-equilibrium deposition of phase pure Cu2O thin films at reduced growth temperature

    Directory of Open Access Journals (Sweden)

    Archana Subramaniyan


    Full Text Available Cuprous oxide (Cu2O is actively studied as a prototypical material for energy conversion and electronic applications. Here we reduce the growth temperature of phase pure Cu2O thin films to 300 °C by intentionally controlling solely the kinetic parameter (total chamber pressure, Ptot at fixed thermodynamic condition (0.25 mTorr pO2. A strong non-monotonic effect of Ptot on Cu-O phase formation is found using high-throughput combinatorial-pulsed laser deposition. This discovery creates new opportunities for the growth of Cu2O devices with low thermal budget and illustrates the importance of kinetic effects for the synthesis of metastable materials with useful properties.

  9. Intrinsic Defect Engineering of Cuprous Oxide to Enhance Electrical Transport Properties for Photovoltaic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lloyd, Michael A.; Siah, Sin-Cheng; Brandt, Riley E.; Serdy, James; Johnston, Steve W.; Lee, Yun Seog; Buonassisi, Tonio


    Intrinsic point-defect species in cuprous oxide films are manipulated based on their thermodynamic properties via the implementation of a controlled annealing process. A wide range of electrical properties is demonstrated, with a window suitable for high-quality solar cell devices. A variation of carrier concentration over two orders of magnitude is demonstrated. Minority carrier lifetime is investigated by means of microwave photoconductance decay measurements, demonstrating a strong correlation with carrier concentration. Spectrally resolved photoluminescence yields are analyzed to provide insight into lifetime limiting mechanisms as a function of Cu2O processing parameters. Hall measurements of carrier mobility and concentration are taken at room temperature to provide insight into the effect of these processing conditions on net ionized defect concentration.

  10. Enhanced photoelectrochemical water splitting and photocatalytic water oxidation of Cu2O nanocube-loaded BiVO4 nanocrystal heterostructures (United States)

    Wang, Wenzhong; Zhang, Weiwei; Meng, Shan; Jia, Lujie; Tan, Miao; Hao, Chenchun; Liang, Yujie; Wang, Jun; Zou, Bin


    Reducing the fast recombination of photogenerated electron-hole pairs of semiconductor photocatalyst is very important to improve its photocatalysis. In this paper we fabricate Cu2O nanocube-decorated BiVO4 nanocrystal (denoted as BiVO4@Cu2O nanocrystal@nanocube) heterostructure photocatalyst by coupling n-type BiVO4 with p-type Cu2O. The BiVO4@Cu2O nanocrystal@nanocube photocatalysts show superior photocatalytic activities in photoelectrochemical (PEC) activity and photocatalytic water oxidation to BiVO4 photocatalysts under visible light illumination. The BiVO4@Cu2O nanocrystal@nanocube heterostructure electrode achieves the highest photocurrent density of 10 μA cm-2 at 0 V versus Ag/AgCl, 5 times higher than that of BiVO4 nanocrystal electrode ( 2 μA cm-2). The light induced evolution rate of O2 generation for BiVO4@Cu2O nanocrystal@nanocube heterostructures is as high as 150 μmol h-1100 mg cat-1, more than 3 times higher than that (48 μmol h-1100 mg cat-1) of BiVO4 nanocrystals. The enhanced photocatalysis activities of the BiVO4@Cu2O nanocrystal@nanocube photocatalysts are attributed to the efficient separation of the photoexcited electron-hole pairs caused by inner electronic field (IEF) of p-n junction. This study opens up new opportunities in designing photoactive materials with highly enhanced performance for solar energy conversion.

  11. Evaluation of defects in cuprous oxide through exciton luminescence imaging

    Energy Technology Data Exchange (ETDEWEB)

    Frazer, Laszlo, E-mail: [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lenferink, Erik J. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chang, Kelvin B. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Poeppelmeier, Kenneth R. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Stern, Nathaniel P. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Ketterson, John B. [Department of Physics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Department of Electrical Engineering and Computer Science, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)


    The various decay mechanisms of excitons in cuprous oxide (Cu{sub 2}O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing that the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies. - Highlights: • We use luminescence to observe defects in high quality cuprous oxide crystals. • Strain is reduced by annealing. • Annealing causes annihilation of oxygen and copper vacancies.

  12. The Absorption of Benzotriazole on Copper and Cuprous Oxide (United States)


    Cornell University, Ithaca INY, 14853 Copper surfaces are commonly treated with benzotriazole ( BTA ), 1. to inhibit cor- rosion. H1+ is thought to be...00 00 SIOFFICE OF NAVAL RESEARCH Contract N00014-82-K-0576 Technical Report No. 38 THE ADSORPTION OF BENZOTRIAZOLE ON COPPER AND CUPROUS OXIDE by M... Benzotriazole on Copper and Cuprous Oxide 12 7- `SONAL AUTHOR(S) M. C. Zonnevylle and R. Hoffmann 13a TYPE OF REPORT 13b TIME COVERED 14 DATE OF REPORT (Year

  13. Effect of reducing agents in the conversion of Cu2O nanocolloid to Cu nanocolloid

    Directory of Open Access Journals (Sweden)

    V. Andal


    Full Text Available Current work reports the conversion of copper (I oxide, nano-colloid to stable copper nanocolloid. Different reduction conditions were attempted to control the stability and size of the Cu nanoparticles. Hydrazine hydrate, ascorbic acid and glucose are found to be good reductants. In our work stable copper nanoparticles are obtained by reducing Cu2O without any special protections like inert gas atmosphere etc. Ascorbic acid, a natural vitamin C not only reduces cuprous oxide but protects the new born copper due to its antioxidant properties. A red shift is observed when Cu2O nanospheres get converted to Cu. UV, XRD, FTIR and TEM were used to characterize the prepared Cu nanoparticles. The mechanism for the growth process of Cu nanomaterials are discussed.

  14. Preparation and Photoelectric Conversion Mechanism of Semiconducting ITO/Cu2O Electrodes

    Institute of Scientific and Technical Information of China (English)

    WANG Hua; HE Wei; WANG Hui-xiu; WANG Shou-xu


    Semiconducting cuprous oxide films were electrodeposited onto conducting glasses coated with Indium Tin Oxide (ITO) using potentiostatic method. The electrodes were examined by means of X-Ray Diffraction (XRD) and X-ray Photoelectron Spectrum (XPS). The results indicate that the prepared films are cubic Cu2O crystals, and annealing enhances the size and preferred orientation of the films. The photoelectric conversion mechanism of semiconducting ITO/Cu2O electrodes in 0.1 mol/L potassium sulfate (K2SO4) solution is further discussed by using Linear Sweep Voltammetry (LSV) method. The differences of photoelectric conversion of electrodes are reasonably deduced and proved through surfactant modifying, annealing or not, respectively.

  15. A Controllable Synthetic Route for Preparing Graphene-Cu and Graphene-Cu2O Nanocomposites Using Graphene Oxide-CuO as a Precursor

    Institute of Scientific and Technical Information of China (English)

    CHEN Li; ZHU Junwu; BI Huiping; MENG Xiaoqian; YAO Pengcheng; HAN Qiaofeng


    The development of convenient method to obtain graphene-based nanocomposites is a key issue for their application. Herein, we described a facile route for synthesizing graphene-Cu and graphene-Cu2O nanocomposites using graphene oxide-CuO as a precursor. Remarkably, the different nanocomposites could be formed just by varying the reaction temperature and time. This work provides a feasible route for the preparation of graphene-based nanocomposites with various constituents.

  16. Memristive Properties of Thin Film Cuprous Oxide (United States)


    Banerjee and D Chakravorty, "Optical absorption by nanoparticles of Cu2O," Europhysics Letters , vol. 52, no. 4, pp. 468-473, November 2000. [20] Gunter...Kotsugi, "Inhomogeneous chemical states in resistance-switching devices with a planar-type Pt/CuO/Pt structure," Applied Physics Letters , vol. 95, p...11] R Dong et al., "Reproducible hysteresis and resistive switching in metal-CuxO- metal," Applied Physics Letters , vol. 90, p. 042107, 2007. [12

  17. Synthesis and Characterization of Cu2O Single-Crystal by Sonochemical Method%氧化亚铜单晶的声化学制备及表征

    Institute of Scientific and Technical Information of China (English)

    张霞; 陶小军; 张治军; 吴志申; 张平余


    Cuprous oxide single crystal has been synthesized by sonochemical method through the thermal decomposition of copper acetate monohydrate in paraffin oil. TEM, XRD, SEM, ED and XPS techniques have been used to characterize its morphology, structure and composition. It is found that when the temperature is increased,decomposition from Cu2O to Cu takes place.

  18. Facile fabrication of electrolyte-gated single-crystalline cuprous oxide nanowire field-effect transistors (United States)

    Stoesser, Anna; von Seggern, Falk; Purohit, Suneeti; Nasr, Babak; Kruk, Robert; Dehm, Simone; Wang, Di; Hahn, Horst; Dasgupta, Subho


    Oxide semiconductors are considered to be one of the forefront candidates for the new generation, high-performance electronics. However, one of the major limitations for oxide electronics is the scarcity of an equally good hole-conducting semiconductor, which can provide identical performance for the p-type metal oxide semiconductor field-effect transistors as compared to their electron conducting counterparts. In this quest, here we present a bulk synthesis method for single crystalline cuprous oxide (Cu2O) nanowires, their chemical and morphological characterization and suitability as active channel material in electrolyte-gated, low-power, field-effect transistors (FETs) for portable and flexible logic circuits. The bulk synthesis method used in the present study includes two steps: namely hydrothermal synthesis of the nanowires and the removal of the surface organic contaminants. The surface treated nanowires are then dispersed on a receiver substrate where the passive electrodes are structured, followed by printing of a composite solid polymer electrolyte (CSPE), chosen as the gate insulator. The characteristic electrical properties of individual nanowire FETs are found to be quite interesting including accumulation-mode operation and field-effect mobility of 0.15 cm2 V-1 s-1.

  19. Synthesis of nano Cu2O on cotton: morphological, physical, biological and optical sensing characterizations. (United States)

    Sedighi, Ali; Montazer, Majid; Samadi, Nasrin


    In this paper, Cu2O nanoparticles were in situ synthesized on cotton fabric through a new simple and cost-effective chemical reduction method using copper sulfate, sodium hydroxide and ammonia. Cotton fabric participates as a reducing agent in reduction of copper sulfate and facilitates synthesis of cuprous oxide in nano-scale as a stabilizer. The produced cotton/nano Cu2O composite were characterized by X-ray diffraction, scanning electron microscopy and Energy-dispersive X-ray spectroscopy. Interaction of Cu2O with cotton fabric in addition to alteration of cotton functional groups were studied by Fourier transforms infrared spectroscopy. The intermediate solution, copper-amine complex, was analyzed by ultraviolet-visible spectroscopy. The mechanical properties of the cotton/nano Cu2O composite were studied using Instron indicated a higher tensile strain. The antibacterial activity of the fabric samples showed considerable behavior against S. aureus and E. coli. Further, the treated fabric became highly hydrophobic and sensed ammonia and hydrogen peroxide chromatically.

  20. Rose rock-shaped nano Cu2O anchored graphene for high-performance supercapacitors via solvothermal route (United States)

    Zhang, Wang; Yin, Zhenxing; Chun, Alvin; Yoo, Jeeyoung; Diao, Guowang; Kim, Youn Sang; Piao, Yuanzhe


    Novel rose rock-shaped cuprous oxide anchored graphene nanocomposite (Cu2O-GN) is successfully synthesized by a simple and efficient one-step solvothermal method. Notably, the reduction of graphene oxide (GO) and deposition of nano-Cu2O on GN occur simultaneously during the polyol reaction process. The nanocomposite is systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). We also explore the formation mechanism of Cu2O-GN including the concentration effect of the precursor, precipitation agent, GO, and heating rate on the morphology of the resulting nanocomposite. It is noteworthy that Cu2O is gradually decorated on the large sheets of GN to form ordered three-dimensional nanostructure with the optimized concentration of GO, which is crucial to the growth of the final nanoarchitectures. In addition, the electrochemical properties of the Cu2O-GN nanocomposite are investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The composite shows a favorable electrochemical capacitance (416 F g-1 at 1 A g-1), rate performance and cycling stability. Also, a high specific capacitance and good retention point to its promising applications as electrode materials in supercapacitors.

  1. Preparation and Photocatalytic Sterilization Property of Cu_2O Nanostructure with Copper Anode Oxidation Method%Cu_2O纳米阵列的铜阳极氧化法制备及其光催化杀菌性能研究

    Institute of Scientific and Technical Information of China (English)

    闫丽丽; 王艳; 熊良斌; 李家麟; 某浩然; 王保强; 余颖


    本文通过阳极氧化法直接在铜片上生长出纳米氧化亚铜阵列,所得到的样品通过扫描电子显微镜(SEM),紫外可见漫反射(UV-Vis diffuser reflectance),X-射线光电子能谱(XPS)等方法进行了表征,并研究了不同形貌氧化亚铜的杀菌效果.实验结果表明:反应过程中在阳极液中加入一定量的CTAB,有助于氧化亚铜的定向生长.通过控制反应条件(如电流密度,温度,和反应时间),可以得到不同形貌的氧化亚铜.随着电流密度的增大,氧化亚铜的形貌从网状,片状到棒状进行转化.所得到氧化亚铜的禁带宽度为1.95 eV.用所得样品进行杀菌实验,1 h内棒状氧化亚铜的杀菌率达到90.85%,而其它形貌的氧化亚铜杀菌率只有50%左右,与空铜片的杀菌率30%相比,所制得氧化亚铜具有较好的杀菌效果.%Cuprous oxide nanostructures were prepared by the method of copper anode oxidation. The obtained cuprous oxide was characterized with the techques of scanning electron microscopy, UV-Vis diffuse reflectance and X-ray photoelectron spectroscopy. The sterilization property of the samples was also investigated. It is found that CTAB plays an important role in the directional growth of the cuprous oxide. By controlling the reaction condition, such as current density, temperature and the reaction time, we can get different morphologies of Cu_2O. With the increase of current density, the morphology of Cu_2O can be nanonet, nanosheet and nanorod arrays respectively. In addition, the nanorod cuprous oxide has the best activity in sterilization and the sterilization efficiency can reach 90.85% in an hour.

  2. Plasmon-induced selective carbon dioxide conversion on earth-abundant aluminum-cuprous oxide antenna-reactor nanoparticles. (United States)

    Robatjazi, Hossein; Zhao, Hangqi; Swearer, Dayne F; Hogan, Nathaniel J; Zhou, Linan; Alabastri, Alessandro; McClain, Michael J; Nordlander, Peter; Halas, Naomi J


    The rational combination of plasmonic nanoantennas with active transition metal-based catalysts, known as 'antenna-reactor' nanostructures, holds promise to expand the scope of chemical reactions possible with plasmonic photocatalysis. Here, we report earth-abundant embedded aluminum in cuprous oxide antenna-reactor heterostructures that operate more effectively and selectively for the reverse water-gas shift reaction under milder illumination than in conventional thermal conditions. Through rigorous comparison of the spatial temperature profile, optical absorption, and integrated electric field enhancement of the catalyst, we have been able to distinguish between competing photothermal and hot-carrier driven mechanistic pathways. The antenna-reactor geometry efficiently harnesses the plasmon resonance of aluminum to supply energetic hot-carriers and increases optical absorption in cuprous oxide for selective carbon dioxide conversion to carbon monoxide with visible light. The transition from noble metals to aluminum based antenna-reactor heterostructures in plasmonic photocatalysis provides a sustainable route to high-value chemicals and reaffirms the practical potential of plasmon-mediated chemical transformations.Plasmon-enhanced photocatalysis holds promise for the control of chemical reactions. Here the authors report an Al@Cu2O heterostructure based on earth abundant materials to transform CO2 into CO at significantly milder conditions.

  3. Ultrasensitive amperometric immunosensor for PSA detection based on Cu2O@CeO2-Au nanocomposites as integrated triple signal amplification strategy. (United States)

    Li, Faying; Li, Yueyun; Feng, Jinhui; Dong, Yunhui; Wang, Ping; Chen, Lei; Chen, Zhiwei; Liu, Hui; Wei, Qin


    In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of prostate specific antigen (PSA). To this end, the amino functionalized cuprous oxide @ ceric dioxide (Cu2O@CeO2-NH2) core-shell nanocomposites were prepared to bond gold nanoparticles (Au NPs) by constructing stable Au-N bond between Au NPs and -NH2. Because the synergetic effect presents in Cu2O@CeO2 core-shell loaded with Au NPs (Cu2O@CeO2-Au), it shows better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than single Cu2O, Au NPs and Cu2O@CeO2. Featured by large specific surface area, good biocompatibility and good electrochemical properties which can greatly improve the electronic transmission rate, Cu2O@CeO2-Au was used as transducing materials to achieve efficiently capture antibodies and triple signal amplification of the proposed immunosensor. Under the optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.1pg/mL to 100ng/mL with a low detection limit of 0.03pg/mL (S/N=3). Furthermore, the proposed label-free immunosensor has been used to determine PSA in human serum with satisfactory results. Meanwhile, it displayed good reproducibility, acceptable selectivity, and long-term stability, which had promising application in bioassay analysis.

  4. Visible-light-driven photodegradation of sulfamethoxazole and methylene blue by Cu2O/rGO photocatalysts. (United States)

    Liu, Shou-Heng; Wei, Yu-Shao; Lu, Jun-Sheng


    The cuprous oxide-reduced graphene oxide (Cu2O/rGO-x) composites were prepared via a simple wet-chemical method by using CuSO4·5H2O and graphene oxide as precursors and ascorbic acid as a reducing agent, respectively. These Cu2O/rGO-x were employed as photocatalysts for degrading emerging contaminants and organic dye pollutants (i.e., sulfamethoxazole (SMX) and methylene blue (MB)) under visible light. A variety of different spectroscopic and analytical techniques, such as X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman scattering spectroscopy and UV-Visible spectroscopy were used to characterize the physical properties of photocatalysts. In the photodegrading experiments, it can be found that the Cu2O/rGO-80 photocatalyst has the superior visible-light response of ca. 50% removal efficiency of SMX within 120 min and 100% removal efficiency of MB within 40 min. These observations may be attributed the well-dispersed and visible-light-responsive Cu2O nanoparticles are supported on the surface of rGO sheets that can enhance absorption of visible light during photocatalysis.

  5. Effects of graphene oxide (GO) on GO-Cu2O composite films grown by using electrochemical deposition for a PEC photoelectrode (United States)

    Kim, Tae Gyoum; Ryu, Hyukhyun; Lee, Won-Jae; Yoon, Jang-Hee


    In this study, GO-Cu2O composite films were grown on fluorine-doped tin-oxide (FTO) substrates with various amounts of GO by using an electrochemical deposition. We investigated the effects of the GO content on the morphological, structural, optical, and photoelectrochemical (PEC) properties of the GO-Cu2O composite film and on its XPS spectrum. The highest XRD (111) peak intensity was obtained for the 10-wt% sample, which had an optical energy band gap of 2.15 eV. However, the highest photocurrent density was -4.74 mA/cm2 for the 1-wt% sample, which had an optical energy band gap of 1.94 eV. The photocurrent density for the 1-wt% sample was approximately 1.75 times greater than that for the 0-wt% sample. From the XPS measurements, we observed that the oxygen concentration for the sample with 1-wt% GO was higher than it was for the 0-wt% GO, which may have improved the photocurrent density of the sample with 1-wt% GO.

  6. Selective oxidation of vinyl chloride on Ag2O(100), Cu2O(100), and Au2O(100) surfaces: A density functional theory study (United States)

    Ren, Rui-Peng; Cheng, Lu; Lv, Yong-Kang


    Vinyl chloride (VC) is the simplest asymmetric olefin molecule and is greatly harmful to the environment and human health. To find an effective oxidation approach to decrease VC emission, the selective oxidation reaction of the VC molecule on Ag2O(100), Cu2O(100), and Au2O(100) surfaces has been investigated by using density functional theory in the present work. Five different reaction pathways in two steps on the three surfaces have been proposed and discussed. The result shows that the formation of chloroacetadehyde is more favored than the formation of chloroethylene epoxide and acetyl chloride, and the activation energy of chloroacetadehyde formation on the Ag2O(100) surface is lower than that on the other two surfaces.

  7. Refractive Index Sensing Using Visible Electromagnetic Resonances of Supported Cu2O Particles. (United States)

    Susman, Mariano D; Vaskevich, Alexander; Rubinstein, Israel


    Plasmonic metal nanostructures, in colloidal or surface-supported forms, have been extensively studied in the context of metamaterials design and applications, in particular as refractometric sensing platforms. Recently, high refractive index (high-n) dielectric subwavelength structures have been experimentally shown to support strong Mie scattering resonances, predicted to exhibit analogous refractive index sensing capabilities. Here we present the first experimental demonstration of the use of supported high-n dielectric nano/microparticle ensembles as refractive index sensing platforms, using cuprous oxide as a model high-n material. Single-crystalline Cu2O particles were deposited on transparent substrates using a chemical deposition scheme, showing well-defined electric and magnetic dipolar resonances (EDR and MDR, respectively) in the visible range, which change in intensity and wavelength upon changing the medium refractive index (nm). The significant modulation of the MDR intensity when nm is modified appears to be the most valuable empirical sensing parameter. The Mie scattering properties of Cu2O particles, particularly the spectral dependence of the MDR on nm, are theoretically modeled to support the experimental observations. MDR extinction changes (i.e., refractive index sensitivity) per particle are >100 times higher compared to localized surface plasmon resonance (LSPR) changes in supported Au nanoislands, encouraging the evaluation of Cu2O and other high-n dielectric particles and sensing modes in order to improve the sensitivity in optical (bio)sensing applications.

  8. High critical current density Bi2Sr2CaCu2O x /Ag wire containing oxide precursor synthesized from nano-oxides (United States)

    Zhang, Yun; Johnson, Stephen; Naderi, Golsa; Chaubal, Manasi; Hunt, Andrew; Schwartz, Justin


    Bi2Sr2CaCu2O x (Bi2212)/Ag-alloy wires are manufactured via the oxide-powder-in-tube route by filling Ag/Ag-alloy tubes with Bi2212 oxide precursor, deforming into wire, restacking and heat treating using partial-melt processing (PMP). Recent studies propose several requirements on precursor properties, including stoichiometry, chemical homogeneity, carbon content and phase purity. Here, nanosize oxides produced by nGimat’s proprietary NanoSpray CombustionTM process are used as starting materials to synthesize Bi2212 oxide precursors via solid-state calcination. Oxide powders for wire fill (precursor powder) with precisely controlled stoichiometry and chemical homogeneity containing over 99 vol% of single Bi2212-phase are synthesized. Alkaline-earth cuprate are found to be the only impurity phase in the precursor powders. Phase transformation, carbon release and grain growth during calcination are studied through a series of quench studies. Effects of particle size, surface area, stoichiometry, chemical homogeneity and microstructures of the starting materials on Bi2212 formation and wire transport properties are discussed. Small particle size, high surface area and short diffusion length of the starting materials result in a rapid and homogeneous phase transformation to Bi2212, along with an early and rapid carbon release. The residual carbon in the precursor powder is between 50 and 90 ppm. The strong dependence of transport J c on precursor stoichiometry indicates that compositional variations within precursor powders should be less than 1.5 mol%. Two Bi-rich and Ca-deficient stoichiometries give higher wire transport critical current density, with the highest being 2520 A mm-2 (4.2 K, 5 T) after 1 bar PMP and 4560 A mm-2 (4.2 K, 5 T) after 100 bar overpressure (OP) processing. The low residual carbon content results in smaller and fewer voids within an OP-processed wire filament. Bi-rich and Ca-deficient stoichiometries and small compositional variations

  9. Chemical bath deposition and characterization of Cu2O-CuxS thin films


    EYA, D. D. O.


    Cu2O-CuxS thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (CuxS) on Copper (I) Oxide (Cu2O) and then Cu2O on CuxS. The peak solar transmittance across the thin films were found to be

  10. Microwave-assisted synthesis and optical properties of cuprous oxide micro/nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Dandan [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Du, Yi, E-mail: [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Tian, Xiuying, E-mail: [Department of Chemistry and Materials Science, Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Li, Zhongfu; Chen, Zhongtao; Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China)


    Graphical abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. Growth mechanism of the prepared Cu{sub 2}O microcrystals were investigated carefully. Furthermore, the optical properties of the prepared cuprous oxide microcrystals were investigated by UV–vis diffuse reflectance spectroscopy, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies. - Abstract: Cuprous oxide micro/nanocrystals were fabricated by a facile and green microwave-assisted method using soluble starch as reductant and dispersant. It was observed that the addition amounts of NaOH had a prominent effect on the morphologies and size of cuprous oxide products, and microwave heating was proved to be a efficient method and was advantageous to the homogeneous nucleation. The as-obtained samples were characterized by X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results indicated that the samples were pure cuprous oxide. Spheres with the diameter of about 100 and 600 nm, octahedron and truncated octahedron with the edge length of about 0.8–3 μm cuprous oxide micro/nanocrystals were successfully obtained. Furthermore, the UV–vis diffuse reflectance spectroscopy was used to investigate the optical properties of the prepared cuprous oxide microcrystals, demonstrating that their band gaps of obtained samples were 1.96–2.07 eV, assigned to their different sizes and morphologies.

  11. Electrostatic-assembly three-dimensional CNTs/rGO implanted Cu2O composite spheres and its photocatalytic properties (United States)

    Zeng, Bin; Chen, Xiaohua; Ning, Xutao; Chen, Chuansheng; Deng, Weina; Huang, Qun; Zhong, Wenbin


    Carbon nanotubes/reduced graphene oxides (CNTs/rGO) implanting cuprous oxide (Cu2O) composite spheres have been successfully prepared via an electrostatic self-assemble with microwave-assisted. Scanning electron microscopy and transmission electron microscopy observations confirmed that the hybrid of CNTs and rGO was implanted into Cu2O matrix and formed a three-dimensional embedded micrometer sphere structure. The possible formation mechanism of this architecture was also proposed. The photocatalytic properties were further investigated by evaluating on photo-degradation of a pollutant methyl orange (MO). The experimental results indicated that this novel architecture enhanced photocatalytic performance with 99.8% decomposition of MO after 40 min in the presence of H2O2 under visible light irradiation, which was much higher than that of pure Cu2O powders (67.9%). This study provides a convenient method for assembling various CNTs/rGO-semiconductor composites in the future applications of water purification as well as optoelectronic fields at a large scale.

  12. Oxidation of cuprous stellacyanin by aminopolycarboxylatocobaltate(III) complexes. (United States)

    Yoneda, G S; Mitchel, G L; Blackmer, G L; Holwerda, R A


    Rate parameters are reported for the oxidation of cuprous stellacyanin by Co(PDTA)-(k(25.0 degrees) = 17.9 M(-1)sec(-1), deltaH not equal to = 8.5 kcal/mol, deltaH not equal to = 8.5 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0, Mu 0.5 M) and Co(CyDTA)-(k(25.1 degrees) = 17.0 M(-1)sec(-1), deltaH not equal to = 8.7 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0 mu 0.5 M). The first order Co(PDTA)- and Co(CyDTA)- dependences observed over wide concentration ranges contrast with the saturation behavior reported previously for Co(EDTA)- as the oxidant. It is concluded that the- CH3 and -(CH2)4-substituents of PDTA and CyDTA, respectively, prevent the alkylated derivatives of Co(EDTA)- from hydrogen bonding with the reduced blue protein, causing precursor complex formation constants to fall far below that of 149M(-1) (25.1 degrees) observed for the EDTA complex. The similarity between deltaH not equal to and deltaS not equal to values for the oxidation of stellacyanin by Co(PDTA)- and Co(CyDTA)- indicates that the size of alkyl substituents linked to the carbon atoms of the EDTA ethylenediamine backbone has little influence on activation requirements for Cu(I) to Co(III) electron transfer. The electron transfer reactivity of aminopolycarboxylatocobalt(III) complexes with cuprous stellacyanin therefore appears to be linked to the accessibility of one or more of the ligated acetate groups to outer-sphere contact with the type 1 Cu(I) center. Saturation in kobsd vs. [oxidant] plots found for the reactions of Co(PDTA)- and Co(CyDTA)- with stellacyanin at pH 6 and at pH 7 in the presence of EDTA is attributed to the formation of "dead-end" oxidant-protein complexes.

  13. Synthesis and characterization of Cu2O/TiO2 photocatalysts for H2 evolution from aqueous solution with different scavengers (United States)

    Li, Yanping; Wang, Baowei; Liu, Sihan; Duan, Xiaofei; Hu, Zongyuan


    A series of Cu2O/TiO2 photocatalysts with different molar fraction of Cu2O were prepared by a facile modified ethanol-induced approach followed by a calcination process. The chemical state of copper compound was proved to be cuprous oxide by the characterization of X-ray photoelectron spectra (XPS). Furthermore, these composite oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption desorption and UV-vis techniques to study the morphologies, structures, and optical properties of the as-prepared samples. The results indicated that the photocatalytic activity of n-type TiO2 was significantly enhanced by combined with p-type Cu2O, due to the efficient p-n heterojunction. The p-n heterojunction between Cu2O and TiO2 can enhance visible-light adsorption, efficiently suppress charge recombination, improve interfacial charge transfer, and especially provide plentiful reaction active sites on the surface of photocatalyst. As a consequence, the prepared 2.5-Cu2O/TiO2 photocatalyst exhibited the highest photocatalytic activity for H2 evolution rate and reached 2048.25 μmol/(g h), which is 14.48 times larger than that of pure P25. The apparent quantum yield (AQY) of the 2.5-Cu2O/TiO2 sample at 365 nm was estimated to be 4.32%. In addition, the influence of different scavengers, namely methanol, anhydrous ethanol, ethylene glycol and glycerol, on the photocatalytic activity for H2 evolution rate was discussed.

  14. A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange (United States)

    Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao


    In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min-1 gcat-1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

  15. Photocatalytic Degradation of Rhodamine B by Cuprous Oxide%氧化亚铜光催化降解罗丹明 B

    Institute of Scientific and Technical Information of China (English)

    黄涛; 吕重安; 杨水金


    Cuprous oxide ( Cu2 O) was successfully prepared by the method of reduction in aqueous at room temperature.All the powders were characterized by X -rays diffraction ( XRD) and scanning electron microscopy ( SEM) .The effect of different factors on the degradation was investigated .The best reaction conditions were found out.The photocatalytic degradation of rhodamine B by Cu 2 O under simulated natural light irradiation was investiga-ted.The results demonstrated that initial concentration of rhodamine B is 10 mg/L, catalyst dosage is 0.38 g/L and the pH is 5.2, the degradation ratio of rhodamine B is as high as 96.5%after 30 minutes simulated natural light ir-radiation .%利用室温液相还原法制备了氧化亚铜,通过XRD、 SEM对其进行了表征,探讨了该催化剂对罗丹明B的光催化降解的活性。在催化剂用量为0.38 g/L,过氧化氢量为1.8 mL,罗丹明B的浓度为10 mg/L, pH为5.2的条件下,光照30 min后罗丹明B的降解率为96.5%。

  16. Synthesis of Cu2O/reduced graphene oxide composites as anode materials for lithium ion batteries%锂离子电池用氧化亚铜/石墨烯负极材料的制备

    Institute of Scientific and Technical Information of China (English)

    颜果春; 李新海; 王志兴; 郭华军; 张倩; 彭文杰


    A facile way was used to synthesize Cu2O/reduced graphene oxide (rGO) composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O particles and rGO distribute hierarchically and the primary Cu2O particles are encapsulated well in the graphene nanosheets. The electrochemical performance of Cu2O/rGOs is enhanced compared with bare Cu2O when they are employed as anode materials for lithium ion batteries. The Cu2O/rGO composites maintain a reversible capacity of 348.4 mA⋅h/g after 50 cycles at a current density of 100 mA/g. In addition, the composites retain 305.8 mA⋅h/g after 60 cycles at various current densities of 50, 100, 200, 400 and 800 mA/g.%在不添加表面活性剂的水溶液体系中,采用水合肼作为还原剂制备得到具有八面体形貌的氧化亚铜/石墨烯复合材料。透射电镜分析表明:氧化亚铜颗粒与石墨烯在复合物中呈多层次分布,而且氧化亚铜一次颗粒很好地嵌入在石墨烯层间。相比于纯氧化亚铜,氧化亚铜/石墨烯复合材料作为锂离子电池负极材料的电化学性能得到了显著的改善。在100 mA/g的电流密度下循环50次后,氧化亚铜/石墨烯复合物的可逆比容量高达348.4 mA⋅h/g,同时,在不同倍率下(50,100,200,400,800 mA/g)循环60次后,其可恢复容量仍达305.8 mA⋅h/g。

  17. Preparation and Instability of Nanocrystalline Cuprous Nitride. (United States)

    Reichert, Malinda D; White, Miles A; Thompson, Michelle J; Miller, Gordon J; Vela, Javier


    Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu3N decomposition, as measured using the colorimetric indophenol method. Because Cu3N decomposition requires H2O and produces substoichiometric amounts of NH3, we conclude that this reaction proceeds through a complex stoichiometry that involves the concomitant release of both N2 and NH3. This is a thermodynamically unfavorable outcome, strongly indicating that H2O (and thus NH3 production) facilitate the kinetics of the reaction by lowering the energy barrier for Cu3N decomposition. The three different Cu2O, Cu3N, and CuO nanocrystalline phases were characterized by a combination of optical absorption, powder X-ray diffraction, transmission electron microscopy, and electronic density of states obtained from electronic structure calculations on the bulk solids. The relative ease of interconversion between these interesting and inexpensive materials bears possible implications for catalytic and optoelectronic applications.

  18. Defect engineering of the electronic transport through cuprous oxide interlayers

    KAUST Repository

    Fadlallah, Mohamed M.


    The electronic transport through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.

  19. Carbon nanotube-cuprous oxide composite based pressure sensors

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Karimov; Muhammad Tariq Saeed Chani; Fazal Ahmad Khalid; Adam Khan; Rahim Khan


    In this paper,we present the design,the fabrication,and the experimental results of carbon nanotube (CNT) and Cu2O composite based pressure sensors.The pressed tablets of the CNT-Cu2O composite are fabricated at a pressure of 353 MPa.The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm.The sizes of the Cu2O micro particles are in the range of 3-4 μrn.The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm,respectively.In order to make low resistance electric contacts,the two sides of the pressed tablet are covered by silver pastes.The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m2.The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.

  20. Microwave Synthesis of Cuprous Oxide Micro-/Nanocrystals with Different Morphologies and Photocatalytic Activities

    Institute of Scientific and Technical Information of China (English)

    Qingwei Zhu; Yihe Zhang; Jiajun Wang; Fengshan Zhou; Paul K. Chu


    Cuprous oxide micro-/nanocrystals were synthesized by using a simple liquid phase reduction process under microwave irradiation. Copper sulfate was used as the starting materials and macromolecule surfactants served as the templates.The morphologies phase and optical properties of them are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflection absorptive spectra (UV-vis/DRS), respectively. The crystals had four different shapes, namely spheres, strips, octahedrons, and dandelions. The photocatalytic behavior of the cuprous oxide particles were investigated by monitoring the degradation of rhodamine B. In spite of the different morphologies, all of the cuprous oxide micro-/nanocrystals exhibited photocatalytic activities under visible light irradiation in the following order: dandelions, strips, spheres, and octahedral crystals. The photocatalytic degradation rates of rhodamine B are 56.37%, 55.68%, 51.83% and 46.16%, respectively. The morphology affects significantly the photocatalytic performance.

  1. Nanometer-Thick Gold on Silicon as a Proxy for Single-Crystal Gold for the Electrodeposition of Epitaxial Cuprous Oxide Thin Films. (United States)

    Switzer, Jay A; Hill, James C; Mahenderkar, Naveen K; Liu, Ying-Chau


    Single-crystal Au is an excellent substrate for electrochemical epitaxial growth due to its chemical inertness, but the high cost of bulk Au single crystals prohibits their use in practical applications. Here, we show that ultrathin epitaxial films of Au electrodeposited onto Si(111), Si(100), and Si(110) wafers can serve as an inexpensive proxy for bulk single-crystal Au for the deposition of epitaxial films of cuprous oxide (Cu2O). The Au films range in thickness from 7.7 nm for a film deposited for 5 min to 28.3 nm for a film deposited for 30 min. The film thicknesses are measured by low-angle X-ray reflectivity and X-ray Laue oscillations. High-resolution TEM shows that there is not an interfacial SiOx layer between the Si and Au. The Au films deposited on the Si(111) substrates are smoother and have lower mosaic spread than those deposited onto Si(100) and Si(110). The mosaic spread of the Au(111) layer on Si(111) is only 0.15° for a 28.3 nm thick film. Au films deposited onto degenerate Si(111) exhibit ohmic behavior, whereas Au films deposited onto n-type Si(111) with a resistivity of 1.15 Ω·cm are rectifying with a barrier height of 0.85 eV. The Au and the Cu2O follow the out-of-plane and in-plane orientations of the Si substrates, as determined by X-ray pole figures. The Au and Cu2O films deposited on Si(100) and Si(110) are both twinned. The films grown on Si(100) have twins with a [221] orientation, and the films grown on Si(110) have twins with a [411] orientation. An interface model is proposed for all Si orientations, in which the -24.9% mismatch for the Au/Si system is reduced to only +0.13% by a coincident site lattice in which 4 unit meshes of Au coincide with 3 unit meshes of Si. Although this study only considers the deposition of epitaxial Cu2O films on electrodeposited Au/Si, the thin Au films should serve as high-quality substrates for the deposition of a wide variety of epitaxial materials.

  2. New Tl-based copper oxide containing double-MO 2-unit fluorite block: (Tl, Cu) Sr 2 (R, Ce) 3Cu 2O 11 (R: rare earth element) (United States)

    Wada, Takahiro; Hamada, Kazuyuki; Ichinose, Ataru; Kaneko, Tetsuyuki; Yamauchi, H.; Tanaka, Shoji


    New Tl-based copper oxides. (Tl, Cu)Sr 2(R, Ce) 3Cu 2O 11 (R: rare earth element) (Tl-based “1232”), have been synthesized. These compounds have tetragonal unit cells with lattice constants approximately equal to a=3.8 Å and c=17.3 Å. A Rietveld analysis using X-ray powder diffraction data shows that the crystal structure of (Tl {4}/{5}Cu {1}/{5})Sr 2(Ho {1}/{3}Ce {2}/{3}) 3Cu 2O 11 consists of a double-MO 2-unit flouride block, i.e. [(Ho, Ce)O 2] 2 and a Tl-based “1212” block, i.e. (Tl, Cu)Sr 2(Ho, Ce)Cu 2O 7. The temperature dependences of the electrical resistivity for all of these compounds are semiconductive. However, these compounds are considered to be candidates for parent materials for new high- Tc superconductors.

  3. Towards printed perovskite solar cells with cuprous oxide hole transporting layers

    DEFF Research Database (Denmark)

    Wang, Yan; Xia, Zhonggao; Liang, Jun


    Solution-processed p-type metal oxide materials have shown great promise in improving the stability of perovskite-based solar cells and offering the feasibility for a low cost printing fabrication process. Herein, we performed a device modeling study on planar perovskite solar cells with cuprous ...

  4. Thermosensitive Cu2O-PNIPAM core-shell nanoreactors with tunable photocatalytic activity

    CERN Document Server

    Jia, He; Angioletti-Uberti, Stefano; Henzler, Katja; Ott, Andreas; Lin, Xianzhong; Möser, Jannik; Kochovski, Zdravko; Schnegg, Alexander; Dzubiella, Joachim; Ballauff, Matthias; Lu, Yan


    We report a facile and novel method for the fabrication of Cu2O@PNIPAM core-shell nanoreactors using Cu2O nanocubes as the core. The PNIPAM shell not only effectively protects the Cu2O nanocubes from oxidation, but also improves the colloidal stability of the system. The Cu2O@PNIPAM core-shell microgels can work efficiently as photocatalyst for the decomposition of methyl orange under visible light. A significant enhancement in the catalytic activity has been observed for the core-shell microgels compared with the pure Cu2O nanocubes. Most importantly, the photocatalytic activity of the Cu2O nanocubes can be further tuned by the thermosensitive PNIPAM shell, as rationalized by our recent theory.

  5. Effect of thermal annealing in vacuum on the photovoltaic properties of electrodeposited Cu2O-absorber solar cell

    Directory of Open Access Journals (Sweden)

    Dimopoulos T.


    Full Text Available Heterojunction solar cells were fabricated by electrochemical deposition of p-type, cuprous oxide (Cu2O absorber on sputtered, n-type ZnO layer. X-ray diffraction measurements revealed that the as-deposited absorber consists mainly of Cu2O, but appreciable amounts of metallic Cu and cupric oxide (CuO are also present. These undesired oxidation states are incorporated during the deposition process and have a detrimental effect on the photovoltaic properties of the cells. The open circuit voltage (VOC, short circuit current density (jSC, fill factor (FF and power conversion efficiency (η of the as-deposited cells are 0.37 V, 3.71 mA/cm2, 35.7% and 0.49%, respectively, under AM1.5G illumination. We show that by thermal annealing in vacuum, at temperatures up to 300 °C, compositional purity of the Cu2O absorber could be obtained. A general improvement of the heterojunction and bulk materials quality is observed, reflected upon the smallest influence of the shunt and series resistance on the transport properties of the cells in dark and under illumination. Independent of the annealing temperature, transport is dominated by the space-charge layer generation-recombination current. After annealing at 300 °C the solar cell parameters could be significantly improved to the values of: VOC = 0.505 V, jSC = 4.67 mA/cm2, FF = 47.1% and η = 1.12%.

  6. Junction studies on electrochemically fabricated p-n Cu(2)O homojunction solar cells for efficiency enhancement. (United States)

    McShane, Colleen M; Choi, Kyoung-Shin


    p-n Cu(2)O homojunction solar cells were electrochemically fabricated by consecutively depositing an n-Cu(2)O layer on a p-Cu(2)O layer. In order to better understand the Fermi levels of the electrochemically grown polycrystalline p- and n-Cu(2)O layers and maximize the overall cell performance, the back and front contacts of the Cu(2)O homojunction cells were systematically changed and the I-V characteristics of the resulting cells were examined. The result shows that the intrinsic doping levels of the electrochemically prepared p-Cu(2)O and n-Cu(2)O layers are very low and they made almost Ohmic junctions with Cu metal with which previously studied p-Cu(2)O layers prepared by thermal oxidation of Cu foils are known to form Schottky junctions. The best cell performance (an η of 1.06%, a V(OC) of 0.621 V, an I(SC) of 4.07 mA cm(-2), and a fill factor (ff) of 42%) was obtained when the p-Cu(2)O layer was deposited on a commercially available ITO substrate as the back contact and a sputter deposited ITO layer was used as the front contact on the n-Cu(2)O layer. The unique features of the p-n Cu(2)O homojunction solar cell are discussed in comparison with other Cu(2)O-based heterojunction solar cells.

  7. 氧化锌/氧化亚铜异质结太阳能电池的研究进展∗%Research Progress in Zinc Oxide/Cuprous Oxide Heterojunction Solar Cell

    Institute of Scientific and Technical Information of China (English)

    冯云珠; 董磊; 于良民


    Much attention recently has been paid on p-n heterojunction solar cells fabricated with cuprous oxide combined with zinc oxide owing to the advantage of favorable alignment of conductive band edges and lattice matching. The formation of heterojunctions can enhance the seperation of photoinduced electrons and holes,as well as the absor-bance of the light.This review compiles the main milestones reached during the last decades in the development of ZnO/Cu2 O heterojunction solar cells comprehensively.Different junction structures of these cells as planar and ZnO nanoarray based ones related to deposition sequences and synthesis methods are introduced separately,while photovol-taic property influence factors as well as improving methods are discussed.Considering the accomplishments achieved in a relatively short period of time,it can be said that this kind of solar cell can be promisingly applied in clean energy exploitation in the future,in spite of improvement of cell performance still in need.%因氧化亚铜(Cu2 O)、氧化锌(ZnO)能级和晶格匹配较好,近年来较多的研究者将两者复合制备异质结太阳能电池。异质结的形成可提高光生电子-空穴对的分离效率,同时拓展复合结构的光响应范围,从而有效提高太阳能电池性能。介绍了3类主流的 ZnO/Cu2 O 异质结结构,分别阐述主要的进展,综述了异质结结构中 Cu2 O、ZnO的制备方法以及制备条件对电池效率的影响,讨论了电池性能的改进措施,并对 ZnO/Cu2 O 异质结太阳能电池未来的发展前景进行展望。

  8. Mapping the Electronic Structure of Each Ingredient Oxide Layer of High-T\\{c} Cuprate Superconductor Bi{2}Sr{2}CaCu{2}O{8+δ}. (United States)

    Lv, Yan-Feng; Wang, Wen-Lin; Peng, Jun-Ping; Ding, Hao; Wang, Yang; Wang, Lili; He, Ke; Ji, Shuai-Hua; Zhong, Ruidan; Schneeloch, John; Gu, Gen-Da; Song, Can-Li; Ma, Xu-Cun; Xue, Qi-Kun


    Understanding the mechanism of high transition temperature (T{c}) superconductivity in cuprates has been hindered by the apparent complexity of their multilayered crystal structure. Using a cryogenic scanning tunneling microscopy (STM), we report on layer-by-layer probing of the electronic structures of all ingredient planes (BiO, SrO, CuO{2}) of Bi{2}Sr{2}CaCu_2}O{8+δ} superconductor prepared by argon-ion bombardment and annealing technique. We show that the well-known pseudogap (PG) feature observed by STM is inherently a property of the BiO planes and thus irrelevant directly to Cooper pairing. The SrO planes exhibit an unexpected van Hove singularity near the Fermi level, while the CuO{2} planes are exclusively characterized by a smaller gap inside the PG. The small gap becomes invisible near T{c}, which we identify as the superconducting gap. The above results constitute severe constraints on any microscopic model for high T{c} superconductivity in cuprates.

  9. Cyclic Voltammetry Measurement for Cu2O Based Homostructure Thin Film (United States)

    Mohamad Arifin, Nurliyana Binti; Mohamad, Fariza Binti; Sikh Anuar, Nur Fathiah Binti; Ahmad, Nabihah Binti; Nor, Nik Hisyamudin Muhd; Izaki, Masanobu


    This experiment is about fabrication of homojunction Copper Oxide (Cu2O) thin film by using electrodeposition method. The p-n homojunction Cu2O was successfully prepared by consecutively depositing p-type Cu2O layer on n-type Cu2O layer by using copper acetate based solution through potentiostatic electrodeposition. At first, the n-type Cu2O was fabricated at pH 6.2 and 6.5 with fixed potential of -0.125V vs Ag/AgCl and time deposition at 30 minutes. Cyclic voltammetry (CV) measurement was carried out on this sample to determine the ideal potential range for fabrication of p-type Cu2O on n-type Cu2O/FTO substrate. From the result, deposition potential of -0.35V and -0.4V vs Ag/AgCl were appropriated for p-type Cu2O thin film fabrication. These potential values were variable with the selected pH values of 12.0 and 12.5 to fabricate the p-type Cu2O thin film. The other parameters such as deposition time fixed at 2 hours bath temperature was set up at 60°C. It was found that the optimum potential deposition was -0.4V vs Ag/AgCl and pH value appropriate for homostructure Cu2O thin film was pH 12.5. Morphological, structural, optical and conductivity characterization of p-n homojunction Cu2O thin film was characterized using Field Emission Scanning Electron Microscopy, X-Ray Diffractometer, Ultraviolet-Visible Spectroscopy and Photoelectrochemical (PEC) cells, respectively.

  10. Preparation of poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) monolithic column modified with β-cyclodextrin and nano-cuprous oxide and its application in polymer monolithic microextraction of polychlorinated biphenyls. (United States)

    Zheng, Haijiao; Liu, Qingwen; Jia, Qiong


    A poly(butyl methacrylate-co-ethyleneglyceldimethacrylate) (poly(BMA-EDMA)) monolithic column was prepared with in situ polymerization method and modified with allylamine-β-cyclodextrin (ALA-β-CD) and nano-cuprous oxide (Cu2O). A polymer monolith microextraction method was developed with the modified monolithic column for the preconcentration of polychlorinated biphenyls combined with gas chromatography-electron capture detector. Various parameters affecting the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, we obtained acceptable linearities, low limits of detection, and good intra-day/inter-day relative standard deviations. Because of the hydrophobic properties of β-CD and the porous nano structure of Cu2O, the enrichment capacity of the poly(BMA-EDMA) monolithic column was significantly improved. The extraction efficiency followed the order: poly(BMA-EDMA-ALA-β-CD-Cu2O)>poly(BMA-EDMA-ALA-β-CD)>poly(BMA-EDMA)>direct GC analysis. When applied to the determination of polychlorinated biphenyls in wine samples, low limits of detection (0.09ngmL(-1)) were obtained under the preoptimized conditions (sample volume 1.0mL, sample flow rate 0.1mLmin(-1), eluent volume 0.1mL, and eluent flow rate 0.05mLmin(-1)). In addition, the present method was employed to determine polychlorinated biphenyls in red wine samples and the accuracy was assessed through recovery experiments. The obtained recovery values were in the range of 78.8-104.1% with relative standard deviations less than 9.0%.

  11. Electronic Structure Engineering of Cu2O Film/ZnO Nanorods Array All-Oxide p-n Heterostructure for Enhanced Photoelectrochemical Property and Self-powered Biosensing Application (United States)

    Kang, Zhuo; Yan, Xiaoqin; Wang, Yunfei; Bai, Zhiming; Liu, Yichong; Zhang, Zheng; Lin, Pei; Zhang, Xiaohui; Yuan, Haoge; Zhang, Xueji; Zhang, Yue


    We have engineered the electronic structure at the interface between Cu2O and ZnO nanorods (NRs) array, through adjusting the carrier concentration of Cu2O. The electrodeposition of Cu2O at pH 11 acquired the highest carrier concentration, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. The optimized Cu2O/ZnO NRs array p-n heterostructures exhibited enhanced PEC performance, such as elevated photocurrent and photoconversion efficiency, as well as excellent sensing performance for the sensitive detection of glutathione (GSH) in PBS buffer even at applied bias of 0 V which made the device self-powered. Besides, the favorable selectivity, high reproducibility and extremely wide detection range, make such heterostructure a promising candidate for PEC biosensing applications, probably for the extended field of PEC water splitting or other solar photovoltaic beacons.

  12. Effect of conductive substrate (working electrode) on the morphology of electrodeposited Cu2O (United States)

    ELmezayyen, Ayman S.; Guan, Shian; Reicha, Fikry M.; El-Sherbiny, Ibrahim M.; Zheng, jianming; Xu, Chunye


    Cu2O thin films were electrodeposited from a Cu(II) acetate solution containing 0.02 M Copper(II) acetate (Cu(OAc)2) and 0.1 M sodium acetate (NaOAc) at pH 5.6, using three different working conductive electrodes with approximately the same square resistance -indium doped tin oxide glass (ITO/Glass), fluorine-doped tin oxide glass (FTO/Glass), and indium doped tin oxide polyethylene terephthalate (ITO/PET)—under identical conditions using a common growth condition. The Cu2O thin films were characterized by means of scanning electron microscopy, x-ray diffraction (XRD), current density versus growth time for Cu2O films, and electrochemical impedance spectroscopy. The results showed that the choice of substrate materials has a crucial role in controlling Cu2O growth. The charge transfer resistance (Rct) of FTO/Glass-Cu2O exhibits the lowest value; this means that FTO/Glass-Cu2O possess the highest electron transfer efficiency. All Cu2O films showed n-type semiconductor characteristic with charge carrier densities varying between 1.4 × 1018-1.2 × 1019 cm-3.

  13. Transition of Resistive Switching to Bidirectional Diode in Cu2O/Cu Nanowires (United States)

    Kim, Deok-kee; Shin, Ho Sun; Song, Jae Yong


    Cu2O/Cu nanowires of about 2 µm length were electrodeposited within anodized aluminum oxide templates in an aqueous acidic solution using template-assisted pulse-reverse electrolysis. In the virgin state, reversible copper filaments were formed by using the copper ions driven by an electric field towards the cathode. Initially, the resistive switching dominated the electrical characteristics of the Cu2O/Cu nanowires due to the low-resistance reversible copper filaments. After the permanent breakup of the copper filaments under the high current density, the Cu2O/Cu nanowire showed bipolar exponential characteristics, which was attributed to mixed ionic and electronic conduction.

  14. Atomic Resolution Mapping of the Excited-State Electronic Structure of Cu2O with Time-Resolved X-Ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hillyard, Patrick B.; Kuchibhatla, Satyanarayana V N T; Glover, T. E.; Hertlein, M. P.; Huse, N.; Nachimuthu, Ponnusamy; Saraf, Laxmikant V.; Thevuthasan, Suntharampillai; Gaffney, Kelly J.


    We have used time-resolved soft x-ray spectroscopy to investigate the electronic structure of optically excited cuprous oxide at the O K-edge and the Cu L3-edge. The 400 nm optical excitation shifts the Cu and O absorptions to lower energy, but does not change the integrated x-ray absorption significantly for either edge. The constant integrated x-ray absorption cross-section indicates that that the conduction band and valence band edges have very similar Cu 3d and O 2p orbital contributions. The 2.1 eV optical band gap of Cu2O significantly exceeds the one eV shift in the Cu L3- and O K-edges absorption edges induced by optical excitation, demonstrating the importance of core-hole excitonic effects and valence electron screening in the x-ray absorption process.

  15. Electrocatalytic Production of C3-C4 Compounds by Conversion of CO2 on a Chloride-Induced Bi-Phasic Cu2O-Cu Catalyst. (United States)

    Lee, Seunghwa; Kim, Dahee; Lee, Jaeyoung


    Electrocatalytic conversion of carbon dioxide (CO2) has recently received considerable attention as one of the most feasible CO2 utilization techniques. In particular, copper and copper-derived catalysts have exhibited the ability to produce a number of organic molecules from CO2. Herein, we report a chloride (Cl)-induced bi-phasic cuprous oxide (Cu2O) and metallic copper (Cu) electrode (Cu2OCl) as an efficient catalyst for the formation of high-carbon organic molecules by CO2 conversion, and identify the origin of electroselectivity toward the formation of high-carbon organic compounds. The Cu2OCl electrocatalyst results in the preferential formation of multi-carbon fuels, including n-propanol and n-butane C3-C4 compounds. We propose that the remarkable electrocatalytic conversion behavior is due to the favorable affinity between the reaction intermediates and the catalytic surface.

  16. Numerical simulation of exciton dynamics in cuprous oxide at ultra low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Som, Sunipa


    This thesis is a theoretical investigation of the relaxation behaviour of excitons in Cuprous Oxide at ultra low temperatures when the excitons are confined within a potential trap and also in a homogeneous system. Under the action of deformation potential phonon scattering only, Bose Einstein Condensation (BEC) occurs for all temperatures in the investigated range. In the case of Auger decay, we do not find at any temperature a BEC due to the heating of the exciton gas. In the case of elastic and phonon-scattering together BEC occurs in this case of 0.1 K.

  17. Ultrathin Cu2O as an efficient inorganic hole transporting material for perovskite solar cells

    KAUST Repository

    Yu, Weili


    We demonstrate that ultrathin P-type Cu2O thin films fabricated by a facile thermal oxidation method can serve as a promising hole-transporting material in perovskite solar cells. Following a two-step method, inorganic-organic hybrid perovskite solar cells were fabricated and a power conversion efficiency of 11.0% was achieved. We find that the thickness and properties of Cu2O layers must be precisely tuned in order to achieve the optimal solar cell performance. The good performance of such perovskite solar cells can be attributed to the unique properties of ultrathin Cu2O, including high hole mobility, good energy level alignment with CH3NH3PbI3, and longer lifetime of photo-excited carriers. Combining merits of low cost, facile synthesis, and high device performance, ultrathin Cu2O films fabricated via thermal oxidation hold promise for facilitating the developments of industrial-scale perovskite solar cells.

  18. Cuprous Oxide Scale up: Gram Production via Bulk Synthesis using Classic Solvents at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hall, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Han, T. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Cuprous oxide is a p-type semiconducting material that has been highly researched for its interesting properties. Many small-scale syntheses have exhibited excellent control over size and morphology. As the demand for cuprous oxide grows, the synthesis method need to evolve to facilitate large-scale production. This paper supplies a facile bulk synthesis method for Cu₂O on average, 1-liter reaction volume can produce 1 gram of particles. In order to study the shape and size control mechanisms on such a scale, the reaction volume was diminished to 250 mL producing on average 0.3 grams of nanoparticles per batch. Well-shaped nanoparticles have been synthesized using an aqueous solution of CuCl₂, NaOH, SDS surfactant, and NH₂OH-HCl at mild temperatures. The time allotted between the addition of NaOH and NH₂OH-HCl was determined to be critical for Cu(OH)2 production, an important precursor to the final produce The effects of stirring rates on a large scale was also analyzed during reagent addition and post reagent addition. A morphological change from rhombic dodecahedra to spheres occurred as the stirring speed was increased. The effects of NH₂OH-HCl concentration were also studied to control the etching effects of the final product.

  19. A Facile One Step Solution Route to Synthesize Cuprous Oxide Nanofluid

    Directory of Open Access Journals (Sweden)

    Shenoy U. Sandhya


    Full Text Available A cuprous oxide nanofluid stabilized by sodium lauryl sulfate, synthesized by using the one step method, has been reported. Nanofluids were synthesized by using a well‐ controlled surfactant‐assisted solution phase synthesis. The method involved reduction of copper acetate by glucose in a mixture of water and ethylene glycol serving as the base fluid. The synthesized fluid was characterized by X‐ray and electron diffraction techniques, in addition, transmission and field emission microscopic techniques and Fourier transform infra red spectroscopic analysis was undertaken. The rheological property, as well as the thermal conductivity of the fluid, were measured. The variation of reaction parameters considerably affected the size of the particles as well as the reaction rate. The uniform dispersion of the particles in the base fluid led to a stability period of three months under stationary state, augmenting the thermal conductivity of the nanofluid. The method is found to be simple, reliable and fast for the synthesis of Newtonian nanofluids containing cuprous oxide nanoparticles.

  20. Doping dependence of electronic structure in Bi2Sr2CaCu2O8+x (United States)

    Onellion, M.; Christensen, S.; Frazer, B.; Gatt, R.; Kelley, R. J.; Misra, S.; Schmauder, T.; Berger, H.; Grioni, M.; Margaritondo, G.; Vobornik, I.; Zwick, F.; Möâle, M.; Kleiner, R.; Müller, P.


    We report on angle-resolved photoemission and superconductor-insulator-superconductor tunneling measurements of the normal and superconducting states of Bi2Sr2CaCu2O8+x single crystal samples and Bi2Sr2CaCu2O8+x-native oxide-lead (S-I-S) tunnel junctions.(1-7).

  1. Gas sensitivity and photocatalytic performance of cuprous oxide with novel morphologies (United States)

    Wu, Ling; Wu, Yulin; Jin, Saijia; Zhang, Lun; Xun, Zhipeng


    In this work, Cu2O nanoparticles (NPs) with quasi-spherical and bookmark-like morphologies were successfully synthesized via a new facile solution method. The morphologies of products were characterized to show porous surfaces and the size is as small as approximately 20-50 nm. Given the special morphology, Cu2O NPs exhibited superior gas sensitivity to either ethanol or acetone vapors and strong adsorption abilities and high degradation activities for methyl orange under visible-light irradiation. The investigation provided not only a way of synthesizing Cu2O particles with dozens of nanoscale, but also a way of improving its gas sensitivity and catalytic degradation ability.

  2. Cuprous Sulfide/Reduced Graphene Oxide Hybrid Nanomaterials: Solvothermal Synthesis and Enhanced Electrochemical Performance (United States)

    He, Zhanjun; Zhu, Yabo; Xing, Zheng; Wang, Zhengyuan


    The cuprous sulfide nanoparticles (CuS NPs)-decorated reduced graphene oxide (rGO) nanocomposites have been successfully prepared via a facile and efficient solvothermal synthesis method. Scanning electron microscopy and transmission electron microscopy images demonstrated that CuS micronspheres composed of nanosheets and distributed on the rGO layer in well-monodispersed form. Fourier-transform infrared spectroscopy analyses and x-ray photoelectron spectroscopy showed that graphene oxide (GO) had been reduced to rGO. The electrochemical performances of CuS/rGO nanocomposites were investigated by cyclic voltammetry and charge/discharge techniques, which showed that the specific capacitance of CuS/rGO nanocomposites was enhanced because of the introduction of rGO.

  3. Zn-VI/Cu2O Heterojunctions for Earth-Abundant Photovoltaics (United States)

    Wilson, Samantha

    The need for sustainable energy production motivates the study of photovoltaic materials, which convert energy from sunlight directly into electricity. This work has focused on the development of Cu2O as an earth-abundant solar absorber due to the abundance of its constituent elements in the earth's crust, its suitable band gap, and its potential for low cost processing. Crystalline wafers of Cu2O with minority carrier diffusion lengths on the order of microns can be manufactured in a uniquely simple fashion --- directly from copper foils by thermal oxidation. Furthermore, Cu2Ohas an optical band gap of 1.9 eV, which gives it a detailed balance energy conversion efficiency of 24.7% and the possibility for an independently connected Si/Cu 2O dual junction with a detailed balance efficiency of 44.3%. However, the highest energy conversion efficiency achieved in a photovoltaic device with a Cu2O absorber layer is currently only 5.38% despite the favorable optical and electronic properties listed above. There are several challenges to making a Cu2O photovoltaic device, including an inability to dope the material, its relatively low chemical stability compared to other oxides, and a lack of suitable heterojunction partners due to an unusually small electron affinity. We have addressed the low chemical stability, namely the fact that Cu2O is an especially reactive oxide due to its low enthalpy of formation (DeltaHf0 = -168.7 kJ/mol), by developing a novel surface preparation technique. We have addressed the lack of suitable heterojunction partners by investigating the heterojunction band alignment of several Zn-VI materials with Cu 2O. Finally, We have addressed the typically high series resistance of Cu2O wafers by developing methods to make very thin, bulk Cu 2O, including devices on Cu2O wafers as thin as 20 microns. Using these methods we have been able to achieve photovoltages over 1 V, and have demonstrated the potential of a new heterojunction material, Zn(O,S).

  4. Copper oxide as a high temperature battery cathode material (United States)

    Ritchie, A. G.; Mullins, A. P.


    Copper oxide has been tested as a cathode material for high temperature primary reserve thermal batteries in single cells at 530 to 600 C and at current densities of 0.1 to 0.25 A cm(exp -2) using lithium-aluminium alloy anodes and lithium fluoride-lithium chloride-lithium bromide molten salt electrolytes. Initial on-load voltages were around 2.3 V, falling to 1.5 V after about 0.5 F mol(exp -1) had been withdrawn. Lithium copper oxide, LiCu2O2, and cuprous oxide, Cu2O, were identified as discharge products.

  5. 防污涂料中氧化亚铜的渗出速率及降解行为研究%Research on Leaching Rate & Degradation Behavior of Cu2O Contained in Antifouling Paints

    Institute of Scientific and Technical Information of China (English)

    于雪艳; 王科; 陈正涛; 余浩杰; 肖玲; 桂泰江


    Cuprous oxide is the main biocide used in marine antifouling paints, it's very important to investigate the leaching rate and degradation behavior of cuprous oxide. The ISO 15181 test method of copper-ion release rate was described in this paper, and the copper - ion release rate in different self - polishing antifouling paints formulations was discussed, and the degradation behavior of cuprous oxide in the marine environment was investigated. The results showed that the release rate of copper - ion could be adjusted by paint formula, the final degradation product of cuprous oxide in the marine environment was basic cupric carbonate.%氧化亚铜( Cu2O)作为在目前海洋防污涂料广泛使用的防污剂,研究其渗出速率和在海洋环境中的降解行为具有重要的意义.介绍了ISO15181铜离子渗出速率测试方法,并研究了不同配方的自抛光型防污涂料的铜离子渗出速率,最后研究了氧化亚铜在海洋环境中的降解行为.结果表明:铜离子渗出速率可通过涂料配方进行调整,氧化亚铜在海洋环境中的最终降解产物是碱式碳酸铜.

  6. Cuprous oxide photovoltaic cells. Final report, September 1, 1978-November 30, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Trivich, D.


    The research described represents the beginning of a second phase of research on cuprous oxide photovoltaic cells. The first phase was concerned with the development of procedures of making Schottky barriers on isolated films of Cu/sub 2/O, including single crystals. It was found that properties of these Schottky barrier cells, in particular the barrier heights, were limited by chemical changes at the junction especially with metals of low work function which tend to be more active chemically, e.g., Al. The motivation of the present phase of the research was to construct junctions that would avoid this chemical degradation while maintaining electrical contact between the Cu/sub 2/O and a low work function material in order to attain larger barrier heights. Essentially the approach involved placing the Cu/sub 2/O in contact with a stable oxide. When this oxide is used as a thin layer between the Cu/sub 2/O and a top metal contact this gives an MIS structure. As another approach the other oxide can be an n-type semiconductor in thicker layers to form a heterojunction. Results are reported. (WHK)

  7. Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO. (United States)

    Ievskaya, Yulia; Hoye, Robert L Z; Sadhanala, Aditya; Musselman, Kevin P; MacManus-Driscoll, Judith L


    Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics.

  8. Electroquímica de Ag2Cu2O3 y síntesis de Ag2Cu2O4

    Directory of Open Access Journals (Sweden)

    Casan-Pastor, N.


    Full Text Available The first silver-copper mixed oxide was recently synthesized in our laboratory. Such synthesis has been possible using soft chemistry methods and low temperatures, which prevent the decomposition of silver oxides. The present work describes the electrochemical behaviour of the silver-copper mixed oxide, Ag2Cu2O3, as studied by cyclic voltametry and electrolysis, both for oxidation and for reduction reactions. This compound undergoes several redox processes when it is reduced, yielding metallic silver and metallic copper as final products. The initial oxide is not regenerated upon re-oxidation. On the other hand, when Ag2Cu2O3 is oxidized a new phase with stoichiometry Ag2Cu2O4±δ appears.The original compound can be regenerated after a new reduction.Recientemente se ha sintetizado en nuestro laboratorio el primer óxido mixto de cobre y plata. Tal síntesis ha sido posible gracias a la utilización de métodos de química suave y baja temperatura, que impiden que los óxidos de plata se descompongan. En este trabajo se describe el estudio llevado a cabo sobre el comportamiento electroquímico del óxido mixto de cobre y plata, Ag2Cu2O3 ,mediante voltametría cíclica y electrólisis tanto para los procesos de oxidación como de reducción. Dicho compuesto sufre varios procesos redox cuando es reducido, obteniéndose plata metálica y cobre metálico como productos finales, sin que se dé regeneración del óxido al volver a oxidar a éstos. En cambio al ser oxidado el Ag2Cu2O3, se observa la formación de una fase oxidada de estequiometría Ag2Cu2O4±δ a partir de la cual se puede regenerar el compuesto original.

  9. One-pot self-assembly of Cu2O/RGO composite aerogel for aqueous photocatalysis (United States)

    Cai, Jingyu; Liu, Wenjun; Li, Zhaohui


    Cu2O/reduced graphene oxide (RGO) composite aerogel was fabricated by a one-pot hydrothermal method using glucose as a reducing agent and cross-linker. The as-obtained Cu2O/RGO composite aerogel showed superior photocatalytic activity for MO degradation owing to its improved light absorption capability, enhanced adsorption toward pollutant and the RGO promoted charge carrier separation. The Cu2O/RGO composite aerogel can also be facilely separated from the reaction system for recycling, which makes it especially appealing for using as a visible light responsive photocatalyst in aqueous photocatalysis.

  10. Cuprous oxide nanoparticle-inhibited melanoma progress by targeting melanoma stem cells. (United States)

    Yu, Bin; Wang, Ye; Yu, Xinlu; Zhang, Hongxia; Zhu, Ji; Wang, Chen; Chen, Fei; Liu, Changcheng; Wang, Jingqiang; Zhu, Haiying


    Recent studies have shown that metal and metal oxide have a potential function in antitumor therapy. Our previous studies demonstrated that cuprous oxide nanoparticles (CONPs) not only selectively induce apoptosis of tumor cells in vitro but also inhibit the growth and metastasis of melanoma by targeting mitochondria with little hepatic and renal toxicities in mice. As a further study, our current research revealed that CONPs induced apoptosis of human melanoma stem cells (CD271(+/high) cells) in A375 and WM266-4 melanoma cell lines and could significantly suppress the expression of MITF, SOX10 and CD271 involved in the stemness maintenance and tumorigenesis of melanoma stem cells. CD271(+/high) cells could accumulate more CONPs than CD271(-/low) through clathrin-mediated endocytosis. In addition, lower dosage of CONPs exhibited good anti-melanoma effect by decreasing the cell viability, stemness and tumorigenesis of A375 and WM266-4 cells through reducing the expression of SOX10, MITF, CD271 and genes in MAPK pathway involved in tumor progression. Finally, CONPs obviously suppressed the growth of human melanoma in tumor-bearing nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice, accompanied with tumors structural necrosis and fibrosis remarkably and decreased expression of CD271, SOX10 and MITF. These results above proved the effectiveness of CONPs in inhibiting melanoma progress through multiple pathways, especially through targeting melanoma stem cells.

  11. Growth of ∼5 cm2V−1s−1 mobility, p-type Copper(I oxide (Cu2O films by fast atmospheric atomic layer deposition (AALD at 225°C and below

    Directory of Open Access Journals (Sweden)

    D. Muñoz-Rojas


    Full Text Available Phase pure, dense Cu2O thin films were grown on glass and polymer substrates at 225°C by rapid atmospheric atomic layer deposition (AALD. Carrier mobilities of 5 cm2V−1s−1 and carrier concentrations of ∼1016 cm−3 were achieved in films of thickness 50 - 120 nm, over a >10 cm2 area. Growth rates were ∼1 nm·min−1 which is two orders of magnitude faster than conventional ALD.. The high mobilities achieved using the atmospheric, low temperature method represent a significant advance for flextronics and flexible solar cells which require growth on plastic substrates.

  12. An ultrasensitive sandwich-type electrochemical immunosensor based on the signal amplification strategy of echinoidea-shaped Au@Ag-Cu2O nanoparticles for prostate specific antigen detection. (United States)

    Yang, Yuying; Yan, Qin; Liu, Qing; Li, Yongpeng; Liu, Hui; Wang, Ping; Chen, Lei; Zhang, Daopeng; Li, Yueyun; Dong, Yunhui


    Highly sensitive determination of tumor markers plays an important role in early diagnosis of cancer. Herein, a novel and ultrasensitive sandwich-type electrochemical immunosensor was fabricated for quantitative detection of prostate specific antigen (PSA). In this process, gold nanoparticles functionalized nitrogen-doped graphene quantum dots (Au@N-GQDs) was synthesized through a simple and green hydrothermal procedure to enhance conductivity, specific electrode surface area and quantity of immobilized primary antibodies (Ab1). Subsequently, the prepared echinoidea-shaped nanocomposites (Au@Ag-Cu2O) composed of Au@Ag core-shell nanoparticles and disordered cuprous oxide were prepared successfully to label the secondary antibodies (Ab2), which convened the advantages of good biocompatibility and high specific surface area. Because of the synergetic effect present in Au, Ag and Cu2O, the novel nanocomposites exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) for the amplified detection of PSA. Therefore, the as-proposed immunosensor for the detection of PSA possessed wide dynamic range from 0.01pg/mL to 100ng/mL with a low detection limit of 0.003pg/mL (S/N = 3). Furthermore, this sandwich-type immunosensor revealed high sensitivity, high selectivity and long-term stability, which had promising application in bioassay analysis. Copyright © 2017. Published by Elsevier B.V.

  13. Advance in Cu2O-ZnO Solar Cells and Investigation of Cu2O-ZnO Heterojunction Fabricated by Magnetron Sputtering%Cu2O-ZnO太阳能电池的研究进展及磁控溅射法制备Cu2O-ZnO异质结的研究

    Institute of Scientific and Technical Information of China (English)

    杨美佳; 朱丽萍


    Cu2O-ZnO heterojunction has shown great potential for photovoltaic application due to the low-cost,nontoxicity,abundance and variety of preparation methods.However,the resistivity of the Cu2O film in present ZnO-Cu2O heterojunction solar cell is relatively high,which seems to be the major problem for the low photoelectric conversion efficiency.Cu2O films were prepared using reactive direct current magnetron sputtering.The microstructures and properties were characterized using X-ray diffraction,X-ray photoelectron spectroscopy (XPS) and Hall-effect measurements.The influences of qv (Ar) ∶ qv (O2) on the structures and properties of deposited films were investigated.Single-phase Cu2O film with a resistivity of 88.5 Ω · cm,a Hall mobility of 16.9 cm2 · V-1 · s-1 and a carrier concentration of 4.19 × 1015 cm-3 were obtained at qv (Ar) ∶ qv (O2) =90∶ 0.3.The as-deposited Cu2O films have a great improvement in electrical performance and have more advantage in photovoltaic application compared with that prepared by electrochemical deposition or thermal oxidation.On that basis,the Cu2O-ZnO heterojunctions were fabricated in reversed growth sequence and the band alignments of the heterojunctions were given to investigate their potential application in solar cells.Possible areas for future work in this field were outlined and some suggestions were made based on our investigation of the Cu2O-ZnO heterojunctions fabricated by magnetron sputtering.%Cu2O-ZnO异质结具有成本低廉、环境友好及制备方法多样等优点,在太阳能电池领域有很好的应用前景.Cu2O薄膜的高电阻率和低载流子浓度是制约其效率提高的主要原因.本文采用磁控溅射法,在qv(Ar)∶qv(O2) =90∶0.3时得到单相p型Cu2O薄膜,电阻率为88.5 Ω·cm,霍尔迁移率为16.9 cm2·V-1·s-1,载流子浓度为4.19×1015cm-3.并结合Cu2O-ZnO异质结能带结构的研究,对Cu2O-ZnO异质结太阳能电池今后的研究提出了一些建议.

  14. Cytotoxicity of cuprous oxide nanoparticles to fish blood cells: hemolysis and internalization

    Energy Technology Data Exchange (ETDEWEB)

    Chen Liqiang, E-mail:; Kang Bin [Yunnan University, Asian International Rivers Center, Yunnan Key Laboratory of International Rivers and Trans-boundary Eco-security (China); Ling Jian [Yunnan University, College of Chemistry and Chemical Engineering (China)


    Cuprous oxide nanoparticles (Cu{sub 2}O NPs) possess unique physical and chemical properties which are employed in a broad variety of applications. However, little is known about the adverse effects of Cu{sub 2}O NPs on organisms. In the current study, in vitro cytotoxicity of Cu{sub 2}O NPs (ca. 60 nm in diameter) to the blood cells of freshwater fish Carassius auratus was evaluated. A concentration-dependent hemolytic activity of Cu{sub 2}O NPs to red blood cells (RBCs) and the phagocytosis of Cu{sub 2}O NPs by leukocytes were revealed. The results showed that dosages of Cu{sub 2}O NPs greater than 40 {mu}g/mL were toxic to blood cells, and could cause serious membrane damage to RBCs. The EC{sub 50} value of Cu{sub 2}O NPs as obtained from RBCs and whole blood exposure was 26 and 63 {mu}g/mL, respectively. The generation of reactive oxygen species and the direct interaction between Cu{sub 2}O NPs and the cell membrane were suggested as the possible mechanism for cytotoxicity, and the intrinsic hemolytic active of Cu{sub 2}O NPs was the main contributor to the toxicity rather than solubilized copper ions. The adsorption of plasma proteins on the surfaces of Cu{sub 2}O NPs led to their aggregation in whole blood, and aggregate formation can significantly alleviate the hemolytic effect and subsequently mediate the phagocytosis of Cu{sub 2}O NPs by leukocytes.

  15. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)


    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  16. Ab initio study of heterojunction discontinuities in the ZnO/Cu2O system (United States)

    Zemzemi, M.; Alaya, S.; Ben Ayadi, Z.


    Solar cells based on transparent conductive oxides such as ZnO/Cu2O constitute a very advanced way to build high-performance cells. In this work, we are interested in the characterization of the interface through nanoscale modeling based on ab initio approaches (density functional theory, local density approximation, and pseudopotential). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconducting to another phase. We build a zinc oxide in the wurtzite structure along [0001] on which we place the copper oxide in the hexagonal (CdI2-type) structure. We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well the density functional theory. Our calculation of the band offset gives a value that corresponds to other experimental and theoretical values.

  17. Hydrometallurgical process for the recycling of copper using anodic oxidation of cuprous ammine complexes and flow-through electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Oishi, T.; Yaguchi, M.; Koyama, K.; Tanaka, M. [Metals Recycling Group, Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Lee, J.-C. [Minerals and Materials Processing Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30 Gajeong-dong, Yuseong-ku, Daejeon 305-350 (Korea)


    Flow-through electrolysis for copper electrowinning from cuprous ammine complex was studied in order to develop a hydrometallurgical copper recycling process using an ammoniacal chloride solution, focusing on the anodic oxidation of cuprous to cupric ammine complexes. The current efficiency of this anodic oxidation was 96% at a current density of 200 A m{sup -2} under a batch condition. In a flow-through electrolysis using a sub-liter cell and a carbon felt anode, the anodic current efficiency increased with the flow rate and was typically higher than 97%. This tendency was explained by the backward flow of the cupric ammine complex, which was formed on the anode, through the diaphragm. The anodic overpotential was lower than 0.3 V even at an apparent current density of 1500 A m{sup -2}. A similar current efficiency and overpotential were also achieved in a liter scale cell, which indicates the scale flexibility of this electrolysis. The power consumption requirements for copper electrowinning in this cell were 460 and 770 kWh t{sup -1} at the current densities of 250 and 500 A m{sup -2}, respectively, which were much lower than that of the conventional copper electrowinning despite the longer interpolar distance. (author)

  18. Flexible carbon nanotube--Cu2O hybrid electrodes for li-ion batteries. (United States)

    Goyal, Anubha; Reddy, Arava L M; Ajayan, Pulickel M


    This study demonstrates the formation of a flexible and free-standing carbon nanotube-copper oxide-poly(vinylidene fluoride) (CNT-Cu(2) O-PVDF) nanocomposite and its application as an electrode-separator material for Li-ion batteries. Binder-free hybrid electrodes are obtained by conformally coating CNTs with Cu(2) O via electrodeposition and then embedding the resulting architecture into a porous poly(vinylidene fluoride-hexafluoropropylene) PVDF-HFP-SiO(2) polymer electrolyte membrane. The synergistic presence of high-capacity transition metal oxides and conductive CNTs results in twice the reversible areal capacity of 2.3 mAh cm(-2) as compared to 1.2 mAh cm(-2) for pure CNTs.

  19. Investigation of Coral-Like Cu2O Nano/Microstructures as Counter Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Chih-Hung Tsai


    Full Text Available In this study, a chemical oxidation method was employed to fabricate coral-like Cu2O nano/microstructures on Cu foils as counter electrodes (CEs for dye-sensitized solar cells (DSSCs. The Cu2O nano/microstructures were prepared at various sintering temperatures (400, 500, 600 and 700 °C to investigate the influences of the sintering temperature on the DSSC characteristics. First, the Cu foil substrates were immersed in an aqueous solution containing (NH42S2O8 and NaOH. After reacting at 25 °C for 30 min, the Cu substrates were converted to Cu(OH2 nanostructures. Subsequently, the nanostructures were subjected to nitrogen sintering, leading to Cu(OH2 being dehydrated into CuO, which was then deoxidized to form coral-like Cu2O nano/microstructures. The material properties of the Cu2O CEs were comprehensively determined using a scanning electron microscope, energy dispersive X-ray spectrometer, X-ray diffractometer, Raman spectrometer, X-ray photoelectron spectroscope, and cyclic voltameter. The Cu2O CEs sintered at various temperatures were used in DSSC devices and analyzed according to the current density–voltage characteristics, incident photon-to-current conversion efficiency, and electrochemical impedance characteristics. The Cu2O CEs sintered at 600 °C exhibited the optimal electrode properties and DSSC performance, yielding a power conversion efficiency of 3.62%. The Cu2O CEs fabricated on Cu foil were generally mechanically flexible and could therefore be applied to flexible DSSCs.

  20. Preparation of 3D nanoporous copper-supported cuprous oxide for high-performance lithium ion battery anodes. (United States)

    Liu, Dequan; Yang, Zhibo; Wang, Peng; Li, Fei; Wang, Desheng; He, Deyan


    Three-dimensional (3D) nanoporous architectures can provide efficient and rapid pathways for Li-ion and electron transport as well as short solid-state diffusion lengths in lithium ion batteries (LIBs). In this work, 3D nanoporous copper-supported cuprous oxide was successfully fabricated by low-cost selective etching of an electron-beam melted Cu(50)Al(50) alloy and subsequent in situ thermal oxidation. The architecture was used as an anode in lithium ion batteries. In the first cycle, the sample delivered an extremely high lithium storage capacity of about 2.35 mA h cm(-2). A high reversible capacity of 1.45 mA h cm(-2) was achieved after 120 cycles. This work develops a promising approach to building reliable 3D nanostructured electrodes for high-performance lithium ion batteries.

  1. Decay and coherence of two-photon excited yellow orthoexcitons in Cu2O

    NARCIS (Netherlands)

    Karpinska, Katarzyna; Mostovoy, M; van der Vegte, MA; Revcolevschi, A; van Loosdrecht, PHM


    Photoluminescence excitation spectroscopy has revealed a highly efficient two-photon excitation method to produce a cold, uniformly distributed high density excitonic gas in bulk cuprous oxide. A study of the time evolution of the density, temperature, and chemical potential of the exciton gas shows

  2. Prototype of a scalable core-shell Cu 2O/TiO 2 solar cell (United States)

    Li, Dongdong; Chien, Chung-Jen; Deora, Suvil; Chang, Pai-Chun; Moulin, Etienne; Lu, Jia G.


    Titanium oxide (TiO2) nanotube membranes are synthesized via a two-step anodization method. The conductivity at the crystallized barrier layer is enhanced by NH4Cl treatment. This facilitates electrodeposition of Cu2O into TiO2 nanotubes, creating Cu2O/TiO2p-n heterojunctions in the radial direction. The photovoltaic performances benefit from the increased junction interface as well as the efficient pathway for separated charges to transport through the one-dimensional channel. Such heterojunction system serves as a promising candidate for solid-state solar cell due to its scalability, abundancy, low cost and environmental friendly nature. In addition, this versatile process can be conducted on various materials with the potential applications in photovoltaics, supercapacitor, battery, catalyst, etc.

  3. Optical Study of Cuprous Oxide and Ferric Oxide Based Materials for Applications in Low Cost Solar Cells (United States)

    Than, Thi Cuc; Bui, Bao Thoa; Wegmuller, Benjamin; Nguyen, Minh Hieu; Hoang Ngoc, Lam Huong; Bui, Van Diep; Nguyen, Quoc Hung; Hoang, Chi Hieu; Nguyen-Tran, Thuat


    One of the interesting forms of cuprous oxide and ferric oxide based materials is CuFeO2 which can be a delafossite-type compound and is a well known p-type semiconductor. This compound makes up an interesting family of materials for technological applications. CuFeO2 thin films recently gained renewed interest for potential applications in solar cell devices especially as absorption layers. One of the interesting facts is that CuFeO2 is made from cheap materials such as copper and iron. In this study, CuFeO2 thin films are intentionally deposited on corning glass and silicon substrates by the radio-frequency and direct current sputtering method with complicated and well developed co-sputtering recipes. The deposition was performed at room temperature which leads to an amorphous phase with extremely low roughness and high density. The films also were annealed at 500°C in 5% H2 in Ar for the passivation. A detailed optical study was performed on these thin films by spectroscopic ellipsometry and by ultra-violet visible near infrared spectroscopy. Depending on sputtering conditions, the direct band gap was extrapolated to be from 1.96 eV to 2.2 eV and 2.92 eV to 2.96 eV and the indirect band gap is about 1.22 eV to 1.42 eV. A good electrical conduction is also observed which is suitable for solar cell applications. In future more study on the structural properties will be carried out in order to fully understand these materials.

  4. Synthesis of Cu or Cu2O-polyimide nanocomposites using Cu powders and their optical properties (United States)

    Choi, Dong Joo; Maeng, Ju Sung; Ahn, Key-one; Jung, Myoung Jin; Song, Seok Ho; Kim, Young-Ho


    Nanocomposites consisting of Cu or Cu2O nanoparticles in various polyimide (PI) films were successfully prepared using polyamic acid (PAA) and Cu powders. Cu powders were dissolved into PAA solutions, and the solutions were spin-coated onto the substrates. Cu or Cu2O nanoparticles were formed in PI film by curing in a reducing or inert atmosphere, respectively. The Cu nanoparticles were transformed to Cu2O nanoparticles by post-heat treatment in an oxidizing atmosphere after curing in a reducing atmosphere. Transmission electron microscopy showed that uniform, round Cu2O nanoparticles 6.0 nm in diameter were dispersed in the PI film by post-heat treatment. The addition of Cu2O nanoparticles in the 4,4‧-(hexafluoroisopropylidene)diphthalic anhydride-4,4‧-oxydianiline (6FDA-ODA) PI film enhanced the refractive index of the 6FDA-ODA PI film from 1.60 to 1.72 at 633 nm, and the transparency of the nanocomposite film was about 70-90% in the visible region and remained around 90% beyond 550 nm.

  5. Photocatalytic performance of Cu2O-loaded TiO2/rGO nanoheterojunctions obtained by UV reduction. (United States)

    Dong, Kaituo; He, Jiandong; Liu, Junxue; Li, Fengting; Yu, Lianqing; Zhang, Yaping; Zhou, Xiaoyan; Ma, Hongzhang


    A novel dot-like Cu2O-loaded TiO2/reduced graphene oxide (rGO) nanoheterojunction was synthesized via UV light reduction for the first time. Cu2O with size of ca. 5 nm was deposited on rGO sheet and TiO2 nanosheets. The products were characterized by infrared spectroscopy, Raman spectrum, UV-Vis diffuse reflectance spectra, XPS techniques, photoluminescence spectra. The results demonstrated that Cu2O and rGO enhanced the absorption for solar light, separation efficiency of electron-hole pairs, charge shuttle and transfer, and eventually improved photoelectrochemical and photocatalytic performance for contaminants degradation. The reaction time and anion precursor could affect the final copper-containing phase. As extending UV irradiation time, Cu(2+) was be first reduced to Cu2O and then transformed to metal Cu. In comparison with CH3COO(-) (copper acetate), NO3(-) (copper nitrate) and Cl(-) (copper chloride), SO4(2-) (copper sulfate) was the optimum for synthesizing pure Cu2O phase.

  6. Cuprous oxide nanoparticles inhibit prostate cancer by attenuating the stemness of cancer cells via inhibition of the Wnt signaling pathway (United States)

    Wang, Ye; Yang, Qi-Wei; Yang, Qing; Zhou, Tie; Shi, Min-Feng; Sun, Chen-Xia; Gao, Xiu-Xia; Cheng, Yan-Qiong; Cui, Xin-Gang; Sun, Ying-Hao


    Disordered copper metabolism plays a critical role in the development of various cancers. As a nanomedicine containing copper, cuprous oxide nanoparticles (CONPs) exert ideal antitumor pharmacological effects in vitro and in vivo. Prostate cancer is a frequently diagnosed male malignancy prone to relapse, and castration resistance is the main reason for endocrine therapy failure. However, whether CONPs have the potential to treat castration-resistant prostate cancer is still unknown. Here, using the castration-resistant PC-3 human prostate cancer cell line as a model, we report that CONPs can selectively induce apoptosis and inhibit the proliferation of cancer cells in vitro and in vivo without affecting normal prostate epithelial cells. CONPs can also attenuate the stemness of cancer cells and inhibit the Wnt signaling pathway, both of which highlight the great potential of CONPs as a new clinical castration-resistant prostate cancer therapy.

  7. P-type Cu2O/SnO bilayer thin film transistors processed at low temperatures

    KAUST Repository

    Al-Jawhari, Hala A.


    P-type Cu2O/SnO bilayer thin film transistors (TFTs) with tunable performance were fabricated using room temperature sputtered copper and tin oxides. Using Cu2O film as capping layer on top of a SnO film to control its stoichiometry, we have optimized the performance of the resulting bilayer transistor. A transistor with 10 nm/15 nm Cu2O to SnO thickness ratio (25 nm total thickness) showed the best performance using a maximum process temperature of 170 C. The bilayer transistor exhibited p-type behavior with field-effect mobility, on-to-off current ratio, and threshold voltage of 0.66 cm2 V-1 s-1, 1.5×10 2, and -5.2 V, respectively. The advantages of the bilayer structure relative to single layer transistor are discussed. © 2013 American Chemical Society.

  8. Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite. (United States)

    Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong


    Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

  9. White-light-controlled resistive switching chearacteristics of TiO2/Cu2O composite nanorods array (United States)

    Sun, Bai; Liu, Yonghong; Lou, Fangming; Chen, Peng


    TiO2/Cu2O composite nanorods array were grown on fluorine-doped tin oxide (FTO) substrate by hydrothermal process, and white-light-controlled resistive switching characteristics of Ag/[TiO2/Cu2O]/FTO structure were further investigated. The current-voltage characteristics of the composite nanorods array represent a good rectifying property and bipolar resistive switching behavior. Specially, the resistive switching behavior can be regulated by white-light illuminating at room temperature. This study is helpful for exploring the memory materials and their applications in nonvolatile light-controlled memory devices.

  10. Cu2O/ZnO复合光催化剂的制备及对甲基蓝的降解%Preparation of Cu2O/ZnO composite photocatalyst and degradation of methyl blue

    Institute of Scientific and Technical Information of China (English)



    Cu2O was fixed by ZnO carrier,Cu2O/ZnO composite photocatalyst was prepared by dip-reduction-air oxidation process in this paper.Cu2O/ZnO composite photocatalyst had better light catalytic properties by controlling reactant ratio,drying temperature and drying time.The composite photocatalyst was used to degrade difficult degradation of acid dye methyl blue in the environment of the common.The influence factors of illumination time,catalyst dosing quantity,pH and initial concentration of solution were investigated.The results showed that the removal rate of methyl blue was 92% incandescent lamp irradiation 60 min.%以ZnO为载体,用其固定Cu2O,利用浸渍-还原-空气氧化法制备Cu2O/ZnO复合光催化剂.通过控制投料比、干燥温度和干燥时间等因素,得到了具有较好光催化性能的Cu2O/ZnO复合光催化剂.利用这种复合光催化剂对环境中常见的难降解的酸性染料甲基蓝进行降解,考察了光照时间、催化剂投加量、溶液pH值、溶液的初始质量浓度等因素对光催化性能的影响.结果表明,在白炽灯照射下反应60 min后,甲基蓝的去除率为92%.

  11. Interfacial effects of the Cu2O nano-dots decorated Co3O4 nanorods array and its photocatalytic activity for cleaving organic molecules (United States)

    Qiu, X. P.; Yu, J. S.; Xu, H. M.; Chen, W. X.; Hu, W.; Chen, G. L.


    A heterogeneous nanocomposite catalyst constructed by the Co3O4 nanorods decorated with the Cu2O quantum dots (QDs) were successfully synthesized via a simple hydrothermal method followed by an oxidation-reduction processing. The fabricated Cu2O/Co3O4 nanocomposite was characterized by the SEM, TEM, XPS, XRD, UV-vis and PL, and the (2 2 0) and (3 1 1) facets of the Co3O4 were exposed. Compared with the original Co3O4 nanorods with an average diameter of 350 nm, a substantial decrease in the band gap was observed after doping the nanorods with the Cu2O QDs (average diameter of 5 nm). Such a dramatic decrease in the band gap indicated a significant enhancement of the photocatalytic activities under visible light. The methylene blue (MB) dye and the phenol were used as model organic pollutants, and the Cu2O/Co3O4 nanocomposite catalyst exhibited both high catalytic activity and good recycling stability. The catalytic activities of the Cu2O/Co3O4/potassium monopersulfate triple salt (PMS) system for cleaving the MB and the phenol were dependent on the dosages of the Cu2O QDs, and the calculated degradation rates achieved by 7.0 wt% Cu2O/Co3O4 nanocomposite catalyst were about 11.3 and 1.8 times than that of the pristine Co3O4 nanorod catalyst for the MB and the phenol, respectively. The reactive species of rad O2- and the holes were determined to be the main active species for the phenol photocatalytic degradation by the 7 wt% Cu2O/Co3O4/PMS system and the 7 wt% Cu2O/Co3O4/H2O2 system, respectively.

  12. Indium-free, highly transparent, flexible Cu2O/Cu/Cu2O mesh electrodes for flexible touch screen panels (United States)

    Kim, Dong-Ju; Kim, Hyo-Joong; Seo, Ki-Won; Kim, Ki-Hyun; Kim, Tae-Wong; Kim, Han-Ki


    We report on an indium-free and cost-effective Cu2O/Cu/Cu2O multilayer mesh electrode grown by room temperature roll-to-roll sputtering as a viable alternative to ITO electrodes for the cost-effective production of large-area flexible touch screen panels (TSPs). By using a low resistivity metallic Cu interlayer and a patterned mesh structure, we obtained Cu2O/Cu/Cu2O multilayer mesh electrodes with a low sheet resistance of 15.1 Ohm/square and high optical transmittance of 89% as well as good mechanical flexibility. Outer/inner bending test results showed that the Cu2O/Cu/Cu2O mesh electrode had a mechanical flexibility superior to that of conventional ITO films. Using the diamond-patterned Cu2O/Cu/Cu2O multilayer mesh electrodes, we successfully demonstrated TSPS of the flexible film-film type and rigid glass-film-film type TSPs. The TSPs with Cu2O/Cu/Cu2O mesh electrode were used to perform zoom in/out functions and multi-touch writing, indicating that these electrodes are promising cost-efficient transparent electrodes to substitute for conventional ITO electrodes in large-area flexible TSPs.

  13. Light scattering by subwavelength Cu2O particles (United States)

    Ullah, Kaleem; Liu, Xuefeng; Yadav, N. P.; Habib, Muhammad; Song, Li; García-Cámara, Braulio


    Novel metamaterials with new capabilities to manipulate light may be used by considering basic building blocks with new optical properties. This is the case with resonant magneto-dielectric particles. In this work, the resonant response of a high-dielectric Cu2O subwavelength particle is analyzed, both analytically and experimentally. The emergence of electric and magnetic resonances and their interferential effects, producing directional behaviors, can be used in a new generation of metamaterials, as well as new integrated optical devices.

  14. Cuprous Oxide as a Potential Low-Cost Hole-Transport Material for Stable Perovskite Solar Cells. (United States)

    Nejand, Bahram Abdollahi; Ahmadi, Vahid; Gharibzadeh, Saba; Shahverdi, Hamid Reza


    Inorganic hole-transport materials are commercially desired to decrease the fabrication cost of perovskite solar cells. Here, Cu2O is introduced as a potential hole-transport material for stable, low-cost devices. Considering that Cu2O formation is highly sensitive to the underlying mixture of perovskite precursors and their solvents, we proposed and engineered a technique for reactive magnetron sputtering. The rotational angular deposition of Cu2O yields high surface coverage of the perovskite layer for high rate of charge extraction. Deposition of this Cu2O layer on the pinhole-free perovskite layer produces devices with power conversion efficiency values of up to 8.93%. The engineered Cu2O layers showed uniform, compact, and crack-free surfaces on the perovskite layer without affecting the perovskite structure, which is desired for deposition of the top metal contact and for surface shielding against moisture and mechanical damages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Effect of gate dielectrics on the performance of p-type Cu2O TFTs processed at room temperature

    KAUST Repository

    Al-Jawhari, Hala A.


    Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling -0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of -2V. The advantages of using STO as a gate dielectric relative to ATO are discussed. © (2014) Trans Tech Publications, Switzerland.

  16. Indium-free, highly transparent, flexible Cu2O/Cu/Cu2O mesh electrodes for flexible touch screen panels


    Dong-Ju Kim; Hyo-Joong Kim; Ki-Won Seo; Ki-Hyun Kim; Tae-Wong Kim; Han-Ki Kim


    We report on an indium-free and cost-effective Cu2O/Cu/Cu2O multilayer mesh electrode grown by room temperature roll-to-roll sputtering as a viable alternative to ITO electrodes for the cost-effective production of large-area flexible touch screen panels (TSPs). By using a low resistivity metallic Cu interlayer and a patterned mesh structure, we obtained Cu2O/Cu/Cu2O multilayer mesh electrodes with a low sheet resistance of 15.1?Ohm/square and high optical transmittance of 89% as well as good...

  17. Intrinsic deep hole trap levels in $Cu_{2}O$ with self-consistent repulsive Coulomb energy


    Huang, Bolong


    The large error of the DFT+U method on full-filled shell metal oxides is due to the residue of self-energy from the localized d orbitals of cations and p orbitals of the anions. U parameters are self-consistently found to achieve the analytical self-energy cancellation. The improved band structures based on relaxed lattices of ${Cu_{2}O}$ are shown based on minimization of self-energy error. The experimentally reported intrinsic p-type trap levels are contributed by both Cu-vacancy and the O-...

  18. Punicalagin Green Functionalized Cu/Cu2O/ZnO/CuO Nanocomposite for Potential Electrochemical Transducer and Catalyst (United States)

    Fuku, X.; Kaviyarasu, K.; Matinise, N.; Maaza, M.


    A novel ternary Punica granatum L-Cu/Cu2O/CuO/ZnO nanocomposite was successfully synthesised via green route. In this work, we demonstrate that the green synthesis of metal oxides is more viable and facile compare to other methods, i.e., physical and chemical routes while presenting a potential electrode for energy applications. The prepared nanocomposite was characterised by both microscopic and spectroscopic techniques. High-resolution scanning electron microscopy (HRSEM) and X-ray diffraction (XRD) techniques revealed different transitional phases with an average nanocrystallite size of 29-20 mm. It was observed that the nanocomposites changed from amorphous-slightly crystalline Cu/Cu2O to polycrystalline Cu/Cu2O/CuO/ZnO at different calcination temperatures (room temperature-RT- 600 °C). The Cu/Cu2O/ZnO/CuO metal oxides proved to be highly crystalline and showed irregularly distributed particles with different sizes. Meanwhile, Fourier transform infrared (FTIR) spectroscopy confirmed the purity while together with ultraviolet-visible (UV-Vis) spectroscopy proved the proposed mechanism of the synthesised nanocomposite. UV-Vis showed improved catalytic activity of the prepared metal oxides, evident by narrow band gap energy. The redox and electrochemical properties of the prepared nanocomposite were achieved by cyclic voltammetry (CV), electrochemical impedance (EIS) and galvanostatic charge-discharge (GCD). The maximum specific capacitance ( C s) was calculated to be 241 F g-1 at 50 mV s-1 for Cu/Cu2O/CuO/ZnO nanoplatelets structured electrode. Moreover, all the CuO nanostructures reveal better power performance, excellent rate as well as long term cycling stability. Such a study will encourages a new design for a wide spectrum of materials for smart electronic device applications.

  19. Synthesis of Cu2 O nanoparticle and amperometric detection of dopamine based on Cu2 O modified electrode%纳米Cu2 O材料的合成及其修饰电极安培法测定多巴胺

    Institute of Scientific and Technical Information of China (English)

    吴芳辉; 程立春; 陈乐; 宋超; 张奥亚; 梅洁


    In this work,a one-step,simple route towards synthesizing cuprous oxide( Cu2 O) nanoparticles with uniform particle size was explored using chemical reduction method. Then nanomaterial of Cu2 O was characterized by scanning electron microscopy ( SEM). In pH 7. 0 phosphate buffer solution,Cu2 O and Nafion complex modified electrode exhibited a strong electrocatalytic effect to dopamine( DA) compare with the bare glassy carbon electrode. Under the optimized experimental conditions,an electroanalytical system of trace dopamine was established based on chronoamperometry of electrocatalytic properties of Cu2 O modified electrode. The detection limit is 0. 17 μmol·L-1 with the sensitivity of 20. 44 μA mM-1 and the reaction time of less than 3 s in a concentration range of 0. 5~270 μmol·L-1 . The concentration of dopamine was able to be accurately measured at 20 times the AA coexistence due to increase Nafion film. The results of voltammetric determinations show a good reproducibility and stability,and the relative standard deviation ( RSD ) was 3. 3% for the slope of the calibration curve based on the 11 measurements of 50 μM dopamine. Moreover,the developed sensor could be successfully applied to determine dopamine in simulation preparations.%本文采用简单的一步化学还原方法合成了粒径均一的纳米Cu2 O材料并采用扫描电子显微镜对其形貌进行了表征。研究发现,在pH 7.0的磷酸盐缓冲溶液中,采用纳米Cu2 O和Nafion(全氟磺酸离子交换树脂)膜制备的复合修饰电极对多巴胺( DA)呈现出较强的电化学催化作用。优化实验条件后,建立了计时电流法直接测定多巴胺的痕量分析体系。在0.5~270μmol·L-1浓度范围内,多巴胺的阳极峰电流与浓度呈良好的线性关系(r=0.9980),检测限为0.17μmol·L-1,灵敏度为20.44μA mM-1且响应时间不超过3 s。该电极可有效屏蔽抗坏血酸( AA)的干扰,在20倍AA共存下

  20. Cu/Cu2O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization (United States)

    Sahai, Anshuman; Goswami, Navendu; Kaushik, S. D.; Tripathi, Shilpa


    In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanoparticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu2O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (μR) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. μR investigations vividly reveal cubic Cu2O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with μRaman analysis, FTIR stretching modes corresponding to Cu2-O and Cu-O were also distinguished. Investigations of μR and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu2O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu2O/CuO nanoparticles are reflected through UV-vis (UV-vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes occurring therein. Iterative X-ray photoelectron spectroscopy (XPS) fitting of core level spectra of Cu (2p3/2) and O (1s), divulges presence of Cu2+ and Cu+ in the lattice with an interesting evidence of O deficiency in the lattice structure and surface adsorption. Magnetic analysis illustrates that the prepared nanomaterial demonstrates ferromagnetic behaviour at room temperature.

  1. Photocatalytic performance of Cu2O composite octahedra prepared by a propanetriol-reduced process (United States)

    Zhang, Lihui; Wang, Xiangfu


    Cu2O and Ag/Cu2O composite octahedra were synthesized via a hydrothermal reaction of CuAc2 with urea in H2O-propanetriol binary solution by adjusting the quantity of AgNO3 at 180 °C for 10 h. The influence of reaction temperature and time on the morphology and phase of the products was investigated, and a possible growth mechanism of Cu2O octahedron was also proposed. The photocatalytic activities of the as-prepared Cu2O and Ag/Cu2O octahedra for the degradation of methyl orange aqueous solution were studied. The results show that they are effective photocatalysts for the degradation of methyl orange, and the photocatalytic ability of Ag/Cu2O composite is stronger than that of Cu2O octahedra, which are expected to be useful in the treatment of wastewaters.

  2. Nonlinear optical properties of bulk cuprous oxide using single beam Z-scan at 790 nm

    Energy Technology Data Exchange (ETDEWEB)

    Serna, J.; Rueda, E. [Grupo de Óptica y Fotónica, Instituto de Física, Universidad de Antioquia U de A, Calle 70 No. 52-21, Medellín (Colombia); García, H., E-mail: [Department of Physics, Southern Illinois University, Edwardsville, Illinois 60026 (United States)


    The two-photon absorption (TPA) coefficient β and the nonlinear index of refraction n{sub 2} for bulk cuprous oxide (Cu{sub 2}O) direct gap semiconductor single crystal have been measured by using a balance-detection Z-scan single beam technique, with an excellent signal to noise ratio. Both coefficients were measured at 790 nm using a 65 fs laser pulse at a repetition rate of 90.9 MHz, generated by a Ti:Sapphire laser oscillator. The experimental values for β were explained by using a model that includes allowed-allowed, forbidden-allowed, and forbidden-forbidden transitions. It was found that the forbidden-forbidden transition is the dominant mechanism, which is consistent with the band structure of Cu{sub 2}O. The low value for β found in bulk, as compared with respect to thin film, is explained in terms of the structural change in thin films that result in opposite parities of the conduction and valence band. The n{sub 2} is also theoretically calculated by using the TPA dispersion curve and the Kramers-Kronig relations for nonlinear optics.

  3. Indium-free, highly transparent, flexible Cu2O/Cu/Cu2O mesh electrodes for flexible touch screen panels

    National Research Council Canada - National Science Library

    Kim, Dong-Ju; Kim, Hyo-Joong; Seo, Ki-Won; Kim, Ki-Hyun; Kim, Tae-Wong; Kim, Han-Ki


    ... production of large-area flexible touch screen panels (TSPs). By using a low resistivity metallic Cu interlayer and a patterned mesh structure, we obtained Cu2O/Cu/Cu2O multilayer mesh electrodes with a low sheet resistance of 15.1...

  4. MgO/Cu2O Superlattices: Growth of Epitaxial Two-Dimensional Nanostructures (United States)

    Yang, M. J.; Wadekar, P. V.; Hsieh, W. C.; Huang, H. C.; Lin, C. W.; Chou, J. W.; Liao, C. H.; Chang, C. F.; Seo, H. W.; You, S. T.; Tu, L. W.; Lo, I. K.; Ho, N. J.; Yeh, S. W.; Liao, H. H.; Chen, Q. Y.; Chu, W. K.


    Alternated stacking of dissimilar layers can produce novel superlattice materials with multiple functionalities. The majority of such work reported in literature on epitaxial superlattices has been on alternating layers with the same space group (SG) and crystal structure (CS), whereas superlattices with the same CS but different SG have not been studied as much. We have grown superlattices with two well-known oxide materials, viz. cuprite (Cu2O, CS = cubic and SG = Pn bar{3} m) and magnesium oxide (MgO, CS = cubic, SG = Fm bar{3} m). An MgO buffer layer grown near 650°C at the film-substrate interface was found to be essential to achieving reasonable long-range atomic order. Grazing-angle x-ray diffraction, x-ray reflectivity, and electron diffraction analyses as well as transmission electron microscopy were used to investigate the interface abruptness, smoothness, and general crystallinity of the individual layers. Interdiffusion between MgO and Cu2O near interfacial regions places a limit of 250°C on the growth temperature for fabrication of superlattices with reasonably sharp interfaces.

  5. Band offset of the ZnO/Cu2O heterojunction from ab initio calculations (United States)

    Zemzemi, M.; Alaya, S.


    The ZnO/Cu2O system has known a recent revival of interest in solar cells for its potential use as a heterojunction able to highly perform under visible light. In this work, we are interested on the characterization of the interface through nanoscale modelization based on ab initio (Density Functional Theory (DFT), Local Density Approximation (LDA), Generalized Gradient Approximation (GGA-PBE), and Pseudopotential (PP)). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconductor to another. We built a zinc oxide in the wurtzite structure along the [0 0 0 1] on which we placed the copper oxide in the hexagonal structure (CdI2-type). We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well with the DFT. Our calculations of the band offset gave us a value that corresponds to other experimental and theoretical values.

  6. Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment(Conference Presentation) (United States)

    Sharma, Dipika; Satsangi, Vibha R.; Dass Kaura, Sahab; Shrivastav, Rohit; Waghmare, Umesh V.


    -principles calculations compare well, thus suggesting that such calculations have the potential to be used in screening various metal oxide heterojunction before performing the experiments thereby saving precious chemicals, time and energy. Keywords: Photoelectrochemical, Water splitting, heterojunction, Cu2O, BaTiO3 References: [1] Surbhi Choudhary, et al. Nanostructured bilayered thin films in photoelectrochemical water splitting - A review: International Journal of Hydrogen Energy, (2012). [2] Dipika Sharma, Anuradha Verma, V.R. Satsangi, Rohit shrivastav, Sahab Dass Nanostructured SrTiO3 thin films sensitized by Cu2O for Photoelectrochemical Hydrogen Generation. International journal of Hydrogen Energy;42:,4230-4241, 2014.

  7. Optical and Morphological Characterization of Sonochemically Assisted Europium Doped Copper (I) Oxide Nanostructures (United States)

    Cosico, J. A. M.; Ruales, P. K.; Marquez, M. C.


    In the age where application of nanotechnology in our society has proven to be eminent, different routes of synthesizing nanoparticles have emerged. In this study nanoparticles of cuprous oxide (Cu2O) doped with different amounts of europium was prepared by using solution precursor route approach with the aid of ultrasonic sound. Copper sulphate and europium (III) nitrate pentahydrate was used as source for copper ions and europium ions respectively. X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) were used to elucidate the cubic crystal structure and organic impurities present on Cu2Onanoparticles. UV-Vis spectroscopy was used to determine the absorption spectrum of the nanoparticles in the wavelength range of 400nm to 700nm. The bandgap of the undoped and doped Cu2O were found to fall between 2.1eV - 2.3eV. Scanning Electron Microscopy (SEM) coupled with energy dispersive x-ray was used to observe the dendritic and rodlike morphology and the presence of europium in the synthesized Cu2O nanoparticles. The observed effect on the absorbance of Cu2O upon adding Eu and a facile way of synthesizing Cu2O nanoparticles could bring a positive impact on the production of functional devices for optoelectronic and energy applications.

  8. Intrinsic deep hole trap levels in Cu2O with self-consistent repulsive Coulomb energy (United States)

    Huang, Bolong


    The large error of the DFT+U method on full-filled shell metal oxides is due to the residue of self-energy from the localized d orbitals of cations and p orbitals of the anions. U parameters are selfconsistently found to achieve the analytical self-energy cancellation. The improved band structures based on relaxed lattices of Cu2O are shown based on minimization of self-energy error. The experimentally reported intrinsic p-type trap levels are contributed by both Cu-vacancy and the O-interstitial defects in Cu2O. The latter defect has the lowest formation energy but contributes a deep hole trap level while the Cuvacancy has higher energy cost but acting as a shallow acceptor. Both present single-particle levels spread over nearby the valence band edge, consistent to the trend of defects transition levels. By this calculation approach, we also elucidated the entanglement of strong p-d orbital coupling to unravel the screened Coulomb potential of fully filled shells.

  9. Low-energy (CaCu{2}O{8+δ}. (United States)

    Plumb, N C; Reber, T J; Koralek, J D; Sun, Z; Douglas, J F; Aiura, Y; Oka, K; Eisaki, H; Dessau, D S


    Using low photon energy angle-resolved photoemission, we study the low-energy dispersion along the nodal (π,π) direction in Bi{2}Sr{2}CaCu{2}O{8+δ} as a function of temperature. Less than 10 meV below the Fermi energy, the high-resolution data reveal a novel "kinklike" feature in the electron self-energy that is distinct from the larger well-known kink roughly 70 meV below E{F}. This new kink is strongest below the superconducting critical temperature and weakens substantially at higher temperatures. A corollary of this finding is that the Fermi velocity v{F}, as measured in this low-energy range, varies rapidly with temperature-increasing by almost 30% from 70 to 110 K. The behavior of v{F}(T) appears to shift as a function of doping, suggesting a departure from simple "universality" in the nodal Fermi velocity of cuprates.

  10. Perspective: Maintaining surface-phase purity is key to efficient open air fabricated cuprous oxide solar cells

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye


    Full Text Available Electrochemically deposited Cu2O solar cells are receiving growing attention owing to a recent doubling in efficiency. This was enabled by the controlled chemical environment used in depositing doped ZnO layers by atomic layer deposition, which is not well suited to large-scale industrial production. While open air fabrication with atmospheric pressure spatial atomic layer deposition overcomes this limitation, we find that this approach is limited by an inability to remove the detrimental CuO layer that forms on the Cu2O surface. Herein, we propose strategies for achieving efficiencies in atmospherically processed cells that are equivalent to the high values achieved in vacuum processed cells.

  11. Fabrication by AC Deposition and Antimicrobial Properties of Pyramidal-Shaped Cu2O-TiO2 Heterostructures



    Nanoparticulate surfaces possessing antimicrobial and fungicidal properties under visible light illumination have found wide applications in a number of fields. In this study, titania nanotubes, as well as titania compact films were designed with pure Cu2O crystals in a mildly acidic copper acetate solution using a simple alternating current (AC) deposition approach. In this way, the thermally oxidized Ti substrate was coated by densely packed pyramidal and bipyramidal ...

  12. A novel reducing graphene/polyaniline/cuprous oxide composite hydrogel with unexpected photocatalytic activity for the degradation of Congo red

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Jie; Xie, Anjian; Li, Shikuo; Huang, Fangzhi; Cao, Juan; Shen, Yuhua, E-mail:


    Graphical abstract: Excellent photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel for CR degradation under UV–vis light irradiation. - Highlights: • The RGO/PANI/Cu{sub 2}O composite hydrogel was first synthesized via a facile method. • Photocatalytic performance was studied under UV–vis light. • The ternary composite hydrogel shows unexpected photocatalytic activity. • A possible photocatalysis mechanism was illustrated. - Abstract: In this work, a novel reducing graphene/polyaniline/cuprous oxide (RGO/PANI/Cu{sub 2}O) composite hydrogel with a 3D porous network has been successfully prepared via a one-pot method in the presence of cubic Cu{sub 2}O nanoparticles. The as-synthesized ternary composites hydrogel shows unexpected photocatalytic activity such that Congo red (CR) degradation efficiency can reaches 97.91% in 20 min under UV–vis light irradiation, which is much higher than that of either the single component (Cu{sub 2}O nanoparticles), or two component systems (RGO/Cu{sub 2}O composite hydrogel and PANI/Cu{sub 2}O nanocomposites). Furthermore, the ternary composite hydrogel exhibits high stability and do not show any significant loss after five recycles. Such outstanding photocatalytic activity of the RGO/PANI/Cu{sub 2}O composite hydrogel was ascribed to the high absorption ability of the product for CR and the synergic effect among RGO, PANI and Cu{sub 2}O in photocatalytic process. The product of this work would provide a new sight for the construction of UV–vis light responsive photocatalyst with high performance.

  13. Development of Cu2O/Carbon Vulcan XC-72 as non-enzymatic sensor for glucose determination. (United States)

    El Khatib, K M; Abdel Hameed, R M


    A novel and stable non-enzymatic glucose sensor was developed based on the chemical reduction of Cu(2)O nanoparticles on Carbon Vulcan XC-72 using NaBH(4) as the reducing agent via the impregnation method. Different molar ratios of NaBH(4) to the copper salt were employed during the reduction step. This was found to affect the morphology; composition and structure of the prepared samples as investigated by TEM, EDX and XRD analyses. Cyclic voltammetry and chronoamperometry were applied to examine the electrocatalytic activity of the different samples of Cu(2)O/Carbon Vulcan XC-72 towards glucose oxidation in alkaline medium. The 'x70' sample got the highest oxidation current density and the lowest oxidation potential. The performance of this sensor was evaluated showing a wide linear range up to 6mM with sensitivity of 629 μA cm(-2)mM(-1) and detection limit of 2.4 μM. Its good tolerance to ascorbic acid with long-term stability elects Cu(2)O/Carbon Vulcan XC-72 as a promising glucose sensor.

  14. Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

    Directory of Open Access Journals (Sweden)

    Luoxiao Zhou


    Full Text Available Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4 core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2 and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer.

  15. Oxygenation and superconductivity of Tl2CaBa2Cu2O8- x (United States)

    Wu, Nae-Lih; Chu, H. T.


    Oxygenation of Tl 2CaBa 2Cu 2O 8- x between 250°C and 800°C was studied. The curves which plotted the amount of oxygen adsorbed as a function of oxygenation temperature indicated the presence of two oxygen adsorption processes, including one which prevailed at temperature below 400°C and the other between 500°C and 700°C. When the compound was oxygenated consecutively at increasing temperatures, the Tc of the oxide first increased and then decreased, exhibiting a maximum after oxygenation at 400°C. The Tc increased almost linearly with the amounts of oxygen adsorbed below 400°C but showed no unique (one-to-one) correlation with the overall oxygen content of the oxide.

  16. 纳米Cu2O及其复合物的制备及光催化性能研究%Preparation and Photocatalytic Property of Nano Cuprous Oxide and Its Composites

    Institute of Scientific and Technical Information of China (English)

    胥桂萍; 邱黎


    Cu2O powders and TiO2-Cu2O composite powders were prepared by chemical deposi-tion method. With prepared Cu2O nanoparticles as photocatalyst,photocatalytic oxidation degrada-tion of methylene blue solution was explored. The effects of dosage of H2O2,the initial concentration of methylene blue and composite samples on the degradation performance were investigated with UV-visible spectrophotometer. The results showed that the degradation efficiency was the best when the amount of H2O2 was 5mL in 30mL methylene blue solution and the initial concentration of methy-lene blue was 10mg/L,and the catalytic efficiency of TiO2-Cu2O composite powders was much high-er than that of Cu2O.%采用化学沉积法制备Cu2O粉体,并且制备了TiO2-Cu2O复合粉体。以制备的纳米Cu2O为光催化剂,对亚甲基蓝溶液进行光催化氧化降解。通过紫外-可见分光光度计考察了H2O2的加入量、亚甲基蓝的初始浓度及复合样品对降解性能的影响。结果表明,当H2O2的用量在5 mL/30 mL,亚甲基蓝的初始浓度为10 mg/L时降解效果最好;复合粉体的催化效率远高于Cu2O的光催化效率。

  17. Normal mode coordinates of high T c superconductors TlCaBa 2Cu 2O 7 and Tl 2CaBa 2Cu 2O 8 (United States)

    Mori, T.; Nakaoka, K.; Onari, S.; Arai, T.


    Normal mode coordinates of high Tc superconductors TlCaBa 2Cu 2O 7- (Tl-1122) and Tl 2CaBa 2Cu 2O 8(Tl-2122) are analyzed by the shell model calculations. The model calculations have reproduced very well the observed Raman frequencies. The vibrational frequencies of the oxygens on the CuO 2 layers are found to depend on the ionic charges of the oxygens on the CuO 2 layers.

  18. Microfluidic synthesis of Ag@Cu2O core-shell nanoparticles with enhanced photocatalytic activity. (United States)

    Tao, Sha; Yang, Mei; Chen, Huihui; Ren, Mingyue; Chen, Guangwen


    A microfluidic-based method for the continuous synthesis of Ag@Cu2O core-shell nanoparticles (NPs) has been developed. It only took 32s to obtain Ag@Cu2O core-shell NPs, indicating a high efficiency of this microfluidic-based method. Triangular Ag nanoprisms were employed as the cores for the overgrowth of Cu2O through the reduction of Cu(OH)4(2-) with ascorbic acid. The as-synthesized samples were characterized by XRD, TEM, SEM, HAADF-STEM, EDX, HRTEM, UV-vis spectra and N2 adsorption-desorption. The characterization results revealed that the as-synthesized Ag@Cu2O core-shell NPs exhibited a well-defined core-shell nanostructure with a polycrystalline shell, which was composed of numbers of Cu2O domains epitaxially growing on the triangular Ag nanoprism. It was concluded that the synthesis parameters such as the molar ratio of trisodium citrate to AgNO3, H2O2 to AgNO3, NaOH to CuSO4, ascorbic acid to CuSO4 and AgNO3 to CuSO4 had significant effect on the synthesis of Ag@Cu2O core-shell NPs. Moreover, Ag@Cu2O core-shell NPs exhibited superior catalytic activity in comparison with pristine Cu2O NPs towards the visible light-driven degradation of methyl orange. This enhanced photocatalytic activity of Ag@Cu2O core-shell NPs was attributed to the larger BET surface area and improved charge separation efficiency. The trapping experiment indicated that holes and superoxide anion radicals were the major reactive species in the photodegradation of methyl orange over Ag@Cu2O core-shell NPs. In addition, Ag@Cu2O core-shell NPs showed no obvious deactivation in the cyclic test.

  19. Silica-Supported Cu2O Nanoparticles with Tunable Size for Sustainable Hydrogen Generation

    NARCIS (Netherlands)

    Wang, Gang; van den Berg, R.; de Mello-Donega, Celso; de Jong, K.P.; de Jongh, P.E.


    Cu2O is a p-type semiconductor which attracts much attention for application in photovoltaics, photocatalysis and solar water splitting. However, Cu2O is not intrinsically stable under illumination in aqueous solutions, and the edge of the valence band is not positive enough to provide sufficient ov

  20. Electrochemical synthesis and characterization of copper (I oxide

    Directory of Open Access Journals (Sweden)

    Bugarinović Sanja J.


    Full Text Available The quest and need for clean and economical energy sources have increased interest in the development of thin film cells technologies. Electrochemical deposition is an attractive method for synthesis of thin films. It offers the advantages of low synthesis temperature, low cost and high purity. Copper (I oxide or cuprous oxide is an oxide semiconductor which is used as the anodic material in the form of thin film in lithium batteries and solar cells. The cathodic process of synthesis of cuprous oxide thin film is carried out in a potentiostatic mode from the organic electrolyte. The process parameters are chosen in that way to accomplish maximum difference between the potentials at which Cu2O and CuO are obtained. The electrochemical characterization was carried out by cyclic voltammetry. The electrodeposition techniques are particularly well suited for the deposition of single elements but it is also possible to carry out simultaneous depositions of several elements and syntheses of well-defined alternating layers of metals and oxides with thicknesses down to a few nm. Nanomaterials exhibit novel physical properties and play an important role in fundamental research. In addition, cuprous oxide is commonly used as a pigment, a fungicide, and an antifouling agent for marine paints. It is insoluble in water and organic solvents. This work presents the examinations of the influence of bath, temperature, pH and current density on the characteristics of electrochemically synthesized cuprous oxide. In the 'classic' process of synthesis, which is carried out under galvanostatic conditions on the anode, the grain size of the powder decreases with the increase in current density while the grain colour becomes lighter. The best commercial quality of the Cu2O (grain size, colour, content of choride was obtained at the temperature of 80°C, concentration of NaCl of 3 mol/dm3 and current density of 400 A/m2.

  1. Bimetallic AgCu/Cu2O hybrid for the synergetic adsorption of iodide from solution. (United States)

    Mao, Ping; Liu, Ying; Liu, Xiaodong; Wang, Yuechan; Liang, Jie; Zhou, Qihang; Dai, Yuexuan; Jiao, Yan; Chen, Shouwen; Yang, Yi


    To further improve the capacity of Cu2O to absorb I(-) anions from solution, and to understand the difference between the adsorption mechanisms of Ag/Cu2O and Cu/Cu2O adsorbents, bimetallic AgCu was doped into Cu2O through a facile solvothermal route. Samples were characterized and employed to adsorb I(-) anions under different experimental conditions. The results show that the Cu content can be tuned by adding different volumes of Ag sols. After doping bimetallic AgCu, the adsorption capacity of the samples can be increased from 0.02 mmol g(-1) to 0.52 mmol g(-1). Moreover, the optimal adsorption is reached within only 240 min. Meanwhile, the difference between the adsorption mechanisms of Ag/Cu2O and Cu/Cu2O adsorbents was verified, and the cooperative adsorption mechanism of the AgCu/Cu2O hybrid was proposed and verified. In addition, the AgCu/Cu2O hybrid showed excellent selectivity, e.g., its adsorption efficiencies are 85.1%, 81.9%, 85.9% and 85.7% in the presence of the Cl(-), CO3(2-), SO4(2-) and NO3(-) competitive anions, respectively. Furthermore, the AgCu/Cu2O hybrid can worked well in other harsh environments (e.g., acidic, alkaline and seawater environments). Therefore, this study is expected to promote the development of Cu2O into a highly efficient adsorbent for the removal of iodide from solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Plasma-produced phase-pure cuprous oxide nanowires for methane gas sensing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Qijin, E-mail:; Zhang, Fengyan [School of Energy Research, Xiamen University, Xiamen City, Fujian Province 361005 (China); Yan, Wei [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Randeniya, Lakshman [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia)


    Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu{sub 2}O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 10{sup 11}–10{sup 13} cm{sup −3}) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu{sub 2}O nanowires feature fast response and recovery for the low-temperature (∼140 °C) detection of methane gas in comparison with polycrystalline Cu{sub 2}O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu{sub 2}O nanowire-based gas sensors are 125 and 147 s, respectively. The Cu{sub 2}O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

  3. Heteroepitaxial Cu2O thin film solar cell on metallic substrates. (United States)

    Wee, Sung Hun; Huang, Po-Shun; Lee, Jung-Kun; Goyal, Amit


    Heteroepitaxial, single-crystal-like Cu2O films on inexpensive, flexible, metallic substrates can potentially be used as absorber layers for fabrication of low-cost, high-performance, non-toxic, earth-abundant solar cells. Here, we report epitaxial growth of Cu2O films on low cost, flexible, textured metallic substrates. Cu2O films were deposited on the metallic templates via pulsed laser deposition under various processing conditions to study the influence of processing parameters on the structural and electronic properties of the films. It is found that pure, epitaxial Cu2O phase without any trace of CuO phase is only formed in a limited deposition window of P(O2) - temperature. The (00l) single-oriented, highly textured, Cu2O films deposited under optimum P(O2) - temperature conditions exhibit excellent electronic properties with carrier mobility in the range of 40-60 cm(2) V(-1) s(-1) and carrier concentration over 10(16) cm(-3). The power conversion efficiency of 1.65% is demonstrated from a proof-of-concept Cu2O solar cell based on epitaxial Cu2O film prepared on the textured metal substrate.

  4. Morphology transformation of Cu2O by adding TEOA and their antibacterial activity (United States)

    Duan, Weijia; Zheng, Min; Li, Rong; Wang, Yuyuan


    Cu2O polyhedral particles and hollow spheres were successfully synthesized by adjusting the concentration of triethanolamine (TEOA). The as-prepared samples were structurally characterized by the scanning electron microscope (SEM), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results revealed that the solid polyhedral Cu2O with sizes ranging from 70 to 150 nm was in good crystallization. The diameter of the hollow Cu2O spheres increased to 350-450 nm. It was found that the sizes and morphologies of the products could be significantly affected by the concentration of TEOA. And the morphology of Cu2O transformed from solid polyhedrons to hollow spheres with the further enrichment of TEOA concentration. A possible mechanism was proposed to explain the formation of the hollow Cu2O spheres. In addition, we investigated the antibacterial activities of the samples. It was demonstrated that the hollow Cu2O sphere exhibited better antibacterial activities for Escherichia coli ( E. coli) and Staphylococcus aureus ( S. aureus) compared with the solid polyhedral Cu2O.

  5. Cu2O quantum dots emitting visible light grown by atomic layer deposition (United States)

    Lee, Min Young; Kim, Soo-Hyun; Park, Il-Kyu


    This paper reports the fabrication of the Cu2O quantum dots (QDs) emitting a controlled wavelength in the visible spectral range prepared by atomic layer deposition (ALD). Cu2O thin film layers formed on the Al2O3 surface showed large density of islands via Volmer-Weber growth mode, which resulting in QD formation. As the number of ALD cycles was increased from 60 to 480, the spatial density and mean diameter of the Cu2O QDs increased systematically from 4.02 × 1011/cm2 to 2.56×1012/cm2 and from 2.1 to 3.2 nm, respectively. The absorption spectral results indicated that the electron energy transition in the Cu2O QDs was a direct process with the optical band gaps decreasing from 2.71 to 2.15 eV with increasing QD size from 2.1 to 3.2 nm because of the quantum confinement effect. The Cu2O QDs showed broad emission peaks composed of multiple elementary emission spectra corresponding to the Cu2O QD ensembles with a different size distribution. As the size of Cu2O QDs decreased, the shoulder peaks at the higher energy side developed due to the quantum confinement effect.

  6. Nano-structured CuO-Cu2O Complex Thin Film for Application in CH3NH3PbI3 Perovskite Solar Cells (United States)

    Chen, Lung-Chieh; Chen, Cheng-Chiang; Liang, Kai-Chieh; Chang, Sheng Hsiung; Tseng, Zhong-Liang; Yeh, Shih-Chieh; Chen, Chin-Ti; Wu, Wen-Ti; Wu, Chun-Guey


    Nano-structured CuO-Cu2O complex thin film-based perovskite solar cells were fabricated on an indium tin oxide (ITO)-coated glass and studied. Copper (Cu) thin films with a purity of 99.995 % were deposited on an ITO-coated glass by magnetron reactive sputtering. To optimize the properties of the nano-structured CuO-Cu2O complex thin films, the deposited Cu thin films were thermally oxidized at various temperatures from 300 to 400 °C. A CH3NH3PbI3 perovskite absorber was fabricated on top of CuO-Cu2O complex thin film by a one-step spin-coating process with a toluene washing treatment. Following optimization, the maximum power conversion efficiency (PCE) exceeded 8.1 %. Therefore, the low-cost, solution-processed, stable nano-structured CuO-Cu2O complex thin film can be used as an alternative hole transport layer (HTL) in industrially produced perovskite solar cells.

  7. Oxygen vacancy in N-doped Cu2O crystals:A density functional theory study

    Institute of Scientific and Technical Information of China (English)

    Li Min; Zhang Jun-Ying; Zhang Yue; Wang Tian-Min


    The N-doping effects on the electronic properties of Cu2O crystals are investigated using density functional theory.The calculated results show that N-doped Cu2O with or without oxygen vacancy exhibits different modifications of electronic band structure.In N anion-doped Cu2O,some N 2p states overlap and mix with the O 2p valence band,leading to a slight narrowing of band gap compared with the undoped Cu2O.However,it is found that the coexistence of both N impurity and oxygen vacancy contributes to band gap widening which may account for the experimentally observed optical band gap widening by N doping.

  8. Influence of Au Nanoparticle Shape on Au@Cu2O Heterostructures

    Directory of Open Access Journals (Sweden)

    Jie Zhu


    Full Text Available Synthesis of metal-semiconductor heterostructures may allow the combination of function of the corresponding components and/or the enhanced performance resulting from the interactions between all the components. In this paper, Au@Cu2O core-shell heterostructures are prepared by a seed-growth method, using different-shaped Au nanocrystals as the seeds such as nanorods, octahedra, decahedra, dots, and nanocubes. The results revealed that the final structure of Au@Cu2O was greatly influenced by the shape of the seeds used. Exposure of Cu2O{111} and Cu2O{001} favored when the overgrowth happened on Au{111} and Au{001} surface, respectively. The size of the product can also be tuned by the amount of the seeds. The results reported here provide a thinking clue to modulate the shape and size of core-shell nanocrystals, which is useful in developing new materials with desired performance.

  9. Facile synthesis and shape evolution of oleic acid decorated Cu2O microcrystals (United States)

    Xu, Bin; Cao, Xiaohai; Zhu, Bingchun; Lou, Baiyang; Ma, Xiaocun; Li, Xiao; Wang, Yuguang


    A facile synthetic method of oleic acid decorated Cu2O microcrystals has been developed by thermal decomposition of copper formate-octylamine complexes in paraffin using oleic acid as dispersing agent. This new method showed many advantages, which include free-reducing agent, enhancing antioxidant properties of Cu2O and good dispersity in paraffin, etc. The phase structure and morphology were investigated by means of XRD, SEM and TEM. It is found that the reaction time and temperature play the important roles in the crystallite morphology. With the increase of the reaction time, the Cu2O rhombic dodecahedron is gradually transformed into the spherical particle by intraparticle ripening. The shape evolution of Cu2O microcrystals can be accelerated with the increase of temperature.

  10. Facile synthesis of hierarchical Cu2O nanocubes as visible light photocatalysts


    Kumar, Santosh; Parlett, Christopher M A; Isaacs, Mark A.; Jowett, Danielle V.; Douthwaite, Richard E.; Cockett, Martin C.R.; Lee, Adam F.


    Hierarchically structured Cu2O nanocubes have been synthesized by a facile and cost-effective one-pot, solution phase process. Self-assembly of 5 nm Cu2O nanocrystallites induced through reduction by glucose affords a mesoporous 375 nm cubic architecture with superior visible light photocatalytic performance in both methylene blue dye degradation and hydrogen production from water than conventional non-porous analogues. Hierarchical nanocubes offer improved accessible surface active sites and...

  11. Combinatorial solar cell libraries for the investigation of different metal back contacts for TiO2-Cu2O hetero-junction solar cells. (United States)

    Rühle, S; Barad, H N; Bouhadana, Y; Keller, D A; Ginsburg, A; Shimanovich, K; Majhi, K; Lovrincic, R; Anderson, A Y; Zaban, A


    Here we present a comprehensive investigation of TiO2-Cu2O hetero-junction solar cells with different back contacts (Au, ITO, Cu or Ag). Combinatorial hetero-junction libraries consisting of a linear TiO2 thickness gradient produced by spray pyrolysis and a bell shaped Cu2O profile synthesized by pulsed laser deposition were chosen to investigate the impact of the two metal oxide layer thicknesses. The back contacts were deposited as round patches onto a grid of 13 × 13 points, 169 contacts for each contact material, forming a library containing 4 × 13 × 13 = 676 back contacts. Each back contact represented a solar cell with an individual TiO2 and Cu2O thickness. I-V measurements show that all four materials provide an ohmic contact and that the open circuit voltage of ∼300 mV is rather independent of both layer thicknesses and contact material. The size of the Cu2O crystals drastically decreases with distance from the center of deposition, which leads to a drastic increase of series resistance when the crystal size is <50 nm.

  12. Visible-light responsive photocatalytic fuel cell based on WO(3)/W photoanode and Cu(2)O/Cu photocathode for simultaneous wastewater treatment and electricity generation. (United States)

    Chen, Quanpeng; Li, Jinhua; Li, Xuejin; Huang, Ke; Zhou, Baoxue; Cai, Weimin; Shangguan, Wenfeng


    A visible-light driven photocatalytic fuel cell (PFC) system comprised of WO(3)/W photoanode and Cu(2)O/Cu photocathode was established for organic compounds degradation with simultaneous electricity generation. The central idea for its operation is the mismatched Fermi levels between the two photoelectrodes. Under light illumination, the Fermi level of WO(3)/W photoanode is higher than that of Cu(2)O/Cu photocathode. An interior bias can be produced based on which the electrons of WO(3)/W photoanode can transfer from the external circuit to combine with the holes of Cu(2)O/Cu photocathode then generates the electricity. In this manner, the electron/hole pairs separations at two photoelectrodes are facilitated to release the holes of WO(3)/W photoanode and electrons of Cu(2)O/Cu photocathode. Organic compounds can be decomposed by the holes of WO(3)/W photoanode due to its high oxidation power (+3.1-3.2 V(NHE)). The results demonstrated that various model compounds including phenol, Rhodamine B, and Congo red can be successfully decomposed in this PFC system, with the degradation rate after 5 h operation were obtained to be 58%, 63%, and 74%, respectively. The consistent operation for continuous water treatment with the electricity generation at a long time scale was also confirmed from the result. The proposed PFC system provides a self-sustained and energy-saving way for simultaneous wastewater treatment and energy recovery.

  13. Creation of Cu2O@TiO2 composite photocatalysts with p-n heterojunctions formed on exposed Cu2O facets, their energy band alignment study, and their enhanced photocatalytic activity under illumination with visible light. (United States)

    Liu, Lingmei; Yang, Weiyi; Sun, Wuzhu; Li, Qi; Shang, Jian Ku


    The creation of photocatalysts with controlled facets has become an important approach to enhance their activity. However, how the formation of heterojunctions on exposed facets could affect their photocatalytic performance ranking had not yet been investigated. In this study, Cu2O@TiO2 core-shell structures were created, and Cu2O/TiO2 p-n heterojunctions were formed on various exposed facets of Cu2O cubes, Cu2O cuboctahedra, and Cu2O octahedra, respectively. These Cu2O@TiO2 polyhedra demonstrated an enhanced photocatalytic degradation effect on Methylene Blue (MB) and 4-nitrophenol (4-NP) under visible light illumination, because of the enhanced charge carrier separation by the formation of Cu2O@TiO2 p-n heterojunctions. It was further found that their photocatalytic performance was also facet-dependent as pure Cu2O polyhedra, while the photocatalytic performance ranking of these Cu2O@TiO2 polyhedra was different with that of their corresponding Cu2O polyhedron cores. By the combination of optical property measurement and XPS analysis, the energy band alignments of these Cu2O@TiO2 polyhedra were determined, which demonstrated that Cu2O@TiO2 octahedra had the highest band offset for the separation of charge carriers. Thus, the charge-carrier-separation-driven force in Cu2O@TiO2 polyhedra was different from their corresponding Cu2O polyhedron cores, which resulted in their different surface photovoltage spectrum (SPS) responses and different photocatalytic performance rankings.

  14. Synergetic effect of dual co-catalysts on the activity of p-type Cu2O crystals with anisotropic facets. (United States)

    Li, Rengui; Tao, Xiaoping; Chen, Ruotian; Fan, Fengtao; Li, Can


    Spatial separation of reduction sites and oxidation sites to inhibit the recombination of photogenerated electrons and holes plays a vital role in improving the efficiency of photocatalyst systems. It is very challenging to rationally deposit cocatalysts on the right facets (sites), namely, the reduction cocatalyst on the reduction facets (sites) and the oxidation cocatalyst on the oxidation facets (sites). Herein, we report that the reduction and oxidation cocatalysts can be selectively constructed on the different facets of p-type Cu2 O crystals with anisotropic facets, but not on the Cu2 O crystal with isotropic facets. The deposition of dual cocatalysts on the different facets resulted in a remarkable synergetic effect in the photocatalytic performance, which could be attributed to the spatial separation of the photogenerated charges between facets. Our work reports an instructive strategy for constructing high-efficiency photocatalyst systems for solar energy conversion.

  15. One-Step Catalytic Synthesis of CuO/Cu2O in a Graphitized Porous C Matrix Derived from the Cu-Based Metal-Organic Framework for Li- and Na-Ion Batteries. (United States)

    Kim, A-Young; Kim, Min Kyu; Cho, Keumnam; Woo, Jae-Young; Lee, Yongho; Han, Sung-Hwan; Byun, Dongjin; Choi, Wonchang; Lee, Joong Kee


    The hybrid composite electrode comprising CuO and Cu2O micronanoparticles in a highly graphitized porous C matrix (CuO/Cu2O-GPC) has a rational design and is a favorable approach to increasing the rate capability and reversible capacity of metal oxide negative materials for Li- and Na-ion batteries. CuO/Cu2O-GPC is synthesized through a Cu-based metal-organic framework via a one-step thermal transformation process. The electrochemical performances of the CuO/Cu2O-GPC negative electrode in Li- and Na-ion batteries are systematically studied and exhibit excellent capacities of 887.3 mAh g(-1) at 60 mA g(-1) after 200 cycles in a Li-ion battery and 302.9 mAh g(-1) at 50 mA g(-1) after 200 cycles in a Na-ion battery. The high electrochemical stability was obtained via the rational strategy, mainly owing to the synergy effect of the CuO and Cu2O micronanoparticles and highly graphitized porous C formed by catalytic graphitization of Cu nanoparticles. Owing to the simple one-step thermal transformation process and resulting high electrochemical performance, CuO/Cu2O-GPC is one of the prospective negative active materials for rechargeable Li- and Na-ion batteries.

  16. Cupric and cuprous oxide by reactive ion beam sputter deposition and the photosensing properties of cupric oxide metal–semiconductor–metal Schottky photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Min-Jyun; Lin, Yong-Chen; Chao, Liang-Chiun, E-mail:; Lin, Pao-Hung; Huang, Bohr-Ran


    Highlights: • CuO and Cu{sub 2}O were deposited by reactive ion beam sputter deposition. • Single phase CuO thin film is obtained with Ar:O{sub 2} = 2:1. • CuO MSM PD shows photoresponse from 400 nm to 1.30 μm. • CuO MSM PD is RC limited with a decay time less than 1 μs. - Abstract: Cupric (CuO) and cuprous (Cu{sub 2}O) oxide thin films have been deposited by reactive ion beam sputter deposition at 400 °C with an Ar:O{sub 2} ratio from 2:1 to 12:1. With an Ar:O{sub 2} ratio of 2:1, single phase polycrystalline CuO thin films were obtained. Decreasing oxygen flow rate results in CuO + Cu{sub 2}O and Cu{sub 2}O + Cu mixed thin films. As Ar:O{sub 2} ratio reaches 12:1, Cu{sub 2}O nanorods with diameter of 250 nm and length longer than 1 μm were found across the sample. Single phase CuO thin film exhibits an indirect band gap of 1.3 eV with a smooth surface morphology. CuO metal–semiconductor–metal (MSM) Schottky photodiodes (PD) were fabricated by depositing Cu interdigitated electrodes on CuO thin films. Photosensing properties of the CuO PD were characterized from 350 to 1300 nm and a maximum responsivity of 43 mA/W was found at λ = 700 nm. The MSM PD is RC limited with a decay time constant less than 1 μs.

  17. Detection of a Cooper-pair density wave in Bi2Sr2CaCu2O8+x (United States)

    Hamidian, M. H.; Edkins, S. D.; Joo, Sang Hyun; Kostin, A.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E.-A.; MacKenzie, A. P.; Fujita, K.; Lee, Jinho; Davis, J. C. Séamus


    The quantum condensate of Cooper pairs forming a superconductor was originally conceived as being translationally invariant. In theory, however, pairs can exist with finite momentum Q, thus generating a state with a spatially modulated Cooper-pair density. Such a state has been created in ultracold 6Li gas but never observed directly in any superconductor. It is now widely hypothesized that the pseudogap phase of the copper oxide superconductors contains such a ‘pair density wave’ state. Here we report the use of nanometre-resolution scanned Josephson tunnelling microscopy to image Cooper pair tunnelling from a d-wave superconducting microscope tip to the condensate of the superconductor Bi2Sr2CaCu2O8+x. We demonstrate condensate visualization capabilities directly by using the Cooper-pair density variations surrounding zinc impurity atoms and at the Bi2Sr2CaCu2O8+x crystal supermodulation. Then, by using Fourier analysis of scanned Josephson tunnelling images, we discover the direct signature of a Cooper-pair density modulation at wavevectors QP ≈ (0.25, 0)2π/a0 and (0, 0.25)2π/a0 in Bi2Sr2CaCu2O8+x. The amplitude of these modulations is about five per cent of the background condensate density and their form factor exhibits primarily s or s‧ symmetry. This phenomenology is consistent with Ginzburg-Landau theory when a charge density wave with d-symmetry form factor and wavevector QC = QP coexists with a d-symmetry superconductor; it is also predicted by several contemporary microscopic theories for the pseudogap phase.

  18. Literature review on the properties of cuprous oxide Cu{sub 2}O and the process of copper oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Korzhavyi, P. A.; Johansson, B. (Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm (Sweden))


    The purpose of the present review is to provide a reference guide to the most recent data on the properties of copper(I) oxide as well as on the atomic processes involved in the initial stages of oxidation of copper. The data on the structure of surfaces, as obtained from atomic-resolution microscopy studies (for example, STM) or from first-principles calculations, are reviewed. Information of this kind may be useful for understanding the atomic mechanisms of corrosion and stress-corrosion cracking of copper

  19. Cu2O/Ag co-deposited TiO2 nanotube array film prepared by pulse-reversing voltage and photocatalytic properties (United States)

    Ding, Qi; Chen, Suiyuan; Shang, Fanmin; Liang, Jing; Liu, Changsheng


    In this experiment, Cu2O/Ag co-deposition TiO2 nanotube array (Cu2O-Ag-TNT) film was prepared on pure Ti substrate with the method of combining anodic oxidation and electrodeposition by pulse-reversing voltage power supply in the electrolyte of NH4F, ethylene glycol, CuNO3 · 3H2O and AgNO3. The morphology, phase, chemical composition, photocatalytic property and mechanism of the nanotube array film were studied by means of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra, photoluminescence and photocatalytic degradation under visible light. The results showed that the depositional Cu2O and Ag existed in two forms, being the small-particle dispersion and large-particle sedimentary phase in the nanotube arrays: Cu2O-Ag-TNTs for different doping amounts of Ag could be prepared by adjusting the concentration of AgNO3 and the reverse voltages; with changing of the doping amount of Ag, the band gap and photo-generated electron-hole pair recombination rate also changed, and under the conditions of annealing and the optimized process parameter, the band gap of the nanotube arrays narrowed 0.49 eV and the rate of electron and pair recombination decreased noticeably; the nanotube array film for the concentration of 0.5 cm2 ml-1 degraded the methylene blue of 8 mg L-1, and the degradation rate reached above 98%. The co-deposition Cu2O-Ag-TNT film prepared by the one-step method performed well in the field of photocatalysis under visible light.

  20. Copper Oxide Thin Films through Solution Based Methods for Electrical Energy Conversion and Storage (United States)

    Zhu, Changqiong

    Copper oxides (Cu2O and CuO), composed of non-toxic and earth abundant elements, are promising materials for electrical energy generation and storage devices. Solution based techniques for creating thin films of these materials, such as electrodeposition, are important to understand and develop because of their potential for realizing substantial energy savings compared to traditional fabrication methods. Cuprous oxide (Cu2O), with its direct band gap, is a p-type semiconductor that is well suited for creating solution-processed photovoltaic devices (solar cells); several key advancements made toward this application are the primary focus of this thesis. Electrodeposition of single-phase, crystalline Cu2O thin films is demonstrated using previously unexplored, acidic lactate/Cu2+ solutions, which has provided additional understanding of the impacts of growth solution chemistry on film formation. The influence of pH on the resulting Cu2O thin film properties is revealed by using the same ligand (sodium lactate) at various solution pH values. Cu2O films grown from acidic lactate solutions can exhibit a distinctive flowerlike, dendritic morphology, in contrast to the faceted, dense films obtained using alkaline lactate solutions. Relative speciation distributions of the various metal complex ions present under different growth conditions are calculated using reported equilibrium association constants and experimentally supported by UV-Visible absorption spectroscopy. Dependence of thin film morphology on the lactate/Cu2+ molar ratio and applied potential is described. Cu2O/eutectic gallium-indium Schottky junction devices are formed and devices are tested under monochromatic green LED illumination. Further surface examination of the Cu2O films using X-ray photoelectron spectroscopy (XPS) reveals the fact that films grown from acidic lactate solution with a small lactate/Cu2+ molar ratio, which exhibit improved photovoltaic performance compared to films grown from

  1. Control of native acceptor density in epitaxial Cu2O thin films grown by electrochemical deposition (United States)

    Ashida, Atsushi; Sato, Shunsuke; Yoshimura, Takeshi; Fujimura, Norifumi


    Controlling the native carrier is essential for using Cu2O in devices such as solar cells. The origin of the native p-type carrier in Cu2O is thought to be copper vacancies (VCu). In this work, epitaxially grown Cu2O thin films were prepared by electrochemical deposition at a low temperature of 45 °C on a Pt (111) cathodic electrode. The sources of Cu and O for Cu2O were Cu2+ and OH- in the electrolyte and the ion concentrations were changed to control the stoichiometry of deposition and the density of VCu. The density of ionized acceptors (NA+) in the Cu2O films was evaluated by the C-V properties measured with Schottky electrodes. NA+ did not depend on [Cu2+], whereas NA+ increased with increasing [OH-] when [OH-] was larger than 10-3 mol/L (electrolyte pH >11) with [Cu2+] fixed at 10-1 mol/L. The ion concentration dependence of NA+ and the dependence of the total cathodic current density revealed that the generation of VCu was affected by a complex combination of the ion concentrations and film growth rate.

  2. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals. (United States)

    Singh, Dinesh Pratap; Srivastava, Onkar Nath


    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  3. Preparation and characterization of Cu2O-TiO2 nanofluid (United States)

    Ilangovan, R.; Kumaraguruparan, G.; Subramaniyan, A. L.


    Nanofluids are engineered suspension of Nanoparticles in a suitable base fluid. Nanofluids have a wide range of applications in thermal cooling, direct absorption solar collectors, enhanced fuel efficiency, medical applications, etc. Nanofluids have been extensively studied for their thermal conductivity and are presently being investigated for their novel electrical, magnetic and optical properties. A wide range of metallic (Ag,Cu,Ti) and ceramic(TiO2, Cu2O, Al2O3) nanofluids with water and ethylene glycol have been extensively prepared and characterized for their thermal applications. The present work deals with preparation of Cu2O-TiO2 Nanofluid by the two step method and nanoparticles of Cu2O-TiO2 nanofluid are characterised by SEM,EDAX. The stability of the nanofluid is investigated by sedimentation method.

  4. Experimental Investigation on Strengthening Effect of Cu2O Film in Micro Sheet Forming of Copper (United States)

    Zheng, Wei; Lin, Xiaojuan; Tang, Bingtao; Wang, Guangchun


    Materials processed using micro-manufacturing technologies exhibit significantly different properties compared to those produced using conventional macro-manufacturing techniques. In this paper, the uniaxial tensile tests were performed on the thin sheet specimens of pure copper to investigate how the sheet thickness impacts the flow stress. The experimental results show a continuous decrease of flow stress as the sheet thickness reduces from 200 to 100 μm, but an increase of flow stress with further reduction in thickness. Firstly, by introducing the ratio of surface grains, the decrease trend of flow stress was explained on the basis of surface layer model. Secondly, the strengthening effect of Cu2O film was clearly demonstrated by the x-ray diffraction and electrodeposition process. Finally, considering the effects of Cu2O film and free surface layer, the mechanical properties of Cu2O film was studied, which is helpful to explain the material behavior in micro sheet forming.

  5. P-Cu2O/n-ZnO nanowires on ITO glass for solar cells. (United States)

    Zhang, Jin; Que, Wenxiu; Zhong, Peng; Zhu, Gangqiang


    In this paper, the fabrication and characterization of a heterojunction solar cell based on p-Cu2O/n-ZnO nanowires on ITO glass are presented. ZnO aligned nanocrystal seed layer is firstly prepared by RF magnetron sputtering technique, and then vertical ZnO nanowire arrays with an acicular crystal structure are obtained by using a chemical bath deposition processing. The results indicate that the ZnO nanowires with a diameter of about 50 nm and 500 nm in length can be easily obtained. The absorption and transmittance of the ZnO nanowires are studied. It is also noted that the Cu2O can fill well into the space between ZnO nanowires by an electrodeposition process. Furthermore, the effect of the Cu2O orientation on the cell performance is also presented.

  6. Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors (United States)

    Wan, Caichao; Jiao, Yue; Li, Jian


    An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

  7. Photocatalytic reduction of carbon dioxide to methanol by Cu2O/SiC nanocrystallite under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Huiling Li; Yonggen Lei; Ying Huang; Yueping Fang; Yuehua Xu; Li Zhu; Xin Li


    The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles(NPs)modified by Cu2O.Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated.The results indicated that besides a small quantity of 6H-SiC,SiC NPs mainly consisted of 3C-SiC.The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra,respectively.The Cu2O modification can enhance the photocatalytic performance of SiC NPs,and the largest yields of methanol on SiC,Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153,104 and 191μmol/g,respectively.

  8. Derivation of Inter-Atomic Force Constants of Cu2O from Diffuse Neutron Scattering Measurement

    Directory of Open Access Journals (Sweden)

    T. Makhsun


    Full Text Available Neutron scattering intensity from Cu2O compound has been measured at 10 K and 295 K with High Resolution Powder Diffractometer at JRR-3 JAEA. The oscillatory diffuse scattering related to correlations among thermal displacements of atoms was observed at 295 K. The correlation parameters were determined from the observed diffuse scattering intensity at 10 and 295 K. The force constants between the neighboring atoms in Cu2O were estimated from the correlation parameters and compared to those of Ag2O

  9. Electronic properties and morphology of copper oxide/n-type silicon heterostructures (United States)

    Lindberg, P. F.; Gorantla, S. M.; Gunnæs, A. E.; Svensson, B. G.; Monakhov, E. V.


    Silicon-based tandem heterojunction solar cells utilizing cuprous oxide (Cu2O) as the top absorber layer show promise for high-efficiency conversion and low production cost. In the present study, single phase Cu2O films have been realized on n-type Si substrates by reactive magnetron sputtering at 400 °C. The obtained Cu2O/Si heterostructures have subsequently been heat treated at temperatures in the 400-700 °C range in Ar flow and extensively characterized by x-ray diffraction (XRD) measurements, transmission electron microscopy (TEM) imaging and electrical techniques. The Cu2O/Si heterojunction exhibits a current rectification of ~5 orders of magnitude between forward and reverse bias voltages. High resolution cross-sectional TEM-images show the presence of a ~2 nm thick interfacial SiO2 layer between Cu2O and the Si substrate. Heat treatments below 550 °C result in gradual improvement of crystallinity, indicated by XRD. At and above 550 °C, partial phase transition to cupric oxide (CuO) occurs followed by a complete transition at 700 °C. No increase or decrease of the SiO2 layer is observed after the heat treatment at 550 °C. Finally, a thin Cu-silicide layer (Cu3Si) emerges below the SiO2 layer upon annealing at 550 °C. This silicide layer influences the lateral current and voltage distributions, as evidenced by an increasing effective area of the heterojunction diodes.

  10. Direct formation of small Cu2O nanocubes, octahedra, and octapods for efficient synthesis of triazoles (United States)

    Tsai, Ya-Huei; Chanda, Kaushik; Chu, Yi-Ting; Chiu, Chun-Ya; Huang, Michael H.


    In most studies describing the preparation of Cu2O crystals of various morphologies, the particle sizes are normally hundreds of nanometers to micrometers due to rapid particle growth, so they are not exactly nanocrystals. Here we report surfactant-free formation of sub-100 nm Cu2O nanocrystals with systematic shape evolution from cubic to octahedral structures by preparing an aqueous mixture of Cu(OAc)2, NaOH, and N2H4 solution. Adjustment of the hydrazine volume enables the particle shape control. Uniform nanocubes and octahedra were synthesized with edge lengths of 37 and 67 nm, respectively. Novel Cu2O octapods with an edge length of 135 nm were also produced by mixing CuCl2 solution, SDS surfactant, NaOH solution, and NH2OH.HCl reductant solution. All of them are nearly the smallest Cu2O nanocrystals of the same shapes ever reported. These small cubes, octahedra, and octapods were employed as catalysts in the direct synthesis of 1,2,3-triazoles from the reaction of alkynes, organic halides, and NaN3 at 55 °C. All of them displayed high product yields in short reaction times. The octahedra enclosed by the {111} facets are the best catalysts, and can catalyze this cycloaddition reaction with high yields in just 2 h when different alkynes were used to make diverse triazole products. Hence, the small Cu2O particles provide time-saving, energy-efficient, and high product yield benefits to organocatalysis.In most studies describing the preparation of Cu2O crystals of various morphologies, the particle sizes are normally hundreds of nanometers to micrometers due to rapid particle growth, so they are not exactly nanocrystals. Here we report surfactant-free formation of sub-100 nm Cu2O nanocrystals with systematic shape evolution from cubic to octahedral structures by preparing an aqueous mixture of Cu(OAc)2, NaOH, and N2H4 solution. Adjustment of the hydrazine volume enables the particle shape control. Uniform nanocubes and octahedra were synthesized with edge

  11. Physico-chemical studies of cuprous oxide (Cu{sub 2}O) nanoparticles coated on amorphous carbon nanotubes (α-CNTs)

    Energy Technology Data Exchange (ETDEWEB)

    Johan, Mohd Rafie, E-mail:; Meriam Suhaimy, Syazwan Hanani; Yusof, Yusliza, E-mail:


    Amorphous carbon nanotubes (α-CNTs) were synthesized by a chemical reaction between ferrocene and ammonium chloride at a temperature (∼250 °C) in an air furnace. As- synthesized α-CNTs were purified with deionized water and hydrochloric acid. A purified α-CNTs were hybridized with cuprous oxide nanoparticles (Cu{sub 2}O) through a simple chemical process. Morphology of the samples was analyzed with field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectra showed the attachment of acidic functional groups onto the surface of α-CNTs and the formation of hybridized α-CNTs-Cu{sub 2}O. Raman spectra reveal the amorphous nature of the carbon. X-ray diffraction (XRD) pattern confirmed the amorphous phase of the carbon and the formation of Cu{sub 2}O crystalline phase. The coating of Cu{sub 2}O was confirmed by FESEM, TEM, and XRD. Optical absorption of the samples has also been investigated and the quantum confinement effect was illustrated in the absorption spectra.

  12. Enhanced Ultraviolet Random Lasing from Au/MgO/ZnO Heterostructure by Introducing p-Cu2O Hole-Injection Layer. (United States)

    Zhang, Cen; Zhang, Juan; Liu, Weizhen; Xu, Haiyang; Hou, Shuai; Wang, Chunliang; Yang, Liu; Wang, Zhongqiang; Wang, Xinhua; Liu, Yichun


    Ultraviolet light-emitting devices (LEDs) were fabricated on the basis of Au/MgO/ZnO metal/insulator/semiconductor (MIS) heterostructures. By introducing a thermally oxidized p-type Cu2O hole-injection layer into this MIS structure, enhanced ultraviolet electroluminescence (EL) and random lasing with reduced threshold injection current are achieved. The enhancement mechanism is attributed to effective hole transfer from p-Cu2O to i-MgO under forward bias, which increases the initial carrier concentration of MgO dielectric layer and further promotes "impact-ionization" effect induced carrier generation and injection. The current study proposes a new and effective route to improve the EL performance of MIS junction LEDs via introducing extrinsic hole suppliers.

  13. Synthesis and microstructural studies of annealed Cu(2)O/Cu(x)S bilayer as transparent electrode material for photovoltaic and energy storage devices. (United States)

    Taleatu, B A; Arbab, E A A; Omotoso, E; Mola, G T


    Cu2 O thin film and a transparent bilayer have been fabricated by electrodeposition method. The growths were obtained in potentiostatic mode with gradual degradation of anodic current. X-ray diffraction (XRD) study showed that the bilayer is polycrystalline and it possesses mixture of different crystallite phases of copper oxides. Surface morphology of the films was investigated by scanning electron microscopy (SEM). The SEM images revealed that the films were uniformly distributed and the starting material (Cu2 O) had cubical structure. Grains agglomeration and crystallinity were enhanced by annealing. Optical studies indicated that all the samples have direct allowed transition. Energy band gap of the bilayer film was reduced by annealing treatment thus corroborating quantum confinement upshot. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  14. Synthesis of Cu/Cu2O nanoparticles by laser ablation in deionized water and their annealing transformation into CuO nanoparticles

    KAUST Repository

    Gondal, M. A.


    Nano-structured Cupric Oxide (CuO) has been synthesized using pulsed laser ablation of pure copper in water using Q-switched pulsed laser beam of 532 nm wavelength and, 5 nanosecond pulse duration and laser pulse energy of 100 mJ/pulse. In the initial unannealed colloidal suspension, the nanoparticles of Copper (Cu) and Cuprious oxide (Cu2O) were identified. Further the suspension was dried and annealed at different temperatures and we noticed the product (Cu/Cu2O) was converted predominantly into CuO at annealing temperature of 300 \\'C for 3 hours. As the annealing temperature was raised from 300 to 900 \\'C, the grain sizes of CuO reduced to the range of 9 to 26 nm. The structure and the morphology of the prepared samples were investigated using X-ray diffraction and Transmission Electron Microscope. Photoluminescence and UV absorption spectrometrystudies revealed that the band gap and other optical properties of nano-structured CuO were changed due to post annealing. Fourier transform spectrometry also confirmed the transformation of Cu/Cu2O into CuO. Copyright © 2013 American Scientific Publishers All rights reserved.

  15. Synthesis of core-shell heterostructured Cu/Cu2O nanowires monitored by in situ XRD as efficient visible-light photocatalysts

    KAUST Repository

    Chen, Wei


    Core-shell heterostructured Cu/Cu2O nanowires with a high aspect ratio were synthesized from Cu foam using a novel oxidation/reduction process. In situ XRD was used as an efficient tool to acquire phase transformation details during the temperature-programmed oxidation of Cu foam and the subsequent reduction process. Based on knowledge of the crucial phase transformation, optimal synthesis conditions for producing high-quality CuO and core-shell Cu/Cu2O nanowires were determined. In favor of efficient charge separation induced by the special core-shell heterostructure and the advanced three-dimensional spatial configuration, Cu/Cu2O nanowires exhibited superior visible-light activity in the degradation of methylene blue. The present study illustrates a novel strategy for fabricating efficiently core-shell heterostructured nanowires and provides the potential for developing their applications in electronic devices, for environmental remediation and in solar energy utilization fields. This journal is © The Royal Society of Chemistry.

  16. Detection of esophageal cancer cell by photoelectrochemical Cu2O/ZnO biosensor (Conference Presentation) (United States)

    Hsu, Chao-Hsin; Chu, Cheng-Hsun; Chen, Weichung; Wu, I.-Chen; Wu, Ming Tsang; Kuo, Chie-Tong; Tsiang, Raymond Chien-Chao; Wang, Hsiang-Chen


    We have demonstrated a Cu2O/ZnO nanorods (NRs) array p-n heterostructures photoelectrochemical biosensor. The electrodeposition of Cu2O at pH 12 acquired the preferably (111) lattice planes, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. High verticality ZnO nanorods by seed layer and thermal annealing assist the hydrothermal growth. The optimized Cu2O/ZnO NRs array p-n heterostructures exhibited enhanced PEC performance, such as elevated photocurrent and photoconversion efficiency, as well as excellent sensing performance for the sensitive detection of four strains of different races and different degree of cancer cell which made the device self-powered. We got spectral response characteristics and operating wavelength range of biosensor, and to verify the biological characteristics of cancer cells wafer react with different stages of cancer characterized by a cancer measured reaction experiment.

  17. Synthesis, surface properties and photocatalytic abilities of semiconductor In2Cu2O5 nanoparticles (United States)

    Xu, Jian; Wan, Yingpeng; Huang, Yanlin; Wang, Yaorong; Qin, Lin; Seo, Hyo Jin


    In2Cu2O5 photocatalyst was prepared by the sol-gel method which produced worm-like nanoparticles. The X-ray powder diffraction (XRD) measurement and Rietveld structural refinement were applied to elucidate the phase formation and structural properties. The morphological properties of the surfaces were measured by scanning electron microscope (SEM), energy dispersive spectrum (EDS), and transmission electron microscopy (TEM). The nanoparticles present optical absorption from both the host lattices and the d-d transitions of distorted Cu2+ octahedra in UV-vis light wavelength region. The band-gap of In2Cu2O5 photocatalyst is about 2.31 eV. The photocatalytic abilities of In2Cu2O5 nanoparticles were verified by photo-degradation of methylene blue (MB) solutions irradiated by visible light. The energy potential and bad structure were discussed. In2Cu2O5 nanoparticles have the potential application for the efficient photocatalysis on MB dye solutions.

  18. One-pot synthesis of hierarchical Cu2O/Cu hollow microspheres with enhanced visible-light photocatalytic activity (United States)

    Hong, Tianjie; Tao, Feifei; Lin, Jiudong; Ding, Wei; Lan, Mingxuan


    The hierarchical Cu2O/Cu hollow microspheres have been fabricated by the one-pot solvothermal redox method, which is one-step approach without any surfactant and template. By using the HRTEM, XRD, XPS and UV-vis spectroscopy, the as-prepared product is composed of Cu2O and Cu with energy band gap of 1.72 eV. Based on the time-dependent experiments, the content of Cu2O and Cu compositions can be effectively controlled by adjusting the reaction time and a possible mechanism is proposed. In addition, using various dye molecules to stimulate pollutants, the hierarchical Cu2O/Cu hollow microspheres reacted for 8 h exhibit excellent visible-light photocatalytic activities, which is much higher than those of the Cu2O/Cu catalysts formed at the shorter reaction time, commercial Cu2O powder and the mixture of alone Cu2O and Cu. This enhanced photocatalytic performance makes these hierarchical Cu2O/Cu hollow microspheres a kind of efficient visible-light photocatalyst in removing some organic compounds in wastewater.

  19. Model of interatomic interaction and dynamic and thermodynamic properties of Tl 2CaBa 2Cu 2O 8 (United States)

    Belosludov, V. R.; Lavrent'ev, M. Yu.; Syskin, S. A.


    A model of interatomic interactions in Tl 2CaBa 2Cu 2O 8, which takes into account Coulombic interaction and covalent bonds, is presented. Using this model, calculations of lattice dynamics and lattice specific heat of Tl 2CaBa 2Cu 2O 8 are performed.

  20. Microwave-assisted hydrothermal synthesis of Cu/Cu2O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature. (United States)

    Zou, Xinwei; Fan, Huiqing; Tian, Yuming; Zhang, Mingang; Yan, Xiaoyan


    Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others.

  1. Morphology, Orientation Relationship and Stability Analysis of Cu2O nanoclusters on SrTiO3 (100)

    Energy Technology Data Exchange (ETDEWEB)

    Kuchibhatla, Satyanarayana V N T; Hu, Shenyang Y.; Yu, Zhongqing; Shutthanandan, V.; Li, Ye; Nachimuthu, Ponnusamy; Jiang, Weilin; Thevuthasan, Suntharampillai; Henager, Charles H.; Sundaram, S. K.


    Reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM) and theoretical studies based on classical nucleation theory have been used to understand the morphology, orientation relationship and stability of Cu2O nanoclusters on SrTiO3 (100) (STO). We propose that the competing interfacial and elastic energies facilitate an in-plane rotation of the Cu2O clusters by 45o with respect to the STO substrate and stabilize Cu2O clusters on STO(100) with an orientation relationship of (001) Cu 2o //(001) SrTiO3 and <100> Cu 2o //<110> SrTiO3. Preliminary theoretical analysis also suggests that this particular orientation results in smaller critical nucleus sizes and lower nucleation barriers. The study also indicates a chemical potential (growth rate) dependence of the orientation relationship.

  2. Enhanced visible light photocatalytic activity in N-doped edge- and corner-truncated octahedral Cu2O (United States)

    Zou, Mingming; Liu, Honghong; Feng, Lu; Thomas, Tiju; Yang, Minghui


    Edge- and corner-truncated octahedral Cu2O is successfully synthesized using an aqueous mixture of CuCl2, sodium dodecyl sulfate, NaOH, and NH2OH3·HCl. Cu2O1-xNx(150 °C, 30 min) samples are synthesized by nitridation of Cu2O using an ammonothermal process. Cu retains a formal valence state through and beyond the nitridation process. N concentration in this sample is 1.73 at%, out of which 1.08 at% is substitutional in nature. Photocatalytic activity of Cu2O1-xNx(150 °C, 30 min) sample is investigated and compared to that of pristine edge- and corner-truncated octahedral Cu2O. Results show that Cu2O1-xNx(150 °C, 30 min) sample with dominant {110} facets has a higher photocatalytic activity than the pristine Cu2O material. Higher surface energy and a greater density of the "Cu" dangling bonds on {110} facets of edge- and corner-truncated octahedral Cu2O1-xNx is the plausible reason for the observed optimum catalytic activity. Furthermore defect states induced by nitridation results in improved visible light adsorption. And also the band edge states changes which brought about by N doping. This is an interesting result since it bypasses the usual challenge faced by pristine Cu2O which have band edge states between which transitions are normally forbidden. Selective radical quenching experiments suggest that photocatalytic activity of Cu2O1-xNx is due to formation of hydroxyl radicals in water, subsequent to photogeneration of charge carriers in the photocatalyst.

  3. Adsorption and dissociation of H2O on Cu2O(100):A computational study

    Institute of Scientific and Technical Information of China (English)

    Yun Li; Lifen Yan; Guichang Wang


    The adsorption and dissociation of water on Cu2O(100)have been investigated by the density functional theory-generalized gradient approximation(DFT GGA)method.The corresponding reaction energies,the structures of the transition states and the activation energies were determined.Calculations with and without dipole correction were both studied to get an understanding of the effect of the dipole moment on the adsorption and reaction of water on dipole surface Cu2O(100).When dipole correction was added,the adsorption energies of H2O on different sites generally decreased.The calculated activation barriers for HxO(x=1,2)dehydrogenation are 0.42 eV(1.01 eV without the dipole correction)and 1.86 eV,respectively,including the zero point energy correction.The first dehydrogenation outcome is energetically the most stable product.

  4. Phonon density of states in Tl 2CaBa 2Cu 2O 8 (United States)

    Chaplot, S. L.; Dasannacharya, B. A.; Mukhopadhyay, R.; Rao, K. R.; Vijayaraghavan, P. R.; Iyer, R. M.; Phatak, G. M.; Yakhmi, J. V.


    The neutron-weighted phonon density of states in the high-temperature superconductor Tl 2CaBa 2Cu 2O 8 ( Tc=107 K) is obtained from coherent inelastic neutron scattering measurements at the Dhruva reactor at 300 K. The phonon spectrum is qualitatively similar to that in the 90 K superconductor YBa 2Cu 3O 7, and compares well with an independent lattice dynamical calculation.

  5. Application of Cu2O-doped phosphate glasses for bandpass filter (United States)

    Elhaes, H.; Attallah, M.; Elbashar, Y.; El-Okr, M.; Ibrahim, M.


    Phosphate glasses doped with copper ions having general composition 42P2O5-39ZnO-(18-x) Na2O-1CaO-xCu2O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV-visible optical absorption. The density was measured by Archimedes' method, and molar volume (VM) was calculated. It is found that density and molar volume show opposite trend by increasing Cu2O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190-1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (Eopt), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. Eopt values for different glass samples are found to decrease with increasing Cu2O content.

  6. Heterogeneous Deposition of Cu2O Nanoparticles on TiO2 Nanotube Array Films in Organic Solvent

    Directory of Open Access Journals (Sweden)

    Xinwen Huang


    Full Text Available A novel method for decoration of anodic TiO2 nanotube array films (NAFs with Cu2O nanoparticles has been reported. The method is based on the reduction of Cu(II in a mixture of ethylene glycol and N,N-dimethylformamide at 120°C for 16 h, where the resulting Cu2O can heterogeneously nucleate and grow on TiO2 NAFs. The nanosized Cu2O is found to be well dispersed on the wall of TiO2 nanotubes without blocking the nanotube, a commonly observed phenomenon in the case of deposition of Cu2O via electrochemical method. The amount of Cu2O deposited on the TiO2 NAFs can be varied by adjusting the concentration of Cu(II in the organic solution. UV-vis spectra measurement indicates that the decoration of TiO2 NAFs with Cu2O nanoparticles greatly improves their ability to respond to visible light. By examining the photocurrent and photodegradation of methyl orange under simulated sunlight, it is found that these Cu2O-decorated TiO2 NAFs show much more photoactive in comparison with the as-prepared TiO2 NAFs.

  7. Facile fabrication of n-ZnO nanorods/p-Cu2O heterojunction and its photodiode property (United States)

    Kathalingam, A.; Vikraman, Dhanasekaran; Kim, Hyun-Seok; Park, Hui Joon


    This report presents the fabrication and characterization of n-ZnO nanorods/p-Cu2O hetrojunction photo-diode. The ZnO nanorods (NRs) were deposited onto electrodeposited Cu2O thin film by hydrothermal method. The structural, morphological and optical properties of ZnO NRs and Cu2O films were studied by X-ray diffraction, scanning electronic microscopy, UV-Vis spectrophotometer, respectively. XRD patterns revealed that the as-grown films were highly crystalline nature with strong predominant orientation of (111) and (002) lattices corresponding to Cu2O and ZnO NRs, respectively. Current-voltage (I-V) characteristic of n-ZnONRs/p-Cu2O structure confirmed the formation of heterojunction exhibiting diode-like rectifying nature. It showed enhanced conversion of UV light, which indicates the suitability of the simple and low-cost n-ZnO NRs/p-Cu2O heterojunction device for optoelectronic applications. The sandwich type ITO/n-ZnO NRs/p-Cu2O/ITO structure is quite novel approach for the efficient and complete collection of carriers in nanorods incorporated devices.

  8. Low temperature syntheses and reactivity of Cu2O2 active-site models. (United States)

    Citek, Cooper; Herres-Pawlis, Sonja; Stack, T Daniel P


    Nature's facility with dioxygen outmatches modern chemistry in the oxidation and oxygenation of materials and substrates for biosynthesis and cellular metabolism. The Earth's most abundant naturally occurring oxidant is-frankly-poorly understood and controlled, and thus underused. Copper-based enzyme metallocofactors are ubiquitous to the efficient consumption of dioxygen by all domains of life. Over the last several decades, we have joined many research groups in the study of copper- and dioxygen-dependent enzymes through close investigation of synthetically derived, small-molecule active-site analogs. Simple copper-dioxygen clusters bearing structural and spectroscopic similarity to dioxygen-activating enzymes can be probed for their fundamental geometrical, electronic, and reactive properties using the tools available to inorganic and synthetic chemistry. Our exploration of the copper-dioxygen arena has sustained product evaluation of the key dynamics and reactivity of binuclear Cu2O2 compounds. Almost exclusively operating at low temperatures, from -78 °C to solution characterization even at -125 °C, we have identified numerous compounds supported by simple and easily accessed, low molecular weight ligands-chiefly families of bidentate diamine chelates. We have found that by stripping away complexity in comparison to extended protein tertiary structures or sophisticated, multinucleating architectures, we can experimentally manipulate activated compounds and open pathways of reactivity toward exogenous substrates that both inform on and extend fundamental mechanisms of oxygenase enzymes. Our recent successes have advanced understanding of the tyrosinase enzyme, and related hemocyanin and NspF, and the copper membrane monooxygenases, specifically particulate methane monooxygenase (pMMO) and ammonia monooxygenase (AMO). Tyrosinase, ubiquitously distributed throughout life, is fundamental to the copper-based oxidation of phenols and the production of chromophores

  9. Fabrication of Cu2O-TiO2 Nano-composite with High Photocatalytic Performance under Simulated Solar Light

    Directory of Open Access Journals (Sweden)

    Yi Wentao


    Full Text Available Cu2O-P25 (TiO2 nano-heterostructures with different mass ratios were synthesized via a wet chemical precipitation and hydrothermal method, and were characterized by X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, UV-vis diffuse reflectance spectra (DRS, and X-ray photoelectron spectroscopy (XPS. DRS results showed that the light absorption of P25 extended to the visible light region with the loading of Cu2O. XPS results showed that Cu existed in the state of Cu+ in the presence of hydroxylamine hydrochloride, confirming the formation of Cu2O. The obtained products exhibited efficient photocatalytic performance in degradation of methyl orange (MO and methylene blue (MB under simulated solar light. The sample of 5% Cu2O-P25 exhibited the highest photocatalytic activity among all as-prepared samples. And the photocatalysts can be recycled without obvious loss of photocatalytic activity.

  10. Fabrication of Cu2O/TiO2 nanotube arrays with enhanced visible-light photoelectrocatalytic activity (United States)

    Xiang, Liyun; Ya, Jing; Hu, Fengjiao; Li, Lixia; Liu, Zhifeng


    A new electrochemical deposition process was developed to uniformly deposit Cu2O nanoparticles on the matrix of TiO2 nanotube (NT) arrays. The Cu2O nanoparticles have a particle size about 20 nm grown both inside and outside of the nanotubes without blocking the pore openings as characterized using XRD, SEM, TEM, and EDS measurements. The Cu2O/TiO2NTs heterogeneous structures also effectively improve the visible-light absorption and response comparing to those of TiO2NTs material. The photodegradation efficiency was increase by about 2.3 times on the Cu2O-decorated TiO2NTs materials as tested by degradation of methylene blue under simulated visible light.

  11. 21 CFR 184.1265 - Cuprous iodide. (United States)


    ... with potassium iodide under slightly acidic conditions. (b) The ingredient must be of a purity suitable... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cuprous iodide. 184.1265 Section 184.1265 Food and... Substances Affirmed as GRAS § 184.1265 Cuprous iodide. (a) Cuprous iodide (copper (I) iodide, CuI, CAS...

  12. Synthesis of novel Cu2O/BiOCl heterojunction nanocomposites and their enhanced photocatalytic activity under visible light (United States)

    Cao, Chunhua; Xiao, Ling; Chen, Chunhua; Cao, Qihua


    Novel Cu2O/BiOCl photocatalyst with unique 3D/2D structure and enhanced visible-light photocatalytic activity was constructed using a facile low-temperature liquid-phase method. The microstructure and properties of Cu2O/BiOCl composites were characterized by XRD, FT-IR, FESEM, HRTEM, BET and UV-vis/DRS. With dye X-3B as a model pollutant, the adsorption and visible-light photocatalytic activities of Cu2O/BiOCl composites were investigated, and the photocatalysis mechanism was explored. The results showed that the staggered spaces and edges of BiOCl nanosheets with about 40 nm thickness were inlaided with some Cu2O sub-microspheres, and the heterojunction structures were formed at the interface between BiOCl nanosheets and Cu2O sub-microspheres. Compared with pure Cu2O, pure BiOCl and the mechanical mixture of both, Cu2O/BiOCl composites exhibited markedly improved efficiency for photocatalytic degradation of X-3B. The unique 3D/2D and heterojunction structure in composites could increase the pore volume and BET specific surface area and improve the adsorption properties, on the other hand, it could efficiently enhance the charge carriers separation and migration. The nanocomposites with Cu2O/BiOCl molar ratio of 1:4 showed the highest photocatalytic activity. The effects of various scavengers on photocatalytic efficiency revealed that the degradation of X-3B was mainly initiated by reactive radial rad O2- and h+.

  13. First-Principles Study of the Local Magnetic Moment on a N-Doped Cu2O(111)Surface

    Institute of Scientific and Technical Information of China (English)



    First-principles calculations based on density functional theory within the generalized gradient approximation are used to study on magnetism in N-doped Cu2O.It is interesting that nitrogen does not induce magnetism in bulk Cu2O,while shows a total magnetism moment of 1.0μB at the Cu2O(111)surface,which is mainly localized on the doped N atoms.The local magnetic moment at the N-doped Cu2O(111)surface can be explained in terms of the surface state.%First-principles calculations based on density functional theory within the generalized gradient approximation are used to study on magnetism in N-doped C112O. It is interesting that nitrogen does not induce magnetism in bulk Cu2O, while shows a total magnetism moment of 1.0μB at the C112O (111) surface, which is mainly localized on the doped JV atoms. The local magnetic moment at the N-doped Cu2O (111) surface can be explained in terms of the surface state.

  14. Electrochemically deposited Cu2O cubic particles on boron doped diamond substrate as efficient photocathode for solar hydrogen generation (United States)

    Mavrokefalos, Christos K.; Hasan, Maksudul; Rohan, James F.; Compton, Richard G.; Foord, John S.


    Herein, we report a novel photocathode for the water splitting reaction. The electrochemical deposition of Cu2O particles on boron doped diamond (BDD) electrodes and the subsequent decoration with NiO nanoparticles by a dip coating method to act as co-catalyst for hydrogen evolution reaction is described. The morphology analysis by scanning electron microscope (SEM) revealed that Cu2O particles are cubic and decorated sporadically with NiO nanoparticles. X-ray photoelectron spectroscopy (XPS) confirmed the electronic interaction at the interface between Cu2O and NiO through a binding energy shift of the main Cu 2p peak. The photoelectrochemical (PEC) performance of NiO-Cu2O/BDD showed a much higher current density (-0.33 mA/cm2) and photoconversion efficiency (0.28%) compared to the unmodified Cu2O/BDD electrode, which are only -0.12 mA/cm2 and 0.06%, respectively. The enhancement in PEC performance is attributable to the synergy of NiO as an electron conduction mediator leading to the enhanced charge separation and transfer to the reaction interface for hydrogen evolution as evidenced by electrochemical impedance spectroscopy (EIS) and charge carrier density calculation. Stability tests showed that the NiO nanoparticles loading content on Cu2O surface is a crucial parameter in this regard.

  15. p-Cu2O/SiO x /n-SiC/n-Si memory diode fabricated with room-temperature-sputtered n-SiC and SiO x (United States)

    Yamashita, Atsushi; Tsukamoto, Takahiro; Suda, Yoshiyuki


    We investigated low-temperature fabrication processes for our previously proposed pn memory diode with a p-Cu2O/SiC x O y /n-SiC/n-Si structure having resistive nonvolatile memory and rectifying behaviors suitable for a cross-point memory array with the highest theoretical density. In previous fabrication processes, n-SiC was formed by sputtering at 1113 K, and SiC x O y and p-Cu2O were formed by the thermal oxidation of n-SiC and Cu at 1073 and 473 K, respectively. In this study, we propose a pn memory diode with a p-Cu2O/SiO x /n-SiC/n-Si structure, where n-SiC and SiO x layers are deposited by sputtering at room temperature. The proposed processes enable the fabrication of the pn memory diode at temperatures of not more than 473 K, which is used for the formation of p-Cu2O. This memory diode exhibits good nonvolatile memory and rectifying characteristics. These proposed low-temperature fabrication processes are expected to expand the range of fabrication processes applicable to current LSI fabrication processes.

  16. Electronic band structure of Cu(2)O by spin density functional theory. (United States)

    French, M; Schwartz, R; Stolz, H; Redmer, R


    The band structure of Cu(2)O is calculated using density functional theory in the generalized gradient approximation. By taking spin-orbit coupling into account the split between the Γ(7)(+) and the Γ(8)(+) valence band states is obtained as 128 meV. The highest valence band shows a noticeable nonparabolicity close to the Γ point. This is important for the quantitative description of excitons in this material, which is considered to be the best candidate for the confirmation that Bose-Einstein condensation also occurs in excitonic systems.

  17. Nanocrystalline Cu2O/p-Si solar light-responsive Schottky photodiode (United States)

    Al-Ghamdi, Ahmed A.; Farag, A. A. M.; Hendi, A. A.; Al Orainy, R. H.; El-Tantawy, Farid; Yakuphanoglu, F.


    Nanocrystalline of Cu2O thin film was synthesized by sol-gel spin-coating technique. The spectrophotometric characteristics of transmission and reflection were studied for the film deposited on glass substrate. The optical absorption measurements near the absorption edge indicate that the absorption mechanism is due to allowed direct transition with energy gap value of 2.09 eV. The current-voltage characteristics of Al/Cu2O/p-Si/Al diode were studied under dark and various light intensities in the range 20-100 mW/cm2. The main diode parameters such as barrier height, ideality factor, series resistance were calculated from the analysis of current-voltage characteristics and studied under various illumination intensities. Moreover, the results indicate that the diode has a high photoresponsivity and the photocurrent increases with increasing light intensity which supports the availability of the diode for photosensor applications. The capacitance and conductance characteristics indicate that the diode highly depends on both voltage and frequency. Higher increase in the capacitance under low frequency as well as the presence of a characteristic peak in the capacitance-frequency characteristics indicates the presence of interface states. Moreover, the stronger parameters of the diode performance such as series resistance and interface states were extracted from the capacitance-voltage-frequency and conductance-voltage-frequency characteristics.

  18. Hopping conductivity in CaCu(2)O(3) single crystals. (United States)

    Lisunov, K G; Arushanov, E; Raquet, B; Broto, J M; Chou, F C; Wizent, N; Behr, G


    The resistivity, ρ, of the spin-ladder compound CaCu(2)O(3) is investigated between T∼130-450 K. The ρ(T) data measured for [Formula: see text] (along the Cu-O-Cu leg) and [Formula: see text] (along the Cu-O-Cu rungs), ρ(a)(T)>ρ(b)(T), exhibit an activated dependence, similar in both directions and characterized by a nearest-neighbour hopping followed by a variable-range hopping (VRH) regime when T is decreased. A detailed analysis of ρ(T) demonstrates that conventional d-dimensional models of the hopping conductivity, based on the electron localization in disordered systems, cannot interpret the experimental data at any d = 1, 2 or 3, leading to the mismatch of the characteristic energies and/or unphysical values of the characteristic length scales. The observed VRH conductivity law on the low-temperature interval, lnρ∼T(-3/4), contradicts the models above, too. Instead, it is found that this law can be substantiated and the correct matching of the energy and length scales can be found within a model of Fogler et al (2004 Phys. Rev. B 69 035413) by treating CaCu(2)O(3) as a three-dimensional array of quasi-one-dimensional electron crystals.

  19. How Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+delta. (United States)

    Kohsaka, Y; Taylor, C; Wahl, P; Schmidt, A; Lee, Jhinhwan; Fujita, K; Alldredge, J W; McElroy, K; Lee, Jinho; Eisaki, H; Uchida, S; Lee, D-H; Davis, J C


    The antiferromagnetic ground state of copper oxide Mott insulators is achieved by localizing an electron at each copper atom in real space (r-space). Removing a small fraction of these electrons (hole doping) transforms this system into a superconducting fluid of delocalized Cooper pairs in momentum space (k-space). During this transformation, two distinctive classes of electronic excitations appear. At high energies, the mysterious 'pseudogap' excitations are found, whereas, at lower energies, Bogoliubov quasi-particles-the excitations resulting from the breaking of Cooper pairs-should exist. To explore this transformation, and to identify the two excitation types, we have imaged the electronic structure of Bi(2)Sr(2)CaCu(2)O(8+delta) in r-space and k-space simultaneously. We find that although the low-energy excitations are indeed Bogoliubov quasi-particles, they occupy only a restricted region of k-space that shrinks rapidly with diminishing hole density. Concomitantly, spectral weight is transferred to higher energy r-space states that lack the characteristics of excitations from delocalized Cooper pairs. Instead, these states break translational and rotational symmetries locally at the atomic scale in an energy-independent way. We demonstrate that these unusual r-space excitations are, in fact, the pseudogap states. Thus, as the Mott insulating state is approached by decreasing the hole density, the delocalized Cooper pairs vanish from k-space, to be replaced by locally translational- and rotational-symmetry-breaking pseudogap states in r-space.

  20. Tailoring oxides of copper-Cu{sub 2}O and CuO nanoparticles and evaluation of organic dyes degradation

    Energy Technology Data Exchange (ETDEWEB)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha, E-mail: [Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307,Uttar Pradesh (India)


    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu{sub 2}O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu{sub 2}O and CuO nanoparticles.

  1. Synthesis and characterization of Cu2O-modified Bi2O3 nanospheres with enhanced visible light photocatalytic activity (United States)

    Luo, Yidan; Huang, Qingqing; Li, Bin; Dong, Lihui; Fan, Minguang; Zhang, Feiyue


    In this work, a series of Cu2O-modified Bi2O3 nanospheres with perfect visible-light catalytic activity were successfully synthesized via the two-step method. The obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, UV-visible diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). In the catalysts of Cu2O-modified Bi2O3 nanospheres, Cu2O was dispersed on the surface of Bi2O3 nanospheres. All of Cu2O-modified Bi2O3 nanospheres showed uniformly nanospheres with the size of 80-150 nm, and exhibited enhanced photocatalytic activity in the degradation of Rhodamine B. The higher BET surface area, the band gap narrowing, and the interfacial charge transfer effect were considered to cause the excellent photocatalysis of Cu2O loading Bi2O3 samples. Furthermore, the possible photocatalysis mechanism was proposed.

  2. One-Pot Synthesis of Cu2O/Cu Self-Assembled Hollow Nanospheres with Enhanced Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Bo Zhou


    Full Text Available Cu2O/Cu hollow spheres are prepared using one-pot template-free solvent-thermal synthesis route with (CH3COO2Cu·H2O as a precursor. With the reaction time increasing gradually from 2 h to 20 h, the morphology of the Cu2O/Cu evolves from nanoparticle to hollow nanosphere. The hollow structure is obtained when the cooling rate falls down to 0.7°C/min. And the content of Cu in the hollow spheres also can be easily controlled by adjusting the solvent-thermal synthesis time. Using photocatalytic degradation of phenol as the probe molecules under visible-light illumination, we have investigated the influence of hollow structure on the photocatalytic activity of Cu2O/Cu. The prepared hollow sphere Cu2O/Cu particles exhibited a higher photodegradation capability than nanoparticles and solid spheres. When the content of Cu lies in the range of 11–86 wt%, the samples exhibit higher photocatalytic performance, indicating that the Cu2O/Cu particles with hollow structure are promising candidates for the processing of pollutants.

  3. Simultaneous enhancement of photovoltage and charge transfer in Cu2O-based photocathode using buffer and protective layers (United States)

    Li, Changli; Hisatomi, Takashi; Watanabe, Osamu; Nakabayashi, Mamiko; Shibata, Naoya; Domen, Kazunari; Delaunay, Jean-Jacques


    Coating n-type buffer and protective layers on Cu2O may be an effective means to improve the photoelectrochemical (PEC) water-splitting performance of Cu2O-based photocathodes. In this letter, the functions of the buffer layer and protective layer on Cu2O are examined. It is found that a Ga2O3 buffer layer can form a buried junction with Cu2O, which inhibits Cu2O self-reduction as well as increases the photovoltage through a small conduction band offset between the two semiconductors. The introduction of a TiO2 thin protective layer not only improves the stability of the photocathode but also enhances the electron transfer from the photocathode surface into the electrolyte, thus resulting in an increase in photocurrent at positive potentials. These results show that the selection of overlayers with appropriate conduction band positions provides an effective strategy for obtaining a high photovoltage and high photocurrent in PEC systems.

  4. Structural verification and optical characterization of SiO2–Au–Cu2O nanoparticles

    Indian Academy of Sciences (India)

    Hossein Rezvani Nikabadi; Nasser Shahtahmasebi; Mahmood Rezaee Rokn-Abadi; Masoud Karimipour; M M Bagheri Mohagheghi


    In this paper, SiO2–Au–Cu2O core/shell/shell nanoparticles were synthesized by reducing gold chloride on 3-amino-propyl-triethoxysilane molecules attached silica nanoparticle cores for several stages. Cu2O nanoparticles were synthesized readily with the size of 4–5 nm using a simple route of sol–gel method. Then, they were clung to the surface of Au seeds. The morphology of the resultant particles was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Transmission electron microscopy images demonstrate growth of monodispersed gold seeds and Cu2O nanoparticles in narrow size up to 10 nm and 5 nm, respectively. The presence of gold and Cu2O coating was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. Absorption spectroscopy shows considerably 40 nm blue shift in absorption edge for SiO2–Au–Cu2O nanostructure rather than SiO2–Au core/shell nanoparticles.

  5. Preparation and Optoelectronic Characteristics of ZnO/CuO-Cu2O Complex Inverse Heterostructure with GaP Buffer for Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Yi-Feng Lin


    Full Text Available This study reports the optoelectronic characteristics of ZnO/GaP buffer/CuO-Cu2O complex (COC inverse heterostructure for solar cell applications. The GaP and COC layers were used as buffer and absorber in the cell structure, respectively. An energy gap widening effect and CuO whiskers were observed as the copper (Cu layer was exerted under heat treatment for oxidation at 500 °C for 10 min, and arose from the center of the Cu2O rods. For preparation of the 30 nm-thick GaP buffer by sputtering from GaP target, as the nitrogen gas flow rate increased from 0 to 2 sccm, the transmittance edge of the spectra demonstrated a blueshift form 2.24 to 3.25 eV. Therefore, the layer can be either GaP, GaNP, or GaN by changing the flow rate of nitrogen gas.

  6. Vortex fluctuations in underdoped Bi(2)Sr(2)CaCu(2)O(8+delta) crystals. (United States)

    Colson, Sylvain; Konczykowski, Marcin; Gaifullin, Marat B; Matsuda, Yuji; Gierłowski, Piotr; Li, Ming; Kes, Peter H; Van Der Beek, Cornelis J


    Vortex thermal fluctuations in heavily underdoped Bi(2)Sr(2)CaCu(2)O(8+delta) (T(c)=69.4 K) are studied using Josephson plasma resonance. From the zero-field data, we obtain the c-axis penetration depth lambda(L,c)(0)=230+/-10 micrometer and the anisotropy ratio gamma(T). The low plasma frequency allows us to study phase correlations over the whole vortex solid state and to extract a wandering length r(w) of vortex pancakes. The temperature dependence of r(w) as well as its increase with dc magnetic field is explained by the renormalization of the vortex line tension by the fluctuations, suggesting that this softening is responsible for the dissociation of the vortices at the first order transition.

  7. Energy gaps in Bi(2)Sr(2)CaCu(2)O(8+δ) cuprate superconductors. (United States)

    Ren, J K; Zhu, X B; Yu, H F; Tian, Ye; Yang, H F; Gu, C Z; Wang, N L; Ren, Y F; Zhao, S P


    The relationship between the cuprate pseudogap (Δ(p)) and superconducting gap (Δ(s)) remains an unsolved mystery. Here, we present a temperature- and doping-dependent tunneling study of submicron Bi(2)Sr(2)CaCu(2)O(8+δ) intrinsic Josephson junctions, which provides a clear evidence that Δ(s) closes at a temperature T(c) (0) well above the superconducting transition temperature T(c) but far below the pseudogap opening temperature T*. We show that the superconducting pairing first occurs predominantly on a limited Fermi surface near the node below T(c) (0), accompanied by a Fermi arc due to the lifetime effects of quasiparticles and Cooper pairs. The arc length has a linear temperature dependence, and as temperature decreases below T(c) it reduces to zero while pairing spreads to the antinodal region of the pseudogap leading to a d-wave superconducting gap on the entire Fermi surface at lower temperatures.

  8. Melt-textured GdSr 2RuCu 2O 8 samples: preliminary results (United States)

    Gombos, M.; Vecchione, A.; Ciancio, R.; Sisti, D.; Uthayakumar, S.; Pace, S.


    The superposition of strongly anisotropic magnetic and superconducting properties, expected in Gd1212 (GdSr 2RuCu 2O 8), makes relevant the fabrication of oriented samples of macroscopic size by melt-texturing techniques. Starting from 1 cm diameter pellets we have grown top-seeded melt-textured samples using MgO seeds. X-ray diffraction analysis shows that a certain degree of orientation is present in our samples. Large oriented domains of millimetre size were observed by polarised light optical microscopy, larger domains are expected by optimisation of growth parameters and seed. Images show even a homogeneous distribution of Gd1210 precipitates with a mean size of a few micrometres. Resistivity measurements show a 12 K wide superconductive transition with Tc onset at about 40 K, optimisation of annealing treatments are expected to reduce this width.

  9. Standard Gibbs free energy of formation for Cu 2O, NiO, CoO, and FexO: High resolution electrochemical measurements using zirconia solid electrolytes from 900-1400 K (United States)

    Holmes, Richard D.; O'Neill, Hugh St. C.; Arculus, Richard J.


    Galvanic cells with oxygen-specific solid electrolytes made of calcia-stabilized zirconia have been used to make equilibrium measurements of the standard Gibbs free energy of formation, ΔfG0m,( T), for copper (I) oxide (Cu 2O), nickel (II) oxide (NiO), cobalt (II) oxide (CoO), and wüstite (Fe xO) over the temperature range from 900-1400 K. The measured values of ΔfG0m at 1300 K are -73950, -123555, -142150, and -179459 J · mol -1 for Cu 2O, NiO, CoO, and Fe 0.947O, respectively. The precision of these measurements is ± 30-60 J · mol -1, and their absolute accuracy is estimated to be ± 100-200 J·mol -1. Using values of -76.557, -94.895, -79.551, and -71.291 J · K -1 · mol -1 for the entropies of formation, ΔfSm0, (298.15 K), the calculated enthalpies of formation, ΔfHm0, (298.15 K), are -170508, -240110, -237390, and -266458 J · mol -1 for Cu 2O, NiO, CoO, and Fe 0.947O, respectively. These values of ΔfSm0 (298.15 K) and ΔfHm0 (298.15 K) are in good agreement with the best available calorimetric measurements.

  10. Thermodynamic study of CuO/Cu2O and Co3O4/CoO redox pairs for solar energy thermochemical storage (United States)

    Alonso, Elisa; Gallo, Alessandro; Pérez-Rábago, Carlos; Fuentealba, Edward


    Thermochemical storage of solar energy consists in reversible chemical reactions that absorb the solar heat during an endothermic step and release it by means of an exothermic reaction. CuO/Cu2O and Co3O4/CoO redox pairs have a high potential as materials to store solar energy at high temperature. Cobalt oxides have been so far studied by several authors and works while copper oxides suitability has been recently proved. However, in both cases, operation parameters need to be optimized. A theoretical study of the effect of total pressure, gas/solid molar rate and composition of working atmosphere on the systems equilibrium is presented. The equilibrium displacement caused by these parameters is calculated and discussed. Finally, some ideas for tentative implementations of these systems are commented.

  11. Heat capacity of Tb2Cu2O5 in the temperature range 379-924 K (United States)

    Denisova, L. T.; Denisov, V. M.; Chumilina, L. G.; Kirik, S. D.; Istomin, S. A.


    The heat capacity of Tb2Cu2O5 in the temperature range 379-924 K has been measured using differential scanning calorimetry. It has been shown that the obtained dependence C p = f( T) can be described by a combination of the Debye and Einstein functions.

  12. Localized electronic states and photoemission superconducting condensate in Bi 2Sr 2CaCu 2O 8+x (United States)

    Ma, Jian; Quitmann, C.; Kelley, R. J.; Margaritondo, G.; Onellion, M.


    We present the first detailed angle-resolved photoemission evidence that there are two types of carriers that contribute to the photoe-mission superconducting condensate in Bi 2Sr 2CaCu 2O 8+x. Our data indicate that both itinerant and somewhat localized normal state carriers can contribute to the formation of Cooper pairs.

  13. Thermally Activated Dissipation in Bi2.2Sr2Ca0.8Cu2O8+δ

    NARCIS (Netherlands)

    Palstra, T.T.M.; Batlogg, B.; Schneemeyer, L.F.; Waszczak, J.V.


    A new dissipation behavior is reported in superconducting Bi2.2Sr2Ca0.8Cu2O8+δ for all temperatures below Tc and all magnetic fields exceeding Hc1. The current-independent electrical resistivity is thermally activated and can be described by an Arrhenius law with a single prefactor and a

  14. Model of Interatomic Interactions and Vibrational Spectrum of Tl2CaBa2Cu2O8 (United States)

    Belosludov, V. R.; Lavrentiev, M. Yu.; Syskin, S. A.

    A model of interatomic interactions of Tl2CaBa2Cu2O8, which takes into account coulombic interaction and covalent bonds, is presented. Vibrational spectrum is calculated using that model, and a comparison with experiments on Raman scattering is given.

  15. Au@Cu2O stellated polytope with core-shelled nanostructure for high-performance adsorption and visible-light-driven photodegradation of cationic and anionic dyes. (United States)

    Wu, Xueqing; Cai, Jiabai; Li, Shunxing; Zheng, Fengying; Lai, Zhanghua; Zhu, Licong; Chen, Tanju


    Au nanoparticles were covered by Cu2O nanoparticles shell and then Au@Cu2O stellated polytope was synthesized by a facile aqueous solution approach. The samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction patterns, X-ray photoelectron spectroscopy, Brunner-Emmet-Teller measurements, and Ultraviolet-visible spectroscopy analysis. With good aqueous dispersibility, surface positive charge, and high chemisorption capacity, Au@Cu2O could be used for anionic dyes removal. Compared with Degussa P25-TiO2, the adsorption of anionic dyes (acid violet 43 or methyl blue, 5.0 mg L(-1)) onto Au@Cu2O was increased by 90.12% and 50.8%, respectively. The photodegradation activity of methyl orange and methyl violet were in the declining order: Au@Cu2O>Cu2O-Au nanocomposites>Cu2O>P25-TiO2. The synergistic effect of coupling Au core with Cu2O shell on the dyes photodegradation was observed. The photoexcited electrons from Cu2O conduction band could be captured by Au nanoparticles, resulting in an improved electron-hole separation. Moreover, a Schottky barrier was assumed to form at the Cu2O-Au interface and Au NPs as electron sink could reduce the recombination of photoinduced electrons and holes, facilitating the photocatalytic interface reaction. The geometry of core-shell and stellated polytope is effective in the design of Cu2O-Au nanocomposites for adsorption and photocatalysis.

  16. Adhesive hydrophobicity of Cu2O nano-columnar arrays induced by nitrogen ion irradiation. (United States)

    Dhal, Satyanarayan; Chatterjee, Sriparna; Manju, Unnikrishnan; Tribedi, Lokesh C; Thulasiram, K V; Fernandez, W A; Chatterjee, Shyamal


    Low energy nitrogen ions are used in this work to manipulate wetting properties of the surface of the array of Cu2O nano-columns, which yields remarkable results. The nano-columnar thin films were grown on a highly conductive silicon surface by a sputter deposition technique. The films were irradiated at two different fluences of 5 × 10(15) and 1 × 10(16) ions per cm(2), respectively. With increasing fluence the shape of column tip changes, columns are bent and porous channels between columns are clogged up. While the surface of the pristine sample is hydrophilic, the irradiated surface turns into hydrophobic but having adhesion properties. We have analysed the structural and chemical properties of the surface in detail to understand the initial and modified wetting properties. Furthermore, the temporal evolutions of different droplet parameters are investigated to realize the interactions between the water droplet, the sample surface and the atmosphere. We envisage that such modified surfaces can be beneficial for transport of a small volume of liquids with minimum loss and spectroscopic studies, where a small amount of water droplet is available for measurements.

  17. Studies of Magnetic Impurities in Bi2Sr2CaCu2O8+δ (United States)

    Calleja, Eduardo; Dai, Jixia; Gu, Genda; McElroy, Kyle


    Impurities in high temperatures superconductors, studied with spectroscopic imaging scanning tunneling spectroscopy (SI-STS) have served as a valuable tool to investigate the electronic structure of these materials (E.W. Hudson et al., Nature 411, 920 (2001), S.H.Pan et al., Nature 403,746 (2000)). These experiments revealed the appearance of a quasi-localized bound state near the impurity site whose structure is sensitive to the superconducting gap symmetry and the band structure and originates from the charge scattering nature of these impurities. We studied the effects of Fe impurities in Bi2Sr2CaCu2O8+δ and discovered that the impurities have a different behavior than those previously observed. In particular the quasi bound state near the impurity seems to be behaving as that predicted for a magnetic impurity. The superconducting gap and local electronic density of states was studied in the vicinity of the impurities using SI-STS and will be presented.

  18. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell (United States)

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping


    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  19. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Directory of Open Access Journals (Sweden)

    Feng Dong


    Full Text Available In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM and Brunauer-Emmett-Teller (BET tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS and cyclic voltammetry (CV results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV and electrochemical impedance spectroscopy (EIS results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode.

  20. Ba 3A2PtCu 2O 10 ( A = Y or Ho): The crystal structure of a reaction by-product of high transition temperature superconductors with platinum metal (United States)

    Geiser, Urs; Porter, Leigh C.; Wang, Hau H.; Allen, Thomas A.; Williams, Jack M.


    Mixtures of CuO, BaCO 3, and A2O 3 ( A = Y, rare earth) react at temperatures between 600 and 1000°C with platinum containers to produce crystals of composition Ba 3A2PtCu 2O 10. The crystal structures of the compounds with A = Y or Ho were determined from single-crystal X-ray diffraction data. They are isostructural, monoclinic, space group {C2}/{m}, with Z = 2. Lattice parameters for Ba 3Y 2PtCu 2O 10 are a = 12.520(3) Å, b = 5.817(1) Å, c = 7.357(1) Å, β = 105.53(2)°, V = 516.2(2) Å 3. Lattice parameters for Ba 3Ho 2PtCu 2O 10 are a = 12.516(3) Å, b = 5.813(1)Å, c = 7.350(3) Å, β = 105.54(2)°, V = 515.2(3)Å 3. The structure of these complex oxides has the four metal ions in five distinct coordination environments: two barium sites with coordination numbers (CN) 8 and 11, yttrium or holmium with CN 7, platinum(IV) with CN 6, and copper with CN 5.

  1. Nonlinear optical processes at quadrupole polariton resonance in Cu2O as probed by a Z-scan technique (United States)

    Mani, S.; Jang, J. I.; Ketterson, J. B.


    Employing a modified Z-scan technique at 2 K, we monitor not only the fundamental (ω) but also the frequency-doubled (2ω) and tripled (3ω) Z-scan responses in Cu2O when the input laser frequency ω is tuned to the two-photon quadrupole polariton resonance. The Z-scan response at ω allows us to accurately estimate the absolute number of polaritons generated via two-photon absorption. A striking dip is observed near the 2ω Z-scan focus which basically arises from Auger-type recombination of polaritons. Under high excitation levels, the 3ω Z-scan shows strong third harmonic generation. Based on the nonlinear optical parameters determined, we estimate the experimental polariton density achievable and propose a direction for polariton-based Bose-Einstein condensation in Cu2O .

  2. Ruthenocuprates RuSr2(Eu,Ce)2Cu2O10-y: Intrinsic magnetic multilayers (United States)

    Živković, I.; Hirai, Y.; Frazer, B. H.; Prester, M.; Drobac, D.; Ariosa, D.; Berger, H.; Pavuna, D.; Margaritondo, G.; Felner, I.; Onellion, M.


    We report ac susceptibility data on RuSr2(Eu,Ce)2Cu2O10-y (Ru-1222, Ce content x=0.5 and 1.0), RuSr2GdCu2O8 (Ru-1212), and SrRuO3. Both Ru-1222 (x=0.5, 1.0) sample types exhibit unexpected magnetic dynamics in low magnetic fields: logarithmic time relaxation, switching behavior, and ``inverted'' hysteresis loops. Neither Ru-1212 nor SrRuO3 exhibit such magnetic dynamics. The results are interpreted as evidence of the complex magnetic order in Ru-1222. We propose a specific multilayer model to explain the data, and note that superconductivity in the ruthenocuprate is compatible with both the presence and absence of the magnetic dynamics.

  3. TiO2 film/Cu2O microgrid heterojunction with photocatalytic activity under solar light irradiation. (United States)

    Zhang, Junying; Zhu, Hailing; Zheng, Shukai; Pan, Feng; Wang, Tianmin


    Coupling a narrow-band-gap semiconductor with TiO(2) is an effective method to produce photocatalysts that work under UV-vis light irradiation. Usually photocatalytic coupled-semiconductors exist mainly as powders, and photocatalytic activity is only favored when a small loading amount of narrow-band-gap semiconductor is used. Here we propose a heavy-loading photocatalyst configuration in which 51% of the surface of the TiO(2) film is covered by a Cu(2)O microgrid. The coupled system shows higher photocatalytic activity under solar light irradiation than TiO(2) and Cu(2)O films. This improved performance is due to the efficient charge transfer between the two phases and the similar opportunity each has to be exposed to irradiation and adsorbates.

  4. Study of iodine-intercalated Bi 2Sr 2CaCu 2O y single crystals (United States)

    Alméras, P.; Berger, H.; Perez, L.; Margaritondo, G.


    Iodine intercalation in Bi 2Sr 2CaCu 2O y crystals enables one to modify the critical temperature, Tc, of the superconducting phase, and to obtain a semiconductor phase. This doping drastically changes the size of the unit cell. A protoemission spectroscopy study enables us to see that the decrease of the critical temperature is not related only to the change in the c-axis lattice parameter but also to an over-doping of copper planes (hole doping).

  5. Temperature-dependent photoemission features for overdoped Bi2Sr2CaCu2O8 + x cuprates (United States)

    Rast, S.; Frazer, B. H.; Onellion, M.; Schmauder, T.; Abrecht, M.; Touzelet, O.; Berger, H.; Margaritondo, G.; Pavuna, D.


    We report temperature-dependent angle-resolved photoemission spectra for overdoped Bi2Sr2CaCu2O8 + x single-crystal samples. The data indicate that there is a special temperature (T+) where the spectral function changes intensity, and where the energy difference between the peak and dip features changes. The data also demonstrate that immediately above the superconducting transition temperature, the system exhibits a non-Lorentzian lineshape. We discuss implications of the data.

  6. The symmetry of the order parameter in highly overdoped Bi 2Sr 2CaCu 2O 8+ x (United States)

    Vobornik, I.; Gatt, R.; Schmauder, T.; Frazer, B.; Kelley, R. J.; Kendziora, C.; Grioni, M.; Onellion, M.; Margaritondo, G.


    We report results of an angle-resolved high-resolution photoemission study of strongly overdoped Bi 2Sr 2CaCu 2O 8+ x single crystals with Tc∼60 K. We find a nonzero superconducting (SC) gap along all three high symmetry directions in the Brillouin zone, in contrast with a d-wave scenario of high temperature superconductivity. Our data indicate that both the maximum gap value and the gap anisotropy decrease with overdoping.

  7. Vortex softening: origin of the second peak effect in Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Correa, V F; Nieva, G; de la Cruz, F


    Magnetic hysteresis and transverse ac permeability measurements in Bi(2)Sr(2)CaCu(2)O(8+delta) allow a comparative analysis of the critical current with the elastic response of vortex structures, in equilibrium with their pinning potential, in the field and temperature region where the second peak is detected. This study provides strong evidence that the second peak has its origin in changes of the elastic equilibrium properties of the vortex structures.

  8. Temperature and wavevector dependence of overdoped Bi_2Sr_2CaCu_2O_8+x single crystal samples (United States)

    Rast, S.; Klohs, A.; Frazer, B. H.; Hirai, Y.; Schmauder, T.; Gatt, R.; Abrecht, M.; Pavuna, D.; Margaritondo, G.; Onellion, M.


    We report on measuring the temperature and wavevector change of angle-resolved photoemission spectra for overdoped Bi_2Sr_2CaCu_2O_8+x single crystal samples. Spectra taken from close to to close to were analyzed. The changes of spectral lineshape with temperature and wave vector indicate qualitatively different behavior in different parts of the Brillouin zone and will be analyzed and presented.

  9. Sandwiched ZnO@Au@Cu2O nanorod films as efficient visible-light-driven plasmonic photocatalysts. (United States)

    Ren, Shoutian; Wang, Benyang; Zhang, Hui; Ding, Peng; Wang, Qiang


    The design of efficient visible-light-driven photocatalysts has become a hot topic due to their potential applications in energy and environmental industries. In this work, sandwiched ZnO@Au@Cu2O nanorod films were prepared on stainless steel mesh substrates in the order of the following steps: electrodeposition, sputtering, and second electrodeposition. The as-synthesized nanocomposites were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and UV-visible spectrophotometry, respectively. Due to their coaxial structure to inhibit the carrier recombination and the localized surface plasmon resonance effect of Au nanoparticles to enhance the visible light absorption, an outstanding visible-light-driven photocatalytic performance is realized. The enhancement magnitude of Au nanoparticles on the catalytic performance of ZnO@Au@Cu2O was estimated as a function of the Cu2O loading amount. The corresponding enhancement mechanism was also explained according to the photocatalytic results under monochromatic visible light irradiation, the active species trapping experiments, and discrete dipole approximation simulation results.

  10. Investigations on the role of alkali to obtain modulated defect concentrations for Cu2O thin films (United States)

    Chowdhury, Anirban; Bijalwan, Pavan Kumar; Sahu, Ranjan Kumar


    An economic successive ionic layer adsorption and reaction (SILAR) method has been investigated for depositing thin Cu2O layers on steel. The mole ratios of the Cu+ ions to OH- ions in the alkali bath were varied and the changes in the properties were characterised by X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM) and Ultraviolet-visible spectroscopy techniques. The increase in the binding energy values of the Cu 2p peaks in XPS established that an optimum copper vacancy concentration can be obtained for a Cu+/OH- mole ratio between 1:10 and 1:15; SEM studies confirmed a dense, uniform microstructure for Cu2O thin films coated with these compositions. The strongest absolute peak intensity counts in PL for the peak at 580 nm along with low energy peaks (1.2-1.4 eV) due to Cu vacancy was found to be most prominent for thin film made with Cu+/OH- mole ratio 1:15. The role of alkali concentration has been explained in relation to create a stable Cu2-δO structure with optimum copper vacancy. This is an easy way to modulate surface reactivity of the Cu2O thin layers and the concept can be utilised for large area device integrations for various electrical and mechanical applications.

  11. Enhancement of YBCO thin film thermal stability under 1 ATM oxygen pressure by intermediate Cu2O nanolayer. (United States)

    Cheng, L; Wang, X; Yao, X; Wan, W; Li, F H; Xiong, J; Tao, B W; Jirsa, M


    The melting process of YBa(2)Cu(3)O(x) (YBCO or Y123) films under an oxygen atmosphere was observed in situ by means of high-temperature optical microscopy. The films were classified by pole figure measurement as c-axis oriented, with two different in-plane orientations (denoted as 0 and 45 degrees). In the 45 degrees-oriented films, electron diffraction and high-resolution transmission electron microscopy (HRTEM) detected an intermediate Cu(2)O nanolayer in the vicinity of the interface. The melting mode and the thermal stability of the YBCO thin films with different in-plane orientations were greatly influenced by oxygen partial pressure. Notably, the thermal stability of the 45 degrees-oriented YBCO films dramatically grew with increasing oxygen partial pressure. We attributed this effect to a change in the intermediate Cu(2)O nanolayer thermal stability. We conclude and suggest that the thermal stability of YBCO films can be significantly enhanced by inserting a Cu(2)O buffer nanolayer.

  12. 恒电流法制备Cu2O/TiO2复合纳米管阵列异质结光电极%Fabrication Cu2O/TiO2 Composition Nanotube Array Heterojunction Photo-electrode by Galvanostatic Method

    Institute of Scientific and Technical Information of China (English)



    A series of Cu2O/TiO2 composite nanotube array p-n heterojunction photo-electrodes were prepared by electrochemical anode oxidation Ti substrate in F-ions contained electrolyte,subsequently the as-prepared TiO2 nanotube array was electro-deposited in a copper lactate complex electrolyte with different times.The field-emission scanning electron microscopy show that the TiO2 nanotube array was prepared successfully,and some other nanoparticles can deposition on the top surface of the TiO2 nanotube array,meanwhile,the mass of nanoparticles can adjustment by varying electrodeposition time.In the X-ray diffraction(XRD) peak patterns,we can find out the characteristic peaks of TiO2 and Cu2O crystals.However the characteristic diffusion intensity of Cu2O is very weaker than TiO2,it is indicate that the crystallinity of the as-deposition Cu2O semiconductor is not high enough.In the Energy Dispersive Spectrometer(EDS),we can figure out the elements of Ti,Cu,O.Combine with the XRD and FE-SEM results,at last,we can point out that the Cu2O was deposited on the top of TiO2 nanotube array successfully by galvanostatic method.%通过在含F-离子的电解液中阳极氧化Ti薄片基底制备了TiO2纳米管阵列,随后通过恒电流沉积的方法在在TiO2纳米管阵列顶部原位电沉积了Cu2O纳米颗粒。场发射电子扫描显微镜显示TiO2纳米管这列被成功制备,通过恒电流电化学沉积后,TiO2纳米管阵列顶部出现大量纳米颗粒物质,并且随着沉积时间的延长,可以控制沉积物的量。通过X-射线衍射谱的特征衍射谱图我们可以发现TiO2锐钛矿的衍射峰以及相对较弱的Cu2O衍射峰,这说明Cu2O晶体的结晶度不高。在能谱(EDS)图中我们可以发现Ti、Cu、O三种元素,结合XRD以及FE-SEM结果我们可以指出,通过恒电流法确实可以在TiO2纳米管阵列顶部原位沉积Cu2O纳米颗粒。

  13. Structural properties of Cu2O epitaxial films grown on c-axis single crystal ZnO by magnetron sputtering (United States)

    Gan, J.; Gorantla, S.; Riise, H. N.; Fjellvâg, Ø. S.; Diplas, S.; Løvvik, O. M.; Svensson, B. G.; Monakhov, E. V.; Gunnæs, A. E.


    Epitaxial Cu2O films grown by reactive and ceramic radio frequency magnetron sputtering on single crystalline ZnO (0001) substrates are investigated. The films are grown on both O- and Zn-polar surface of the ZnO substrates. The Cu2O films exhibit a columnar growth manner apart from a ˜5 nm thick CuO interfacial layer. In comparison to the reactively sputtered Cu2O, the ceramic-sputtered films are less strained and appear to contain nanovoids. Irrespective of polarity, the Cu2O grown by reactive sputtering is observed to have (111)Cu2O||(0001)ZnO epitaxial relationship, but in the case of ceramic sputtering the films are found to show additional (110)Cu2O reflections when grown on O-polar surface. The observed CuO interfacial layer can be detrimental for the performance of Cu2O/ZnO heterojunction solar cells reported in the literature.

  14. Evidence for K-substitution in the Tl-sites of superconducting Tl 2CaBa 2Cu 2O χ: Neutron diffraction studies (United States)

    Sequeira, A.; Rajagopal, H.; Gopalakrishnan, I. K.; Sastry, P. V. P. S. S.; Phatak, G. M.; Yakhmi, J. V.; Iyer, R. M.


    A comparison of the Rietveld profile refinement of neutron diffraction data of the superconducting compounds Tl-2122 (i.e. Tl 2CaBa 2Cu 2O χ) and Tl 1K 1Ca 1Ba 2Cu 2O y provides evidence that nearly half of the Tl-sites belonging to the pure Tl-2122 structure get substituted by K-ions in Tl 1K 1Ca 1Ba 2Cu 2O y. The consequence of this is reflected in a substantial movement of Ba-ions towards the plane of the O(2)-ions in the K-substituted compound.

  15. Cu2O/累托石纳米复合材料处理模拟染料废水试验%Treating dye wastewater by nano-composites with Cu2O/rectorite

    Institute of Scientific and Technical Information of China (English)

    段颖姗; 陈云; 张文蓉; 陈金毅; 蔡忠丽; 孙家寿


    The Cu2O/rectorite composite which took the rectoite as the carrier was prepared by liquid phase synthesis and was characterized by means of SEM and XRD. The adsorption performances and photocatalysis properties of the composite was based on the photocatalytic degradation of simulate xylenol orange dye wastewater. The results indicate that the photodegradation efficiency of rectorite / CU2O is 81. 56% when stirring time is 40 min,initial pH of 13;simulate xylenol orange dye wastewater is 20-30 mg/L and the addtion of composite is 5 g/L. The photodegradation rate still reaches 70% even after repeated use for three times.%以累托石为载体,用液相合成法制备和表征了Cu2 O/累托石纳米复合材料,并以吸附降解二甲酚橙的效果,探讨复合材料的吸附及光催化氧化性能.试验结果表明:当模拟二甲酚橙染料废水的初始质量浓度为20~30 mg/L,初始pH值为13,搅拌时间为40 min,纳米累托石/Cu2O复合材料的投加量为5 g/L时,对模拟二甲酚橙染料废水中二甲酚橙的去除率可达81.56%.三次重复使用后的复合材料对二甲酚橙的去除率仍可达70%.

  16. Fluctuating stripes at the onset of the pseudogap in the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8+x). (United States)

    Parker, Colin V; Aynajian, Pegor; da Silva Neto, Eduardo H; Pushp, Aakash; Ono, Shimpei; Wen, Jinsheng; Xu, Zhijun; Gu, Genda; Yazdani, Ali


    Doped Mott insulators have a strong propensity to form patterns of holes and spins often referred to as stripes. In copper oxides, doping also gives rise to the pseudogap state, which can be transformed into a high-temperature superconducting state with sufficient doping or by reducing the temperature. A long-standing issue has been the interplay between the pseudogap, which is generic to all hole-doped copper oxide superconductors, and stripes, whose static form occurs in only one family of copper oxides over a narrow range of the phase diagram. Here we report observations of the spatial reorganization of electronic states with the onset of the pseudogap state in the high-temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+x), using spectroscopic mapping with a scanning tunnelling microscope. We find that the onset of the pseudogap phase coincides with the appearance of electronic patterns that have the predicted characteristics of fluctuating stripes. As expected, the stripe patterns are strongest when the hole concentration in the CuO(2) planes is close to 1/8 (per copper atom). Although they demonstrate that the fluctuating stripes emerge with the onset of the pseudogap state and occur over a large part of the phase diagram, our experiments indicate that the stripes are a consequence of pseudogap behaviour rather than its cause.

  17. Bayesian Analysis of an Excitonic Absorption Spectrum in a Cu2O Thin Film Sandwiched by Paired MgO Plates (United States)

    Iwamitsu, Kazunori; Aihara, Shingo; Okada, Masato; Akai, Ichiro


    We analyzed the absorption spectrum of a Cu2O thin film sandwiched by paired MgO plates with the Metropolis algorithm of Bayesian estimation to estimate the energy shift of a yellow excitonic band gap. In the absorption spectrum, discrete excitonic resonant transitions with homogeneous and inhomogeneous widths are superimposed upon the tail parts of excitonic continuum and band-to-band absorption bands. On the basis of the Metropolis samplings with 2.5 million steps after sufficient burn-in steps, the spectral parameters of the excitonic resonant transitions can be estimated satisfactorily with a high degree of accuracy. In particular, we demonstrated that the yellow excitonic band gap in the Cu2O thin film shifts to the lower energy side than that of Cu2O bulk crystals. This result is consistent with the stress relaxation model for such Cu2O thin films, which was reported in Eur. Phys. J. B 86, 194 (2013).

  18. Structural phase transition in early growth of Bi2Sr2CaCu2O8+x films on SrTiO3 substrates (United States)

    Abrecht, M.; Ariosa, D.; Onellion, M.; Margaritondo, G.; Pavuna, D.


    We used pulsed laser deposition, with a Bi2Sr2CaCu2O8+x target, to grow films ranging from (1/4) to 10 unit cells thick. We studied these films, and reference Bi2Sr2CaCu2O8+x single crystal samples, using angle-integrated photoemission, core level photoemission, and x-ray diffraction. The data indicate that all films exhibit a metallic-like Fermi edge in the photoemission data. More strikingly, a structural phase transition occurs at a nominal Bi2Sr2CaCu2O8+x thickness of approximately one unit cell, converting the precursor Bi2O2.33 highly coherent thin film into a Bi2Sr2CaCu2O8+x structure.

  19. Nanocrystal Cu2O-loaded TiO2 nanotube array films as high-performance visible-light bactericidal photocatalyst. (United States)

    Zhang, Shengsen; Liu, Chang; Liu, Xiaolu; Zhang, Haimin; Liu, Porun; Zhang, Shanqing; Peng, Feng; Zhao, Huijun


    In this work, we report the use of a non-toxic nanocrystal Cu(2)O-loaded TiO(2) nanotube array (Cu(2)O/TNTs) film as high-performance visible-light bactericidal photocatalyst. The samples were characterized by field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible diffusion reflection spectroscopy. This Cu(2)O/TNTs film photocatalyst is capable of complete inactivation of Escherichia coli in 5 × 10(7) colony-forming units/mL within a record short disinfection time of 20 min under visible-light irradiation. The average bactericidal percentage of the Cu(2)O/TNTs for E. coli under visible-light irradiation are 20 times and 6.6 times higher than those of TNTs under the same conditions and Cu(2)O/TNTs without light, respectively. This superior bactericidal performance is mainly attributed to the high ability to produce OH radicals by both photogenerated electron and hole of the prepared photocatalyst under visible light. The Cu(2)O/TNTs film photocatalyst makes it applicable to broad fields including drinking water disinfection.

  20. Doping controlled superconductor-insulator transition in Bi2Sr2-xLaxCaCu2O8+delta. (United States)

    Oh, Seongshik; Crane, Trevis A; Van Harlingen, D J; Eckstein, J N


    We show that the doping-controlled superconductor-insulator transition (SIT) in a high critical temperature cuprate system (Bi(2)Sr(2-x)La(x)CaCu(2)O(8+delta)) exhibits a fundamentally different behavior than is expected from conventional SIT. At the critical doping, the sheet resistance seems to diverge in the zero-temperature limit. Above the critical doping, the transport is universally scaled by a two-component conductance model. Below, it continuously evolves from weakly to strongly insulating behavior. The two-component conductance model suggests that a collective electronic phase-separation mechanism may be responsible for this unconventional SIT behavior.

  1. Localized electronic states and the superconducting gap in Bi 2Sr 2CaCu 2O 8+y (United States)

    Quitmann, C.; Ma, Jian; Kelley, R. J.; Margaritondo, G.; Onellion, M.


    Angle-resolved photoemission data taken on some Bi 2Sr 2CaCu 2O 8+y single crystals exhibit the formation of a superconducting gap in the absence of a quasiparticle normal state band. We observe the opening of the superconducting gap in the same regions of the Brillouin zone for which it is observed for samples that do exhibit a quasiparticle normal state. The absence of a dispersing quasiparticle normal state indicates that the normal state electronic states in these samples are almost localized in real space. Our data suggest that two types of carriers can coexist, and contribute to forming a superconducting gap, in these materials.

  2. Spectroscopic Signatures of Defect-Induced Pair Breaking in Bi2Sr2CaCu2O8+x (United States)

    Vobornik, I.; Berger, H.; Pavuna, D.; Onellion, M.; Margaritondo, G.; Rullier-Albenque, F.; Forró, L.; Grioni, M.


    We investigated the effect of disorder on the spectral properties of the high temperature superconductor Bi2Sr2CaCu2O8+x. We find that small defect densities, in the low 10-3 range, already suppress the characteristic spectral signature of the superconducting state, while new excitations appear within the gap. We conclude that, due to defect-induced pair breaking, superconducting pairs and normal carriers coexist below Tc. At higher levels of disorder the normal state is also strongly affected, and the quasiparticle features progressively smeared out.

  3. Doping-Induced Change of Superconducting Gap Anisotropy in Bi_2Sr_2Ca_1Cu_2O8+δ (United States)

    Kelley, R. J.; Quitmann, C.; Onellion, M.; Berger, H.; Almeras, P.; Margaritondo, G.


    High-resolution angle-resolved photoemission measurements were performed on single crystals of Bi_2Sr_2Ca_1Cu_2O8+δ with different oxygen stoichiometries. The data establish that the gap anisotropy (ratio of the gap along Gamma-M to the gap along Gamma-X) can be reversibly changed from ~20:1 (optimal or underdoped) to ~2:1 (overdoped). Differences in sample doping explain the conflicting reports on gap anisotropy in the literature. Possible effects of this change in gap anisotropy on the symmetry of the order parameter are discussed. There remains some ambiguity as to the relation between the order parameter and doping.

  4. Advances in single-crystal Bi 2Sr 2CaCu 2O 8+δ superconductors (United States)

    Kendziora, C.; Kelley, R. J.; Skelton, E.; Onellion, M.


    Susceptibility, resistivity and X-ray diffraction measurements have been performed on single crystals of Bi 2Sr 2CaCu 2O 8+δ. Very sharp (0.5 K width) superconducting transition temperatures as low as 55 K have been reached in the overdoped part of the phase diagram. Anneals in low oxygen pressures have allowed us to access the entire undordoped region of the phase diagram. The samples have been reversibly changed from a high-temperature superconductor to an insulator.

  5. Co-doped Bi 2Sr 2CaCu 2O x: Anderson localization and superconductivity (United States)

    Alméras, P.; Berger, H.; Margaritondo, G.; Ma, Jian; Quitmann, C.; Kelley, R. J.; Onellion, M.


    Cobalt-doping of Bi 2Sr 2CaCu 2O x beyond a critical level of 1.5-1.6 at % produces both a large decrease in the superconducting transition critical temperature and all of the classic symptoms of Anderson localization. These include: a negative slope of the abplane resistivity vs temperature, no dispersing states near the Fermi level and a decrease of the photoemission signal in the same region. The correlation between Anderson localization and high-temperature superconductivity at low doping levels supports a non-local interaction for the paring mechanism, such as antiferromagnetic spin fluctuations.

  6. Flux Creep Investigation in Bi2Sr2CaCu2O8+d High-Temperature Superconductor

    Directory of Open Access Journals (Sweden)

    G. R. Blanca


    Full Text Available The flux creep process in a c-axis Bi2Sr2CaCu2O8+d thin film was investigated at different temperatures and applied fields using the Kim-Anderson (KA approach. The peaked behavior shown in the magnetoresistance profile was attributed to the competing mechanisms of flux motion and sample-intrinsic transition near Tc.Within the temperature range where the competition occurs, U increases with temperature and consequently a decrease in the superconducting volume corresponds to a decrease in the flux creep. Moreover, the flux creep potential barrier varies with applied current I at all temperatures consistent with the KA model.

  7. New vortex-matter size effect observed in Bi(2)Sr(2)CaCu(2)O(8 + delta). (United States)

    Wang, Y M; Fuhrer, M S; Zettl, A; Ooi, S; Tamegai, T


    The vortex-matter 3D to 2D phase transition is studied in micron-sized Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals using local Hall magnetization measurements. At a given temperature, the second magnetization peak, the signature of a possible 3D--2D vortex phase transition, disappears for samples smaller than a critical length. We suggest that this critical length should be equated with the 2D vortex lattice ab-plane correlation length R(2D)(c). The magnitude and temperature dependence of R(2D)(c) agree well with Larkin-Ovchinnikov collective pinning theory.

  8. Andreev Bound States at the Onset of Phase Coherence in Bi(2)Sr(2)CaCu(2)O(8). (United States)

    Aubin, H; Greene, L H; Jian, Sha; Hinks, D G


    A new technique of planar tunneling spectroscopy has been developed to access the in-plane density of states of optimally doped Bi(2)Sr(2)CaCu(2)O(8) single crystals. The low energy spectrum is observed to depend on crystallographic orientation. When tunnel current is injected nominally along the Cu-Cu bond direction, a zero-bias conductance peak is observed to appear simultaneously with the onset of bulk superconductivity. These data demonstrate the existence of surface-induced states in this system and confirm the d-wave symmetry of the superconducting order parameter.

  9. Bilayer splitting in the electronic structure of heavily overdoped Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Feng, D L; Armitage, N P; Lu, D H; Damascelli, A; Hu, J P; Bogdanov, P; Lanzara, A; Ronning, F; Shen, K M; Eisaki, H; Kim, C; Shen, Z X; Shimoyama, J; Kishio, K


    The electronic structure of heavily overdoped Bi(2)Sr(2)CaCu(2)O(8+delta) is investigated by angle-resolved photoemission spectroscopy. The long-sought bilayer band splitting in this two-plane system is observed in both normal and superconducting states, which qualitatively agrees with the bilayer Hubbard model calculations. The maximum bilayer energy splitting is about 88 meV for the normal state feature, while it is only about 20 meV for the superconducting peak.

  10. Supercooling of the disordered vortex lattice in Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    van Der Beek CJ; Colson; Indenbom; Konczykowski


    Time-resolved local induction measurements near the vortex lattice order-disorder transition in optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) crystals show that the high-field, disordered phase can be quenched to fields as low as half the transition field. Over an important range of fields, the electrodynamical behavior of the vortex system is governed by the coexistence of ordered and disordered vortex phases in the sample. We interpret the results as supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the "second magnetization peak."

  11. Quasiparticles in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Kaminski; Mesot; Fretwell; Campuzano; Norman; Randeria; Ding; Sato; Takahashi; Mochiku; Kadowaki; Hoechst


    Recent improvements in momentum resolution lead to qualitatively new angle-resolved photoemission spectroscopy results on the spectra of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212) along the (pi,pi) direction, where there is a node in the superconducting gap. We now see the intrinsic line shape, which indicates the presence of true quasiparticles at all Fermi momenta in the superconducting state, and lack thereof in the normal state. The region of momentum space probed here is relevant for charge transport, motivating a comparison of our results to conductivity measurements by infrared reflectivity.

  12. Nodal quasiparticle lifetime in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Corson; Orenstein; Oh; O'Donnell; Eckstein


    We have measured the complex conductivity sigma of a Bi(2)Sr(2)CaCu(2)O(8+delta) thin film between 0.2 and 0.8 THz. We find sigma in the superconducting state to be well described as the sum of contributions from quasiparticles, condensate, and order parameter fluctuations which draw 30% of the spectral weight from the condensate. An analysis based on this decomposition yields a quasiparticle scattering rate on the order of k(B)T/Planck's over 2pi for temperatures below T(c).

  13. Possible pressure-induced valence changes in Tl2CaBa2Cu2O8 superconductors (United States)

    Morosin, B.; Venturini, E. L.


    The reported nonlinear pressure dependence of the superconducting critical temperature Tc in Tl2CaBa2Cu2O8 can be explained by valence changes deduced from the annealing behavior under various environments for single crystals of several Tl-Ca-Ba-Cu-O structure types. The pressure data are consistent with partial conversion of Tl+ to Tl3+ with increasing pressure (decreasing c-axis length), resulting in electron transfer from the Tl-O layers to the Cu-O2 sheets.

  14. X-ray Photoelectron Spectroscopy on Superconducting Tl2CaBa2Cu2O8 Thin Film (United States)

    Zeng, Wensheng; Qiu, Ping; Yan, Shaolin; Li, Zengfa; Zhang, Guangyin


    We have prepared single-phase superconducting Tl2CaBa2Cu2O8 thin film by dc magnetron sputtering process and measured x-ray photoelectron spectra of the film at room and liquid nitrogen temperatures. From the relative intensities of the Ba3d, Tl4f. O1s and Cu2p spectra taken at different take-off angles, we have concluded that there is an adventitious contamination (nonsuperconducting phase) surface layer. After excluding contributions from these spurious phases, we have tentatively assigned which core-level shifts should be caused by the superconducting phase transition.

  15. Synthesis of a new layered cuprate, Gd 2CaBa 2Ti 2Cu 2O 12 (United States)

    Fukuoka, A.; Adachi, S.; Sugano, T.; Wu, X.-J.; Yamauchi, H.


    A new layered cuprate, Gd 2CaBa 2Ti 2Cu 2O 12, which has a perovskite-related structure, has been discovered. The crystal structure is investigated by powder X-ray diffraction, electron diffraction and Rietveld analysis. It has a tetragonal symmetry with lattice parameters a=3.894 Å and c=35.49 Å. In the crystal there are sheets consisting of CuO 5 pyramids, which is one of the common features of p-type high- Tc superconducting cuprates.

  16. Effective phototransformation in a heterostructure based on copper(I) oxide and cadmium tin oxide (United States)

    Shelovanova, G. N.; Patrusheva, T. N.


    We present a heterostructure consisting of anodic copper oxide Cu2O on a copper substrate and a transparent Cd-Sn-O conducting film for use in solar cells. Focusing on simplicity and the availability of film fabrication techniques, we chose anodic oxidation for forming the Cu2O film and the extraction-pyrolysis technique for forming the transparent Cd-Sn-O conducting layer. We demonstrate the possibility of considerable enhancement of the phototransformation efficiency in the Cu-Cu2O/Cd-Sn-O structure over this parameter in the Cu-Cu2O structure.

  17. Electric field control of magnetization in Cu2O/porous anodic alumina hybrid structures at room temperature (United States)

    Qi, L. Q.; Liu, H. Y.; Sun, H. Y.; Liu, L. H.; Han, R. S.


    Cu2O nanoporous films are deposited on porous anodic alumina (PAA) substrates by DC-reactive magnetron sputtering. This paper focuses on voltage driven magnetization switching in Cu2O/PAA (CP) composite films prepared by DC-reactive magnetron sputtering. By applying a dc electric field, the magnetization of the CP composite films can be controlled in a reversible and reproducible way and shows an analogous on-off behavior. The magnitude of the change in the magnetization was about 75 emu/cm3 as the electric field was switched on and off. Resistive switching behavior was also observed in as-prepared CP composite films. Further analysis indicated that the formation/rupture of conducting filaments composed of oxygen vacancies is likely responsible for the changes in the magnetization as well as in the resistivity. Such reversible change of magnetization controlled by an electric field at room temperature may have applications in spintronics and power efficient data storage technologies.

  18. Transport properties governed by surface barriers in Bi2Sr2CaCu2O8 (United States)

    Fuchs, Dan T.; Zeldov, Eli; Rappaport, Michael; Tamegai, Tsuyoshi; Ooi, Shuuichi; Shtrikman, Hadas


    One of the most common investigation techniques of type-II superconductors is the transport measurement, in which an electrical current is applied to a sample and the corresponding resistance is measured as a function of temperature and magnetic field. At temperatures well below the critical temperature, Tc, the resistance of a superconductor is usually immeasurably low. But at elevated temperatures and fields, in the so-called vortex liquid phase, a substantial linear resistance is observed. In this dissipative state, which in anisotropic high-temperature superconductors like Bi2Sr2CaCu2O8 may occupy most of the mixed-state phase diagram, the transport current is usually assumed to flow uniformly across the sample as in a normal metal. To test this assumption, we have devised a measurement approach which allows determination of the flow pattern of the transport current across the sample. The surprising result is that, in Bi2Sr2CaCu2O8 crystals, most of the current flows at the edges of the sample rather than in the bulk, even in the highly resistive state, due to the presence of strong surface barriers. This finding has significant implications for the interpretation of existing resistivity data and may be of importance for the development of high-temperature superconducting wires and tapes.

  19. The k-space origins of scattering in Bi2Sr2CaCu2O8+x (United States)

    Alldredge, Jacob W.; Calleja, Eduardo M.; Dai, Jixia; Eisaki, H.; Uchida, S.; McElroy, Kyle


    We demonstrate a general, computer automated procedure that inverts the reciprocal space scattering data (q-space) that are measured by spectroscopic imaging scanning tunnelling microscopy (SI-STM) in order to determine the momentum space (k-space) scattering structure. This allows a detailed examination of the k-space origins of the quasiparticle interference (QPI) pattern in Bi2Sr2CaCu2O8+x within the theoretical constraints of the joint density of states (JDOS). Our new method allows measurement of the differences between the positive and negative energy dispersions, the gap structure and an energy dependent scattering length scale. Furthermore, it resolves the transition between the dispersive QPI and the checkerboard ({q}_{1}^{\\ast } excitation). We have measured the k-space scattering structure over a wide range of doping (p ˜ 0.22-0.08), including regions where the octet model is not applicable. Our technique allows the complete mapping of the k-space scattering origins of the spatial excitations in Bi2Sr2CaCu2O8+x, which allows for better comparisons between SI-STM and other experimental probes of the band structure. By applying our new technique to such a heavily studied compound, we can validate our new general approach for determining the k-space scattering origins from SI-STM data.

  20. Calculation of Raman- and infrared-active modes of Tl2CaBa2Cu2O8 (United States)

    Kulkarni, A. D.; Prade, J.; de Wette, F. W.; Kress, W.; Schröder, U.


    We present the frequencies and polarizaton vectors of the infrared- and Raman-active modes for Tl2CaBa2Cu2O8 (Tl 2:1:2:2). Our calculations are carried out in the framework of shell models, which are based on short-range overlap and long-range Coulomb potentials, as well as ionic polarizabilities. A guiding principle of this work is that the shell models for the different superconducting compounds should be mutually compatible, i.e., the short-range potentials for given ion pairs in equivalent environments should be transferable from one compound to the other. The optical data presented here for Tl 2:1:2:2 are obtained with a model which is applicable not only for six different thallium superconductors, but also for Bi2CaSr2Cu2O8 and YBa2Cu3O7. The model for Tl 2:1:2:2 reproduces the measured infrared and Raman data quite well and yields a reliable first approximation for the displacement patterns of the modes at the Γ point. This is far from trivial since a mere force constant fit to the measured eigenvalues may yield rather arbitrary eigenvectors.

  1. Multicomponent (Ce, Cu, Ni) oxides with cage and core-shell structures: tunable fabrication and enhanced CO oxidation activity (United States)

    Liu, Wei; Tang, Ke; Lin, Ming; June, Lay Ting Ong; Bai, Shi-Qiang; Young, David James; Li, Xu; Yang, Yan-Zhao; Hor, T. S. Andy


    Solvothermal synthesis of Cu2O cubes from Cu(OAc)2 in ethanol provided templates for tunable formation of novel multicomponent composites: hollow CeO2-Cu2O (1), core-shell NiO@Cu2O (2) and hollow CeO2-NiO-Cu2O (3). Composites 1-3 catalyze the oxidation of CO at a lower temperature than the parent Cu2O cubes.Solvothermal synthesis of Cu2O cubes from Cu(OAc)2 in ethanol provided templates for tunable formation of novel multicomponent composites: hollow CeO2-Cu2O (1), core-shell NiO@Cu2O (2) and hollow CeO2-NiO-Cu2O (3). Composites 1-3 catalyze the oxidation of CO at a lower temperature than the parent Cu2O cubes. Electronic supplementary information (ESI) available: Experimental section: materials and characterization; synthesis of materials; catalytic test. Tables S1-S3 and Fig. S1-S8. See DOI: 10.1039/c6nr02383e

  2. Co-Pi和Cu2O共修饰TiO2薄膜及其光电化学性质研究%Fabrication and Photoelectrochemical Properties of Co-Pi and Cu2O Co-decorated TiO2 films

    Institute of Scientific and Technical Information of China (English)

    姜春香; 沈明荣


    用阳极氧化法在Ti基片上制备出TiO2薄膜,然后通过电化学沉积法将Co-Pi和Cu2O沉积在TiO2薄膜表面。通过扫描电镜、X-射线衍射和光电化学性质测试,发现TiO2薄膜表面先沉积Co-Pi能够有效阻止Cu2O颗粒堆积,光电流显著提高。而先沉积Cu2O后沉积Co-Pi,则会使Cu2O还原为Cu,同时形貌发生改变。特别地,沉积300秒Co-Pi后再沉积Cu2O颗粒,能得到200 mA/cm2的最大光电流。%TiO2 film is prepared on Ti substrates by anodic oxidation method. Then Co-Pi and Cu2O particles are fabricated on TiO2 flat surface using a facial electrochemical deposition method. Scanning electron microsco-py, X-ray diffraction and photoelectrochemical properties reflect that depositing Co-Pi particles in advance on the surface of TiO2 thin films can prevent Cu2O forming stacked particle structure, increase the photocurrent sig-nificantly, and deposit Co-Pi after Cu2O makes Cu2O reduction to Cu and that at the same time the morphology changes a lot. Specifically, when the deposition time of Co-Pi is set to be 300 s, the structure of TiO2/Co-Pi/Cu2O can get the maximum photocurrent of 200 A cm-2 .

  3. Formation of Bi2Sr2CaCu2O x /Ag multifilamentary metallic precursor powder-in-tube wires (United States)

    Zhang, Yun; Koch, Carl C.; Schwartz, Justin


    Previously, a metallic precursor (MP) approach to synthesizing Bi2Sr2CaCu2O x (Bi2212), with a homogeneous mixture of Bi, Sr, Ca, Cu and Ag was produced by mechanical alloying. Here, Bi2212/Ag round multifilamentary wire is manufactured using a metallic precursor powder-in-tube (MPIT) process. The MP powders were packed into a pure Ag tube in an Ar atmosphere and then sealed. After deformation, multifilamentary round wires and rolled tapes were heat treated in flowing oxygen through three stages: oxidation, conversion and partial-melt processing (PMP). Processing-microstructure-property relationships on 20-50 mm long multifilamentary round wires and rolled tapes were studied extensively. It is shown that conventional wire deformation processes, optimized for oxide-powder-in-tube wires, are not effective for deforming MPIT wires, and that as with prior studies of MPIT Bi2Sr2Ca2Cu3O y conductors, hot extrusion is required for obtaining a multifilamentary structure with fine filaments. As a result, the Bi2212 MPIT wires reported here have low engineering critical current density. Nonetheless, by focusing on sections of wires that remain intact after deformation, it is also shown that the first heat treatment stage, the oxidation stage, plays a crucial role in chemical homogeneity, phase transformation, and microstructural evolution and three reaction pathways for MP oxidation are presented. Furthermore, it is found the Bi2212 grain alignment within an MPIT filament is significantly different from that found in OPIT filaments after PMP, indicating the formation of highly dense filaments containing Bi2212 fine grains and Ag particles before PMP aids the formation of large, c-axis textured Bi2212 filaments during PMP. These results show that, with improved wire deformation, high critical current density may be obtained via a MPIT process.

  4. In situ Fenton reagent generated from TiO2/Cu2O composite film: a new way to utilize TiO2 under visible light irradiation. (United States)

    Zhang, Yong-Gang; Ma, Li-Li; Li, Jia-Lin; Yu, Ying


    TiO2/Cu2O composite is prepared by a simple electrochemical method and coated on glass matrix through a spraying method. The obtained composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of TiO2/Cu2O composite films with different ratio of TiO2 and Cu2O on photodegradation of the dye methylene blue under visible light is investigated in detail. It is found that the photocatalytic activity of TiO2/Cu2O composite film with the presence of FeSO4 and EDTA is much higher than that for the similar system with only TiO2 and Cu2O film respectively. Without the presence of FeSO4 and EDTA, there is no degradation for methylene blue. The exploration of the optimized parameters for the degradation of methylene blue by using TiO2/Cu2O composite film as catalyst under visible light was also carried out. The most significant factor is the amount of Ti02 in the composite, and the second significant factor is the concentration of FeSO4. During the degradation of methylene blue under visible light, TiO2/Cu2O composite film generates H202, and Fenton regent is formed with Fe2+ and EDTA, which is detected in this study. The mechanism for the great improvement of photocatalytic activity of TiO2/Cu2O composite film under visible light is proposed by the valence band theory. Electrons excitated from TiO2/Cu2O composite under visible light are transferred from the conduction band of Cu2O to that of Ti02. The formed intermediate state of Ti 3+ ion is observed by X-ray photoelectron spectroscopy (XPS) on the TiO/Cu2O composite film. Additionally, the accumulated electrons in the conduction band of TiO2 are transferred to oxygen on the TiO2 surface for the formation of O2- or O2(2-), which combines with H+ to form H2O2. The evolved H202 with FeSO4 and EDTA forms Fenton reagentto degrade methylene blue. Compared to the traditional Fenton reagent, this new kind of in situ Fenton reagent generated from TiO2/Cu2O composite film does not need to

  5. Electrodeposition of flake-like Cu2O on vertically aligned two-dimensional TiO2 nanosheet array films for enhanced photoelectrochemical properties (United States)

    Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi


    A novel Cu2O/TNS composite structure of single crystal TiO2 nanosheet (TNS) arrays decorated with flake-like Cu2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectrophotometer. When the deposition potential is higher than -0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu2O become agglomerating, and transform into dense Cu2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at -0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu2O and n-type TiO2 heterojunctions combined with two-dimensional TiO2 nanosheet with exposed highly reactive {001} facets.

  6. Comment on magnetism and superconductivity in rutheno cuprates: RuSr2GdCu2O8 and RuSr2Gd1.5Ce0.5Cu2O10

    Indian Academy of Sciences (India)

    V P S Awana; M Karppinen; H Yamauchi


    Both RuSr2GdCu2O8- (Ru-1212) and RuSr2Gd1.5Ce0.5Cu2O10- (Ru-1222) exhibits magnetism and superconductivity, as seen by magnetization vs. temperature behavior measured in 5 Oe field. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization data show branching at around 140 K and 100 K with a cusp at 135 K and 80 K and a diamagnetic transition around 20 K and 30 K in the ZFC part, for Ru-1212 and Ru-1222, respectively. The isothermal magnetization possesses a non-linear contribution due to a ferromagnetic component at low temperatures below 50 K for both samples. The resistance vs. temperature behavior of the samples in applied fields of 0, 3 and 7 T confirmed superconductivity, with a different type of broadening of the superconductivity transition under magnetic fields for Ru-1212 from that known for conventional high-c superconductors. The magnetoresistance (MR) is negative above the Ru magnetic ordering temperature at 135 K. Below the Ru magnetic ordering temperature, MR displays a positive peak at low fields and becomes negative at higher fields for Ru-1212. For Ru-1222, MR remains negative both above and below the ordering temperature. A maximum of 2% is observed for the negative MR value at the Ru magnetic ordering temperature. An electron diffraction pattern obtained for the Ru-1212 sample shows two types of superstructure: one has a weak spot at the centre of the - rectangle, and the other only along the direction. Interestingly, Ru-1222 shows only clean - and - planes, without any superstructures.

  7. Development of Copper-Catalyzed Electrophilic Trifluoromethylation and Exploiting Cu/Cu2O Nanowires with Novel Catalytic Reactivity

    KAUST Repository

    Li, Huaifeng


    This thesis is based on research in Cu-catalyzed electrophilic trifluoromethylation and exploiting Cu/Cu2O nanowires with novel catalytic reactivity for developing of catalytic and greener synthetic methods. A large number of biological active pharmaceuticals and agrochemicals contain fluorine substituents (-F) or trifluoromethyl groups (-CF3) because these moieties often result in profound changes of their physical, chemical, and biological properties, such as metabolic stability and lipophilicity. For this reason, the introduction of fluorine or trifluoromethyl groups into organic molecules has attracted intensive attention. Among them, transition metal-catalyzed trifluoromethylation reactions has proved to be an efficient and reliable strategy to construct carbon-fluorine (C-F) and carbontrifluoromethyl (C-CF3) bond. We have developed a catalytic process for the first time for trifluoromethylation of terminal alkynes with Togni’s reagent, affording trifluoromethylated acetylenes in good to excellent yields. The reaction is conducted at room temperature and exhibits tolerance to a range of functional groups. Derived from this discovery, the extension of work of copper catalyzed electrophilic trifluoromethylation were investigated which include the electrophilic trifluoromethylation of arylsulfinate salts and electrophilic trifluoromethylation of organotrifluoroborates. Because of growing environmental concern, the development of greener synthetic methods has drawn much attention. Nano-sized catalysts are environment-friendly and an attractive green alternative to the conventional homogeneous catalysts. The nano-sized catalysts can be easily separated from the reaction mixture due to their insolubility and thus they can be used recycled. Notably, because of the high reactivities of nano-sized metal catalysts, the use of ligands can be avoided and the catalysts loadings can be reduced greatly. Moreover, the nano-sized catalysts can increase the exposed surface

  8. Chlorination of bromide-containing waters: Enhanced bromate formation in the presence ofsynthetic metal oxides and deposits formed indrinking water distribution systems

    KAUST Repository

    Liu, Chao


    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate>>sulfate>bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. © 2013 Elsevier Ltd.

  9. Chlorination of bromide-containing waters: enhanced bromate formation in the presence of synthetic metal oxides and deposits formed in drinking water distribution systems. (United States)

    Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe


    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate > sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Photoinduced filling of near-nodal gap in Bi2Sr2CaCu2O8 +δ (United States)

    Zhang, Z.; Piovera, C.; Papalazarou, E.; Marsi, M.; d'Astuto, M.; van der Beek, C. J.; Taleb-Ibrahimi, A.; Perfetti, L.


    We report time- and angle-resolved spectroscopic measurements in optimally doped Bi2Sr2CaCu2O8 +δ . The photoelectron intensity maps are monitored as a function of temperature, photoexcitation density, and delay time from the pump pulse. We evince that thermal fluctuations are effective only for temperatures near the critical value whereas photoinduced fluctuations scale linearly at low pumping fluence. The minimal energy to fully disrupt the superconducting gap slightly increases when moving off the nodal direction. No evidence of a pseudogap arising from other phenomena than pairing has been detected in the explored region of reciprocal space. On the other hand, a model accounting for the finite pair breaking explains the gap filling both in the near-nodal as well as in the off-nodal direction. Finally, we observed that nodal quasiparticles develop a faster dynamics when pumping the superconductor with fluence large enough to induce the total collapse of the gap.

  11. Magnetic phase diagram of Josephson vortices in Bi2Sr2CaCu2O2+

    Indian Academy of Sciences (India)

    K Hirata


    We show experimental results on magnetic phases of Josephson vortices (JVs) in Bi2Sr2CaCu2O2+, obtained from the JV flow-resistance measurements. Periodic oscillations in the flow-resistance enable us to assign the phase of the long-range 3D ordered state, which was confirmed by the beating effect. We have made preliminary experiments on the doping effect to the JV magnetic phase. The doping effect is rejected not only in the lower boundary of 3D ordered phase, but also in the upper boundary. Above the upper boundary, the flow-resistance shows different behaviours, which may be related to the strength of the interlayer coupling of the JVs along the c-axis, and to the creation/annihilation of pancake vortex/anti-vortex pairs, thermally and magnetically.

  12. Alternative pseudogap scenario: Spectroscopic analogies between underdoped and disordered Bi2Sr2CaCu2O8+x (United States)

    Vobornik, I.; Berger, H.; Grioni, M.; Margaritondo, G.; Forró, L.; Rullier-Albenque, F.


    Disorder has a strong influence on the spectral properties of the Bi2Sr2CaCu2O8+x high-Tc superconductor, both in the normal and in the superconducting state. High-resolution photoemission reveals a progressive quasiparticle suppression with increasing disorder in electron-irradiated optimally doped single crystals. The spectral line shapes of the disordered samples show striking analogies with those of underdoped samples specifically the widely discussed pseudogap at the chemical potential. Disorder provides therefore an alternative mechanism for spectral weight suppression near the Fermi surface, possibly coexisting and competing with other mechanisms. Since doping unavoidably introduces disorder, these results require a reconsideration of the relative importance of intrinsic effects vs disorder in high temperature superconductivity.

  13. Temperature Dependence of the Superconducting Gap Anistropy in Bi_2 Sr_2CaCu_2O8+x (United States)

    Ma, Jian; Quitmann, C.; Kelley, R. J.; Berger, H.; Margaritondo, G.; Onellion, M.


    Detailed data on the momentum-resolved temperature dependence of the superconducting gap of Bi_2Sr_2CaCu_2O8+x are presented, complemented by similar data on the intensity of the photoemission superconducting condensate spectral area. The gap anisotropy between the Gamma-overline{M} and Gamma-X directions increases markedly with increasing temperature, contrary to what happens for conventional anisotropic-gap superconductors, such as lead. Specifically, the size of the superconducting gap along the Gamma-X direction decreases to values indistinguishable from zero at temperatures for which the gap retains virtually full value along the Gamma-overline{M} direction. These data rule out the simplest type of d-wave order parameter.

  14. Acid etching process for fabrication of Bi2Sr2CaCu2O8+x stack

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jie; CHEN Jian; WU JingBo; KANG Lin; XU WeiWei; WU PeiHeng


    We adopted a new method, acid etching process, to fabricate the intrinsic Josephson junctions based on the Bi2Sr2CaCu2O8+x single crystals. By soaking the crystals into the dilute hydrochloric acid, we fabricated a junction stack successfully, and meantime made the surrounding area insulated. A certain concentration of hydrochloric acid was used to maintain the roughness of the modified layer. The current-voltage characteristic was achieved through the four terminal measurement. We could control the junctions' number by changing the concentration and the soaking time. We also found that the thickness of the stack was equal to the average height of the insulation layer. Such a simple, convenient and controllable fabrication method with a high yield might widen the applications of the intrinsic Josephson junctions.

  15. Quasiparticle liquid in the highly overdoped Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Yusof, Z M; Wells, B O; Valla, T; Fedorov, A V; Johnson, P D; Li, Q; Kendziora, C; Jian, Sha; Hinks, D G


    Results from the study of a highly overdoped (OD) Bi(2)Sr(2)CaCu(2)O(8+delta) with a T(c) = 51 K using angle-resolved photoemission spectroscopy are presented. We observe a sharp peak in the spectra near ( pi,0) that persists well above T(c), a nodal self-energy which approaches that seen for the Mo(110) surface state, and a more k-independent line shape at the Fermi surface than the lower-doped cuprates. This allows for a realistic comparison of the lifetime values to the experimental resistivity measurements. These observations point to the validity of the quasiparticle picture for the OD even in the normal state.

  16. Spin polarization in photoemission from the cuprate superconductor Bi2Sr2CaCu2O8 +δ (United States)

    Fanciulli, Mauro; Muff, Stefan; Weber, Andrew P.; Dil, J. Hugo


    Photoelectrons produced from the excitation of spin-degenerate states in solids can have a sizable spin polarization, which is related to the phase of interfering channels in the photoemission matrix elements. Such spin polarization can be measured by spin-resolved photoemission spectroscopy to gain information about the transitions and the Wigner time delay of the process. Incorporating strongly correlated electron systems into this paradigm could yield a novel means of extracting phase information crucial to understanding the mechanism of their emergent behavior. In this work, we present, as a case study, experimental measurements of the cuprate superconductor Bi2Sr2CaCu2O8 +δ by spin-resolved photoemission while maintaining full angular and energy resolution. A spin polarization of at least 10 % is observed, which is related to the phase of the photoelectron wave function.

  17. Periodic oscillations of Josephson-vortex flow resistance in Bi(2)Sr(2)CaCu(2)O(8+y). (United States)

    Ooi, S; Mochiku, T; Hirata, K


    To study the Josephson-vortex system, we have measured the vortex-flow resistance as a function of magnetic field parallel to the ab plane in Bi(2)Sr(2)CaCu(2)O(8+y) single crystals. Novel periodic oscillations of the vortex-flow resistance have been observed in a wide range of temperatures and magnetic fields. The period of the oscillations corresponds to the field needed to add "one" vortex quantum per "two" intrinsic Josephson junctions. The flow velocity is related to a matching effect between the lattice spacing of Josephson vortices along the layers and the width of the sample. These results suggest that Josephson vortices form a triangular lattice in the ground state where the oscillations occur.

  18. Ultraslow fluctuations in the pseudogap states of HgBa2CaCu2O6 +δ (United States)

    Itoh, Yutaka; Machi, Takato; Yamamoto, Ayako


    We report the transverse relaxation rates 1 /T2 's of the 63Cu nuclear spin-echo envelope for double-layer high-Tc cuprate superconductors HgBa2CaCu2O6 +δ from underdoped to overdoped. The relaxation rate 1 /T2 L of the exponential function (Lorentzian component) shows a peak at 220 -240 K in the underdoped (Tc=103 K) and the optimally doped (Tc=127 K) samples but no peak in the overdoped (Tc=93 K) sample. The enhancement in 1 /T2 L suggests a development of the zero frequency components of local field fluctuations. Ultraslow fluctuations are hidden in the pseudogap states.

  19. Quantum tunneling of vortices in single crystal Tl2CaBa2Cu2O8 superconductors (United States)

    Zuo, F.; Shi, A. C.; Berlinsky, A. J.; Duan, H. M.; Hermann, A. M.


    Data are presented on the temperature-dependent time-logarithmic magnetic relaxation rate S(T) = ¦dM/din t¦ of the high-Tc superconductor Tl2CaBa2 Cu2O8. It is found that at low temperatures the relaxation rate has the form S(T) = A(H) exp[(T/T*)2], which does not extrapolate to zero at T = 0, thus excluding conventional thermally activated flux creep and providing evidence of quantum vortex tunneling. From a quantum flux tunneling theory, it is shown that S(T) ∝ I/ηer{p/2}. The measurements of the relaxation rate thus provide information about the effective viscosity ηe of fluxons.

  20. Degradation of some typical pharmaceuticals and personal care products with copper-plating iron doped Cu2O under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Jing An; Qixing Zhou


    A mixture of five commonly used pharmaceuticals and personal care products (PPCPs) was degraded using a new combined catalyst under visible light irradiation.Scanning electron microscopy and X-ray diffraction analysis revealed that the combined catalyst was composed of copper-plating iron doped Cu2O (FeCu/Cu2O).Compared with the Fe/C inner micro-circuit,the electric currents flowing between Cu and Fe increase the speed of anodic Fe dissolution.Moreover,due to the photochemical properties,Cu2O can accelerate the PPCPs degradation processes under the irradiation of visible light.In addition,shaking increased the dissolved oxygen concentration in the solution,which not only preconditioned the photo-catalysis reaction,but also set the stage for Fe reduction.Aocording to the experimental results,we propose the possible reaction mechanism of the reaction.

  1. Direct production of carbon nanofibers decorated with Cu2O by thermal chemical vapor deposition on Ni catalyst electroplated on a copper substrate

    Directory of Open Access Journals (Sweden)

    MA Vesaghi


    Full Text Available  Carbon nanofibers (CNFs decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal. chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 35˚C. These nanoparticles provide the nucleation sites for CNF growth, removing the need for a buffer layer. High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at atmospheric environment, during the CNFs growth, lead to the production of CNFs decorated with Cu2O particles. The surface morphology of the Ni catalyst films and grown CNFs over it was studied by scanning electron microscopy. Transmission electron microscopy and Raman spectroscopy revealed the formation of CNFs. The selected area electron diffraction pattern and electron diffraction studies show that these CNFs were decorated with Cu2O nanoparticles.

  2. Synthesis of highly uniform Cu2O spheres by a two-step approach and their assembly to form photonic crystals with a brilliant color (United States)

    Su, Xin; Chang, Jie; Wu, Suli; Tang, Bingtao; Zhang, Shufen


    Monodisperse semiconductor colloidal spheres with a high refractive index hold great potential for building photonic crystals with a strong band gap, but the difficulty in separating the nucleation and growth processes makes it challenging to prepare highly uniform semiconductor colloidal spheres. Herein, real monodisperse Cu2O spheres were prepared via a hot-injection & heating-up two-step method using diethylene glycol as a milder reducing agent. The diameter of the as prepared Cu2O spheres can be tuned from 90 nm to 190 nm precisely. The SEM images reveal that the obtained Cu2O spheres have a narrow size distribution, which permits their self-assembly to form photonic crystals. The effects of precursor concentration and heating rates on the size and morphology of the Cu2O spheres were investigated in detail. The results indicate that the key points of the method include the burst nucleation to form seeds at a high temperature followed by rapid cooling to prevent agglomeration, and appropriate precursor concentration as well as a moderate growth rate during the further growth process. Importantly, photonic crystal films exhibiting a brilliant structural color were fabricated with the obtained monodisperse Cu2O spheres as building blocks, proving the possibility of making photonic crystals with a strong band gap. The developed method was also successfully applied to prepare monodisperse CdS spheres with diameters in the range from 110 nm to 210 nm.Monodisperse semiconductor colloidal spheres with a high refractive index hold great potential for building photonic crystals with a strong band gap, but the difficulty in separating the nucleation and growth processes makes it challenging to prepare highly uniform semiconductor colloidal spheres. Herein, real monodisperse Cu2O spheres were prepared via a hot-injection & heating-up two-step method using diethylene glycol as a milder reducing agent. The diameter of the as prepared Cu2O spheres can be tuned from 90 nm to

  3. Effect of patterning on the performance of p-type Cu2O TFTs: a 3D simulation using COMSOL multiphysics (United States)

    Alsharif, Sarah; Farhan, Hanaa; Al-Jawhari, Hala


    A 3D model for p-type Cu2O thin-film transistor (TFT) was simulated for the first time using COMSOL Multiphysics. The main objective of this modeling is to investigate the effect of patterning either the channel or the gate on the performance of Cu2O TFTs. Considering the ideal case, where traps and leakage current are not incorporated, we compared the performance of three different designs; unpatterned, patterned channel and patterned channel and gate TFTs. In each case, the transfer curve, output characteristics, current flow and potential distribution were clarified. The comparison between main parameters showed that the unpatterned model overestimated the field effect mobility µFE by 37.4% over the fully patterned TFT, nevertheless, the latter exhibited the highest on/off current ratio and the lowest off-current. A simulation of experimental output characteristics reported for Cu2O TFT was performed to check the model viability.

  4. Cu2O nanoparticles decorated BiVO4 as an effective visible-light-driven p-n heterojunction photocatalyst for methylene blue degradation (United States)

    Min, Shixiong; Wang, Fang; Jin, Zhiliang; Xu, Jing


    Bismuth vanadate (BiVO4) is a chemically stable and nontoxic semiconductor (SC) photocatalyst that can absorb visible light to degrade most of pollutants in aqueous solution due to suitable band-gap energy (ca. 2.4 eV), but it usually shows a low activity in its pristine form owing to poor charge-separation characteristics and the weak surface adsorption properties. In this paper, we demonstrated that the photocatalytic activity of BiVO4 can be greatly enhanced by surface modification with Cu2O nanoparticles through polyol reduction method. The modified photocatalysts (Cu2O/BiVO4) with proper loading amount of Cu2O (0.75 wt%) showed the highest photocatalytic degradation activity for methylene blue (MB) degradation with the pseudo-first-order rate constant kapp and degradation efficiency two times higher than pristine BiVO4 under visible light and solar light irradiation. The characterizations of resulting photocatalysts revealed that decoration of Cu2O nanoparticles led to the formation of a p-n heterojunction at the contact interface of Cu2O and BiVO4, which narrowed the band gap of BiVO4 for extending the absorption range of visible light and promoted the charge transfer across interface for suppressing the recombination of photogenerated electron-hole pairs, thus improving the catalytic performance of photocatalysts. This work demonstrates that the structural integration of p-type Cu2O SC with n-type BiVO4 SC will be a new promising strategy to develop a high-efficient heterojunction photocatalyst for visible-light-driven degradation of pollutants.

  5. Superconducting transition in ruthenocuprate RuSr2GdCu2O8 viewed from the studies of the imaginary part of ac susceptibility (United States)

    Zivkovic, I.; Drobac, D.; Ariosa, D.; Berger, H.; Pavuna, D.; Prester, M.


    We have measured two structurally similar superconducting systems, RuSr2GdCu2O8 and GdBa2Cu3O7 by means of high-resolution ac susceptibility. The real and the imaginary part of ac susceptibility of both bulk-ceramic and powdered samples have been studied down to the very small magnetic-field levels. We show that there are significant differences in the evolution of superconductivity in the two studied superconducting systems. In particular, we show that the superconducting transition in the grains in RuSr2GdCu2O8 system is masked with intrinsic magnetism of complex origin.

  6. Size-controlled synthesis of Cu2O nanoparticles via reaction-diffusion (United States)

    Badr, Layla; Epstein, Irving R.


    Copper (I) oxide nanoparticles are synthesized by a simple reaction-diffusion process involving Cu+ ions and sodium hydroxide in gelatin. The mean diameter and the size dispersion of the nanoparticles can be controlled by two experimental parameters, the percent of gelatin in the medium and the hydroxide ion concentration. UV-visible spectroscopy, transmission electron microscopy and X-ray diffraction are used to analyze the size, morphology, and chemical composition of the nanoparticles generated.

  7. Fluctuation induced excess conductivity in Tl 2CaBa 2Cu 2O 8 (United States)

    Srinivasan, R.; Krishnan, H.; Sankaranarayanan, V.; Gopalakrishnan, I. K.; Sastry, P. V. P. S. S.; Yakhmi, J. V.; Iyer, R. M.


    Two samples of single phase thallium-calcium-barium-copper-oxide were prepared using a precursor matrix technique. The resistivity of these samples was determined from 300 K to the temperature of zero resistance, Tzero, using the Montgomery technique. The room temperature resistivity of sample 2 was approximately seven times the room temperature resistivity of sample 1. From these measurements it was found that the temperature dependence of the fluctuation-induced excess conductivity in both the samples was in agreement with the Aslamazov-Larkin expression for three dimensional fluctuations.

  8. Prototype of a Scalable Core-Shell Cu2O/TiO2 Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dongdong; Chien, Chung-Jen; Deora, Suvil; Chang, Pai-Chun; Moulin, Etienne; Lu, Jia Grace

    Titanium oxide (TiO{sub 2}) nanotube membranes are synthesized via a two-step anodization method. The conductivity at the crystallized barrier layer is enhanced by NH{sub 4}Cl treatment. This facilitates electrodeposition of Cu{sub 2}O into TiO{sub 2} nanotubes, creating Cu{sub 2}O/TiO{sub 2}p–n heterojunctions in the radial direction. The photovoltaic performances benefit from the increased junction interface as well as the efficient pathway for separated charges to transport through the one-dimensional channel. Such heterojunction system serves as a promising candidate for solid-state solar cell due to its scalability, abundancy, low cost and environmental friendly nature. In addition, this versatile process can be conducted on various materials with the potential applications in photovoltaics, supercapacitor, battery, catalyst, etc.

  9. Effects of copper(II) and copper oxides on THMs formation in copper pipe. (United States)

    Li, Bo; Qu, Jiuhui; Liu, Huijuan; Hu, Chengzhi


    Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu(2)O, CuO and Cu(OH)(2) or CuCO(3). Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu(2)O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.

  10. Superhydrophobic Cu2S@Cu2O film on copper surface fabricated by a facile chemical bath deposition method and its application in oil-water separation (United States)

    Pi, Pihui; Hou, Kun; Zhou, Cailong; Li, Guidong; Wen, Xiufang; Xu, Shouping; Cheng, Jiang; Wang, Shuangfeng


    Cu2S and Cu2O composite (Cu2S@Cu2O) film with micro/nano binary structure was created on copper surface using the mixing solution of sodium thiosulphate and copper sulfate by a facile chemical bath deposition method. After modification with low-cost polydimethylsioxane (PDMS), the superhydrophobic Cu2S@Cu2O film was obtained. The as-prepared film shows outstanding water repellency with a water contact angle larger than 150° and long-term storage stability. The geometric morphology and chemical composition of the film were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), respectively. Moreover, the same method was used to fabricate superhydrophobic/superoleophilic copper mesh, and it could realize separation of various oily sewages with separation efficiency above 94%. This strategy has potential to fabricate the practical superhydrophobic Cu2S@Cu2O film on copper surface on a large scale due to its simplicity and low cost.

  11. Origin of flux-flow resistance oscillations in Bi2Sr2CaCu2O8+y: Possibility of Fiske steps in a single junction

    DEFF Research Database (Denmark)

    Ustinov, A.V.; Pedersen, Niels Falsig


    We propose an alternative explanation to the oscillations of the flux-flow resistance found in several previously published experiments with Bi2Sr2CaCu2O8+y stacks. It has been argued by the previous authors that the period of the oscillations corresponding to the field needed to add one vortex per...

  12. ab-plane anisotropy in single-domain Bi 2Sr 2CaCu 2O 8 high-temperature superconductors (United States)

    Quijada, M. A.; Tanner, D. B.; Kelley, R. J.; Onellion, M.


    The anisotropy of the ab-plane optical conductivity and de resistivity of single-domain Bi 2Sr 2CaCu 2O 8 crystals has been measured between 20 and 300 K. There is a modest normal-state anisotropy, optical anisotropy below Tc, and an unexpected anisotropy in the resistive transition.

  13. Tuning the near-gap electronic structure of Cu2O by anion-cation co-doping for enhanced solar energy conversion (United States)

    Si, Yuan; Yang, Hao-Ming; Wu, Hong-Yu; Huang, Wei-Qing; Yang, Ke; Peng, Ping; Huang, Gui-Fang


    Doping is an effective strategy to tune the electronic properties of semiconductors, but some side effects caused by mono-doping degrade the specific performance of matrixes. As a model system to minimize photoproduced electron-hole pairs recombination by anion-cation co-doping, we investigate the electronic structures and optical properties of (Fe+N) co-doped Cu2O using the first-principles calculations. Compared to the case of mono-doping, the FeCuNO (a Fe (N) atom substituting a Cu (O) atom) co-doping reduces the energy cost of doping as a consequence of the charge compensation between the iron and nitrogen impurities, which eliminates the isolated levels (induced by mono-dopant) in the band gap. Interestingly, it is found that the contributions of different host atoms (Cu and O) away from anion (N) and cation (Fe) dopants to the variation of near band gap electronic structure of the co-doped Cu2O are different. Moreover, co-doping reduces the band gap and increases the visible-light absorption of Cu2O. Both band gap reduction and low recombination rate are critical elements for efficient light-to-current conversion in co-doped semiconductor photocatalysts. These findings raise the prospect of using co-doped Cu2O with specifically engineered electronic properties in a variety of solar applications.

  14. Surface plasmon resonance enhanced visible-light-driven photocatalytic activity in Cu nanoparticles covered Cu2O microspheres for degrading organic pollutants (United States)

    Cheng, Yahui; Lin, Yuanjing; Xu, Jianping; He, Jie; Wang, Tianzhao; Yu, Guojun; Shao, Dawei; Wang, Wei-Hua; Lu, Feng; Li, Lan; Du, Xiwen; Wang, Weichao; Liu, Hui; Zheng, Rongkun


    Micron-sized Cu2O with different coverage of Cu nanoparticles (NPs) on the sphere has been synthesized by a redox procedure. The absorption spectra show that Cu NPs induce the surface plasmon resonance (SPR) at the wavelength of ∼565 nm. Methylene blue (MB) photodegrading experiments under visible-light display that the Cu2O-Cu-H2O2 system exhibits a superior photocatalytic activity to Cu2O-H2O2 or pure H2O2 with an evident dependency on Cu coverage. The maximum photodegradation rate is 88% after visible-light irradiating for 60 min. The role of the Cu NPs is clarified through photodegradation experiments under 420 nm light irradiation, which is different from the SPR wavelength of Cu NPs (∼565 nm). By excluding the SPR effect, it proves that Cu SPR plays a key role in the photodegradation. Besides, a dark catalytic activity is observed stemming from the Fenton-like reaction with the aid of H2O2. The radical quenching experiments indicate that both •O2- and •OH radicals contribute to the photocatalysis, while the dark catalysis is only governed by the •OH radicals, leading to a lower activity comparing with the photocatalysis. Therefore, with introducing Cu NPs and H2O2, the Cu2O-based photocatalytic activity could be significantly improved due to the SPR effect and dark catalysis.

  15. Femtosecond Optical Detection of Quasiparticle Dynamics in Single-Crystal Bi2Sr2CaCu2O8+δ

    Institute of Scientific and Technical Information of China (English)

    CAO Ning; WEI Yan-Feng; ZHAO Ji-Min; ZHAO Shi-Ping; YANG Qian-Sheng; ZHANG Zhi-Guo; FU Pan-Ming


    Quasiparticle dynamics of an optimally doped Bi2Sr2 CaCu2O8+δ single crystal is investigated by the femtosecond pump-probe technique. Temperature dependences of amplitude of the photoinduced differential reflectivity and the relaxation time show the evidence of strong phonon bottleneck. The experimental results are analysed by the Rothwarf-Taylor model.

  16. Ag doped (Bi1.6Pb0.4Sr2CaCu2O8+δ textured rods

    Directory of Open Access Journals (Sweden)

    Díez, J. C.


    Full Text Available In this work, superconducting samples of (Bi1.6Pb0.4Sr2CaCu2O8+δ with Ag additions have been studied. (Bi1.6Pb0.4Sr2CaCu2O8+δ + x wt.% Ag (with x = 0, 1 and 3 powders were synthesized using a sol-gel method. The obtained powders were used as precursors to fabricate long textured cylindrical bars through a floating zone melting method. A drastic change on the microstructure has been found when comparing with undoped Bi2Sr2CaCu2O8+δ samples. The results showed that electrical resistivity at room temperature, critical current as well as flexural strength are improved when Ag is added to these Pb doped samples, while critical temperature does not change. On the other hand, it has been found that samples with composition (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag shown E-I curves with very high sharpness values on the zone of the superconducting to normal transition, reaching n-values (E∼In as high as 45 at 65K.Se han preparado polvos cerámicos de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + x % Ag en peso (con x = 0, 1 y 3 mediante un proceso sol-gel. Estos polvos se han utilizado para fabricar precursores que se texturaron por medio del método de fusión zonal flotante. Se ha encontrado un gran cambio en la microestructura cuando se compara con muestras de composición pura Bi2Sr2CaCu2O8+δ. Tanto la resistividad eléctrica a temperatura ambiente, como la corriente crítica, así como la resistencia a flexión se mejoran cuando la Ag se adiciona a estas muestras dopadas con Pb, mientras que no se observa cambio en la temperatura crítica. Por otra parte, se ha encontrado que las muestras de composición (Bi1.6Pb0.4Sr2CaCu2O8+δ + Ag presentan una gran pendiente de la curva E-I en la zona de transición entre el estado superconductor y el estado normal. Con estas composiciones, se han encontrado valores de n (E∼In de hasta 45 a 65K.

  17. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    KAUST Repository

    Shi, Le


    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  18. Cu2O Photocathode for Low Bias Photoelectrochemical Water Splitting Enabled by NiFe-Layered Double Hydroxide Co-Catalyst (United States)

    Qi, Huan; Wolfe, Jonathan; Fichou, Denis; Chen, Zhong


    Layered double hydroxides (LDHs) are bimetallic hydroxides that currently attract considerable attention as co-catalysts in photoelectrochemical (PEC) systems in view of water splitting under solar light. A wide spectrum of LDHs can be easily prepared on demand by tuning their chemical composition and structural morphology. We describe here the electrochemical growth of NiFe-LDH overlayers on Cu2O electrodes and study their PEC behavior. By using the modified Cu2O/NiFe-LDH electrodes we observe a remarkable seven-fold increase of the photocurrent intensity under an applied voltage as low as -0.2 V vs Ag/AgCl. The origin of such a pronounced effect is the improved electron transfer towards the electrolyte brought by the NiFe-LDH overlayer due to an appropriate energy level alignment. Long-term photostability tests reveal that Cu2O/NiFe-LDH photocathodes show no photocurrent loss after 40 hours of operation under light at -0.2 V vs Ag/AgCl low bias condition. These improved performances make Cu2O/NiFe-LDH a suitable photocathode material for low voltage H2 production. Indeed, after 8 hours of H2 production under -0.2 V vs Ag/AgCl the PEC cell delivers a 78% faradaic efficiency. This unprecedented use of Cu2O/NiFe-LDH as an efficient photocathode opens new perspectives in view of low biasd or self-biased PEC water splitting under sunlight illumination.

  19. Atomic positional disorder, phonon spectrum, and molecular-dynamics simulation of Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10 (United States)

    Chaplot, S. L.


    The nature of the atomic positional disorder in the high-temperature superconducting ceramic oxides Tl2CaBa2Cu2O8 (Tl 2:1:2:2) and Tl2Ca2Ba2Cu3O10 (Tl 2:2:2:3) is studied with the help of an ionic-type interatomic potential and molecular-dynamics computer simulations. The pair distribution function and the phonon spectrum are calculated using this model and compared with results of neutron-scattering experiments on Tl 2:1:2:2. Calculated results on the partial pair distribution function, partial phonon density of states, mean square atomic vibrational amplitudes, and lattice specific heat are also presented.

  20. Growth and properties of laser-ablated Bi2Sr2CaCu2O8+#delta# thin films

    DEFF Research Database (Denmark)

    Seemann, R.; Hanisch, F.; Sewing, A.;


    Thin films of Bi2Sr2CaCu2O8+delta have been fabricated by laser ablation on single crystal M(g)O (001), LaAlO3 (001) and NdGaO3 (001) substrates. The superconducting transition temperature T(C0) is above 80 K with critical current densities of 4 x 10(5) A/cm2 at 55 K. The structure and morphology...... of the films were investigated using scanning electron microscopy, scanning tunnel microscopy and X-ray diffraction. All films show c-axis orientation with a texture of less than 0.2-degrees. Films deposited on MgO (001) are mostly randomly oriented in the a, b-plane although preferential orientations...... with rotational angles of 11.5-degrees and 45-degrees were observed close to the substrate/film interface. On LaAlO3 (001) and NdGaO3 (001) substrates the a, b-plane orientation is improved and about half of the film is epitaxially oriented....

  1. Size and topology of Bi_2Sr_2CaCu_2O_8+x Fermi surface versus doping (United States)

    Larosa, S.; Berger, H.; Margaritondo, G.; Kendziora, C.; Kelley, R. J.; Chubukov, A.; Onellion, M.


    We have studied the size and topology of the Fermi surface of Bi_2Sr2 CaCu_2O_8+x single crystal samples from underdoped samples with superconducting transition temperature, T_c=20K to overdoped samples with T_c=55K.[1] Compared to optimally doped samples, underdoped samples exhibit: * a reduction in the size of the Fermi surface by at least a factor of (x10); * a much weaker extended van Hove singularity around the (π,0) and conjugate points; * the large Fermi surface section around the X-point (π,π) are collapsed to small sections around the (π/2,π/2), while that around the Y-point (π,-π) remains but is much (x4) smaller.[2] These data are in excellent agreement with the calculations of A. Chubukov.[3] Our data indicate that the shadow band arises from short-range antiferromagnetic (AFM) fluctuations; the data are consistent with either a structural or a long-range AFM model to explain the shadow band. Finally, we find that the light polarization symmetry of the Fermi surface electronic states in the (π,±π) directions depends on the doping level.[2,4

  2. Effects of doping on superconducting gap anisotropy in Bi_2Sr2 CaCu_2O8+x (United States)

    Onellion, Marshall; Ma, Jian; Quitmann, Christoph; Kelley, R. J.; Kendziora, C.; Larosa, S.; Berger, H.; Margaritondo, G.


    We report on recent fabrication of Bi_2Sr_2CaCu_2O_8+x single crystals that span the phase diagram from insulators, all of the underdoped part, and as far into the overdoped part as a superconducting transition temperature, T_c=55K.[1,2] Optimally doped and overdoped samples exhibit narrow susceptibility transition widths. However, the c-axis between insulators-underdoped-optimally doped materials is almost identical, indicating that oxygen is added and removed from different part of the unit cell.[1,2] We have studied the superconducting gap anisotropy for optimally doped and overdoped samples. We find that the ratio gap along the (0,π)direction to that along the (π,π) is 20:1 for optimally doped or slightly underdoped samples, consistent with earlier report. The gap along the (π,π) direction is indistiguishable from zero. However, for somewhat overdoped samples, the gap anisotropy is 2:1, with the smaller gap 10meV, definitely non-zero.

  3. The structure of oxygen-annealed La1.9Ca1.1Cu2O6 superconductor (United States)

    Hu, Hefei; Zhu, Yimei; Zhong, Ruidan; Schneeloch, John; Liu, Tiansheng; Gu, Genda; Tranquada, John; Hill, John; Billinge, Simon


    Effect of annealing under high oxygen pressure on La1.9Ca1.1Cu2O6 (2126) is studied and structure change at the nanometer scale is investigated by using transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The as-grown single crystal is non-superconducting, which is thought to be due to oxygen deficiency. With annealing under a high oxygen pressure, superconductivity is induced with Tc ~ 53 K. While the as-grown 2126 shows homogenous structure at a large scale, after oxygen annealing, the sample develops a secondary phase La2-xCaxCuO4(214) at nanometer scale, which is evidenced by electron diffraction patterns together with EELS analysis. The content of 214 phase is estimated to be around 20% based on the analysis of scanning TEM images. Magnetization measurements indicate that the 214 phase is also superconducting. Chemical change of the remaining 2126 phase after oxygen annealing will also be discussed.

  4. Bipartite electronic superstructures in the vortex core of Bi2Sr2CaCu2O8+δ (United States)

    Machida, T.; Kohsaka, Y.; Matsuoka, K.; Iwaya, K.; Hanaguri, T.; Tamegai, T.


    The central issue in the physics of cuprate superconductivity is the mutual relationship among superconductivity, pseudogap and broken-spatial-symmetry states. A magnetic field B suppresses superconductivity, providing an opportunity to investigate the competition among these states. Although various B-induced electronic superstructures have been reported, their energy, spatial and momentum-space structures are unclear. Here, we show using spectroscopic-imaging scanning tunnelling microscopy on Bi2Sr2CaCu2O8+δ that there are two distinct B-induced electronic superstructures, both being localized in the vortex core but appearing at different energies. In the low-energy range where the nodal Bogoliubov quasiparticles are well-defined, we observe the so-called vortex checkerboard that we identify as the B-enhanced quasiparticle interference pattern. By contrast, in the high-energy region where the pseudogap develops, the broken-spatial-symmetry patterns that pre-exist at B=0 T is locally enhanced in the vortex core. This evidences the competition between superconductivity and the broken-spatial-symmetry state that is associated with the pseudogap.

  5. Vortex states in micron-sized Bi2Sr2CaCu2O8+y crystals (United States)

    Ooi, Shuuichi; Mochiku, Takashi; Tachiki, Minoru; Hirata, Kazuto


    Large thermal fluctuation, owing to high superconducting transition temperature, short coherence length and quasi-two-dimensionality, brings about a rich variety of vortex phases in Bi2Sr2CaCu2O8+y (Bi2212). To study how the vortex states and the transitions would be modified when vortices are confined in a small-sized crystal, we have measured the c-axis resistance using a stack of the intrinsic Josephson junctions (IJJs) of Bi2212. In tiny Bi2212 crystals of several micron, it is possible to observe the series of vorticity transitions using the c-axis resistance measurements. Combining the observation of vorticity changes and detection of a melting transition, we found an oscillating behavior of melting transition temperatures T m as a function of magnetic field (or number of vortices) in small squared Bi2212 with a lateral dimension of 5-10 μm. In the case of the square-shaped crystals, it seems that Tm is enhanced around the vortex numbers N v of i 2 (i: integer), indicating a matching of square vortex lattices in the square boundary. However, the frustration between the square boundary shape and vortex lattice that prefers a triangular lattice complicates the situation. A deformed square lattice without topological defects is probably realized at large i 2 as a geometrical matching state.

  6. High-resolution study of the yellow excitons in Cu2O subject to an electric field (United States)

    Heckötter, J.; Freitag, M.; Fröhlich, D.; Aßmann, M.; Bayer, M.; Semina, M. A.; Glazov, M. M.


    We have used high-resolution transmission spectroscopy to study the exciton level spectrum in Cu2O subject to a longitudinal external electric field, i.e., in the geometry where the transmitted light is propagating along the field direction. Different experimental configurations given by the field orientation relative to the crystal and the light polarization have been explored. We focus on the range of small principal quantum numbers n ≤7 . The number of exciton states belonging to a particular principal quantum number increases with n , leading to an enhanced complexity of the spectra. Still, in particular, for n =3 ,...,5 , a spectral separation of the different lines is feasible and identification as well as assignment of the dominant state character are possible. We find a strong dependence of the spectra on the chosen light propagation direction and polarization configuration, reflecting the inadequacy of the hydrogen model for describing the excitons. With increasing the field excitonic states with different parity become mixed, leading to optical activation of states that are dark in zero field. As compared with atoms, due to the reduced Rydberg energy states with different n can be brought into resonance in the accessible electric field strength range. When this occurs, we observe mostly crossing of levels within the experimental accuracy showing that the electron and hole motion remains regular. The observed features are well described by detailed calculations accounting for the spin-orbit coupling, the cubic anisotropy effects, and the symmetry-imposed optical selection rules.

  7. The fictile coordination chemistry of cuprous-thiolate sites in copper chaperones. (United States)

    Pushie, M Jake; Zhang, Limei; Pickering, Ingrid J; George, Graham N


    Copper plays vital roles in the active sites of cytochrome oxidase and in several other enzymes essential for human health. Copper is also highly toxic when dysregulated; because of this an elaborate array of accessory proteins have evolved which act as intracellular carriers or chaperones for the copper ions. In most cases chaperones transport cuprous copper. This review discusses some of the chemistry of these copper sites, with a view to some of the structural factors in copper coordination which are important in the biological function of these chaperones. The coordination chemistry and accessible geometries of the cuprous oxidation state are remarkably plastic and we discuss how this may relate to biological function. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

  8. Cavity mode waves during terahertz radiation from rectangular Bi(2)Sr(2)CaCu(2)O(8 + δ) mesas. (United States)

    Klemm, Richard A; Laberge, Erica R; Morley, Dustin R; Kashiwagi, Takanari; Tsujimoto, Manabu; Kadowaki, Kazuo


    We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi(2)Sr(2)CaCu(2)O(8 + δ), in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length l of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean l/ω = 5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which nl/2ω is integral, where n is the index of the rectangular TM(z)(n, 0) mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.

  9. Cavity mode waves during terahertz radiation from rectangular Bi2Sr2CaCu2O8 + δ mesas (United States)

    Klemm, Richard A.; LaBerge, Erica R.; Morley, Dustin R.; Kashiwagi, Takanari; Tsujimoto, Manabu; Kadowaki, Kazuo


    We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi2Sr2CaCu2O8 + δ, in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length \\ell of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett. 105 057002). We derived analytical forms for the angular dependence expected in both cases for a general cavity mode in which the width of the mesa corresponds to an integer multiple of one-half the wavelength of the radiation. Assuming the coherent radiation from the ac Josephson current source and the cavity magnetic surface current density source combine incoherently, fits to the data of Kadowaki et al (2010 J. Phys. Soc. Japan 79 023703) on a mesa with mean \\ell /w=5.17 for both wave directions using two models for the incoherent combination were made, which correspond to standing and traveling waves, respectively. The results suggest that the combined output from the uniform ac Josephson current source plus a cavity wave forming along the rectangle length is equally probable as that of the combined output from the uniform ac Josephson current plus a cavity wave across the width. However, for mesas in which n\\ell /2w is integral, where n is the index of the rectangular TMzn, 0 mode, it is shown that standing cavity mode waves along the length of the mesa do not radiate in the xz plane perpendicular to the length of the mesa, suggesting experiments on such mesas could help to resolve the question.

  10. Quench degradation limit of multifilamentary Ag/Bi2Sr2CaCu2O x round wires (United States)

    Ye, Liyang; Li, Pei; Shen, Tengming; Schwartz, Justin


    Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density J c degradation in commercial Ag/Bi2Sr2CaCu2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index of the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when T max exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt process and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A mm-2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.

  11. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates (United States)

    Wang, Xianghu; Li, Rongbin; Fan, Donghua


    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS:; 73.40.Lq; 73.50.Pz.

  12. Synthesis of Cu2O, CuCl, and Cu2OCl2 nanoparticles by ultrafast laser ablation of copper in liquid media

    Indian Academy of Sciences (India)

    Syed Hamad; G Krishna Podagatlapalli; Surya P Tewari; S Venugopal Rao


    Copper complex nanoparticles were fabricated from bulk copper using picosecond laser ablation in water and chloroform. We found that composition of the nanoparticles was CuCl and Cu2OCl2 in chloroform at three different input fluences; Cu2O in water which was confirmed from the data of EDAX, UV-Visible absorption spectra, and selected area electron diffraction pattern. We have also performed nonlinear optical studies of colloidal nanoparticles using Z-scan technique at 800 nm and ∼2 ps laser pulses. Cu2O NPs exhibited two-photon absorption at lower peak intensities while three-photon absorption was observed at higher peak intensities. Other samples exhibited two-photon absorption at all peak intensities.


    Directory of Open Access Journals (Sweden)

    Chandiramouli RAMANATHAN


    Full Text Available The realistic structures of CuO, CuO2 and Cu2O were completely optimized using density functional theory approach. The different structures were optimized to study the structural stability, dipole moment, point symmetry, HOMO-LUMO gap, ionization potential, electron affinity and binding energy of CuO, CuO2 and Cu2O. The electronic properties of clusters were discussed in terms of HOMO-LUMO gap, density of states, ionization potential and electron affinity. This information will provide an insight for the synthesis of nanomaterials with proper geometry which finds its potential importance in engineering applications.DOI:

  14. Linear and field-independent relation between vortex core state energy and gap in Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Hoogenboom, B W; Kadowaki, K; Revaz, B; Li, M; Renner, C; Fischer, Ø


    We present a scanning tunneling spectroscopy study on quasiparticle states in vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta). The energy of the observed vortex core states shows an approximately linear scaling with the superconducting gap in the region just outside the core. This clearly distinguishes them from conventional localized core states and is a signature of the mechanism responsible for their discrete appearance in high-temperature superconductors. The energy scaling of the vortex core states also suggests a common nature of vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta) and YBa(2)Cu(3)O(7-delta). Finally, these states do not show any dependence on the applied magnetic field between 1 and 6 T.

  15. Stepwise behavior of vortex-lattice melting transition in tilted magnetic fields in single crystals of Bi(2)Sr(2)CaCu(2)O(8 + delta). (United States)

    Mirković, J; Savel'ev, S E; Sugahara, E; Kadowaki, K


    The vortex-lattice melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals was studied using in-plane resistivity measurements in magnetic fields tilted away from the c axis to the ab plane. In order to avoid the surface barrier effect which hinders the melting transition in the conventional transport measurements, we used the Corbino geometry of electric contacts. The complete H(c) - H(ab) phase diagram of the melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) is obtained for the first time. The c-axis melting field component H(c)(melt) exhibits the novel, stepwise dependence on the in-plane magnetic fields H(ab) which is discussed on the basis of the crossing vortex-lattice structure. The peculiar resistance behavior observed near the ab plane suggests the change of phase transition character from first to second order.

  16. The “irreversibility line” of a Tl 2Ba 2CaCu 2O 8 single crystal: Evidence for a phase transition (United States)

    Giordanengo, B.; Genicon, J. L.; Sulpice, A.; Chaussy, J.; Tournier, R.; Frison, J. C.; Chaminade, J. P.; Pouchard, M.; Etourneau, J.


    The irreversibility line H *(T) of a Tl 2Ba 2CaCu 2O 8 single crystal varies as {ie1147-1} and diverges below 20 K. These phenomena could be related to a breakdown field of a weak superconductivity induced in BaO-TlO-TIO-BaO layer blocks by superconducting CuO layer blocks. The magnetization at the transition can be calculated assuming the existence of a second order phase transition.

  17. Synergistic effects of TiO2 and Cu2O in UV/TiO2/zeolite-based systems on photodegradation of bisphenol A. (United States)

    Kuo, Chao-Yin; Wu, Chung-Hsin; Lin, Han-Yu


    In this study, TiO2/zeolite (TZ)-based composite was utilized to degrade bisphenol A (BPA) under ultraviolet (UV) irradiation. The effects of the TiO2 and Cu2O doses in TZ and Cu2O/TiO2/zeolite (CTZ) on the rate of BPA removal were identified, respectively. The surface area of TZ declined as the TiO2 loading increased. The photodegradation rate (k) of BPA in the TZ and CTZ systems fitted pseudo-first-order kinetics. Under UV (365 nm) irradiation, the k values of TiO2 (20%)/zeolite (80%), TiO2 (40%)/zeolite (60%), TiO2 (60%)/zeolite (40%), and TiO2 (80%)/zeolite (20%) were 0.51, 0.55, 0.97, and 0.91 h-1, respectively. In the UV (365nm)/TiO2 (60%)/zeolite (40%) system, the k values of CTZ with 1%, 5%, 10%, 20%, and 30% Cu2O added were 1.50, 1.04, 1.15, 1.88, and 0.47h-1, respectively. The photocatalytic activity of TZ was enhanced by adding Cu2O. The optimal dosage of TiO2 in the TZ system was 60% and that of Cu20 in the CTZ system was 20%. p-Hydroxybenzaldehyde (p-HBA), p-hydroxyacetophenone (p-HAP), p-hydroxybenzoic acid (p-HBA acid) and hydroquinone (HQ) were intermediates ofBPA photodegradation in the UV/TZ system and the rates of degradation followed the order HQ > p - HBA acid > BPA > p - HAP > p - HBA.

  18. Response to tilted magnetic fields in Bi(2)Sr(2)CaCu(2)O(8) with columnar defects: evidence for transverse Meissner effect. (United States)

    Ta Phuoc, V; Olive, E; De Sousa, R; Ruyter, A; Ammor, L; Soret, J C


    The transverse Meissner effect (TME) in the highly layered superconductor Bi(2)Sr(2)CaCu(2)O(8+y) with columnar defects is investigated by transport measurements. We present evidence for the persistence of the Bose glass phase for H(perpendicular)H(+)(perpendicular c), moving kink chains consistent with a commensurate-incommensurate transition scenario are observed. These results show the existence of the TME for H(perpendicular)

  19. Metal-organic framework derived porous CuO/Cu2O composite hollow octahedrons as high performance anode materials for sodium ion batteries. (United States)

    Zhang, Xiaojie; Qin, Wei; Li, Dongsheng; Yan, Dong; Hu, Bingwen; Sun, Zhuo; Pan, Likun


    Porous CuO/Cu2O composite hollow octahedrons were synthesized simply by annealing Cu-based metal-organic framework templates. When evaluated as anode materials for sodium ion batteries, they exhibit a high maximum reversible capacity of 415 mA h g(-1) after 50 cycles at 50 mA g(-1) with excellent cycling stability and good rate capability.

  20. Superconducting thin films of Tl 2Ca 2Ba 2Cu 3O y and Tl 2CaBa 2Cu 2O y (United States)

    Ginley, D. S.; Kwak, J. F.; Hellmer, R. P.; Baughman, R. J.; Venturini, E. L.; Mitchell, M. A.; Morosin, B.


    We present techniques for preparing unoriented polycrystalline and epitaxial superconducting thin films of the Tl 2CaBa 2Cu 2O y and Tl 2Ca 2Ba 2Cu 3O y phases on a wide variety of substrates. The crucial steps determining the properties of the films are shown to be the air sintering and oxygen annealing following the initial metal deposition by electron beam evaporation under a slight oxygen overpressure. A sintered Tl-Ca-Ba-Cu-O pellet is employed as a source of excess Tl during sintering and annealing of the thin film. The Tl concentration in the final films controls the nature of the intergrain connections. The films are characterized by their structural, chemical, magnetic and transport properties. Zero resistance typically occurs at 97 K for Tl 2CaBa 2Cu 2O and at 106 K for Tl 2Ca 2Ba 2Cu 3O y. Transport critical currents of up to 110 000 A/cm 2 have been obtained at 77 K for unoriented Tl 2CaBa 2Cu 2O y, up to 160 000 A/cm 2 for epitaxial Tl 2Ca 2Ba 2Cu 3O y and up to 240 000 A/cm 2 for unoriented Tl 2Ca 2Cu 3O y films with little field dependence of the critical current observed.

  1. Effects of sputtering power on properties of copper oxides thin films deposited on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, P. K.; Ng, S. S.; Abdullah, M. J. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)


    Copper oxides are deposited by radio frequency sputtering using copper target in the mixture of argon and oxygen gasses. The structural and optical properties of the copper oxides deposited at different sputtering powers have been investigated. All the films are single phase polycrystalline. At low RF power (100 W), the film is monoclinic structure of cupric oxide (CuO). Meanwhile, the films are cubic structure of cuprous oxide (Cu2O) at higher RF power. Field emission scanning electron microscopy images show the films have different morphologies with small grain size and consist of a lot of voids. The analysis of energy dispersive X-ray spectroscopy shows that the ratio of Cu to O is increased as the RF power increased. From the ultraviolet–visible spectroscopy, the films have a broad absorption edge in the range of 300–500 nm. The band gap of the films grown at RF power of 100 W, and 120 W and above, were 1.18 eV and 2.16 eV, respectively.


    Institute of Scientific and Technical Information of China (English)

    张曙光; 陈瑜; 王风云



  3. New photocatalyst based on graphene oxide/chitin for degradation of dyes under sunlight. (United States)

    Wang, Yuntao; Pei, Yaqiong; Xiong, Wenfei; Liu, Tingguo; Li, Jing; Liu, Shilin; Li, Bin


    Sunlight photocatalyst was fabricated by in situ synthesis of Cu2O in the regenerated chitin (RC)/graphene oxide (GO) composite film, where the porous chitin film was used as the microreactor for the formation of nano Cu2O. Nano Cu2O was immobilized and evenly distributed in the matrix and Cu2O tended to grow on the GO sheets. Cu2O inside the matrix excite and generate free photoelectrons and electron holes, which was responsible for the degradation of dyes, while GO transferred the yielded photoelectrons to prevent the generation of local high potential zone and induce the chain degradation at more points. So it was found that the porous chitin film could load Cu2O and graphene at the same time, controlling the size of Cu2O and leading to easy recycle and reuse of the photocatalyst. Moreover, the introduction of GO has dramatically improved the photocatalytic activity of Cu2O in the Cu2O/GO/RC film, showing great potential application in wastewater treatment utilizing solar energy.

  4. Präparation, strukturelle Charakterisierung und Transporteigenschaften epitaktischer Filme der Hochtemperatursupraleiter $Bi_{2}Sr_{2}CaCu_{2}O_{8+\\delta}$ und $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+\\delta}$

    CERN Document Server

    Wagner, P H


    Präparation, strukturelle Charakterisierung und Transporteigenschaften epitaktischer Filme der Hochtemperatursupraleiter $Bi_{2}Sr_{2}CaCu_{2}O_{8+\\delta}$ und $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+\\delta}$

  5. Tube-like ternary α-Fe2O3@SnO2@Cu2O sandwich heterostructures: synthesis and enhanced photocatalytic properties. (United States)

    Tian, Qingyong; Wu, Wei; Sun, Lingling; Yang, Shuanglei; Lei, Mei; Zhou, Juan; Liu, Ying; Xiao, Xiangheng; Ren, Feng; Jiang, Changzhong; Roy, Vellaisamy A L


    Heterogeneous photocatalysis is of great interest for environmental remediation applications. However, fast recombination of photogenerated electron-hole pair and a low utilization rate of sunlight hinder the commercialization of currently available semiconductor photocatalysts. In this regard, we developed a unique ternary single core-double shell heterostructure that consists of α-Fe2O3@SnO2@Cu2O. This heterostructure exhibits a tube-like morphology possessing broad spectral response for the sunlight due to the combination of narrow bandgap and wide bandgap semiconductors forming a p-n heterojunction. To fabricate such a short nanotube (SNT), we used an anion-assisted hydrothermal route for deposition of α-Fe2O3, a seed-mediated deposition strategy for SnO2, and finally an aging process to deposit a Cu2O layer to complete the tube-like ternary α-Fe2O3@SnO2@Cu2O single core-double shell heterostructures. The morphology, composition, and photocatalytic properties of those ternary core-shell-shell heterostructures were characterized by various analytical techniques. These ternary heterostructures exhibited enhanced photocatalytic properties on the photodegradation of the organic dye of Rhodamine B (RhB) under simulated sunlight irradiation. The origin of enhanced photocatalytic activity is due to the synergistic effect of broad spectral response by combining narrow bandgap and wide bandgap semiconductors and, hence, an efficient charge separation of photogenerated electron-hole pairs facilitated through the p-n heterojunction. Furthermore, our unique structure provides an insight on the fabrication and controlled preparation of multilayer heterostructural photocatalysts that have intriguing properties.

  6. Bulk superconductivity in Tl 2Ba 2CaCu 2O 8 and TlBa 2Ca 2Cu 3O 9 phases (United States)

    Sulpice, A.; Giordanengo, B.; Tournier, R.; Hervieu, M.; Maignan, A.; Martin, C.; Michel, C.; Provost, J.


    Well-crystallized Tl 2Ba 2CaCu 2O 8 phases have been observed superconducting or normal below 108 K depending on their stoichiometry. This observation is an evidence that a (Cu IL&.zbnd;O -) mixed valence induced by vacancies or substitution on different sites gives rise to superconductivity in this phase. The new phase TlBa 2Ca 2CuO 9 which intrinsically contains a mixed valence has been observed as having a sharp transition to bulk superconductivity in the Meissner effect at a critical temperature of 120 K. This temperature is much higher than the recently observed one.

  7. Atomic scale imaging and spectroscopy of a CuO(2) plane at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Misra, S; Oh, S; Hornbaker, D J; DiLuccio, T; Eckstein, J N; Yazdani, A


    We have used a scanning tunneling microscope to demonstrate that a single CuO2 plane can form a stable and atomically ordered layer at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta). In contrast to previous studies on high-T(c) surfaces, the CuO2-terminated surface exhibits a strongly suppressed tunneling conductance at low voltages. We consider a number of different explanations for this phenomena and propose that it may be caused by how the orbital symmetry of the CuO2 plane's electronic states affects the tunneling process.

  8. Evidence for quantum critical behavior in the optimally doped cuprate Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Valla; Fedorov; Johnson; Wells; Hulbert; Li; Gu; Koshizuka


    The photoemission line shapes of the optimally doped cuprate Bi(2)Sr(2)CaCu(2)O(8+delta) were studied in the direction of a node in the superconducting order parameter by means of very high resolution photoemission spectroscopy. The peak width or inverse lifetime of the excitation displays a linear temperature dependence, independent of binding energy, for small energies, and a linear energy dependence, independent of temperature, for large binding energies. This behavior is unaffected by the superconducting transition, which is an indication that the nodal states play no role in the superconductivity. Temperature-dependent scaling suggests that the system displays quantum critical behavior.

  9. Signature of superfluid density in the single-particle excitation spectrum of Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Feng; Lu; Shen; Kim; Eisaki; Damascelli; Yoshizaki; Shimoyama; Kishio; Gu; Oh; Andrus; O'Donnell; Eckstein; Shen


    We report that the doping and temperature dependence of photoemission spectra near the Brillouin zone boundary of Bi(2)Sr(2)CaCu(2)O(8+delta)exhibit unexpected sensitivity to the superfluid density. In the superconducting state, the photoemission peak intensity as a function of doping scales with the superfluid density and the condensation energy. As a function of temperature, the peak intensity shows an abrupt behavior near the superconducting phase transition temperature where phase coherence sets in, rather than near the temperature where the gap opens. This anomalous manifestation of collective effects in single-particle spectroscopy raises important questions concerning the mechanism of high-temperature superconductivity.

  10. Dynamic and thermodynamic properties of porous vortex matter in Bi(2)Sr(2)CaCu(2)O(8) in an oblique magnetic field. (United States)

    Avraham, Nurit; Goldschmidt, Y Y; Liu, J T; Myasoedov, Y; Rappaport, M; Zeldov, E; van der Beek, C J; Konczykowski, M; Tamegai, T


    Vortex matter in Bi(2)Sr(2)CaCu(2)O(8) with a low concentration of tilted columnar defects (CDs) was studied using magneto-optical measurements and molecular dynamics simulations. It is found that while the dynamic properties are significantly affected by tilting the magnetic field away from the CDs, the thermodynamic transitions are angle independent. The simulations indicate that vortex pancakes remain localized on the CDs even at large tilting angles. This preserves the vortex thermodynamics, while vortex pinning is considerably weakened due to kink sliding.

  11. Collapse of the normal-state pseudogap at a Lifshitz transition in the Bi(2)Sr(2)CaCu(2)O(8+δ) cuprate superconductor. (United States)

    Benhabib, S; Sacuto, A; Civelli, M; Paul, I; Cazayous, M; Gallais, Y; Méasson, M-A; Zhong, R D; Schneeloch, J; Gu, G D; Colson, D; Forget, A


    We report a fine tuned doping study of strongly overdoped Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} single crystals using electronic Raman scattering. Combined with theoretical calculations, we show that the doping, at which the normal-state pseudogap closes, coincides with a Lifshitz quantum phase transition where the active holelike Fermi surface becomes electronlike. This conclusion suggests that the microscopic cause of the pseudogap is sensitive to the Fermi surface topology. Furthermore, we find that the superconducting transition temperature is unaffected by this transition, demonstrating that their origins are different on the overdoped side.

  12. STM studies of the electronic structure of vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Pan; Hudson; Gupta; Ng; Eisaki; Uchida; Davis


    We report on low temperature scanning tunneling microscopy (STM) studies of the electronic structure of vortex cores in Bi 2Sr 2CaCu 2O (8+delta). At the vortex core center, an enhanced density of states is observed at energies near Omega = +/-7 meV. Spectroscopic imaging at these energies reveals an exponential decay of these "core states" with a decay length of 22+/-3 A. The fourfold symmetry sometimes predicted for d-wave vortices is not seen in spectroscopic vortex images. A locally nodeless order parameter induced by the magnetic field may be consistent with these measurements.

  13. Imaging the impact of single oxygen atoms on superconducting Bi(2+y)Sr(2-y)CaCu2O(8+x). (United States)

    Zeljkovic, Ilija; Xu, Zhijun; Wen, Jinsheng; Gu, Genda; Markiewicz, Robert S; Hoffman, Jennifer E


    High-temperature cuprate superconductors display unexpected nanoscale inhomogeneity in essential properties such as pseudogap energy, Fermi surface, and even superconducting critical temperature. Theoretical explanations for this inhomogeneity have ranged from chemical disorder to spontaneous electronic phase separation. We extend the energy range of scanning tunneling spectroscopy on Bi(2+y)Sr(2-y)CaCu(2)O(8+x), allowing a complete mapping of two types of interstitial oxygen dopants and vacancies at the apical oxygen site. We show that the nanoscale spatial variations in the pseudogap states are correlated with disorder in these dopant concentrations, particularly that of apical oxygen vacancies.

  14. Crossover from coherent to incoherent electronic excitations in the normal state of Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Kaminski, A; Rosenkranz, S; Fretwell, H M; Li, Z Z; Raffy, H; Randeria, M; Norman, M R; Campuzano, J C


    Angle resolved photoemission spectroscopy (ARPES) and resistivity measurements are used to explore the overdoped region of the high temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+delta). We find evidence for a new crossover line in the phase diagram between a coherent metal phase, for lower temperatures and higher doping, and an incoherent metal phase, for higher temperatures and lower doping. The former is characterized by two well-defined spectral peaks in ARPES due to coherent bilayer splitting and superlinear behavior in the resistivity, whereas the latter is characterized by a single broad spectral feature in ARPES and a linear temperature dependence of the resistivity.

  15. Geometrical resonance conditions for THz radiation from the intrinsic Josephson junctions in Bi(2)Sr(2)CaCu(2)O(8+δ). (United States)

    Tsujimoto, Manabu; Yamaki, Kazuhiro; Deguchi, Kota; Yamamoto, Takashi; Kashiwagi, Takanari; Minami, Hidetoshi; Tachiki, Masashi; Kadowaki, Kazuo; Klemm, Richard A


    Subterahertz radiation emitted from a variety of short rectangular-, square-, and disk-shaped mesas of intrinsic Josephson junctions fabricated from a Bi(2)Sr(2)CaCu(2)O(8+δ) single crystal was studied from the observed I-V characteristics, far-infrared spectra, and spatial radiation patterns. In all cases, the radiation frequency satisfies the conditions both for the ac Josephson effect and for a mesa cavity resonance mode. The integer higher harmonics observed in all spectra imply that the ac Josephson effect plays the dominant role in the novel dual-source radiation mechanism.

  16. Doping and temperature dependence of the mass enhancement observed in the cuprate Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Johnson, P D; Valla, T; Fedorov, A V; Yusof, Z; Wells, B O; Li, Q; Moodenbaugh, A R; Gu, G D; Koshizuka, N; Kendziora, C; Jian, S; Hinks, D G


    High-resolution photoemission is used to study the electronic structure of the cuprate superconductor, Bi(2)Sr(2)CaCu(2)O(8+delta), as a function of hole doping and temperature. A kink observed in the band dispersion in the nodal line in the superconducting state is associated with coupling to a resonant mode observed in neutron scattering. From the measured real part of the self-energy it is possible to extract a coupling constant which is largest in the underdoped regime, then decreasing continuously into the overdoped regime.

  17. Doping-induced change in the interlayer transport mechanism of Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} near the superconducting transition temperature. (United States)

    Katterwe, S O; Rydh, A; Krasnov, V M


    We perform a detailed study of temperature, bias, and doping dependence of interlayer transport in the layered high temperature superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+delta}. We observe that the shape of interlayer characteristics in underdoped crystals exhibits a remarkable crossover at the superconducting transition temperature: from thermal activation-type above T_{c} to almost T-independent quantum tunneling-type below T_{c}. Our data provide insight into the nature of interlayer transport and indicate that its mechanism changes with doping: from the conventional single quasiparticle tunneling in overdoped to a progressively increasing Cooper pair contribution in underdoped crystals.

  18. Superconducting correlations above Tc in the pseudogap state of Bi2Sr2CaCu2O8 +δ cuprates revealed by angular-dependent magnetotunneling (United States)

    Jacobs, Th.; Katterwe, S. O.; Krasnov, V. M.


    We present an angular-dependent magnetotunneling technique, which facilitates unambiguous separation of superconducting (supporting circulating screening currents) and nonsuperconducting (not supporting screening currents) contributions to the pseudogap phenomenon in layered Bi2Sr2CaCu2O8 +δ cuprates. Our data indicate persistence of superconducting correlations at temperatures up to 1.5 Tc in a form of both phase and amplitude fluctuations of the superconducting order parameter. However, despite a profound fluctuations region, only a small fraction of the pseudogap spectrum is caused by superconducting correlations, while the dominating part comes from a competing nonsuperconducting order, which does not support circulating orbital currents.

  19. Temperature dependent scattering rates at the fermi surface of optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Valla; Fedorov; Johnson; Li; Gu; Koshizuka


    For optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta), scattering rates in the normal state are found to have a linear temperature dependence over most of the Fermi surface. In the immediate vicinity of the (pi, 0) point, the scattering rates are nearly constant in the normal state, consistent with models in which scattering at this point determines the c-axis transport. In the superconducting state, the scattering rates away from the nodal direction appear to level off and become temperature independent.

  20. Scanning Josephson tunneling microscopy of single-crystal Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} with a conventional superconducting tip. (United States)

    Kimura, Hikari; Barber, R P; Ono, S; Ando, Yoichi; Dynes, R C


    We have performed both Josephson and quasiparticle tunneling in vacuum tunnel junctions formed between a conventional superconducting scanning tunneling microscope tip and overdoped Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} single crystals. A Josephson current is observed with a peak centered at a small finite voltage due to the thermal-fluctuation-dominated superconducting phase dynamics. Josephson measurements at different surface locations yield local values for the Josephson I_{C}R_{N} product. Corresponding energy gap measurements were also performed and a surprising inverse correlation was observed between the local I_{C}R_{N} product and the local energy gap.

  1. Investigating the Effects of Doping Inhomogeneity on the ARPES Spectrum of Bi2Sr2CaCu2O8 (United States)

    Parham, Stephen; Li, Haoxiang; Zhou, Xiaoqing; Calleja, Eduardo; Gu, Genda; McElroy, Kyle; Dessau, Daniel


    Bi2Sr2CaCu2O8 (Bi2212) is a dirty material. This is readily seen with STM, which shows nanoscale variations in the gap parameter and local doping level. Through numerical simulation we investigate the effects of this doping inhomogeneity on the ARPES spectrum of Bi2212. We find that the main effect of the inhomogeneity is to broaden the spectrum in momentum, with an increasing magnitude towards the antinode. This has implications for the scattering rates extracted from MDC or EDC analysis. We show that after removing the doping inhomogeneity the scattering rate measured with ARPES qualitatively agrees with that from STM and Optical Reflectivity.

  2. Effect of argon-annealing and subsequent oxygen-annealing on the superconductivity and structure of Tl 2CaBa 2Cu 2O 8- x (United States)

    Gopalakrishnan, I. K.; Sastry, P. V. P. S. S.; Rajagopal, H.; Sequeira, A.; Yakhmi, J. V.; Iyer, R. M.


    Annealing the single-phase Tl 2CaBa 2Cu 2O 8 superconductor ( Tc=108 K) in argon environment at 950 K for 24 h brings the Tc down to ≅80 K. Re-annealing the samples in oxygen under similar conditions restores the Tc to 105±5 K. Rietveld profile refinement of the neutron diffraction spectra of the argon-annealed samples indicates that some Tl-ions, presumably Tl 1+, move from the Tl double-layers to occupy Ca-sites. Upon subsequent annealing in oxygen, however, these Tl-ions escape from the lattice. Implications of this and other structural features are described.

  3. Bioactive Potential of 3D-Printed Oleo-Gum-Resin Disks: B. papyrifera, C. myrrha, and S. benzoin Loading Nanooxides-TiO2, P25, Cu2O, and MoO3. (United States)

    Horst, Diogo José; Tebcherani, Sergio Mazurek; Kubaski, Evaldo Toniolo; de Almeida Vieira, Rogério


    This experimental study investigates the bioactive potential of filaments produced via hot melt extrusion (HME) and intended for fused deposition modeling (FDM) 3D printing purposes. The oleo-gum-resins from benzoin, myrrha, and olibanum in pure state and also charged with 10% of metal oxide nanoparticles, TiO2, P25, Cu2O, and MoO3, were characterized by ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray microanalysis (EDXMA), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Disks were 3D-printed into model geometries (10 × 5 mm) and the disk-diffusion methodology was used for the evaluation of antimicrobial and antifungal activity of materials in study against the clinical isolates: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Due to their intrinsic properties, disks containing resins in pure state mostly prevent surface-associated growth; meanwhile, disks loaded with 10% oxides prevent planktonic growth of microorganisms in the susceptibility assay. The microscopy analysis showed that part of nanoparticles was encapsulated by the biopolymeric matrix of resins, in most cases remaining disorderly dispersed over the surface of resins. Thermal analysis shows that plant resins have peculiar characteristics, with a thermal behavior similar to commercial available semicrystalline polymers, although their structure consists of a mix of organic compounds.

  4. Effect of copper oxide electrocatalyst on CO2 reduction using Co3O4 as anode

    Directory of Open Access Journals (Sweden)

    V.S.K. Yadav


    Full Text Available The reduction of carbon dioxide (CO2 to products electrochemically (RCPE in 0.5 M NaHCO3 and Na2CO3 liquid phase electrolyte solutions was investigated. Cobalt oxide (Co3O4 as anode and cuprous oxide (Cu2O as the cathode were considered, respectively. The impacts of applied potential with time of reaction during reduction of CO2 to products were studied. The anode and cathode were prepared by depositing electrocatalysts on the graphite plate. Ultra-fast liquid chromatography (UFLC was used to analyze the products obtained from the reduction of CO2. The feasible way of reduction by applying voltages with current densities was clearly correlated. The results illustrate the capability of electrocatalyst successfully to remove atmospheric CO2 in the form of valuable chemicals. Maximum Faradaic efficiency of ethanol was 98.1% at 2 V and for formic acid (36.6% at 1.5 V was observed in NaHCO3. On the other hand, in Na2CO3 electrolyte solution maximum efficiency for ethanol was 55.21% at 1.5 V and 25.1% for formic acid at 2 V. In both electrolytes other end products like methanol, propanol, formaldehyde and acetic acid were formed at various applied voltage and output current densities.

  5. Theoretical and experimental study on the effects of particle size and temperature on the reaction kinetics of cubic nano-Cu2O (United States)

    Tang, Huanfeng; Huang, Zaiyin; Xiao, Ming; Liang, Min; Chen, Liying; Tan, XueCai


    The activities, selectivities, and stabilities of nanoparticles in heterogeneous reactions are size-dependent. In order to investigate the influencing laws of particle size and temperature on kinetic parameters in heterogeneous reactions, cubic nano-Cu2O particles of four different sizes in the range of 40-120 nm have been controllably synthesized. In situ microcalorimetry has been used to attain thermodynamic data on the reaction of Cu2O with aqueous HNO3 and, combined with thermodynamic principles and kinetic transition-state theory, the relevant reaction kinetic parameters have been evaluated. The size dependences of the kinetic parameters are discussed in terms of the established kinetic model and the experimental results. It was found that the reaction rate constants increased with decreasing particle size. Accordingly, the apparent activation energy, pre-exponential factor, activation enthalpy, activation entropy, and activation Gibbs energy decreased with decreasing particle size. The reaction rate constants and activation Gibbs energies increased with increasing temperature. Moreover, the logarithms of the apparent activation energies, pre-exponential factors, and rate constants were found to be linearly related to the reciprocal of particle size, consistent with the kinetic models. The influence of particle size on these reaction kinetic parameters may be explained as follows: the apparent activation energy is affected by the partial molar enthalpy, the pre-exponential factor is affected by the partial molar entropy, and the reaction rate constant is affected by the partial molar Gibbs energy. [Figure not available: see fulltext.

  6. The effect of Yttrium on the Ca and Sr planes of Y-doped Bi 2Sr 2Ca 1Cu 2O 8 (United States)

    Alméras, P.; Berger, H.; Margaritondo, G.


    Photoemission spectromicroscopy experiments on a series of Y-doped Bi 2Sr 2Ca 1Cu 2O 8 single crystals show that the doping changes the valence of copper as required for the observed modification of the critical temperature. The doping, however, affects with substitutional reactions not only the CaO planes, but also the SrO planes. Des expériences de photoémission sur une série de monocristaux de Bi 2Sr 2Ca 1Cu 2O 8 dopés avec de l'yttrium montrent que le dopage change la valence du cuivre, comme on dopage, pourtant, ne modifie pas seulement les plans CaO par des réactions de substitution, mais également les plans SrO. Esperimenti di fotoemissione condotti su una serie di monocristalli di Bi 2Sr 2Ca 2O 8 con impurezze di Y mostrano che tali impurezze modificano la valenza del rame, com'é indipendentemente reso necessario dal fatto che si osservano dei cambiamenti della temperature di transizione. Si nota peraltro che le impurezze non modificano solamente i piani CaO mediante reazioni di sostituzione, ma anche i piani SrO.

  7. Primary study of the isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ in air

    Institute of Scientific and Technical Information of China (English)


    The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction (XRD) and in situ high-temporature XRD quantitative analysis, in addition to scanning electron microscopy measurement, the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem, the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area, the approximate composition areas of two two-phase regions and one three-phase region, (L2 + Cr), (L2 + M), and (L1 + L2 + Tr), were determined. Moreover, the precise composition areas of both of the three-phase regions (L2 + Cr + M) and (L2 + M + A) were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.

  8. Orbital control of effective dimensionality: from spin-orbital fractionalization to confinement in the anisotropic ladder system CaCu(2)O(3). (United States)

    Bisogni, Valentina; Wohlfeld, Krzysztof; Nishimoto, Satoshi; Monney, Claude; Trinckauf, Jan; Zhou, Kejin; Kraus, Roberto; Koepernik, Klaus; Sekar, Chinnathambi; Strocov, Vladimir; Büchner, Bernd; Schmitt, Thorsten; van den Brink, Jeroen; Geck, Jochen


    Fractionalization of an electronic quasiparticle into spin, charge, and orbital parts is a fundamental and characteristic property of interacting electrons in one dimension. However, real materials are never strictly one dimensional and the fractionalization phenomena are hard to observe. Here we studied the spin and orbital excitations of the anisotropic ladder material CaCu_{2}O_{3}, whose electronic structure is not one dimensional. Combining high-resolution resonant inelastic x-ray scattering experiments with theoretical model calculations, we show that (i) spin-orbital fractionalization occurs in CaCu_{2}O_{3} along the leg direction x through the xz orbital channel as in a 1D system, and (ii) no fractionalization is observed for the xy orbital, which extends in both leg and rung direction, contrary to a 1D system. We conclude that the directional character of the orbital hopping can select different degrees of dimensionality. Using additional model calculations, we show that spin-orbital separation is generally far more robust than the spin-charge separation. This is not only due to the already mentioned selection realized by the orbital hopping, but also due to the fact that spinons are faster than the orbitons.

  9. Interfacial band-edge engineered TiO2 protection layer on Cu2O photocathodes for efficient water reduction reaction (United States)

    Choi, Jaesuk; Song, Jun Tae; Jang, Ho Seong; Choi, Min-Jae; Sim, Dong Min; Yim, Soonmin; Lim, Hunhee; Jung, Yeon Sik; Oh, Jihun


    Photoelectrochemical (PEC) water splitting has emerged as a potential pathway to produce sustainable and renewable chemical fuels. Here, we present a highly active Cu2O/TiO2 photocathode for H2 production by enhancing the interfacial band-edge energetics of the TiO2 layer, which is realized by controlling the fixed charge density of the TiO2 protection layer. The band-edge engineered Cu2O/TiO2 (where TiO2 was grown at 80 °C via atomic layer deposition) enhances the photocurrent density up to -2.04 mA/cm2 at 0 V vs. RHE under 1 sun illumination, corresponding to about a 1,200% enhancement compared to the photocurrent density of the photocathode protected with TiO2 grown at 150 °C. Moreover, band-edge engineering of the TiO2 protection layer prevents electron accumulation at the TiO2 layer and enhances both the Faraday efficiency and the stability for hydrogen production during the PEC water reduction reaction. This facile control over the TiO2/electrolyte interface will also provide new insight for designing highly efficient and stable protection layers for various other photoelectrodes such as Si, InP, and GaAs. [Figure not available: see fulltext.

  10. Highly sensitive H2S sensors based on Cu2O/Co3O4 nano/microstructure heteroarrays at and below room temperature (United States)

    Cui, Guangliang; Zhang, Pinhua; Chen, Li; Wang, Xiaoli; Li, Jianfu; shi, Changmin; Wang, Dongchao


    Gas sensors with high sensitivity at and below room temperature, especially below freezing temperature, have been expected for practical application. The lower working temperature of gas sensor is better for the manufacturability, security and environmental protection. Herein, we propose a H2S gas sensor with high sensitivity at and below room temperature, even as low as −30 °C, based on Cu2O/Co3O4 nano/microstructure heteroarrays prepared by 2D electrodeposition technique. This heteroarray was designed to be a multi-barrier system, and which was confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and scanning probe microscopy. The sensor demonstrates excellent sensitivity, sub-ppm lever detection, fast response, and high activity at low temperature. The enhanced sensing property of sensor was also discussed with the Cu2O/Co3O4 p-p heterojunction barrier modulation and Cu2S conductance channel. We realize the detection of the noxious H2S gas at ultra-low temperature in a more security and environmental protection way. PMID:28252012

  11. Post-illumination activity of SnO2 nanoparticle-decorated Cu2O nanocubes by H2O2 production in dark from photocatalytic "memory". (United States)

    Liu, Lingmei; Sun, Wuzhu; Yang, Weiyi; Li, Qi; Shang, Jian Ku


    Most photocatalysts only function under illumination, while many potential applications require continuous activities in dark. Thus, novel photocatalysts should be developed, which could store part of their photoactivity in "memory" under illumination and then be active from this "memory" after the illumination is turned off for an extended period of time. Here a novel composite photocatalyst of SnO2 nanoparticle-decorated Cu2O nanocubes is developed. Their large conduction band potential difference and the inner electrostatic field formed in the p-n heterojunction provide a strong driving force for photogenerated electrons to move from Cu2O to SnO2 under visible light illumination, which could then be released to react with O2 in dark to produce H2O2 for its post-illumination activity. This work demonstrates that the selection of decoration components for photocatalysts with the post-illumination photocatalytic "memory" could be largely expanded to semiconductors with conduction band potentials less positive than the two-electron reduction potential of O2.

  12. Highly sensitive H2S sensors based on Cu2O/Co3O4 nano/microstructure heteroarrays at and below room temperature (United States)

    Cui, Guangliang; Zhang, Pinhua; Chen, Li; Wang, Xiaoli; Li, Jianfu; Shi, Changmin; Wang, Dongchao


    Gas sensors with high sensitivity at and below room temperature, especially below freezing temperature, have been expected for practical application. The lower working temperature of gas sensor is better for the manufacturability, security and environmental protection. Herein, we propose a H2S gas sensor with high sensitivity at and below room temperature, even as low as -30 °C, based on Cu2O/Co3O4 nano/microstructure heteroarrays prepared by 2D electrodeposition technique. This heteroarray was designed to be a multi-barrier system, and which was confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and scanning probe microscopy. The sensor demonstrates excellent sensitivity, sub-ppm lever detection, fast response, and high activity at low temperature. The enhanced sensing property of sensor was also discussed with the Cu2O/Co3O4 p-p heterojunction barrier modulation and Cu2S conductance channel. We realize the detection of the noxious H2S gas at ultra-low temperature in a more security and environmental protection way.

  13. 3种负载Cu2O的载体对印染废水处理的比较%Treatment Comparison of Dyeing Wastewater by Three Supporter Loaded Cu2O

    Institute of Scientific and Technical Information of China (English)



    Attapulgite, activated carbon and the supermicro porous polyurethane as the supporter, the three supporter load of Cu2O were prepared by liquid phase synthesis, and their photocatalytic oxidation effect was investigated by the adsorption and degradation of Rhodamine B. The results showed that when the simulated Rhodamine B dye wastewater initial concentration was 200mg/L, reaction time was 50 min, the loaded Cu2O dosage of three supporter was 11.0g/L, 9.0g/L and 5.0g/L, respectively, the removal rate of rhodamine B in the simulated wastewater were 81.64%, 87.21% and 78.46%, respectively. The removal rate of Rhodamine B was still better after five repeated use of the three catalysts.%  以凹凸棒石、活性炭和超微孔聚氨酯为载体,用液相合成法制备3种负载Cu2O的载体,并以吸附降解罗丹明B的效果,探讨其光催化氧化性能。试验结果表明,当模拟罗丹明B染料废水的初始质量浓度为200mg·L-1,反应时间为50min,该3种负载Cu2O的载体投加量分别为11.0g·L-1,9.0g·L-1和5.0g·L-1,对模拟染料废水中罗丹明B的去除率分别达到81.64%、87.21%和78.46%。5次重复使用该3种催化剂后对罗丹明B的去除率仍较好。

  14. A Au/Cu2O-TiO2 system for photo-catalytic hydrogen production. A pn-junction effect or a simple case of in situ reduction?

    KAUST Repository

    Sinatra, Lutfan


    Photo-catalytic H2 production from water has been studied over Au-Cu2O nanoparticle deposited on TiO2 (anatase) in order to probe into both the plasmon resonance effect (Au nanoparticles) and the pn-junction at the Cu2O-TiO2 interface. The Au-Cu2O composite is in the form of ∼10 nm Au nanoparticles grown on ∼475 nm Cu2O octahedral nanocrystals with (111) facets by partial galvanic replacement. X-ray Photoelectron Spectroscopy (XPS) Cu2p and Auger L3M4,5M4,5 lines indicate that the surface of Cu2O is mainly composed of Cu+. The rate for H2 production (from 95 water/5 ethylene glycol; vol.%) over 2 wt.% (Au/Cu2O)-TiO2 is found to be ∼10 times faster than that on 2 wt.% Au-TiO2 alone. Raman spectroscopy before and after reaction showed the disappearance of Cu+ lines (2Eu) at 220 cm-1. These observations coupled with the induction time observed for the reaction rate suggest that in situ reduction from Cu+ to Cu0 occurs upon photo-excitation. The reduction requires the presence of TiO2 (electron transfer). The prolonged activity of the reaction (with no signs of deactivation) despite the reduction to Cu0 indicates that the latter takes part in the reaction by providing additional sites for the reaction, most likely as recombination centers for hydrogen atoms to form molecular hydrogen. This phenomenon provides an additional route for enhancing the efficiency and lifetime of Cu2O-TiO2 photocatalytic systems, beyond the usually ascribed pn-junction effect.

  15. Strong electronic consequences of intercalation in cuprate superconductors: the case of a trigonal planar AuI(3) complex stabilized in the Bi(2)Sr(2)CaCu(2)O(y) lattice. (United States)

    Munzarová, Markéta L; Hoffmann, Roald


    Recently, a molecular AuI(3) complex was stabilized in the interlayer space of the Bi(2)Sr(2)CaCu(2)O(y) (Bi2212) high-T(c) superconducting phase, adopting an exceptional D(3)(h) structure (Choy, J.-H.; et al. J. Phys.Chem. B 2000, 104, 7273). If the gold were formally Au(III), a strong Jahn-Teller distortion to T- and Y-shaped structures would be expected. In this work, we try to understand the structural preferences of AuI(3) in both the gas phase and the Bi2212 lattice, as well as the influence of the AuI(3) intercalation on the superconductor lattice. What we think actually happens is that there is an effective electron transfer from the s-type Bi lone pair to the gold, increasing the formal oxidation state of Bi from +3 to +5 and decreasing that of Au from +3 to +1. A trigonal Au(I) trihalide is just fine. The DFT results confirm in the Bi-rich regions the same kind of electron transfer as encountered on the EHT level of theory, but they reveal additional complexities of the problem. The effect of the Bi to intercalating molecule electron transfer on the cuprate layer may be important, quite apart from this specific example, in tuning superconductivity in the cuprates.

  16. Design of Cu-Cu2O/g-C3N4 nanocomponent photocatalysts for hydrogen evolution under visible light irradiation using water-soluble Erythrosin B dye sensitization (United States)

    Zhang, Piyong; Wang, Tingting; Zeng, Heping


    Cu-Cu2O nanoparticles (NPs) decorated porous graphitic carbon nitride (g-C3N4) (Cu-Cu2O/g-C3N4) photocatalysts were prepared. When investment of copper source materials in the experiment increased to 7 wt%, the highest H2 evolution rate (400 μmol g-1 h-1) was obtained under visible light irradiation in triethanolamine solution. This is about triple of pure g-C3N4 (140 μmol g-1 h-1). Moreover, various amount of Erythrosin B dye was added into Cu-Cu2O/g-C3N4 photoreaction solution and a significant enhancement of H2 production rate was achieved. The highest H2 production rate was 5000 μmol g-1 h-1 with 5 mg Erythrosin B in photoreaction system. Erythrosin B dye sensitized Cu-Cu2O/g-C3N4 presented stable photocatalytic H2 evolution ability and no noticeable degradation or change of photocatalyst were detected after six recycles. A possible photocatalytic mechanism of Erythrosin B dye sensitized Cu-Cu2O/g-C3N4 for the enhancement of photocatalytic H2 evolution is proposed.

  17. Tunable Electrical Conductivity and Magnetic Property of the Two Dimensional Metal Organic Framework [Cu(TPyP)Cu2(O2CCH3)4]. (United States)

    Sengupta, Ananya; Datta, Subhadeep; Su, Chenliang; Herng, Tun Seng; Ding, Jun; Vittal, Jagadese J; Loh, Kian Ping


    The coordination chemistry between copper acetate [Cu2(OAc)4] and 5,10,15,20-tetra-4-pyridyl-21H,23H-porphine (porphyrin, H2TPyP) is found to give rise to either a 2D metal-organic framework (MOF) [Cu(TPyP)Cu2(O2CCH3)4] or a 3D MOF [Cu(TPyP)CuCl2]·2.5TCE·7H2O], depending on the choice of solvent. The 2D MOF can be made into a film, which was doped with 7,7,8,8-tetracyanoquinodimethane (TCNQ), and the electrical conductivity of the thin film was increased by 3 orders of magnitude with respect to that of the undoped Cu-MOF. The formation of a charge-transfer complex between TCNQ and the 2D Cu-MOF also imparts stronger paramagnetic properties than for the undoped MOF.

  18. Oxygen desorption from YBa2Cu3O(7-x) and Bi2CaSr2Cu2O(8 + delta) superconductors (United States)

    Mesarwi, A.; Levenson, L. L.; Ignatiev, A.


    Oxygen desorption experiments from YBa2Cu3O(7-x) (YBCO) and Bi2CaSr2Cu2O(8 + delta) (BSCCO) superconductors were carried out using a quadrupole mass spectrometer for monitoring the desorbing species and X-ray photoemission spectroscopy for surface characterization. Molecular oxygen was found to desorb from both superconductors following photoirradiation with ultraviolet/optical radiation and subsequent heating at over 150 C. Both YBCO and BSCCO were found to have similar oxygen desorption rates and similar activation energies. The desorption data as well as the X-ray photoemission data indicate that the oxygen desorption is not intrinsic to the superconductors but rather due to molecular oxygen entrapped in the material.

  19. Inductance of Long Intrinsic Josephson Junction Arrays Composed of Misaligned Tl2Ba2CaCu2O8 Thin Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tie-Ge; YAN Shao-Lin; FANG Lan; ZUO Xu; LI Song; JI Lu; ZHAO Xin-Jie


    @@ We observe and measure the inductance of long intrinsic Josephson junction arrays composed of misaligned Tl2 Ba2 CaCu2 O8 thin films grown on LaAlO3 substrates. The array consists of about 9.1 × 103 intrinsic Josephson junctions, where 90° phase shift between ac voltage across the array and ac current flowing through has been measured. Furthermore, the voltage is proportional to the frequency of the current. The measured inductance values of the intrinsic Josephson junction arrays are basically consistent with the theoretically calculated results, confirming that the inductance is mainly due to the Josephson effect. The dependence of the array inductance on its critical current is also discussed.

  20. Shapiro Steps in Flux-Trapped Surface Intrinsic Junctions of Bi2Sr2CaCu2O8+δ

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-Feng; ZHAO Shi-Ping; ZHU Xiao-Bo; CHEN Geng-Hua; REN Yu-Feng; YU Hong-Wei; YANG Qian-Sheng; HU Yun


    @@ Microwave-field responses of the surface intrinsic Josephson junctions (IJJs) of Bi2Sr2 CaCu2 O8+δ superconductors are investigated. The IJJs are fabricated using an in situ low-temperature cleavage technique, which leads to the well-characterized surface CuO2 double layers and surface junctions. For the surface junctions in the largejunction limit, usually no Shapiro steps appear when a microwave field is applied. It is found that when thejunctions are in a flux-trapped state, which is produced by a pulsed current and in which the critical current is significantly suppressed, clear Shapiro steps can be observed. These results are important for the study of the microwave-field properties of vortex-carrying IJJs and may find their use in device applications.

  1. Anisotropy in the ab-plane optical properties of Bi2Sr2CaCu2O8 single-domain crystals (United States)

    Quijada, M. A.; Tanner, D. B.; Kelley, R. J.; Onellion, M.; Berger, H.; Margaritondo, G.


    The ab-plane optical properties of the high-temperature superconductor Bi2Sr2CaCu2O8 are anisotropic in both the normal and the superconducting state. Consistent with the orthorhombic structure, the principal axes lie along the a and b crystallographic axes, nearly 45° from the Cu-O bond direction. In the normal state, analysis of the temperature-dependent optical conductivity suggests a scattering rate for the free carriers that shows ab anisotropy in both magnitude and temperature dependence. In the superconducting state, the anisotropy in the oscillator strength of the superfluid response determined from the far-infrared frequency dependence of σ2(ω) and from a sum-rule analysis leads to a penetration depth λD that is larger along the b axis than the a axis: (λbL>λaL).

  2. Electron-beam induced disorder effects in optimally doped Bi2Sr2CaCu2O8+x single crystal samples (United States)

    Vobornik, I.; Berger, H.; Pavuna, D.; Margaritondo, G.; Forro, L.; Grioni, M.; Rullier-Albenque, F.; Onellion, M.; EPFL Collaboration; Laboratoire Des Solides Irradiés Collaboration


    We report on the effects of electron-beam induced disorder in optimally doped Bi2Sr2CaCu2O8+x single crystal samples, measured with angle-resolved photoemission. In the superconducting state, the disorder fills in the gap, without changing the binding energy or the width of the narrow coherent feature.[1] In the normal state, disorder leads to an anisotropic pseudogap in angle-resolved photoemission, with the largest pseudogap near the (0,p) point and no pseudogap in the direction.[2,3] We discuss implications of these data. 1. I. Vobornik, Phys. Rev. Lett. 82 , 3128 (1999). 2. I. Vobornik, Ph.D. thesis, EPFL, Lausanne, Switzerland, October, 1999. 3. I. Vobornik, unpublished.

  3. Síntesis y Caracterización de Ag2Cu2O3, el primer óxido de cobre y plata


    Tejada Rosales, E. M.; Palacín, M. R.; Gómez-Romero, P.


    [ES] A pesar de las similitudes cristaloquímicas entre los iones de cobre y los de plata, no existe ningún óxido mixto de cobre y plata ni natural ni sintético. En este trabajo se presenta la síntesis a bajas temperaturas del primer óxido mixto de cobre y plata, de fórmula Ag2Cu2O3 (tetragonal, a=5.8857(3)Å, c=10.6868(7)Å, grupo espacial I41/amd, Z=4). Este óxido posee una estabilidad térmica superior a los correspondientes óxidos de cobre y de plata. Contiene cadenas de iones Cu(II)...

  4. Tuning THz emission properties of Bi2Sr2CaCu2O8+δ intrinsic Josephson junction stacks by charge carrier injection (United States)

    Kizilaslan, O.; Rudau, F.; Wieland, R.; Hampp, J. S.; Zhou, X. J.; Ji, M.; Kiselev, O.; Kinev, N.; Huang, Y.; Hao, L. Y.; Ishii, A.; Aksan, M. A.; Hatano, T.; Koshelets, V. P.; Wu, P. H.; Wang, H. B.; Koelle, D.; Kleiner, R.


    We report on doping and undoping experiments of terahertz (THz) emitting intrinsic Josephson junction stacks, where the change in charge carrier concentration is achieved by heavy current injection. The experiments were performed on stand-alone structures fabricated from a Bi2Sr2CaCu2O{}8+δ single crystal near optimal doping. The stacks contained about 930 intrinsic Josephson junctions. On purpose, the doping and undoping experiments were performed over only a modest range of charge carrier concentrations, changing the critical temperature of the stack by less than 1 K. We show that both undoping and doping is feasible also for the large intrinsic Josephson junction stacks used for THz generation. Even moderate changes in doping introduce large changes in the THz emission properties of the stacks. The highest emission power was achieved after doping a pristine sample.

  5. Millimeter wave inducing subharmonic steps in the Tl2Ba2CaCu2O8 thin film bicrystal Josephson junction (United States)

    Liu, X.; Hu, L.; Xie, W.; Wang, P.; Ma, L. J.; Zhao, X. J.; He, M.; Zhang, X.; Ji, L.


    The bicrystal Josephson junction (BJJ) was fabricated by patterning microbridge into Tl2Ba2CaCu2O8 (Tl-2212) thin film grown epitaxially on the bicrystal SrTiO3 (STO) substrate. The millimeter wave responses of BJJ were researched by experiment and numerical simulation. Shapiro steps and subharmonic steps were both observed in the current-voltage (I-V) curve at the liquid nitrogen temperature. In the resistive-capacitive-inductive shunted junction (RCLSJ) model, both of the Shapiro steps and subharmonic steps were reproduced with varying capacitances and inductances. The result of simulation has a good agreement with the experiment. The relative large capacitance and inductance correspond to distinct subharmonic steps.

  6. Perturbed angular correlations studies in the HgBa$_2$CaCu$_2$O$_{6+\\delta}$ high-T$_c$ superconductor

    CERN Document Server

    Mendonca, Tania Melo; Haas, Heinz; Odier, Philippe; Tavares, Pedro; SIlva, Manuel Ribeiro; Lopes, Armandina; Darie, Celine; Araujo, Joao Pedro


    The electric field gradients at $^{199m}$Hg nuclei have been measured via the perturbed angular correlation (PAC) technique, allowing a full characterization of the Hg neighborhood charge distribution at high oxygen doping on the Hg planes. The PAC technique has been applied to investigate the effect of high oxygen pressure during the measurement. Polycrystalline HgBa$_2$CaCu$_2$O$_{6+\\delta}$ (Hg-1212) samples have been annealed at 152 bar pressurized oxygen. The influence of oxygen pressure during the experiment was then investigated by measuring the samples at atmospheric pressure and under 152 bar oxygen pressure. The present set of PAC experiments shows that at high oxygen concentrations there is a non-uniform oxygen distribution. Moreover, the Hg environment is not free from oxygen and the results hint to a new type of ordering.

  7. Ultrafast electron relaxation in superconducting Bi(2)Sr(2)CaCu(2)O(8+delta) by time-resolved photoelectron spectroscopy. (United States)

    Perfetti, L; Loukakos, P A; Lisowski, M; Bovensiepen, U; Eisaki, H; Wolf, M


    Time-resolved photoelectron spectroscopy is employed to study the dynamics of photoexcited electrons in optimally doped Bi{2}Sr{2}CaCu{2}O{8+delta} (Bi-2212). Hot electrons thermalize in less than 50 fs and dissipate their energy on two distinct time scales (110 fs and 2 ps). These are attributed to the generation and subsequent decay of nonequilibrium phonons, respectively. We conclude that 20% of the total lattice modes dominate the coupling strength and estimate the second momentum of the Eliashberg coupling function lambdaOmega{0}{2}=360+/-30 meV{2}. For the typical phonon energy of copper-oxygen bonds (Omega{0} approximately 40-70 meV), this results in an average electron-phonon coupling lambda<0.25.

  8. Absence of a loss of in-plane infrared spectral weight in the pseudogap regime of Bi(2)Sr(2)CaCu(2)O(8+delta). (United States)

    Santander-Syro, A F; Lobo, R P S M; Bontemps, N; Konstantinovic, Z; Li, Z; Raffy, H


    The ab-plane reflectance of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi-2212) thin films was measured in the 30-25 000 cm(-1) range for one underdoped ( T(c) = 70 K), and one overdoped sample ( T(c) = 63 K) down to 10 K. We find similar behaviors in the temperature dependence of the normal-state infrared response of both samples. Above T(c), the effective spectral weight, obtained from the integrated conductivity, does not decrease when T decreases, so that no opening of an optical pseudogap is seen. We suggest that these are consequences of the pseudogap opening in the k = (0,pi) direction and of the in-plane infrared conductivity being mostly sensitive to the k = (pi,pi) direction.

  9. Abrupt change of josephson plasma frequency at the phase boundary of the bragg glass in Bi(2)Sr(2)CaCu(2)O(8+delta) (United States)

    Gaifullin; Matsuda; Chikumoto; Shimoyama; Kishio


    We report the first detailed and quantitative study of the Josephson coupling energy in the vortex liquid, Bragg glass, and vortex glass phases of Bi(2)Sr(2)CaCu(2)O(8+delta) by the Josephson plasma resonance. The measurements revealed distinct features in the T and H dependencies of the plasma frequency omega(pl) for each of these three vortex phases. When going across either the Bragg-to-vortex glass or the Bragg-to-liquid transition line, omega(pl) shows a dramatic change. We provide a quantitative discussion on the properties of these phase transitions, including the first order nature of the Bragg-to-vortex glass transition.

  10. Vertical temperature boundary of the pseudogap under the superconducting dome in the phase diagram of Bi2Sr2CaCu2O8 +δ (United States)

    Loret, B.; Sakai, S.; Benhabib, S.; Gallais, Y.; Cazayous, M.; Méasson, M. A.; Zhong, R. D.; Schneeloch, J.; Gu, G. D.; Forget, A.; Colson, D.; Paul, I.; Civelli, M.; Sacuto, A.


    Combining electronic Raman scattering experiments with cellular dynamical mean field theory, we present evidence of the pseudogap in the superconducting state of various hole-doped cuprates. In Bi2Sr2CaCu2O8 +δ we track the superconducting pseudogap hallmark, a peak-dip feature, as a function of temperature T and doping p , well beyond the optimal one. We show that, at all temperatures under the superconducting dome, the pseudogap disappears at the doping pc, between 0.222 and 0.226, where also the normal-state pseudogap collapses at a Lifshitz transition. This demonstrates that the superconducting pseudogap boundary forms a vertical line in the T -p phase diagram.

  11. Oscillatory behavior of vortex-lattice melting transition line in mesoscopic Bi_{2}Sr_{2}CaCu_{2}O_{8+y} superconductors. (United States)

    Ooi, S; Mochiku, T; Tachiki, M; Hirata, K


    The vortex-lattice melting transition of a limited number of vortices confined in mesoscopic square superconductors was studied by c-axis resistance measurements using stacks of intrinsic Josephson junctions in Bi_{2}Sr_{2}CaCu_{2}O_{8+y}. In contrast to the melting transition in bulk crystals, we have first found a clear oscillatory behavior in the field dependence of the melting temperature in small samples of 5-10  μm square. The periods of the oscillations roughly obey the regularity of the matching conditions of square vortex lattices surrounded by a square boundary and the melting temperatures are enhanced around the vortex number of i^{2} (where i is an integer). The results suggest that a confinement effect by the square boundary stabilizes square lattice structures which are realized around i^{2} vortex number even in competition with the favorable Abrikosov triangular lattice in the bulk.

  12. Transmission electron microscopy study of focused ion beam damage in small intrinsic Josephson junctions of single crystalline Bi2Sr2CaCu2O y (United States)

    Kakizaki, Yoshihiro; Koyama, Junpei; Yamaguchi, Ayami; Umegai, Shunpei; Ayukawa, Shin-ya; Kitano, Haruhisa


    We report a transmission electron microscopy (TEM) study on the damage produced by the focused ion beam (FIB) etching for small Bi2Sr2CaCu2O y (Bi2212) intrinsic Josephson junctions (IJJs). The selected area diffraction patterns of TEM images demonstrate that the FIB damage causes the formation of an amorphous layer. The thickness of FIB damage is at least 30 nm for the Ga+ ion beam emitted at 50 pA and 30 kV, independent of the incident direction of the Ga+ ion beam. We also confirmed that the damage or the redeposition due to the FIB etching was effectively removed by the additional irradiation of Ar ions after the FIB etching. This suggests the advantage of the combinatorial method of the FIB and Ar-ion etchings in the successful fabrication of small and high-quality IJJs.

  13. Crossovers in the out-of-plane resistivity of superconducting Tl2Ba2CaCu2O8 single crystals (United States)

    Salvetat, J.-P.; Berger, H.; Halbritter, A.; Mihály, G.; Pavuna, D.; Forró, L.


    We report the in-plane (ρab) and out-of-plane (ρc) resistivities in the 4 800 K range on single crystals of Tl2Ba2CaCu2O8 high-Tc cuprate with Tc = 111 K (ρc/ρab approx 1000). ρab(T) exhibits "usual" linear behavior and ρc(T) follows generally metallic-like, positive slope in the 150 400 K temperature range. There is a clear crossover to semiconductor-like behavior close to Tc. However, for the first time in a chainless high-Tc cuprate we observe a crossover above 500 K due to hopping conduction. Under high pressures ( < 15 kbar) the magnitude of ρc strongly decreases, yet the ρc(T) slope does not change. This suggests that the out-of-plane charge transport is governed by the interplane tunneling rate.

  14. Consistent behaviour of AC susceptibility and transport properties in magnetic superconductor RuSr 2GdCu 2O 8 (United States)

    Očko, M.; Živkovic, I.; Prester, M.; Drobac, Dj.; Ariosa, D.; Berger, H.; Pavuna, D.


    We report on AC susceptibility, resistivity, thermopower and measurements of sintered magnetic superconductor RuSr 2GdCu 2O 8. The antiferromagnetic phase transition at 133 K is seen clearly in the AC susceptibility as well as in the derivative of resistivity and thermopower. Above the antiferromagnetic transition, we have found some new evidences of the similarity between HTC compounds and the magnetic superconductor. The onset of superconductivity is observed by both transport methods at 46 K, and an explanation why it is not seen in the AC susceptibility data is given. The end of the SC transition occurs at about 24 K in all measured properties. We discuss the steps of broad SC transition, especially the maximum in susceptibility at 34 K, and compare our results with related studies reported in the literature.

  15. Spin-glass and variable range hopping quantum interference magnetoresistance in FeSr2Y1.3Ce0.7Cu2O10-x (United States)

    Sambale, S.; Williams, G. V. M.; Stephen, J.; Chong, S. V.


    Electronic transport and magnetic measurements have been made on FeSr2Y1.3Ce0.7Cu2O10-x. We observe a spin-glass at ˜23 K and a magnetoresistance that reaches -22% at 8 T. The magnetoresistance is due to variable range hopping quantum interference where at low temperatures each hop is over a large number of scatterers. This magnetoresistance is negative at and above 5 K and can be described by the Nguen, Spivak, and Shklovskii (NSS) model. However, there is an increasingly positive contribution to the magnetoresistance for temperatures below 5 K that may be due to scattering from localized free spins during each hop that is not accounted for in the NSS model.

  16. Novel anisotropy in the superconducting gap structure of Bi2Sr2CaCu2O(8+delta) probed by quasiparticle heat transport. (United States)

    Ando, Yoichi; Takeya, J; Abe, Yasushi; Sun, X F; Lavrov, A N


    Since the nature of pairing interactions is manifested in the superconducting gap symmetry, the exact gap structure, particularly any deviation from the simple d(x(2)-y(2)) symmetry, would help in elucidating the pairing mechanism in high- T(c) cuprates. Anisotropic heat transport measurement in Bi(2)Sr(2)CaCu(2)O(8+delta) reveals that the quasiparticle populations are different for the two nodal directions and thus the gap structure must be uniquely anisotropic, suggesting that pairing is governed by interactions with a rather complicated anisotropy. Intriguingly, it is found that the "plateau" in the magnetic-field dependence of the thermal conductivity is observed only in the b-axis transport.

  17. Electroanalysis of Dopamine at Nano Cu2O and Nitrogen Doped Graphene Modified Electrode%纳米Cu2O/氮掺杂石墨烯复合修饰电极对多巴胺的电化学分析研究

    Institute of Scientific and Technical Information of China (English)

    梁秀丽; 吴芳辉; 江彬彬; 徐帆; 刘飞跃; 黄晓洁


    本文通过化学还原法制备纳米Cu2O/氮掺杂石墨烯(NG)复合材料,用于构建一种新型的多巴胺(DA)电化学传感器.采用X射线衍射法和扫描电镜对纳米Cu2O/氮掺杂石墨烯复合材料进行表征.在pH为7.0的磷酸盐缓冲液中,采用循环伏安法和计时电流法分别研究了DA在纳米Cu2O/氮掺杂石墨烯复合修饰电极上的电化学行为.结果表明,该修饰电极对DA表现出显著的电催化活性,且DA在修饰电极上的反应受吸附控制.在最佳实验条件下,催化电流与DA的浓度在0.5~700 μ mol/L之间呈线性关系(r=0.9943),检测限达0.17 μ mol/L.该修饰电极的选择性高、重复性和再现性好.方法用于实际样品中DA的检测,获得结果较好.

  18. Cu2O/TiO2光催化降解罗丹明B工艺条件的研究%Study on technical conditions for photocatalytic degradation of Rhodamine B by using Cu2O/TiO2

    Institute of Scientific and Technical Information of China (English)

    孙伟; 梁光远; 赵丽平; 叶兆伟; 殷东林


    The photocatalytic degradation of soluble dye Rhodamine B by using Cu2O/TiO2 as supported catalyst and sunlight as light source has been studied. The effects of the conditions ,such as concentration of catalyst ,concentra-tion of H2O2,acidity of solution,initial concentration of reactants on the course of photocatalytic degradation of Rho-damine B are mainly investigated,so as to study the technological conditions of photocatalytic degradation. The re-sults show that Cu2O/TiO2 has pretty good degradation effect on Rhodamine B . The optimal conditions are as follows:concentration of catalyst is 1 g/L,concentration of H2O2 1.5%(volume ratio),pH 5-7. Under these condi-tions,it takes only 10 min for 5 mg/L of Rhodamine B solution to reach the degradation rate 96%.%采用负载型催化剂Cu2O/TiO2,以太阳光为光源,研究了其对可溶性染料罗丹明B的降解情况。主要考察了催化剂投加量,H2O2投加体积分数,溶液的酸度和反应物初始浓度等条件对罗丹明B催化降解过程的影响,从而研究催化降解的工艺条件。结果表明:Cu2O/TiO2对罗丹明B有较好的降解效果,其最佳工艺条件为:催化剂用量为1g/L,H2O2投加体积分数为1.5%,pH为5~7。此条件下,10 min就能使5 mg/L的罗丹明B溶液达到96%的降解率。

  19. Mechanism of copper selenide growth on copper-oxide selenium system (United States)

    Ishikawa, Y.; Kido, O.; Kimura, Y.; Kurumada, M.; Suzuki, H.; Saito, Y.; Kaito, C.


    Transmission electron microscopy was used to study spontaneous copper selenide formation on Cu particles covered with an oxide layer. Even if the copper particle surface was covered with a Cu 2O layer, selenides were formed by diffusion through the metal oxide layer. For a particle size less than 50 nm, selenide was formed in Cu particles by the diffusion of Se atoms passing through the Cu 2O layer. For particles larger than 100 nm in size, selenide was formed in Se film. It was also found that the thickness of the Cu 2O layer on the surface of Cu particle accelerated diffusion of Se atoms to the copper particle.

  20. Novel visible-light-responding InVO4-Cu2O-TiO2 ternary nanoheterostructure:Preparation and photocatalytic characteristics%新型可见光响应的 InVO4-Cu2O-TiO2三元纳米异质结:制备及其光催化性能

    Institute of Scientific and Technical Information of China (English)

    冯海波; 李亚萍; 罗冬明; 谭功荣; 蒋剑波; 袁惠敏; 彭三军; 钱东


    A novel visible‐light‐responding InVO4‐Cu2O‐TiO2 ternary nanoheterostructure was designed on the basis of the strategy of energy gap engineering and prepared through ordinary wet chemistry methods. The as‐prepared nanoheterostructure was characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM) and diffuse reflectance ultraviolet‐visible spectroscopy (UV‐vis/DRS). The TEM and HRTEM images of 10%InVO4‐40%Cu2O‐50%TiO2 confirm the formation of nanoheterostructures resulting from contact of the nanosized TiO2, Cu2O and InVO4 in the size of 5–20 nm in diameter. The InVO4‐Cu2O‐TiO2 nanoheterostructure, when compared with TiO2, Cu2O, InVO4, InVO4‐TiO2 and Cu2O‐TiO2, shows significant enhancement in the photocatalytic performance for the degradation of methyl orange (MO) under visible‐light irradiation. With a 9 W energy‐saving fluorescent lamp as the visible‐light source, the MO degradation rate of 10%InVO4‐40%Cu2O‐50%TiO2 reaches close to 90%during 5 h, and the photocatalytic efficiency is maintained at over 90%after six cycles. This may be mainly ascribed to the matched bandgap configurations of TiO2, Cu2O and InVO4, and the formations of two p‐n junctions by the p‐type semiconductor Cu2O with the n‐type semiconductors TiO2 and InVO4, all of which favor spatial photogenerated charge carrier separation. The X‐ray pho‐toelectron spectroscopy (XPS) characterization for the used 10%InVO4‐40%Cu2O‐50%TiO2 reveals that only a small shakeup satellite peak appears for Cu(II) species, implying bearable photocorro‐sion of Cu2O. This work could provide new insight into the design and preparation of novel visi‐ble‐light‐responding semiconductor composites.%由于日益严重的环境和能源危机,可见光催化剂的开发已成为当今最具挑战和紧迫的任务之一.将 TiO2和其它窄禁带半导体复合,已被证明是

  1. Cu2O/Bi2O3光催化降解罗丹明B的工艺条件研究%Process Conditions of the Degradation of Rhodamine B by Cu2O/Bi2O3 Photocatalytic

    Institute of Scientific and Technical Information of China (English)

    梁光远; 孙伟


    This paper used supported catalyst Cu2O/Bi2O3 to study the degradation of soluble dye rhodamine B, and surveyed the impact of degradation conditions on catalytic degradation process of Rhodamine B. The results show that it has better degradation effect, degradation of 5mg/L Rhodamine B solution nearly to 100% for 5 minutes, under the optimum conditions its pH is 3-5, the catalyst is 1g/L, and the amount of hydrogen peroxide is 1.0% (volume ratio).%  本文采用负载型催化剂 Cu2O/Bi2O3,研究了对可溶性染料罗丹明 B 的降解情况。考察了降解条件对罗丹明 B 催化降解过程的影响。结果表明,对罗丹明 B 有较好的降解效果,5分钟使5mg/L 的罗丹明 B 溶液降解近100%,最佳工艺条件下 pH 为3-5,催化剂为1g/L,双氧水加入量为1.0%(体积比)。

  2. Superconductores de alta temperatura crítica Bi2Sr2CaCu2O8+δ altamente texturados: propiedades mecánicas

    Directory of Open Access Journals (Sweden)

    Llorca, J.


    Full Text Available The mechanical properties of Bi2Sr2CaCu2O8+δ superconductor fibres processed by laser-induced directional solidification at different growth rates were studied. Tensile and diametral compression (Brazilian test tests were performed to analyse the longitudinal and transversal strength. The elastic modulus was determined using the flexural vibration resonance method. Flexure tests were also carried out to compare with the literature data. In addition, polished sections of the as-received fibres and the fracture surfaces of the broken samples were analysed in the scanning electron microscope. The fibres were highly anisotropic and the transverse fibre strength was very low due to the early failure by cleavage of the grains perpendicularly to the c axis. The degree of anisotropy and the longitudinal strength increased as the fibre growth rate decreased while the transverse strength followed the opposite trend. This behaviour was due to changes in the porosity and the alignment of the crystals along the fibre axis.En este trabajo se han estudiado las propiedades mecánicas de fibras superconductoras Bi2Sr2CaCu2O8+δ fabricadas por solidificación direccional inducida por láser y crecidas a distintas velocidades. Se realizaron ensayos de tracción directa e indirecta (ensayo brasileño para evaluar la resistencia a tracción en las direcciones longitudinal y transversal respecto a la de crecimiento. El módulo elástico de las fibras en la dirección longitudinal se obtuvo midiendo la frecuencia fundamental de resonancia en flexión y se realizaron ensayos de flexión para comparar con los resultados disponibles en la literatura. El trabajo se completa con el estudio de las secciones longitudinales y transversales del material sin ensayar y el análisis fractográfico de las probetas rotas. Las fibras resultaron altamente anisótropas siendo su resistencia en la dirección transversal muy baja, debido a la fractura por clivaje de los planos

  3. Preparation and Photocatalytic Activity of Magnetically Separable Cu2O Photocatalyst%可磁分离Cu2O光催化剂的制备与光催化活性

    Institute of Scientific and Technical Information of China (English)

    陈伟; 李燕; 徐海燕


    采用共沉淀法制备了镍锌铁氧体,水合肼还原法制备了镍锌铁氧体负载Cu2O可磁分离光催化剂.采用X射线粉末衍射(XRD),高分辨透射电子显微镜(HRTEM)对所制得的样品进行了表征;并以甲基橙为降解对象,考察了镍锌铁氧体负载Cu2O可磁分离光催化剂的光催化性能.结果表明:Cu2O/镍锌铁氧体复合粉体对甲基橙溶液有较高的降解能力,重复使用4次光催化效率仍保持在81%,而且Cu2O/镍锌铁氧体光催化剂可通过外加磁场进行分离,具有较好的应用前景.%Nickel-zinc ferrite powders were prepared by coprecipitation method, and magnetically separable Cu2O/nickel-zinc ferrite photocatalyst was prepared by hydrazine hydrate reduction method. The as-prepared sample was characterized by X-ray diffraction (XRD) and high resolution transmission electron microscopy (TEM). The photocatalytic activities of magnetically separable Cu2O/nickel-zinc ferrite photocatalyst were investigated by the degradation of methyl orange. The results show that the composite Cu2O-coated nickel-zinc ferrite powders had higher photocatalytic activity for methyl orange solution. In addition, its photocatalytic efficiency could be maintained at 81% when it was repeatedly used for 4 times. The magnetically separable Cu2O/nickel-zinc ferrite photocatalyst could be separated from the system by applying an external magnetic field to it. It's considered that the Cu2O-coated nickel-zinc ferrite is a promising photocatalyst.

  4. High-Tc superconductivity in ultrathin Bi2Sr2CaCu2O(8+x) down to half-unit-cell thickness by protection with graphene. (United States)

    Jiang, Da; Hu, Tao; You, Lixing; Li, Qiao; Li, Ang; Wang, Haomin; Mu, Gang; Chen, Zhiying; Zhang, Haoran; Yu, Guanghui; Zhu, Jie; Sun, Qiujuan; Lin, Chengtian; Xiao, Hong; Xie, Xiaoming; Jiang, Mianheng


    High-Tc superconductors confined to two dimension exhibit novel physical phenomena, such as superconductor-insulator transition. In the Bi2Sr2CaCu2O(8+x) (Bi2212) model system, despite extensive studies, the intrinsic superconducting properties at the thinness limit have been difficult to determine. Here, we report a method to fabricate high quality single-crystal Bi2212 films down to half-unit-cell thickness in the form of graphene/Bi2212 van der Waals heterostructure, in which sharp superconducting transitions are observed. The heterostructure also exhibits a nonlinear current-voltage characteristic due to the Dirac nature of the graphene band structure. More interestingly, although the critical temperature remains essentially the same with reduced thickness of Bi2212, the slope of the normal state T-linear resistivity varies by a factor of 4-5, and the sheet resistance increases by three orders of magnitude, indicating a surprising decoupling of the normal state resistance and superconductivity. The developed technique is versatile, applicable to investigate other two-dimensional (2D) superconducting materials.

  5. Crystal Growth and Electronic Raman Scattering Study of Model High-Tc Cuprate HgBa2 CaCu2 O6 +Ä (United States)

    Wang, Lichen; Li, Yuan; Luo, Xiangpeng; Li, Jiarui; Yuan Li's Group in ICQM Team

    In this talk, I will report our recent progress on crystal growth of HgBa2CaCu2O6 +x (Hg1212), which possesses a simple tetragonal crystal structure and the highest ambient-pressure Tc (128 K) among all cuprate superconductors with two CuO2 sheets in the primitive cell. Improvement in single-crystal synthesis was made possible by using self-designed high-pressure furnaces and a two-layer encapsulation method, and we demonstrate that the hole concentration can be homogeneously tuned in the underdoped region by post-growth annealing. Our electronic Raman scattering experiments reveal that the maximum of the d-wave superconducting gap increases from single-layer HgBa2CuO4 +x to double-layer Hg1212. In the same spectra, it is found that the characteristic energy of spin excitations, as manifested by the energy of the two-magnon signal, also increases in a nearly proportional fashion. This result is consistent with the idea that magnetic interactions are closely related to the Cooper pairing mechanism.

  6. Quasi-one-dimensional hopping conductivity of the spin-ladder CaCu2O3 single crystals: Influence of the cation and oxygen nonstoichiometry (United States)

    Lisunov, K. G.; Wizent, N.; Waske, A.; Werner, J.; Tristan, N.; Sekar, C.; Krabbes, G.; Behr, G.; Arushanov, E.; Büchner, B.


    The resistivity ρ(T) of the spin-ladder compound CaCu2O3 measured along the Cu-O-Cu leg (j ∥b) exhibits a strongly activated character. It increases from ˜104 to ˜109 Ωm if T decreases from 350 to 100 K. The charge transfer above T ˜200 K is governed by a quasi-one-dimensional (1D) nearest-neighbor hopping (NNH) conductivity mechanism characterized by the law ρ(T )˜exp(Ea/kT). Below 200 K a novel quasi-1D variable-range hopping (VRH) conductivity law ρ(T )˜exp[(T0/T)3/4] is observed, predicted recently by Fogler, Teber, and Shklovskii [Phys. Rev. B 69, 035413 (2004)]. The NNH activation energy Ea and the VRH characteristic temperature T0 exhibit high sensitivity to the cation (Ca, Cu) content, decreasing by 2.3-2.5 times and by 3.0-3.2 times, respectively, when the composition of Ca is changed from 0.854 to 0.786-0.798 and the composition of Cu from 2.039 to 2.159-2.163. The behavior of Ea and T0 can be attributed to a corresponding variation of the concentration of intrinsic defects associated with Cu vacancies. On the other hand, no direct dependence of Ea and T0 to the excess oxygen concentration is observed.

  7. Magnetic relaxation in Tl2Ba2CaCu2O8 single crystals by SQUID magnetometer and micro-Hall sensor (United States)

    Chowdhury, P.; Kim, Heon-Jung; Kang, W. N.; Zang, Dong-Jin; Lee, Sung-Ik; Kim, D. H.


    Measurements of the isothermal magnetization hysteresis loops M(H) and the magnetic relaxation for a Tl2Ba2CaCu2O8 single crystal were carried out by using a superconducting quantum interference device magnetometer and a micro-Hall sensor. In the temperature window from 30 to 60 K, the measurements for M(H) show a second anomalous peak at a field Hsp and an onset field of Hon. From these relaxation data measured by two different techniques, the activation barrier U0 and the creep exponent μ were separately calculated as functions of H based on the weak collective pinning theory. The variation of the normalized creep rate, S=(|d ln M/d ln t|), with H is also presented. The results at T=35 K indicate that at a characteristic field H* lying between Hon and Hsp, a minimum is observed in S(H) whereas a maximum is observed in U0(H). These analyses also show that below H*, the creep phenomenon is controlled by an elastic process. However, above Hsp a negative power law, U0(H)∝Hν with ν˜-0.9, is observed suggesting the existence of plastic creep. At a low temperature of T=20 K, where no second peak is observed, both S(H) and U0(H) behave differently. A comparative study of the different creep parameters obtained from the two different measurement techniques is also discussed.

  8. Resistivity Measurements on Bulk Bi2Sr2CaCu2O8+δ: Contribution of Vortices at Low Magnetic Fields

    Directory of Open Access Journals (Sweden)

    Clarina de la Cruz


    Full Text Available The behavior of high-temperature superconductors in the presence of an external magnetic field is of particular interest in light of its technological application and commercialization. In this paper, we performed resistivity measurements on bulk superconducting pellets of Bi2Sr2CaCu2O8+δ in the presence of external magnetic fields below 0.5T. The broadening of the transition region below Tc in the resistivity plots, was attributed to the residual resistance imparted by flux flow in the sample. From I-V measurements at 50 K at fields below 0.6T, the contribution of vortices was quantitatively measured as a flux flow resistivity which range from 0.1231 to 1.700 (m(-mm for applied magnetic fields from 0.04T to 0.6T. The increase in the flux flow resistivity with increasing applied field was due to the increase in the number of vortices moving in steady state motion brought about by the interaction of the vortices with the transport current.

  9. Millimeter wave characteristics of intrinsic Josephson junctions with planar equiangular spiral antenna in misaligned Tl2Ba2CaCu2O8 thin film (United States)

    Liu, X.; Wang, P.; Xie, W.; Ma, L. J.; Zhao, X. J.; He, M.; Ji, L.; Zhang, X.


    An intrinsic Josephson junctions (IJJs) microbridge with planar equiangular spiral antenna (PESA) is proposed and studied by simulation and experiment. This IJJs circuit is simulated firstly to obtain the minimum of reflection coefficient and pattern. Secondly, IJJs with PESA are fabricated on misaligned Tl2Ba2CaCu2O8 superconducting film. The millimeter wave characteristics are investigated by a Febry-Pérot resonator, which consists of a spherical mirror antenna and a plane mirror. At 37.4 GHz, the IJJs and the millimeter wave show an optimum coupling, which deviate from the simulation for only 0.004 GHz. In addition, the extent of the coupling between IJJs and the resonator is discussed at different angle for the polarization direction of the spherical mirror antenna with the microbridge. The result shows that the strongest coupling is obtained at 0-30° angle. Good conformance of measurements and simulations illustrate the effectiveness of our design in strong coupling between sample and resonator.

  10. Localization effects in transition-metal doped Bi2Sr2CaCu2O8+y high-temperature superconductors (United States)

    Quitmann, C.; Almeras, P.; Ma, Jian; Kelley, R. J.; Berger, H.; Margaritondo, G.; Onellion, M.


    Doping Bi2Sr2Ca1Cu2O8+y with Co causes a superconductor-insulator transition. We study correlations between changes in the electrical resistivity RHOab(T) and the electronic bandstructure using identical single crystalline samples. For undoped samples the resistivity is linear in temperature and has a vanishing residual resistivity. In angle resolved photoemission these samples show dispersing band-like states. Co-doping decreases TC and causes and increase in the residual resistivity. Above a threshold Co-concentration the resistivity is metallic (drab/dT >0) at room temperature, turns insulating below a characteristic temperature Tmin and becomes super- conducting at even lower temperature. These changes in the resistivity correlate with the disappearance of the dispersing band-like states in angle resolved photoemission. We show that Anderson localization caused by the impurity potential of the doped Co-atoms provides a consistent explanation of all experimental features. Therefore the TC reduction in 3d-metal doped high- temperature superconductors is not caused by Abrikosov Gor'kov pair- breaking but by spatial localization of the carriers. The observed suppression of TC indicates that the system is in the homogenous limit of the superconductor-insulator transition. The coexistance of insulating (dRHOab/dT superconducting ground state is formed out of spatially almost localized carriers.

  11. Development of TiO2 electrical insulation coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x round-wire (United States)

    Kandel, H.; Lu, J.; Jiang, J.; Chen, P.; Matras, M.; Craig, N.; Trociewitz, U. P.; Hellstrom, E. E.; Larbalestier, D. C.


    We have developed TiO2 coating on Ag-alloy sheathed Bi2Sr2CaCu2O8-x (Bi-2212) round-wire conductor for electrical insulation in Bi-2212 magnets. The green coating has a base layer comprised of TiO2, polyvinyl butyral (PVB) and a small amount of polysilicate and a top layer made of polyacrylic. The coating was applied on the conductor using a continuous reel-to-reel dip coating process and showed very good adherence and flexibility that is suitable for magnet coil winding. The thickness of the coating is a function of slurry viscosity, wire withdrawal speed and wire radius. Small test coils were built with the coated Bi-2212 round-wires and were heat treated at 100 atm pressure. During the heat treatment, the PVB and polyacrylic were removed from the green coating and the polysilicate decomposed to SiO2 that served as a sintering aid for TiO2. After the heat treatment, the coating remained strongly adhered to the conductor and did not have a detrimental effect on the critical current (Ic) values. The breakdown voltage was about 150 V across a 7 μm thick heat treated coating on Bi-22112 round-wire conductor, corresponding to a dc dielectric strength of about 21 MV m-1.

  12. Indications of a Quantum Critical Point in Bi2Sr2CaCu2O8+δ Using a Local Kondo Effect (United States)

    Calleja, Eduardo; Dai, Jixia; Arnold, Gerald; Gu, Genda; McElroy, Kyle


    A complete understanding of the complex phase diagrams that are present in high temperature superconductors remains elusive. While there is an overwhelming amount of experimental data on the existence and interplay of the phases present in high Tc superconductors from local probes, much of the existing data only looks at the charge degree of freedom of the material. By substituting Fe atoms for Cu atoms in the CuO plane of Bi2Sr2CaCu2O8+δ (Bi2212), we gain the ability to access the spin degree of freedom since the Fe atoms retain their magnetization below the superconducting transition temperature. This leads to a local Kondo effect which can be observed using Spectroscopic-Imaging Scanning Tunneling Microscopy (SI-STM) and the local Kondo temperature can be extracted from spectra via a theoretical model. We show that the examination of this local Kondo temperature across local and sample average doping leads to the observation of a change in the quasiparticle spin degree of freedom at a quantum critical point (QCP) with a nominal hole doping of roughly 0.22, in agreement with other probes. The observation of the QCP in Bi2212 with this new method to access the spin degree of freedom helps to unravel some of the mystery behind the complex phase diagram of Bi2212.

  13. Citrate sol gel synthesis, phase formation, optical-properties and TEM analysis of nanocrystalline TaSr2SmCu2O8 materials (United States)

    Balamurugan, S.; George, Jincymol; Parthiban, P.


    We report the citrate sol gel (CSG) derived synthesis of nanocrystalline tantalo-cuprate, TaSr2SmCu2O8 (Ta1212Sm) materials and studied the thermal, phase formation, photoluminescence (PL) and photo-catalytic properties and TEM analysis. Like Ta1212Eu phase, the present Ta1212Sm phase is also successfully crystallized in tetragonal symmetry with lattice parameter, a = 0.3875(1) nm and c = 1.1690(5) nm with average crystalline size of ~61.5 nm upon subsequent annealing of the combustion product at 1100°C for 24 h under O2 atmosphere. The room temperature PL emission spectrum of nanocrystalline Ta1212Sm materials exhibits an emission peak at ~605 nm under excitation wavelength of 404 nm. The photo-degradation (~89 %) of methyl orange (MO) by the Ta1212Sm catalyst in the presence of H2O2 is explored. The TEM micro-images reveal that the particles are in nano-scale and irregular morphology.

  14. A new behaviour of ac losses in superconducting Bi(2)Sr(2)CaCu(2)O(8) single crystals. (United States)

    Chockalingam, S P; Sarangi, S; Bhat, S V; Oka, K; Nishihara, Y


    A new ac loss behaviour is observed in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8) single crystals using a novel technique of measuring dissipation at radio frequencies. It is found that the ac loss in the superconducting state is larger than that in the normal state. This counter-intuitive result is explained in terms of the cumulative effect of repetitive decoupling of intrinsic Josephson junctions in the crystals and analysed in the framework of Ambegaokar-Baratoff theory. The ac losses are studied as a function of temperature, rf amplitude and magnetic field applied at different orientations. A peak in ac losses is observed in the superconducting state along the temperature scale. The amplitude of the peak decreases and shifts towards lower temperature with increasing field and also when the field orientation with respect to the c axis of the crystal changes from the perpendicular to parallel direction. The origin of the peak and its behaviour are discussed in the context of coupling energy of Josephson junctions present in the sample. In the presence of a magnetic field another peak in ac losses arises at temperatures close to T(c), which is associated with the Lorentz-force-driven motion of vortices.

  15. Oxygen ordering in the high-T$_c$ superconductor HgBa$_2$CaCu$_2$O$_{6+\\delta}$ as revealed by perturbed angular correlation

    CERN Document Server

    Mendonca, Tania Melo; Haas, Heinz; Odier, Philippe; Tavares, Pedro; Silva, Manuel Ribeiro; Lopes, Armandina; Pereira, Andre; Goncalves, Joao Nuno; Amaral, Joao; Darie, Celine; Araujo, Joao Pedro


    Lattice sites and collective ordering of oxygen atoms in HgBa$_2$CaCu$_2$O$_{6+\\delta}$ were studied using the perturbed angular correlation (PAC) technique at ISOLDE/CERN. The electric field gradients (EFG) at $^{199m}$Hg nuclei have been measured as functions of oxygen doping on the Hg planes, above and below T$_c$. In comparison with the results obtained for oxygen and fluorine doping in Hg-1201, the analysis shows a different oxygen ordering exhibited by Hg-1212. Moreover, for all studied cases, the experimental results show that at a local scale there is non-uniform oxygen distribution. A series of ab initio EFG calculations allowed to infer that at low concentrations, regions without oxygen coexist with regions where O$_{2\\delta}$ dumbbell molecules are located at the center of the Hg mesh. On the other side, at high concentrations, O$_{2\\delta}$ dumbbell molecules coexist with single O$_\\delta$ atoms occupying the center of the Hg mesh. The present results suggest that oxygen sits on the Hg planes in t...

  16. Estimation of critical current distribution in Bi2Sr2CaCu2O x cables and coils using a self-consistent model (United States)

    Liu, Donghui; Xia, Jing; Yong, Huadong; Zhou, Youhe


    Superconducting magnets can generate high magnetic fields. Multi-filamentary Ag-alloy sheathed Bi2Sr2CaCu2O x (Bi-2212) round wire can have a high critical current density in a very high magnetic field. Thus, Bi-2212 has great potential for the development of high-field magnets. For safe and reliable operation of superconducting magnets, it is necessary to estimate the critical current during the design of cables and coils. In this paper, we extend the self-consistent model proposed by Zermeño et al to study the critical current of Bi-2212 cables and coils. First, based on the distribution of Bi-2212 filaments and the experimental test of the critical current of a single strand, the critical currents in cables and coils are calculated. The self-field effect on the critical current is also analyzed. Then, we use an equivalent model to to estimate critical current of large superconducting coils. The equivalent model can effectively estimate the critical current in coils. Using the equivalent model, the results of coils in self-field and high field are compared and discussed. The method and results could be useful for the design of high-field coils.

  17. Angle-resolved photoemission with circularly polarized light in the nodal mirror plane of underdoped Bi2Sr2CaCu2O8+δ superconductor (United States)

    He, Junfeng; Mion, Thomas R.; Gao, Shang; Myers, Gavin T.; Arita, Masashi; Shimada, Kenya; Gu, G. D.; He, Rui-Hua


    Unraveling the nature of pseudogap phase in high-temperature superconductors holds the key to understanding their superconducting mechanisms and potentially broadening their applications via enhancement of their superconducting transition temperatures. Angle-resolved photoemission spectroscopy (ARPES) experiments using circularly polarized light have been proposed to detect possible symmetry breaking state in the pseudogap phase of cuprates. The presence (absence) of an electronic order which breaks mirror symmetry of the crystal would in principle induce a finite (zero) circular dichroism in photoemission. Different orders breaking reflection symmetries about different mirror planes can also be distinguished by the momentum dependence of the measured circular dichroism. Here, we report ARPES experiment on an underdoped Bi2Sr2CaCu2O8+δ (Bi2212) superconductor in the Γ (0,0)-Y (π,π) nodal mirror plane using circularly polarized light. No circular dichroism is observed on the level of ˜2% at low temperature, which places a clear constraint on the forms of possible symmetry breaking orders in this sample. Meanwhile, we find that the geometric dichroism remains substantial very close to its perfect extinction such that a very small sample angular offset is sufficient to induce a sizeable dichroic signal. It highlights the importance to establish a perfect extinction of geometric dichroism as a prerequisite for the identification of any intrinsic circular dichroism in this material.

  18. Hot Spot and THz Wave Generation in Bi2Sr2CaCu2O8 Intrinsic Josephson Junction Stacks (United States)

    Kleiner, Reinhold


    Stacks of intrinsic Josephson junctions made of the high temperature superconductor Bi2Sr2CaCu2O8 have been shown to emit coherent radiation at THz frequencies. Emission is observed both in a low bias regime and a high bias regime. While at low bias the temperature of the stack is close to the bath temperature, at high bias a hot spot and a standing wave, formed in the ``cold'' part of the stack, coexist. THz radiation is very stable in this regime, exhibiting a linewidth which is much smaller than expected from a purely cavity-induced synchronization mechanism. We investigate the interaction of hot spots and THz waves using a combination of transport measurement, direct electromagnetic wave detection and low temperature scanning laser microscopy (LTSLM). In this talk recent developments will be presented, with a focus on the mechanism of hot spot formation. In collaboration with B. Gross, S. Guénon, M. Y. Li, J. Yuan, N. Kinev, J. Li, A. Ishii, K. Hirata, T. Hatano, R. G. Mints, D. Koelle, V. P. Koshelets, H. B. Wang and P. H. Wu.

  19. High, magnetic-field-insensitive transport critical currents in unoriented polycrystalline thin films of Tl 2CaBa 2Cu 2O y (United States)

    Kwak, J. F.; Venturini, E. L.; Baughman, R. J.; Morosin, B.; Ginley, D. S.


    We report critical current measurements for unoriented polycrystalline films of Tl 2CaBa 2Cu 2O y. At 77 K these films show critical current densities ranging from 10 000 to 110 000 A/cm 2, with a median value of 50 000 A/cm 2. Moreover, the best films' critical currents at 77 K drop less than 50% in an applied magnetic field of 1 T, and less than a factor of 20 at 6 T. At 4 K, critical current densities over 10 6A/cm 2 with less than 15% drop at 6 T have been obtained. The zero-field temperature dependence of the critical current from 4 to 95 K is well described as quadratic. High-field magnetization loops on the films at 76 K show a striking collapse in hysteresis below 0.6 T. Our results indicate that, although the grains in these films are Josephson-coupled, the strength of the coupling is greatly improved over other high- Tc granular systems.

  20. Sensitivity of cuprous azide towards heat and impact

    Directory of Open Access Journals (Sweden)

    Kartar Singh


    Full Text Available "Rates of thermal decomposition of azide at six different temperatures have been measured. The sigmoid shapes of the curves representing increase in pressure with time suggest that a given temperature a fixed number of nuclei are formed at the end of the induction period. The nuclei increase in size in three dimensions. The radius of any nucleus at any instant (tis directly proportional to (t-t/Sub/owhere t/Sub/o is the induction period. The activation energy involved in thermal has been found decomposition to be 26.5K calories. It is suggested that this activation energy corresponds to the energy required for thermal transition of an electron 3 d band to the Fermi level of the metallic copper nuclei. The impact sensitivity and induction period necessary for explosion at various temperatures for crystalline and precipitated samples of cuprous azide have been measured. The results indicate that cuprous azide is more sensitive towards heat and impact than lead azide. The impact sensitivity of cuprous azide is found to increase in crystal size."

  1. Interlayer coupling and the metal-insulator transition in Pr-substituted Bi2Sr2CaCu2O8+y (United States)

    Quitmann, C.; Beschoten, B.; Kelley, R. J.; Güntherodt, G.; Onellion, M.


    Substitution of rare-earth ions for Ca in Bi2Sr2CaCu2O8+y is known to cause a metal-insulator transition. Using resonant photoemission we study how this chemical substitution affects the electronic structure of the material. For the partial Cu density of states at EF and in the region of the valence band we observe no significant difference between a pure superconducting and an insulating sample with 60% Pr for Ca substitution. This suggests that the states responsible for superconducting are predominantly O states. The Pr 4f partial density of states was extracted utilizing the super-Coster-Kronig Pr 4d-4f resonance. It consists of a single peak at 1.36 eV binding energy. The peak shows a strongly asymmetric Doniach-Šunjic line shape indicating the presence of a band of electronic states with a cutoff at EF even in this insulating sample. This finding excludes a band gap in the insulating sample and supports the existence of a mobility gap caused by spatial localization of the carriers. The presence of such carriers at the Pr site between the CuO2 planes shows that the electronic structure is not purely two dimensional but that there is finite interlayer coupling. The resonance enhancement of the photoemission cross section at the Pr 4d threshold was studied for the Pr 4f and for Cu states. Both the Pr 4f and the Cu states show a Fano-like resonance. This resonance of Cu states with Pr states is another indication of coupling between the Pr states and those in the CuO2 plane. Because of the statistical distribution of the Pr ions this coupling leads to a nonperiodic potential for the states in the CuO2 planes which can lead to localization and thus to the observed metal-insulator transition.

  2. Electrical potential distribution in terahertz-emitting rectangular mesa devices of high- T c superconducting Bi2Sr2CaCu2O{}_{8+\\delta } (United States)

    Watanabe, Chiharu; Minami, Hidetoshi; Kitamura, Takeo; Saiwai, Yoshihiko; Shibano, Yuki; Katsuragawa, Takuya; Kubo, Hiroyuki; Sakamoto, Kazuki; Kashiwagi, Takanari; Klemm, Richard A.; Kadowaki, Kazuo


    Excessive Joule heating of conventional rectangular mesa devices of the high-transition-temperature {T}{{c}} superconductor Bi2Sr2CaCu2O{}8+δ leads to hot spots, in which the local temperature T({\\boldsymbol{r}})\\gt {T}{{c}}. Similar devices without hot spots are known to obey the ac-Josephson relation, emitting sub-terahertz (THz) waves at frequencies f\\propto V/N, where V is the applied dc voltage or electrostatic potential and N is the number of active junctions in the device. However, it often has been difficult to predict the emission f from the applied V for two reasons: N is generally unknown and therefore has been assumed to be a fitting parameter, and especially when hot spots are present, V could develop a spatial dependence that cannot be accurately determined using two-terminal measurements. To clarify the situation, simultaneous SiC microcrystalline photoluminescence measurements of T({\\boldsymbol{r}}), Fourier-transform infrared (FTIR) measurements of f, and both two and four-terminal measurements of the local V({\\boldsymbol{r}}) were performed. The present four-probe measurements provide strong evidence that when a constant V is measured within the device's superconducting region outside of the hot spot, the only requirement for the accuracy of the ac-Josephson relation is the ubiquitous adjustment of the fitting parameter N. The four-probe measurements demonstrate that the electric potential distribution is strongly non-uniform near to the hot spot, but is essentially uniform sufficiently far from it. As expected, the emission frequency follows the ac-Josephson relation correctly even for low bath temperatures at which the system jumps to inner IV characteristic branches with smaller N values, reconfirming the ac-Josephson effect as the primary mechanism for the sub-THz emission.

  3. Understanding the densification process of Bi2Sr2CaCu2O x round wires with overpressure processing and its effect on critical current density (United States)

    Matras, M. R.; Jiang, J.; Larbalestier, D. C.; Hellstrom, E. E.


    Overpressure (OP) processing increases the critical current density ({{\\boldsymbol{J}}}{{C}}) of Bi2Sr2CaCu2O x (2212) round wires by shrinking the surrounding Ag matrix around the 2212 filaments, driving them close to full density and greatly increasing the 2212 grain connectivity. Indeed densification is vital for attaining the highest {{\\boldsymbol{J}}}{{C}}. Here, we investigate the time and temperature dependence of the wire densification. We find that the wire diameter decreases by 3.8 ± 0.3% after full heat treatment at 50 atm and 100 atm OP. At 50 atm OP pressure, the filaments start densifying above 700 °C and reach a 3.30 ± 0.07% smaller diameter after 2 h at 820 °C, which is below the melting point of 2212 powder. The densification is homogeneous and does not change the filament shape before melting. The growth of non-superconducting phases is observed at 820 °C, suggesting that time should be minimized at high temperature prior to melting the 2212 powder. Study of an open-ended 2.2 m long wire sample shows that full densification and the high OP {{\\boldsymbol{J}}}{{C}} ({{\\boldsymbol{J}}}{{C}} varies by about 3.1 times over the 2.2 m long wire) is reached about 1 m from the open ends, thus showing that coil-length wires can be protected from leaky seals by adding at least 1 m of sacrificial wire at each end.

  4. On the magnetization relaxation of ring-shaped Tl 2Ba 2CaCu 2O 8 thin films as determined by superconducting quantum interference device measurements (United States)

    Wen, Hai-hu; Ziemann, Paul; Radovan, Henri A.; Herzog, Thomas


    By using a superconducting quantum interference device (SQUID), the temporal relaxation of the magnetization was determined for ring-shaped Tl 2Ba 2CaCu 2O 8 thin films at various temperatures between 10 K and 80 K in magnetic fields ranging from 2 mT to 0.3 T. Based on these data, a detailed analysis has been performed related to the following methods or models: (1) Fitting the data to the thermally activated flux motion and collective pinning model; (2) Applying the Generalized Inversion Scheme to extract the temperature dependence of the unrelaxed critical current density jc( T) and pinning potential Uc( T); (3) Testing a modified Maley's method to obtain the current dependent activation energy for flux motion; (4) 2D vortex glass scaling. It is found that, for low fields (2 mT, 10 mT, 40 mT) the experimental data can be described by an elastic flux motion, most probably due to 3D single vortex creep. At higher fields (0.1 T, 0.2 T, 0.3 T), the observed behavior can be interpreted in terms of plastic flux motion which is probably governed by dislocation mediated flux creep. These high field data can also be consistently described by the 2D vortex glass scaling with scaling parameters ν2D, T0 and p being consistent with those derived from corresponding transport measurement. Also, results are presented demonstrating the importance of optimizing the scan length of the sample in a moving sample SQUID magnetometer to avoid artifacts.

  5. Highly stable copper oxide composite as an effective photocathode for water splitting via a facile electrochemical synthesis strategy

    KAUST Repository

    Zhang, Zhonghai


    Hydrogen generation through photoelectrochemical (PEC) water splitting using solar light as an energy resource is believed to be a clean and efficient way to overcome the global energy and environmental problems. Extensive research effort has been focused on n-type metal oxide semiconductors as photoanodes, whereas studies of p-type metal oxide semiconductors as photocathodes where hydrogen is generated are scarce. In this paper, highly efficient and stable copper oxide composite photocathode materials were successfully fabricated by a facile two-step electrochemical strategy, which consists of electrodeposition of a Cu film on an ITO glass substrate followed by anodization of the Cu film under a suitable current density and then calcination to form a Cu 2O/CuO composite. The synthesized Cu 2O/CuO composite was composed of a thin layer of Cu 2O with a thin film of CuO on its top as a protecting coating. The rational control of chemical composition and crystalline orientation of the composite materials was easily achieved by varying the electrochemical parameters, including electrodeposition potential and anodization current density, to achieve an enhanced PEC performance. The best photocathode material among all materials prepared was the Cu 2O/CuO composite with Cu 2O in (220) orientation, which showed a highly stable photocurrent of -1.54 mA cm -2 at a potential of 0 V vs reversible hydrogen electrode at a mild pH under illumination of AM 1.5G. This photocurrent density was more than 2 times that generated by the bare Cu 2O electrode (-0.65 mAcm -2) and the stability was considerably enhanced to 74.4% from 30.1% on the bare Cu 2O electrode. The results of this study showed that the top layer of CuO in the Cu 2O/CuO composite not only minimized the Cu 2O photocorrosion but also served as a recombination inhibitor for the photogenerated electrons and holes from Cu 2O, which collectively explained much enhanced stability and PEC activity of the Cu 2O/CuO composite

  6. Process the Experimental Data of Time-resolved Photoluminescence Lifetime Spectra on Cu2 O Nanowires by Origin%用Origin拟合Cu2 O纳米线时间分辨荧光光谱寿命

    Institute of Scientific and Technical Information of China (English)



    The time-resolved photoluminescence spectra of synthesized Cu2 O nanowires are fitted by the func-tion of exponential decay in Origin. The time-resolved photoluminescence lifetimes of the Cu2 O nanowires are obtained in the temperature region of 77-300 K.%基于用Origin软件的指数衰减拟合函数对制备得到的Cu2 O纳米线的时间分辨荧光光谱进行拟合,得到了Cu2 O纳米线在77-300 K温度范围内的瞬态荧光寿命值。

  7. The effect of the thickness of tunneling layer on the memory properties of (Cu2O)0.5(Al2O3)0.5 high-k composite charge-trapping memory devices (United States)

    Liu, Jinqiu; Lu, Jianxin; Yin, Jiang; Xu, Bo; Xia, Yidong; Liu, Zhiguo


    The charge-trapping memory devices namely Pt/Al2O3/(Al2O3)0.5(Cu2O)0.5/SiO2/p-Si with 2, 3 and 4 nm SiO2 tunneling layers were fabricated by using RF magnetron sputtering and atomic layer deposition techniques. At an applied voltage of ±11 V, the memory windows in the C-V curves of the memory devices with 2, 3 and 4 nm SiO2 tunneling layers were about 4.18, 9.91 and 11.33 V, respectively. The anomaly in memory properties among the three memory devices was ascribed to the different back tunneling probabilities of trapped electrons in the charge-trapping dielectric (Al2O3)0.5(Cu2O)0.5 due to the different thicknesses of SiO2 tunneling layer.

  8. ab-plane optical spectra of iodine-intercalated Bi1.9Pb0.1Sr2CaCu2O8+δ: Normal and superconducting properties (United States)

    Liu, H. L.; Tanner, D. B.; Berger, H.; Margaritondo, G.


    We report on the ab-plane optical reflectance of an iodine-intercalated Bi1.9Pb0.1Sr2CaCu2O8+δ single crystal in the 80-40 000 cm-1 (10 meV-5 eV) frequency range and at temperatures between 10 and 300 K. As compared to the iodine-free Bi2Sr2CaCu2O8+δ, we find that the visible-ultraviolet interband transitions are strongly modified after intercalation. Estimates of the low-frequency spectral weight indicate that there is an increase of hole concentration in the CuO2 planes. This behavior is a consequence of charge transfer between intercalated iodine atoms and the CuO2 sheets leading to an ionized iodine species. The ab-plane optical conductivity is analyzed in both the one-component and the two-component pictures, suggesting that the intercalated iodine does not have any significant effect on the in-plane scattering rate. In the superconducting state, a sum-rule evaluation finds that the superfluid contains about 25% of the total doping-induced, or nearly 86% of the free-carrier oscillator strength in the normal state. The value of the superconducting penetration depth is estimated to be 1980 Å, slightly larger than the 1860 Å found in iodine-free Bi2Sr2CaCu2O8+δ.

  9. New Reaction Routes for Preparing Single-Phase Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10 Powders from Stoichiometric Mixtures (United States)

    Wu, Nae-Lih; Lee, Sern-Nan; Yao, Yeong Der


    Single-phase Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10 powders were prepared from stoichiometric mixtures by the following two reactions: (1) CaBa2CuO4+Tl2O3+CuO→Tl2CaBa2Cu2O8 and (2) Tl2CaBa2Cu2O8+CaO+CuO→Tl2Ca2Ba2Cu3O10. Single-phase powders were obtained at 830°C for the first reaction, and at 870°C for the second reaction. At these temperatures, the extent of powder melting and the rate of Tl loss were small. Powders thus prepared showed superconducting temperatures (both the zero-resistivity and diamagnetic onset temperatures) of above 110 K and a saturation Meissner effect of 20% of (-1/4π) at a field of 20 G.

  10. Synthesis of silanes containing poly (ethylene glycol ) and their modification to nano-Cu2O surface%含PEG硅烷的合成及其对纳米氧化亚铜的表面修饰

    Institute of Scientific and Technical Information of China (English)

    刘明光; 余红伟; 晏欣; 朱金华; 王源升


    使用甲苯二异氰酸酯、3-氨基丙基三乙氧基硅烷和聚乙二醇制备了聚合物硅烷 ,对其进行了表征并利用所合成的聚合物硅烷对纳米氧化亚铜(nano-Cu2O)表面进行了修饰.测试结果表明 :自制硅烷可接枝到氧化亚铜纳米粒子表面 ,并能有效抑制纳米粒子的团聚 ;随着硅烷添加量的增加 ,纳米氧化亚铜与水的接触角逐渐减小 ;改性以后的产物分散性有了显著的改善 ,相比于未改性的样品 ,其吸光度都有了不同程度的增加 ,并且在不同极性的溶剂中 ,其分散性能随硅烷用量的改变而不同.%The silanes containing poly (ethylene glycol) (PEG) units are synthesized by the reactions of toluene diisocyanate with 3-aminopropyltriethoxysilane and PEG .The silanes are used to modify the surface of nano-Cu2O .The results of FTIR show that nano-Cu2O modified by PEG-silane can ef-fectively restrain the agglomeration of the nanoparticles .The results of contact angle measurements show that along with the increase of adding silane ,the contact angle decreases ;the dispersive proper-ties of nano-Cu2O are investigated with the spectrophotometer and transmission electron microscope . The experimental results indicate that the addition of silane can significantly improve the dispersibility of nano-Cu2O ,and the dispersibility varies with the amount of silane in different polar solvents .

  11. The electrical and magnetic properties of ferromagnetic-superconducting compound Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ

    Directory of Open Access Journals (Sweden)

    A Khajehnezhad


    Full Text Available   Coexistence of superconductivity and magnetic ordering or their mutually exclusive existence in solids is one of the fundamental problems of solid state physics. To determine the effect of Pr substitution for Gd on electrical and magnetic properties of RuGd1.5Ce0.5Sr2Cu2O10-δ (Ru-1222, Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ with x=0.0, 0.01, 0.03, 0.03 3 , 0.04, 0.05, 0.06, 0.1 have been prepared by the standard solid-state reaction technique. The XRD patterns for various x have been obtained to show their phase purity. The resistivity and magnetoresistivity of samples have been measured at various temperatures and different magnetic fields up to 1.5T . Superconductivity and magnetic parameters such as superconducting transition temperature Tc and magnetic transition Tirr, have been obtained through resistivity curves. The sharp decrease in Tc with x in Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ shows competition between pair breaking by magnetic impurity, hole doping because of different valance of ions, difference in ionic radii and oxygen stoichiometry, which affect on superconducting transition. In Pr substitution for Gd, the small difference between Gd3+ and Pr3+,4+ ionic radii decreases the mean Ru-Ru distance, and as a result, the magnetic exchange interaction can become stronger with increasing x. Both Tc and Tirr decrease with external magnetic field .

  12. Ag掺杂Cu2O薄膜的制备及光催化性能研究%The Preparation and Photocatalytic Performance of Ag-Doped Cu2 O film

    Institute of Scientific and Technical Information of China (English)

    刘一鸣; 温婧; 王红霞


    Ag‐doped Cu2 O thin films were prepared by magnetron sputtering method .X‐ray diffractometry (XRD) ,scanning electron microscopy (SEM ) ,X‐ray photoelectric spectroscopy (XPS) and fluorescence spectrometry (FLO) were used to charactevize the crystal structure ,sur‐face morphology and properties ,and catalytic performance of the films .Studies show that Ag‐doped Cu2O films had higher catalytic activity than pure Cu2O films ,which is attributed to the de‐crease of particle size ,the increase in surface roughness ,and the decreased recombination of light‐induced electrons and holes by Ag‐doping .%通过磁控溅射方法制备了Ag掺杂Cu2 O纳米薄膜。用X射线衍射仪(XRD)、扫描电子显微镜(SEM )、X射线光电能谱(XPS)和荧光光谱仪(FLO)对薄膜的晶体结构、表面形貌、表面性能和光催化性能进行了分析。研究表明,Ag的掺杂使得Cu2 O薄膜表面粗糙度增加、光生电子和空穴的复合率降低,并且可见光催化活性明显提高;在光照120 min后,降解率达到了50%以上;Ag掺杂也了改进了薄膜的稳定性和可重复性。

  13. X-ray diffraction measurements of the c-axis Debye-Waller factors of YBa2Cu3O7 and HgBa2CaCu2O6



    We report the first application of x-rays to the measurement of the temperature dependent Bragg peak intensities to obtain Debye-Waller factors on high-temperature superconductors. Intensities of (0,0,l) peaks of YBa2Cu3O7 and HgBa2CaCu2O6 thin films are measured to obtain the c-axis Debye-Waller factors. While lattice constant and some Debye-Waller factor measurements on high Tc superconductors show anomalies at the transition temperature, our measurements by x-ray diffraction show a smooth ...

  14. Nodal and nodeless gap in proximity-induced superconductivity: Application to monolayer CuO2 on a Bi2Sr2CaCu2O8 +δ substrate (United States)

    Wang, Yimeng; Wang, Zhen-Hua; Chen, Wei-Qiang


    We present a detailed analysis on the hopping between monolayer CuO2 and bulk CuO2 plane in the Bi2Sr2CaCu2O8 +δ substrate. With a two-band model, we demonstrate that the nodeless gap can only exist when the hole concentration in the monolayer CuO2 plane is very large. We argue that the possible phase separation may play an important role in the recent experimental observation of a nodeless gap.

  15. Circular dichroism in the angle-resolved photoemission spectrum of the high-temperature Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} superconductor: can these measurements be interpreted as evidence for time-reversal symmetry breaking? (United States)

    Arpiainen, V; Bansil, A; Lindroos, M


    We report first-principles computations of the angle-resolved photoemission response with circularly polarized light in Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} for the purpose of delineating contributions to the circular dichroism resulting from distortions and modulations of the crystal lattice. Comparison with available experimental results shows that the measured circular dichroism from antinodal mirror planes is reproduced in quantitative detail in calculations employing the average orthorhombic crystal structure. We thus conclude that the existing angle-resolved photoemission measurements can be understood essentially within the framework of the conventional picture, without the need to invoke unconventional mechanisms.

  16. Muon-spin rotation measurements of an unusual vortex-glass phase in the layered superconductor Bi2.15Sr1.85CaCu2O8+δ. (United States)

    Heron, D O G; Ray, S J; Lister, S J; Aegerter, C M; Keller, H; Kes, P H; Menon, G I; Lee, S L


    Muon-spin rotation measurements, performed on the mixed state of the classic anisotropic superconductor Bi(2.15)Sr(1.85)CaCu(2)O(8+δ), obtain quantities directly related to two- and three-body correlations of vortices in space. A novel phase diagram emerges from such local probe measurements of the bulk, revealing an unusual glassy state at intermediate fields which appears to freeze continuously from the equilibrium vortex liquid but differs both from the lattice and the conventional high-field vortex glass state in its structure.

  17. Paracoherence studies in Tl 2CaBa 2Cu 2O 8,CaLaBaCu 3O 7-y and CaSmBaCu 3O 7-y (United States)

    Krishnan, H.; Sankaranarayanan, V.; Srinivasan, R.


    In ceramic superconductors, where the intergrain coupling is weak, the phase transition at T co corresponds to the temperature at which phase coherence occurs in all the grains. The region between T m, the mid point of the superconducting transition, and T co, the temperature at which the resistivity goes to zero, is called the paracofioerence region. The resistivity behaviour of single phase Tl 2CaBa 2Cu 2O 8, CaLaBaCu 3O 7-y and CaSmBaCu 3O 7-y has been studied in the above region and the results indicate that the excess conductivity varies as (T - T co) -γ.

  18. Ordering in Tl 2CaBa 2Cu 2O 8 and Tl 2Ba 2CuO 6 studied by pair distribution function and rietveld analysis (United States)

    Toby, B. H.; Dmowski, W.; Egami, T.; Jorgensen, J. D.; Subramanian, M. A.; Gopalakrishnan, J.; Sleight, A. W.; Parise, J. B.


    Rietveld analysis indicates that the only long-range structural variation in Tl 2CaBa 2Cu 2O 8 with temperature is a shift of O(2) away from Cu and toward Ba with increasing T. Atomic pair distribution function analysis on two samples of Tl 2Ba 2CuO 6, one superconducting, the other not, shows substantial differences in their short range structure, but similar medium range structures, while Rietveld analysis shows very similar lattice constants and long-range structures.


    Institute of Scientific and Technical Information of China (English)

    张炳森; 李茂林; 王晶晶; 孙本哲; 祁阳


    在BiO-(Sr+Ca)O-CuO相图上的Bi2Sr2CaCu2O8+6(Bi-2212)相附近选择不同成分,用分子束外延法制备成薄膜,利用XRD,EDS,SEM和AFM研究了成分,衬底温度和臭氧分压对Bi-2212相薄膜成相的影响,分析了生长速率和错配度对Bi-2212相薄膜质量的影响.结果表明,Bi-2212相薄膜单相生成的成分范围(原子分数)分别为Bi 26.3%-32.4%,(Sr+Ca) 37.4%-146.5%,Cu 24.8%-32.6%;当衬底温度为720℃且臭氧分压为1.3×10-3 Pa时,在MgO(100)衬底上生长出质量较高的c轴外延Bi-2212相薄膜;通过调整生长速率、更换衬底和插入不同厚度的Bi2Sr2CuO(6+δ)过渡层的方法,可以改善Bi-2212相薄膜的结晶质量.表面形貌和导电特性.

  20. Optimization of parameters for the synthesis of Y2Cu2O5 nanoparticles by Taguchi method and comparison of their magnetic and optical properties with their bulk counterpart (United States)

    Farbod, Mansoor; Rafati, Zahra; Shoushtari, Morteza Zargar


    Y2Cu2O5 nanoparticles were synthesized by sol-gel combustion method and effects of different factors on the size of nanoparticles were investigated. In order to reduce the experimental stages, Taguchi robust design method was employed. Acid citric:Cu+2 M ratio, pH, sintering temperature and time were chosen as the parameters for optimization. Among these factors the solution pH had the most influence and the others had nearly the same influence on the nanoparticles sizes. Based on the predicted conditions by Taguchi design, the sample with a minimum particle size of 47 nm was prepared. The magnetic behavior of Y2Cu2O5 nanoparticles were measured and found that at low fields they are soft ferromagnetic but at high fields they behave paramagnetically. The magnetic behavior of nanoparticles were compared to their bulk counterparts and found that the Mr of the samples was slightly different, but the Hc of the nanoparticles was 76% of the bulk sample. The maximum absorbance peak of UV-vis spectrum showed a blue shift for the smaller particles.

  1. Short-range effect at the semi-coherent metal/its native oxide interface (United States)

    Yin, Deqiang; Wu, Mingxia; Cen, Wanglai; Li, Hongping; Yang, Yi; Fang, Hui


    Fundamentally understanding the variations of atomistic and electronic properties at the interface of metal/its native oxide systems plays a critical role in many important technological processes and applications, such as oxidization, corrosion, chemical catalysis, fuel reactions, and thin-film process. Here, we have adopted the representatively semi-coherent Cu2O(111)/Cu(100) interface and demonstrated, by first-principles calculations on energetic and electronic structures of a total 9 candidate interfacial models, that the preferred geometries (i.e., that having the largest adhesion energy) are those possess the shortest interfacial distance between O terminated Cu2O and substrate Cu. Using several analytic methods, we have thoroughly characterized the variation of electronic states from the interface to Cu2O constituent, and determined that the large degree of charge accumulation at the interface is at the expense of depletion of charge in both substrate Cu and neighboring Cu (Cu2O) to the interfacial O atoms. Strikingly, in Cu2O the conducting states appear only in monolayer proximal to Cu2O/Cu interface, as well, the second layer remains in semi-conducting state as its bulk, indicating a short-range effect in electronic properties induced by Cu substrate. The theoretical calculations provide insight into the complex electronic properties of the functional Cu2O/Cu interface, which was quite difficult to observe by experimental methods alone. The unique properties are of practical importance for further understanding and improvement of such a promising class of metal/native oxide interface at the atomic scale.

  2. N掺杂Cu_2O薄膜的光学性质及第一性原理分析%Optical properties of N-doped Cu_2O films and relevant analysis with first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    濮春英; 李洪婧; 唐鑫; 张庆瑜


    N-doped Cu_2O films are deposited at different temperatures by sputtering a CuO target in the mixture of Ar and N2.By the analysis of transmission spectra,it is found that the N-doped Cu_2O films are changed into a direct allowed band-gap semiconductor and the optical band gap energy is enlarged to 2.52±0.03 eV for the films deposited at different temperatures.The first-principles calculations indicate that the energy band gap increase by 25%,which is in good agreement with the experimental result.The change from a direct forbidden band-gap transition to a direct allowed band-gap transition can be attributed to the occupation of 2p electrons of N at the top of valence band in the N-doped Cu_2O film.%采用射频磁控溅射技术,在不同温度下制备了N掺杂Cu_2O薄膜.透射光谱分析发现,N掺杂导致Cu_2O成为允许的带隙直接跃迁半导体,并使Cu_2O的光学禁带宽度增加.不同温度下沉积的薄膜光学禁带宽度E_g=2.52±0.03 eV.第一性原理计算表明,N掺杂导致Cu_2O的禁带宽度增加了约25%,主要与价带顶下移和导带底上移有关,与实验报道基本符合.N的2p电子态分布不同于O原子,在价带顶附近具有较大的态密度是N掺杂Cu_2O变成允许的带隙直接跃迁半导体的根本原因.

  3. Spectral investigation of hot-spot and cavity resonance effects on the terahertz radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ single crystal mesa structures (United States)

    Kadowaki, Kazuo; Watanabe, Chiharu; Minami, Hidetoshi; Yamamoto, Takashi; Kashiwagi, Takanari; Klemm, Richard


    Terahertz (THz) electromagnetic radiation emitted from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures in the case of single mesa and series-connected mesas is investigated by the FTIR spectroscopic technique while observing its temperature distribution simultaneously by a SiC photoluminescence technique. Changing the bias level, sudden jumps of the hot-spot position were clearly observed. Although the radiation intensity changes drastically associated with the jump of the hot spot position, the frequency is unaffected as long as the voltage per junction is kept constant. Since the frequency of the intense radiation satisfies the cavity resonance condition, we confirmed that the cavity resonance is of primarily importance for the synchronization of whole intrinsic Josephson junctions in the mesa for high power radiation. This work was supported in part by the Grant-in-Aid for challenging Exploratory Research, the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

  4. Metal-organic deposition of YBa2Cu3O and Bi2Sr2Ca1Cu2O films on various substrates starting from different fluorine-free metallorganic compounds

    Indian Academy of Sciences (India)

    Paola Benzi; Elena Bottizzo; Chiara Demaria; Nicoletta Rizzi


    YBa2Cu3O (Y-123 ) and Bi2Sr2Ca1Cu2O (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature (c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

  5. Nanoscale coherent intergrowthlike defects in a crystal of La1.9Ca1.1Cu2O6 +δ made superconducting by high-pressure oxygen annealing (United States)

    Hu, Hefei; Zhu, Yimei; Shi, Xiaoya; Li, Qiang; Zhong, Ruidan; Schneeloch, John A.; Gu, Genda; Tranquada, John M.; Billinge, Simon J. L.


    Superconductivity with Tc=53.5 K has been induced in a large La1.9Ca1.1Cu2O6 (La-2126) single crystal by annealing in a high partial pressure of oxygen at 1200 °C. Using transmission electron microscopy techniques, we show that a secondary Ca-doped La2CuO4 (La-214) phase, not present in the as-grown crystal, appears as a coherent intergrowthlike defect as a consequence of the annealing. A corresponding secondary superconducting transition near 13 K is evident in the magnetization measurement. Electron energy-loss spectroscopy reveals a pre-edge peak at the O-K edge in the superconducting La-2126 phase, which is absent in the as-grown crystal, confirming the hole doping by interstitial oxygen.

  6. Bond stretching phonon softening and angle-resolved photoemission kinks in optimally doped Bi2Sr1:6La0:4Cu2O6+sigma superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Jeff; d& #39; Astuto, M.; Jozwiak, C.; Garcia, D.R.; Saini, N.L.; Krisch, M.; Ikeuchi, K.; Baron, A.Q.R.; Eisaki, H.; Lanzara, Alessandra


    We report the first measurement of the Cu-O bond stretching phonon dispersion in optimally doped Bi2Sr1.6La0.4Cu2O6+delta using inelastic x-ray scattering. We found a softening of this phonon at q=(0.25,0,0) from 76 to 60 meV, similar to the one reported in other cuprates. A comparison with angle-resolved photoemission data on the same sample revealed an excellent agreement in terms of energy and momentum between the angle-resolved photoemission nodal kink and the soft part of the bond stretching phonon. Indeed, we find that the momentum space where a 63+-5 meV kink is observed can be connected with a vector q=(xi,0,0) with xi>= 0.22, corresponding exactly to the soft part of the bond stretching phonon.

  7. A variable field neutron study of the negative magnetoresistive ruthenocuprate RuSr 2Nd 0.9Y 0.2Ce 0.9Cu 2O 10-δ (United States)

    Mclaughlin, A. C.; Attfield, J. P.


    A variable field neutron diffraction study of the ruthenocuprate RuSr 2Nd 0.9Y 0.2Ce 0.9Cu 2O 10-δ, which exhibits large negative magnetoresistance, has been performed in order to determine the variation of the magnetic structure with magnetic field. Upon application of a magnetic field the ({1}/{2} {1}/{2} {1}/{2}) and ({1}/{2} {1}/{2} l) magnetic peaks reduce in intensity as the spins in the RuO 2 and CuO 2 layer cant into a ferromagnetic alignment in the ab-plane. This results in increased spin polarised transport in the CuO 2 plane and hence large negative magnetoresistance.

  8. High-energy magnetic excitations in the cuprate superconductor Bi(2)Sr(2)CaCu(2)O(8+δ): towards a unified description of its electronic and magnetic degrees of freedom. (United States)

    Dean, M P M; James, A J A; Springell, R S; Liu, X; Monney, C; Zhou, K J; Konik, R M; Wen, J S; Xu, Z J; Gu, G D; Strocov, V N; Schmitt, T; Hill, J P


    We investigate the high-energy magnetic excitation spectrum of the high-T(c) cuprate superconductor Bi(2)Sr(2)CaCu(2)O(8+δ) (Bi-2212) using Cu L(3) edge resonant inelastic x-ray scattering. Broad, dispersive magnetic excitations are observed, with a zone boundary energy of ∼ 300 meV and a weak dependence on doping. These excitations are strikingly similar to the bosons proposed to explain the high-energy "kink" observed in photoemission. A phenomenological calculation of the spin response, based on a parametrization of the the angle-resolved photoemission spectroscopy derived electronic structure and Yang-Rice-Zhang quasiparticles, provides a reasonable prediction of the energy dispersion of the observed magnetic excitations. These results indicate a possible unified framework to reconcile the magnetic and electronic properties of the cuprates and we discuss the advantages and disadvantages of such an approach.

  9. Evidence for a pseudogap in underdoped Bi{2}Sr_{2}CaCu{2}O{8+delta} and YBa2Cu3O6.50 from in-plane optical conductivity measurements. (United States)

    Hwang, J; Carbotte, J P; Timusk, T


    The real part of the in-plane optical self-energy data in underdoped Bi_{2}Sr_{2}CaCu_{2}O_{8+delta} (Bi-2212) and ortho II YBa2Cu3O6.5 contains new and important information on the pseudogap. Using a theoretical model approach, a major new finding is that states lost below the pseudogap Delta_{pg} are accompanied by a pileup of states just above this energy. The pileup along with a sharp mode in the bosonic spectral function leads to an unusually rapid increase in the optical scattering rate as a function of frequency and a characteristically sloped peak in the real part of the optical self-energy. These features are not found in optimally doped and overdoped samples and represent the clearest signature so far in the in-plane optical conductivity of the opening of a pseudogap.

  10. C-axis Josephson plasma resonance observed in Tl(2)Ba(2)CaCu(2)O(8) superconducting thin films by use of terahertz time-domain spectroscopy. (United States)

    Thorsmølle, V K; Averitt, R D; Maley, M P; Bulaevskii, L N; Helm, C; Taylor, A J


    We have unambiguously observed the c -axis Josephson plasma resonance (JPR) in high-critical-temperature (T(c)) cuprate (Tl(2)Ba(2)CaCu(2)O(8)) superconducting thin films, employing terahertz time-domain spectroscopy in transmission as a function of temperature in zero magnetic field. These are believed to be the first measurements of the JPR temperature dependence of a high-T(c) material in transmission. With increasing temperature, the JPR shifts from 705 GHz at 10 K to ~170 GHz at 98 K, corresponding to an increase in c-axis penetration depth from 22.4+/-0.6mum to 94+/-9mum . The linewidth of the JPR peak increases with temperature, which indicates an increase in the quasi-particle scattering rate. We have probed the onset of the c -axis phase coherence to ~0.95T(c) . The JPR vanishes above T(c) as expected.

  11. Photogenerated carriers in La 2CuO 4, YBa 2Cu 3O 7-δ, and Tl 2Ba 2Ca (1-x)Gd xCu 2O 8: Polarizability-induced pairing of polarons (United States)

    Foster, C. M.; Heeger, A. J.; Kim, Y. H.; Stucky, G.; Herron, N.


    Photoinduced absorption measurements have been carried out on Tl 2Ba 2Ca (1-x)Gd xCu 2O 8 (x=0.02), YBa 2Cu 3O 7-δ (δ=0.75) and La 2CuO 4. The observation of infrared active vibrational (IRAV) modes and an associated electronic transition with common intensity and temperature dependence indicate the formation of self-localized polarons as photogenerated carriers. The photoinduced electronic transition deep in the infrared implies a major shift of oscillator strength leading to a large local polarizability in the vicinity of the polaron. We suggest that the enhanced local polarizability may provide an important mechanism for pairing.

  12. Inside-out Core–shell Architecture: Controllable Fabrication of Cu2O@Cu with High Activity for the Sonogashira Coupling Reaction (United States)

    As low-cost and versatile materials, Cu and its oxides have attracted great interest due to their excellent performance in the field of catalysis, superconductivity, photovoltaics, magnetic storage, electrochemistry, and biosensing. It is well known that morphology has an import...

  13. Inside-out Core–shell Architecture: Controllable Fabrication of Cu2O@Cu with High Activity for the Sonogashira Coupling Reaction (United States)

    As low-cost and versatile materials, Cu and its oxides have attracted great interest due to their excellent performance in the field of catalysis, superconductivity, photovoltaics, magnetic storage, electrochemistry, and biosensing. It is well known that morphology has an import...

  14. Copper oxide transistor on copper wire for e-textile (United States)

    Han, Jin-Woo; Meyyappan, M.


    A Cu2O-based field effect transistor was fabricated on Cu wire. Thermal oxidation of Cu forms Cu-Cu2O core-shell structure, where the metal-semiconductor Schottky junction was used as a gate barrier with Pt Ohmic contacts for source and drain. The device was coated with polydimethylsiloxane (PDMS) to protect from contamination and demonstrated as a humidity sensor. The cylindrical structure of the Cu wire and the transistor function enable embedding of simple circuits into textile which can potentially offer smart textile for wearable computing, environmental sensing, and monitoring of human vital signs.

  15. Copper electrodeposition from cuprous chloride solutions containing lead, zinc or iron ions

    Institute of Scientific and Technical Information of China (English)

    M. Tchoumou; M. Roynette Ehics


    Cuprous chloride hydrochloric acid solutions were electrolysed in a two compartments cell without agitation for copper extraction. It is found that the current density affects the colour and the size of copper deposits. During electrodeposition of copper from cuprous solution in the presence of various concentrations of lead, zinc or iron ions at different current densities, it is observed that lead is codeposited with copper by increasing current density.In all experiments, the current efficiency for the copper deposition reaction fluctuates between 88.50% and 95.50%.

  16. Formation and characterization of infrared absorbing copper oxide surfaces (United States)

    Arslan, Burcu; Demirci, Gökhan; Erdoğan, Metehan; Karakaya, İshak


    Copper oxide formation has been investigated to combine the advantages of producing different size and shapes of coatings that possess good light absorbing properties. An aqueous blackening solution was investigated and optimum composition was found as 2.5 M NaOH and 0.225 M NaClO to form velvet copper oxide films. A two-step oxidation mechanism was proposed for the blackening process by carefully examining the experimental results. Formation of Cu2O was observed until the entire copper surface was covered at first. In the second step, Cu2O surface was further oxidized to CuO until the whole Cu2O surface was covered by CuO. Therefore, blackened copper surfaces consisted of Cu2O/CuO duplex oxides. Characterization of the coatings were performed in terms of microstructure, phase analysis, chemical state, infrared specular and total reflectivity by SEM, XRD, XPS, FTIR and UV-vis spectrophotometry, respectively.

  17. Embedment of anodized p-type Cu₂O thin films with CuO nanowires for improvement in photoelectrochemical stability. (United States)

    Wang, Peng; Ng, Yun Hau; Amal, Rose


    A highly stable p-type cuprous oxide (Cu2O) photoelectrode has been fabricated by direct anodization of the Cu foil, followed by a thermal treatment to introduce a protective layer of copper oxide (CuO) nanowires penetrating the surface of the Cu2O layer. The anodized Cu2O served as the seeding sites for the growth of CuO nanowires. The embedment of CuO nanowires within the Cu2O matrix enhanced the adhesion of the nanowires onto the Cu substrate. In addition, the presence of CuO nanowires on the outer layer of the composite film, in turn stabilized the Cu2O layer by passivating the redox activities of Cu2O when exposed to the environment. This nanostructured p-type Cu2O photoelectrode generated 360 μA cm(-2) of photocathodic current density upon visible light illumination and managed to retain its photocathodic current density after being used and kept for one month. The improvement in photoelectrochemical (PEC) stability by introducing a passive layer of CuO nanowires provides useful insights into the development of a Cu2O photoelectrode, as its stability remained as the main challenge.

  18. Fabrication of copper oxide-coated hollow waveguides for CO2 laser radiation. (United States)

    Matsuura, Y; Miura, D; Miyagi, M


    Hollow fibers for transmitting CO(2) laser light were fabricated by the chemical vapor deposition (CVD) method. A dielectric film of copper oxide (Cu(2)O) was deposited upon the inside of a Ag-coated glass capillary by use of a metal acetylacetonate as the precursor. The waveguide, which was coated with Cu(2)O and had a bore diameter of 700 microm, showed a loss of 0.9 dB/m for CO(2) laser light. The Cu(2)O film deposited by CVD had high chemical and heat resistivity. Therefore a hollow fiber coated with copper oxide is suitable for high-power laser applications in a severe environment.

  19. Effects of critical fluctuations and dimensionality on the jump in specific heat at the superconducting transition temperature: Application to YBa2Cu3O7 -δ ,Bi2Sr2CaCu2O8 +δ , and KOs2O6 compounds (United States)

    Keumo Tsiaze, R. M.; Wirngo, A. V.; Mkam Tchouobiap, S. E.; Fotue, A. J.; Baloïtcha, E.; Hounkonnou, M. N.


    We report on a study of the superconducting order parameter thermodynamic fluctuations in YBa2Cu3O7 -δ ,Bi2Sr2CaCu2O8 +δ , and KOs2O6 compounds. A nonperturbative technique within the framework of the renormalized Gaussian approach is proposed. The essential features are reported (analytically and numerically) through Ginzburg-Landau (GL) model-based calculations which take into account both the dimension and the microscopic parameters of the system. By presenting a self-consistent approach improvement on the GL theory, a technique for obtaining corrections to the asymptotic critical behavior in terms of nonuniversal parameters is developed. Therefore, corrections to the specific heat and the critical transition temperature for one-, two-, and three-dimensional samples are found taking into account the fact that fluctuations occur at all length scales as the critical point of a system is approached. The GL model in the free-field approximation and the 3D-X Y model are suitable for describing the weak and strong fluctuation regimes respectively. However, with a modified quadratic coefficient, the renormalized GL model is able to explain certain experimental observations including the specific heat of complicated systems, such as the cup-rate superconductors and the β -pyrochlore oxides. It is clearly shown that the enhancement, suppression, or rounding of the specific heat jump of high-Tc cup-rate superconductors at the transition are indicative of the order parameter thermodynamic fluctuations according to the dimension and the nature of interactions.

  20. Effects of critical fluctuations and dimensionality on the jump in specific heat at the superconducting transition temperature: Application to YBa_{2}Cu_{3}O_{7-δ},Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}, and KOs_{2}O_{6} compounds. (United States)

    Keumo Tsiaze, R M; Wirngo, A V; Mkam Tchouobiap, S E; Fotue, A J; Baloïtcha, E; Hounkonnou, M N


    We report on a study of the superconducting order parameter thermodynamic fluctuations in YBa_{2}Cu_{3}O_{7-δ},Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}, and KOs_{2}O_{6} compounds. A nonperturbative technique within the framework of the renormalized Gaussian approach is proposed. The essential features are reported (analytically and numerically) through Ginzburg-Landau (GL) model-based calculations which take into account both the dimension and the microscopic parameters of the system. By presenting a self-consistent approach improvement on the GL theory, a technique for obtaining corrections to the asymptotic critical behavior in terms of nonuniversal parameters is developed. Therefore, corrections to the specific heat and the critical transition temperature for one-, two-, and three-dimensional samples are found taking into account the fact that fluctuations occur at all length scales as the critical point of a system is approached. The GL model in the free-field approximation and the 3D-XY model are suitable for describing the weak and strong fluctuation regimes respectively. However, with a modified quadratic coefficient, the renormalized GL model is able to explain certain experimental observations including the specific heat of complicated systems, such as the cup-rate superconductors and the β-pyrochlore oxides. It is clearly shown that the enhancement, suppression, or rounding of the specific heat jump of high-T_{c} cup-rate superconductors at the transition are indicative of the order parameter thermodynamic fluctuations according to the dimension and the nature of interactions.

  1. Preparation of Cystein from Cysteine Cuprous Mercaptide%由半胱氨酸亚铜制取半胱氨酸

    Institute of Scientific and Technical Information of China (English)

    刘勋; 胡敏; 姚小平


    In this paper ,a new preparation method of cysteine hydrochloride monohydrate from cysteine cu‐prous mcercaptide ,which is prepared by the reduction and precipitation of cystine with cuprous oxide has been introduced ,including re‐precipitation of cysteine cuprous mercaptide ,removal of copper using H2 S , decoloration ,crystallization and recrystalization .The yield of the product is up to 12 .4% ,with the quality according with the Japanese AJI standards .%研究了一种用氧化亚铜将胱氨酸还原沉淀为半胱氨酸亚铜,再由此制备半胱氨酸盐酸盐一水物的新方法.该方法包含半胱氨酸亚铜再沉淀,H2 S法脱铜,脱色,产品结晶,重结晶等步骤,半胱氨酸盐酸盐一水物收率达12.4%,产品质量符合日本味之素标准.

  2. 聚乙烯吡咯烷酮与柠檬酸钠的加入量对葡萄糖还原法制备Cu2O颗粒形貌的影响%Effects of Amount of Poly (Vinyl Pyrrolidone) and Sodium Citrate on the Shape of Cu2O Particles Prepared by Glucose-reduction Method

    Institute of Scientific and Technical Information of China (English)

    杨宇婷; 张洁; 刘宗健; 吕德义


    Cu2O particles were prepared by the reaction of Benedict's solution with glucose, and the effect of the amount of poly (vinyl pyrrolidone) (PVP) or sodium citrate on the morphology of the as-prepared products was investigated by X-ray diffraction and scanning electron microscopy. It is found that the size and shape of Cu2 O crystals can be controlled by altering the amount of PVP and with increasing the PVP amount the Cu2O crystals evolve from ca. 500 nm sized cubes, to ca. 1μm sized truncated octahedra, and finally to ca. 2μm sized octahedra. Our results have also revealed that in the absence of sodium citrate the as-prepared products are spherical Cu2O particles self-assembled from small-sized nanocrystals and the sizes of the spherical particles are not uniform. However, when small amount of sodium citrate is added Cu2O particles with uniform sizes can be formed, and self-assembled Cu2O particles gradually evolve into perfect crystals as the amount of sodium citrate increases, indicating that sodium citrate favors the growth of Cu2O crystals.%利用葡萄糖与本尼迪特试剂反应制备Cu2O颗粒,以X射线衍射、扫描电镜为表征手段,研究了聚乙烯吡咯烷酮(PVP)与柠檬酸钠的加入量对Cu2O颗粒形貌的影响.结果表明,通过改变PVP量可调控Cu2O的形貌与大小,即随着PVP量的增加,Cu2O颗粒由边长约为500 nm的立方体变为大小约为1μm的切角八面体再演变为大小约为2μm的八面体.研究结果还表明,在没有柠檬酸钠存在的情况下,产物是由Cu2O小纳米晶自组装而成的、大小不均的球形颗粒;柠檬酸钠的加入有助于Cu2O晶体的生长,随着柠檬酸钠加入量的增加,球形Cu2O颗粒逐渐变为大小均一的晶体.

  3. Absence of a proximity effect for a thin-films of a Bi2Se3 topological insulator grown on top of a Bi2Sr2CaCu2O(8+δ) cuprate superconductor. (United States)

    Yilmaz, T; Pletikosić, I; Weber, A P; Sadowski, J T; Gu, G D; Caruso, A N; Sinkovic, B; Valla, T


    Proximity-induced superconductivity in a 3D topological insulator represents a new avenue for observing zero-energy Majorana fermions inside vortex cores. Relatively small gaps and low transition temperatures of conventional s-wave superconductors put hard constraints on these experiments. Significantly larger gaps and higher transition temperatures in cuprate superconductors might be an attractive alternative to considerably relax these constraints, but it is not clear whether the proximity effect would be effective in heterostructures involving cuprates and topological insulators. Here, we present angle-resolved photoemission studies of thin Bi(2)Se(3) films grown in situ on optimally doped Bi(2)Sr(2)CaCu(2)O(8+δ) substrates that show the absence of proximity-induced gaps on the surfaces of Bi(2)Se(3) films as thin as a 1.5 quintuple layer. These results suggest that the superconducting proximity effect between a cuprate superconductor and a topological insulator is strongly suppressed, likely due to a very short coherence length along the c axis, incompatible crystal and pairing symmetries at the interface, small size of the topological surface state's Fermi surface, and adverse effects of a strong spin-orbit coupling in the topological material.

  4. Development of Bulk Bi2+xSr3-yCa yCu 2O8+delta Superconductors by Partial-Melting Route for Fault Current Limiters Application

    Directory of Open Access Journals (Sweden)

    Bojan A. Marinkovic


    Full Text Available The production of bulk Bi2+xSr3-yCa yCu 2O8+delta (Bi-2212 superconductors for fault current limiter application was developed via a partial-melting route. Aiming high Ic (critical current, which is the essential superconducting characteristic for application of this material in the construction of Fault Current Limiters (FCL, the produced blocks have predominance of Bi-2212 phase (83 wt%, which characterizes with high values of zero and onset transport critical temperature of 92K and 97.5K, respectively. A relatively low transition width, deltaT, from the superconducting to the normal state of 5.5K, revealed a good intergrain connectivity. Consequently, current measurements on the blocks of Bi-2212 show promising Ic values of 230A and 850A for direct and alternate current, respectively. It is expected that further increases in the Ic values will depend on the elimination of an observed amorphous phase and further reduction of amount and grain sizes of secondary phases, still present in the blocks obtained by the proposed partial-melting route. This may be achieved by a further optimization of the partial-melting processing parameters.

  5. Crossover from paramagnetic to diamagnetic ac-susceptibility in Bi2Sr2CaCu2O{}_{8+\\delta } superconductor for {\\bf{H}}| | c {-} {\\rm{axis}} (United States)

    Pissas, M.; Tamegai, T.


    Ac-susceptibility measurements of the superconducting Bi2Sr2CaCu2O{}8+δ single crystal for {H}| | c-axis are presented. In low frequency measurements the first harmonic ac-susceptibility, {χ }1={χ }1{\\prime }-{{i}}{χ }1{\\prime\\prime }, is real and independent of the amplitude of the ac-magnetic field (linear behavior) and positive, implying that it represents the slope of the magnetization curve as the temperature changes below T c2. The positive ac-susceptibility before becoming negative, at low temperatures, forms a positive local maximum arising from the melting transition of the Abrikosov vortex lattice. For higher frequencies the response becomes diamagnetic due to the eddy currents. The signature of the discontinuous change of the magnetization, at the melting transition in higher frequency measurements, is a sharp shoulder near the complete screening. The presence of second harmonic susceptibility in the liquid regime implies nonlinear variation of the equilibrium magnetization.

  6. Negative correlation between enhanced crossover temperature and fluctuation-free critical current of the second switch in Bi2Sr2CaCu2O{}_{8+\\delta } intrinsic Josephson junction (United States)

    Nomura, Y.; Okamoto, R.; Kakeya, I.


    We have investigated the switching dynamics of the first and second switches in intrinsic Josephson junctions (IJJs) of Bi2Sr2CaCu2O{}8+δ with different maximum Josephson current density J c to reveal the doping evolution of interaction between IJJs. For the second switch, the crossover temperature between temperature-independent switching similar to quantum tunneling and thermally activated switching {T}2{nd}* is remarkably higher than that for the first switch. Moreover, {T}2{nd}* slightly decreases with increasing J c, which violates the conventional relation between the crossover temperature and the critical current density. These features can be explained not by a change in the Josephson coupling energy but by a change in the charging energy of the Josephson junction. We argue that the capacitive coupling model explains the increase in the fluctuation in the quantum regime of the second switch and the anti-correlation between {T}2{nd}* and J c. Furthermore, inductive coupling does not contribute to these peculiar phenomena in the switching dynamics of stacked IJJs.

  7. Quasiparticle dynamics across the full Brillouin zone of Bi2Sr2CaCu2O8+δ traced with ultrafast time and angle-resolved photoemission spectroscopy

    Directory of Open Access Journals (Sweden)

    Georgi L. Dakovski


    Full Text Available A hallmark in the cuprate family of high-temperature superconductors is the nodal-antinodal dichotomy. In this regard, angle-resolved photoemission spectroscopy (ARPES has proven especially powerful, providing band structure information directly in energy-momentum space. Time-resolved ARPES (trARPES holds great promise of adding ultrafast temporal information, in an attempt to identify different interaction channels in the time domain. Previous studies of the cuprates using trARPES were handicapped by the low probing energy, which significantly limits the accessible momentum space. Using 20.15 eV, 12 fs pulses, we show for the first time the evolution of quasiparticles in the antinodal region of Bi2Sr2CaCu2O8+δ and demonstrate that non-monotonic relaxation dynamics dominates above a certain fluence threshold. The dynamics is heavily influenced by transient modification of the electron-phonon interaction and phase space restrictions, in stark contrast to the monotonic relaxation in the nodal and off-nodal regions.

  8. Superconducting properties of (Tl1-xPbx)Sr2CaCu2O7-δ (x = 0.1 - 0.7) prepared using nano-sized PbO (United States)

    Elmasroub, Hanan Saleh; Abd-Shukor, R.


    The effect of Pb substitution on Tl-1212 high Tc superconductor with nominal starting composition (Tl1-xPbx)Sr2CaCu2O7-δ (x = 0.1 - 0.7) has been investigated. Nano-sized PbO (10-30 nm) was used as a starting component. The samples were synthesized using the solid-state reaction technique and studied by powder X-ray diffraction method, electrical resistance measurements and scanning electron microscopy. The resistance-temperature curves showed metallic behavior for all samples. Samples with x = 0.6 showed the highest Tc onset (89 K) and Tc zero (78 K). This sample also showed the highest peak temperature for the derivative of the resistivity (ρ) versus temperature (T) curve, dρ/dT = 85 K. The X-ray diffraction patterns showed a major Tl-1212 phase with few weak diffraction lines of the Tl-1201. The deviation of electrical resistivity from linear behavior near the transition temperature was explained in terms of excess conductivity associated with Cooper pair formation. This work showed that nano-sized PbO could be used to enhance the formation of the superconducting Tl-1212 phase.

  9. Investigation of inter-grain critical current density in Bi2Sr2CaCu2O8+δ superconducting wires and its relationship with the heat treatment protocol (United States)

    Pallecchi, I.; Leveratto, A.; Braccini, V.; Zunino, V.; Malagoli, A.


    In this work we investigate the effect of each different heat treatment stage in the fabrication of Bi2Sr2CaCu2O8+δ superconducting wires on intra-grain and inter-grain superconducting properties. We measure magnetic critical temperature T c values and transport critical current density J c at temperatures from 4 K to 40 K and in fields up to 7 T. From an analysis of the temperature dependence of the self-field critical current density J c(T) that takes into account weak link behavior and the proximity effect, we study grain boundary (GB) transparency to supercurrents; we also establish a relationship between GB oxygenation in the different steps of the fabrication process and GB transparency to supercurrents. We find that GB oxygenation starts in the first crystallization stage, but it becomes complete in the plateau at 836 °C and in slow cooling stages and is further enhanced in the prolonged post-annealing step. Such oxygenation makes GBs more conductive, thus improving the inter-grain J c value and temperature dependence. On the other hand, from inspection of the T c values in the framework of the phase diagram dome, we find that grains are already oxygenated in the crystallization step up to the optimal doping, while successive slow cooling and post-annealing treatments further enhance the degree of overdoping, especially if carried out in oxygen atmosphere rather than in air.

  10. Electronic structure of the ingredient planes of the cuprate superconductor Bi2Sr2CuO6 +δ : A comparison study with Bi2Sr2CaCu2O8 +δ (United States)

    Lv, Yan-Feng; Wang, Wen-Lin; Ding, Hao; Wang, Yang; Ding, Ying; Zhong, Ruidan; Schneeloch, John; Gu, G. D.; Wang, Lili; He, Ke; Ji, Shuai-Hua; Zhao, Lin; Zhou, Xing-Jiang; Song, Can-Li; Ma, Xu-Cun; Xue, Qi-Kun


    By means of low-temperature scanning tunneling microscopy, we report on the electronic structures of the BiO and SrO planes of the Bi2Sr2CuO6 +δ (Bi-2201) superconductor prepared by argon-ion bombardment and annealing. Depending on post annealing conditions, the BiO planes exhibit either a pseudogap (PG) with sharp coherence peaks and an anomalously large gap magnitude of 49 meV or van Hove singularity (vHS) near the Fermi level, while the SrO is always characteristic of a PG-like feature. This contrasts with the Bi2Sr2CaCu2O8 +δ (Bi-2212) superconductor where vHS occurs solely on the SrO plane. We disclose the interstitial oxygen dopants (δ in the formulas) as a primary cause for the occurrence of vHS, which are located dominantly around the BiO and SrO planes, respectively, in Bi-2201 and Bi-2212. This is supported by the contrasting structural buckling amplitude of the BiO and SrO planes in the two superconductors. Our findings provide solid evidence for the irrelevance of PG to the superconductivity in the two superconductors, as well as insights into why Bi-2212 can achieve a higher superconducting transition temperature than Bi-2201, and by implication, the mechanism of cuprate superconductivity.

  11. Possible Nodeless Superconducting Gaps in Bi2Sr2CaCu2O8+δ and YBa2Cu3O7-x Revealed by Cross-Sectional Scanning Tunneling Spectroscopy (United States)

    Ren, Ming-Qiang; Yan, Ya-Jun; Zhang, Tong; Feng, Dong-Lai


    Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/ spectroscopy, we clearly reveal the spatial-dependence or inhomogeneity of the superconducting gap structure of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\\delta}$ (Bi2212) and YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) along their $c$-axes on a scale shorter than the interlayer spacing. By tunneling into the (100) plane of a Bi2212 single crystal and a YBCO film, we observe both U-shaped tunneling spectra with extended flat zero-conductance bottoms, and V-shaped gap structures, in different regions of each sample. On the YBCO film, tunneling into a (110) surface only reveals a U-shaped gap without any zero-bias peak. Our analysis suggests that the U-shaped gap is likely a nodeless superconducting gap. The V-shaped gap has a very small amplitude, and is likely proximity-induced by regions having the larger U-shaped gap.

  12. Electrochromism in copper oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, T.J.; Slack, J.L.; Rubin, M.D.


    Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

  13. Picometer registration of zinc impurity states in Bi2Sr2CaCu2O8+δ for phase determination in intra-unit-cell Fourier transform STM (United States)

    Hamidian, M. H.; Firmo, I. A.; Fujita, K.; Mukhopadhyay, S.; Orenstein, J. W.; Eisaki, H.; Uchida, S.; Lawler, M. J.; Kim, E.-A.; Davis, J. C.


    Direct visualization of electronic-structure symmetry within each crystalline unit cell is a new technique for complex electronic matter research (Lawler et al 2010 Nature 466 347-51, Schmidt et al 2011 New J. Phys. 13 065014, Fujita K et al 2012 J. Phys. Soc. Japan 81 011005). By studying the Bragg peaks in Fourier transforms of electronic structure images and particularly by resolving both the real and imaginary components of the Bragg amplitudes, distinct types of intra-unit-cell symmetry breaking can be studied. However, establishing the precise symmetry point of each unit cell in real space is crucial in defining the phase for such a Bragg-peak Fourier analysis. Exemplary of this challenge is the high-temperature superconductor Bi2Sr2CaCu2O8+δ for which the surface Bi atom locations are observable, while it is the invisible Cu atoms that define the relevant CuO2 unit-cell symmetry point. Here we demonstrate, by imaging with picometer precision the electronic impurity states at individual Zn atoms substituted at Cu sites, that the phase established using the Bi lattice produces a ˜2%(2π) error relative to the actual Cu lattice. Such a phase assignment error would not diminish reliability in the determination of intra-unit-cell rotational symmetry breaking at the CuO2 plane (Lawler et al 2010 Nature 466 347-51, Schmidt et al 2011 New J. Phys. 13 065014, Fujita K et al 2012 J. Phys. Soc. Japan 81 011005). Moreover, this type of impurity atom substitution at the relevant symmetry site can be of general utility in phase determination for the Bragg-peak Fourier analysis of intra-unit-cell symmetry.

  14. Nb Substitution Effects on Superconducting Properties of Ru1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ

    Directory of Open Access Journals (Sweden)

    J. L. Maldonado-Mejía


    Full Text Available In order to gain further insight into the role of substitution of Ru by Nb on superconductivity, polycrystalline samples of Ru1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ  (0.0 ≤ x ≤ 1.0 have been synthesized by solid-state reaction method. Substitution of Nb at the Ru site in the system takes place isostructurally in the tetragonal structure (space group I4/mmm with full solubility (x = 1.0. Superconductivity exists for all compositions. Resistivity measurements in function of temperature from 0 to 300 K were done using the four-probe technique. It is found that the substitution of Ru5+ for Nb5+ depresses the superconductivity of samples from Tc = 29 K for x = 0.0 to Tc = 5 K for x = 1.0 (where Tc is the critical temperature, when resistivity becomes equal to zero. In the normal state, the dependence of resistivity with temperature, for compositions with x = 0.0 and 0.2, shows a metallic behavior, while for compositions between x = 0.4 and x = 1 it shows a semiconducting behavior. In that way, the density of charge carriers is reduced with niobium doping, leading to the semiconducting behavior. The resistive transition to the superconducting state of all samples is found to be affected by granularity. Samples undergo double superconducting transition.

  15. Role of copper oxides in contact killing of bacteria. (United States)

    Hans, Michael; Erbe, Andreas; Mathews, Salima; Chen, Ying; Solioz, Marc; Mücklich, Frank


    The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.

  16. Controlling the Formation of Nanocavities in Kirkendall Nanoobjects through Sequential Thermal Ex Situ Oxidation and In Situ Reduction Reactions. (United States)

    Mel, Abdel-Aziz El; Tessier, Pierre-Yves; Buffiere, Marie; Gautron, Eric; Ding, JunJun; Du, Ke; Choi, Chang-Hwan; Konstantinidis, Stephanos; Snyders, Rony; Bittencourt, Carla; Molina-Luna, Leopoldo


    Controlling the porosity, the shape, and the morphology of Kirkendall hollow nanostructures is the key factor to tune the properties of these tailor-made nanomaterials which allow in turn broadening their applications. It is shown that by applying a continuous oxidation to copper nanowires following a temperature ramp protocol, one can synthesize cuprous oxide nanotubes containing periodic copper nanoparticles. A further oxidation of such nanoobjects allows obtaining cupric oxide nanotubes with a bamboo-like structure. On the other hand, by applying a sequential oxidation and reduction reactions to copper nanowires, one can synthesize hollow nanoobjects with complex shapes and morphologies that cannot be obtained using the Kirkendall effect alone, such as necklace-like cuprous oxide nanotubes, periodic solid copper nanoparticles or hollow cuprous oxide nanospheres interconnected with single crystal cuprous oxide nanorods, and aligned and periodic hollow nanospheres embedded in a cuprous oxide nanotube. The strategy demonstrated in this study opens new avenues for the engineering of hollow nanostructures with potential applications in gas sensing, catalysis, and energy storage.

  17. All-Oxide Photovoltaics. (United States)

    Rühle, Sven; Anderson, Assaf Y; Barad, Hannah-Noa; Kupfer, Benjamin; Bouhadana, Yaniv; Rosh-Hodesh, Eli; Zaban, Arie


    Recently, a new field in photovoltaics (PV) has emerged, focusing on solar cells that are entirely based on metal oxide semiconductors. The all-oxide PV approach is very attractive due to the chemical stability, nontoxicity, and abundance of many metal oxides that potentially allow manufacturing under ambient conditions. Already today, metal oxides (MOs) are widely used as components in PV cells such as transparent conducting front electrodes or electron-transport layers, while only very few MOs have been used as light absorbers. In this Perspective, we review recent developments of all-oxide PV systems, which until today were mostly based on Cu2O as an absorber. Furthermore, ferroelectric BiFeO3-based PV systems are discussed, which have recently attracted considerable attention. The performance of all-oxide PV cells is discussed in terms of general PV principles, and directions for progress are proposed, pointing toward the development of novel metal oxide semiconductors using combinatorial methods.

  18. Nanowire-based All Oxide Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong


    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  19. Optical and electrical properties of Cu-based all oxide semi-transparent photodetector (United States)

    Kim, Hong-Sik; Patel, Malkeshkumar; Yadav, Pankaj; Kim, Joondong; Sohn, Ahrum; Kim, Dong-Wook


    Zero-bias operating Cu oxide-based photodetector was achieved by using large-scale available sputtering method. Cu oxide (Cu2O or CuO) was used as p-type transparent layer to form a heterojunction by contacting n-type ZnO layer. All metal-oxide materials were employed to realize transparent device at room temperature and showed a high transparency (>75% at 600 nm) with excellent photoresponses. The structural, morphological, optical, and electrical properties of Cu oxides of CuO and Cu2O are evaluated in depth by UV-visible spectrometer, X-ray diffraction, scanning electron microscopy, atomic force microscopy, Kelvin probe force microscopy, and Hall measurements. We may suggest a route of high-functional Cu oxide-based photoelectric devices for the applications in flexible and transparent electronics.

  20. Inorganic precursor peroxides for antifouling coatings

    DEFF Research Database (Denmark)

    Olsen, S.M.; Pedersen, L.T.; Hermann, M.H.


    Modern antifouling coatings are generally based on cuprous oxide (Cu2O) and organic biocides as active ingredients. Cu2O is prone to bioaccumulation, and should therefore be replaced by more environmentally benign compounds when technically possible. However, cuprous oxide does not only provide...... antifouling properties, it is also a vital ingredient for the antifouling coating to obtain its polishing and leaching mechanism. In this paper, peroxides of strontium, calcium, magnesium, and zinc are tested as pigments in antifouling coatings. The peroxides react with seawater to create hydrogen peroxide...... and highly seawater-soluble ions of the metal. The goals have been to establish the antifouling potency of an antifouling coating that releases hydrogen peroxide as biocide, and to investigate the potential use of peroxides as water-soluble polishing and leaching pigments. The investigations have shown...

  1. Comparison of the Oxidation Rates of Some New Copper Alloys (United States)

    Ogbuji, Linus U. J. Thomas; Humphrey, Donald L.


    Copper alloys were studied for oxidation resistance and mechanisms between 550 and 700 C, in reduced-oxygen environments expected in rocket engines, and their oxidation behaviors compared to that of pure copper. They included two dispersion-strengthened alloys (precipitation-strengthened and oxide-dispersion strengthened, respectively) and one solution-strengthened alloy. In all cases the main reaction was oxidation of Cu into Cu2O and CuO. The dispersion-strengthened alloys were superior to both Cu and the solution-strengthened alloy in oxidation resistance. However, factors retarding oxidation rates seemed to be different for the two dispersion-strengthened alloys.

  2. Robust p-type doping of copper oxide using nitrogen implantation (United States)

    Jorge, Marina; Polyakov, Stanislav M.; Cooil, Simon; Schenk, Alex K.; Edmonds, Mark; Thomsen, Lars; Mazzola, Federico; Wells, Justin W.


    We demonstrate robust p-type doping of Cu2O using low/medium energy ion implantation. Samples are made by controlled oxidation of annealed Cu metal foils, which results in Cu2O with levels of doping close to intrinsic. Samples are then implanted with nitrogen ions using a kinetic energy in the few keV range. Using this method, we are able to produce very high levels of doping, as evidenced by a 350 meV shift in the Fermi level towards the VB maximum. The robustness of the nitrogen implanted samples are tested by exposing them to atmospheric contaminants, and elevated temperatures. The samples are found to survive an increase in temperature of many hundreds of degrees. The robustness of the samples, combined with the fact that the materials used are safe, abundant and non-toxic and that the methods used for the growth of Cu2O and N+ implantation are simple and cheap to implement industrially, underlines the potential of Cu2O:N for affordable intermediate band photovoltaics.

  3. 205Tl nuclear spin lattice relaxation in the one layer (Tl 2Ba 2CuO 6), two layer (Tl 2CaBa 2Cu 2O 8) and three layer (Tl 2Ca 2Ba 2CuO 10 ) high-T c superconductors (United States)

    Hentsch, F.; Winzek, N.; Mehring, M.; Mattausch, Hj.; Simon, A.; Kremer, R.


    We report on the comparison of the 205Tl nuclear spin lattice relaxation rate 1/ T1 versus temperature below and above Tc in the three title compounds. Although Tc varies significantly for the three compounds, their relaxation rates 1/ T1 behave almost identical above and below Tc. In the regime T > Tc non-Korringa behaviour is observed, resembling the 63Cu relaxation in the CuO 2 layer (Cu(2)) of YBa 2Cu 3O 7, whereas for TCaBa 2Cu 2O 8.

  4. Fabrication of Three-Dimensional Nanostructures for Thermal Study (United States)


    production at low cost [45]. Due to its photovoltaic properties, it has a promising application as solar cell material. Furthermore, Cu2O exhibits...Farrow, R. F. C.; Marks, R. F.; Thiele, J. U. et al., Epitaxial growth and properties of ferromagnetic co-deoped TiO2 anatase., Applied Physics Letters...Materials, 2001, 13 (7), 482 – 485. 45. A. E. Rakhsani, Preparation, Characteristics, and Photovoltaic Properties of Cuprous Oxide – A Review., Solid

  5. Theory and experiment on the cuprous-cupric electron transfer rate at a copper electrode.

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J. W.; Smith, B. B.; Walbran, S.; Curtiss, L. A.; Rigney, R. O.; Sutjianto, A.; Hung, N. C.; Yonco, R. M.; Nagy, Z.; Univ. of Minnesota; NREL


    We describe results of experiment and theory of the cuprous-cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous-ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous-ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric-ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here.

  6. Theory and experiment on the cuprous{endash}cupric electron transfer rate at a copper electrode

    Energy Technology Data Exchange (ETDEWEB)

    Halley, J.W. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Smith, B.B. [National Renewable Energy Laboratory, Golden, Colorado (United States); Walbran, S. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Curtiss, L.A.; Rigney, R.O.; Sutjianto, A.; Hung, N.C.; Yonco, R.M.; Nagy, Z. [Argonne National Laboratory, Divisions of Materials Science, Chemistry and Chemical Technology, Argonne, Illinois 60439-4837 (United States)


    We describe results of experiment and theory of the cuprous{endash}cupric electron transfer rate in an aqueous solution at a copper electrode. The methods are similar to those we reported earlier for the ferrous{endash}ferric rate. The comparison strongly suggests that, in marked distinction to the ferrous{endash}ferric case, the electron transfer reaction is adiabatic. The model shows that the activation barrier is dominated by the energy required for the ion to approach the electrode, rather than by the energy required for rearrangement of the solvation shell, also in sharp distinction to the case of the ferric{endash}ferrous electron transfer at a gold electrode. Calculated activation barriers based on this image agree with the experimental results reported here. {copyright} {ital 1999 American Institute of Physics.}

  7. Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires

    Directory of Open Access Journals (Sweden)

    Emanuele Francesco Marano


    Full Text Available Metallic porous microtubes were obtained from commercial wires (200–250 µm diameter of Cu-65Ni-2Fe, Cu-44Ni-1Mn and Cu-23Ni, alloys (wt. % by surface oxidation at 1173 K in air, removal of the unoxidized core by chemical etching, and reduction in annealing in the hydrogen atmosphere. Transversal sections of the partially oxidized wires show a porous layered structure, with an external shell of CuO (about 10 μm thick and an inner layer of NiO (70–80 μm thick. In partially oxidized Cu-44Ni-1Mn and Cu-23Ni, Cu2O is dispersed in NiO because the maximum solubility of Cu in NiO is exceeded, whereas in Cu-65Ni-2Fe, a Cu2O shell is present between CuO and NiO layers. Chemical etching removed the unoxidized metallic core and Cu2O with formation of porous oxide microtubes. Porosity increases with Cu content because of the larger amount of Cu2O in the partially oxidized wire. After reduction, the transversal sections of the metallic porous microtubes show a series of f.c.c.-(Cu,Ni solid solutions with different compositions, due to the segregation of CuO and NiO during oxidation caused by the different diffusion coefficients of Ni and Cu in the respective oxides. Pore formation occurs at each step of the process because of the Kirkendall effect, selective phase removal and volume contraction.

  8. Formation of copper oxychloride and reactive oxygen species as causes of uterine injury during copper oxidation of Cu-IUD. (United States)

    Beltran-Garcia, M J; Espinosa, A; Herrera, N; Perez-Zapata, A J; Beltran-Garcia, C; Ogura, T


    The lining of the uterus and cervix might be injured by a variety of oxidation products of Cu in a Cu-IUD, including cuprous ions, dissolved and precipitated cupric ions, and reactive oxygen species such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals. In this study, the human amnious WISH cell line was employed as a model of uterine cells in the presence of copper. The cell viability was decreased by elemental copper, which was alleviated up to 70% by the addition of catalase. The addition of copper oxychloride caused cell death in a dose-dependent manner. Hydroxyl radicals in the presence of copper were determined by the formation of malondialdehyde. Soluble cuprous chloride complexes are formed in the uterus by slowly entering oxygen. The complexes are partly oxidized to insoluble copper oxychloride. which damages the endometrium. Unoxidized cuprous ions migrate to the oxygen-rich cervix and are oxidized to copper oxychloride, causing cervix damage.

  9. Chemical Looping with Copper Oxide as Carrier and Coal as Fuel Boucle chimique pour la combustion du charbon avec un transporteur d’oxygène à base d’oxyde de cuivre

    Directory of Open Access Journals (Sweden)

    Eyring E.M.


    Full Text Available A preliminary analysis has been conducted of the performance of a Chemical Looping system with Oxygen Uncoupling (CLOU with copper oxide as the oxygen carrier and coal approximated by carbon as the fuel. The advantages of oxygen uncoupling are demonstrated by providing the energy balances, the circulation rate of oxygen carrier, the oxygen carrier mass loadings, the carbon burnout and oxygen partial pressure in the fuel reactor. Experimental data on the cycling of cuprous oxide to cupric oxide and kinetics for the oxidation and decomposition reactions of the oxides were obtained for use in the analysis. For this preliminary study unsupported oxides were utilized. The decomposition temperatures were rapid at the high temperature of 950°C selected for the fuel reactor. The oxidation kinetics peaked at about 800°C with the decrease in rate at higher temperatures, a decrease which is attributed in the literature to the temperature dependence of the diffusional resistance of the CuO layer surrounding the Cu2O; the diffusion occurs through grain boundaries in the CuO layers and the rate of diffusion decreases as a consequence of growth of CuO grains with increasing temperature. The analysis shows the advantages of CLOU in providing rapid combustion of the carbon with carbon burnout times lower than the decomposition times of the oxygen carrier. For the full potential of CLOU to be established additional data are needed on the kinetics of supported oxides at the high temperatures (>850°C at which oxygen is released by the CuO in the fuel reactor. Une analyse préliminaire a été conduite pour estimer les performances d’un procédé en boucle chimique découplé (CLOU, chemical looping uncoupling pour la combustion du charbon avec un transporteur d’oxygène à base d’oxyde de cuivre. Les avantages de ce système sont démontrés en établissant le bilan énergétique, l’inventaire et le débit de circulation du matériau transportant l

  10. “Cu核-Cu2O壳”粒子可见光催化降解酚类废水的研究%Photocatalytic degradation of phenolic poilutants by using visible light responsive “Cu core-Cu2O shell” catalyst

    Institute of Scientific and Technical Information of China (English)

    梁伟夏; 何星存; 张良军; 钟彤; 陆志发


    The article is concerned about our research findings in photocatalytic degradation of phenolic pollutants by using visible light responsive " Cu core-Cu2O shell " catalyst micron-sized " Cu core-Cu2O shell" catalyst. The photo-catalysts we have used are prepared by reducing CuSO4 to "Cu core-Cu2O shell" catalyst characterized by X-ray diffraction ( XRD) and transmission electron microscope (TEM). For our research purpose, we have investigated photo-catalytic degradation of phenolic compounds in aqueous solution under the visible light. The results of our experiments show that the new catalyst under way was highly responsive under the visible light. The so-called "Cu core-Cu2O shell" type catalyst was found to involve a few factors, such as the reaction time, the quantity of catalyst, the initial concentration of p-nitrophenol, the solution of pH and the different kinds of sources light, of which may affect the photocatalytic and degradative properties. The optimum conditions as we found can be stated as follows: the initial concentration of p-nitrophenol-40 mg- L'; the quantity of catalyst-2 g* L1; the solution of pH is equal to 3 to 11 while the visible light resource is irradiating during 120 min in the optimal perspective moment. All the above said conditions permitted, the degradation rate of p-nitrophenol is expected to reach 95% . However, it is the UV-visible absorption spectra that substantiated the result of degradation. In addition, the TOC studies indicate that the main part of p-nitrophenol has been mineralized into CO2 and H2O. When the industrial phenol sewage was used to examine the photoactivity, we have found that the degradation of industrial phenol sewage is likely to take place under either sunlight or metal halide light at a similar rate (about 90%). Compared with other similar photocatalysts, it would be more significant to note the photocatalytic activity of "Cu core-Cu2O shell" particles. Besides, we have also studied the kinetics of

  11. Simultaneous glucose sensing and biohydrogen evolution from direct photoelectrocatalytic glucose oxidation on robust Cu₂O-TiO₂ electrodes. (United States)

    Devadoss, Anitha; Sudhagar, P; Ravidhas, C; Hishinuma, Ryota; Terashima, Chiaki; Nakata, Kazuya; Kondo, Takeshi; Shitanda, Isao; Yuasa, Makoto; Fujishima, Akira


    We report simultaneous photoelectrocatalytic (PEC) glucose sensing and biohydrogen generation for the first time from the direct PEC oxidation of glucose at multifunctional and robust Cu2O-TiO2 photocatalysts. Striking improvement of 30% in overall H2 gas evolution (∼122 μmol h(-1) cm(-2)) by photoholes assisted glucose oxidation opens a new platform in solar-driven PEC biohydrogen generation.

  12. Efficient visible-light photocatalytic performance of cuprous oxide porous nanosheet arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xianghua; Wang, Jianqiang [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yihe [Beijing Key Laboratory of Mineral Materials and Utilization of Solid Waste, National Laboratory of Mineral Materials, School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Cao, Minhua, E-mail: [Key Laboratory of Cluster Science, Ministry of Education of China, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)


    Graphical Abstract: We demonstrated a facile and efficient process for fabricating Cu{sub 2}O porous nanosheet arrays on Cu mesh. Benefiting from the 1D array structure and porous structure, the as-prepared Cu{sub 2}O sample exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation. - Highlights: • Cu{sub 2}O porous nanosheet arrays on Cu mesh were synthesized via the facile and efficient process. • The Cu{sub 2}O sample exhibited the 1D array structure and porous nanosheet morphology. • The as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity. - Abstract: One-dimensional nanostructures are of great interest for a wide range of applications. In this work, we demonstrated the fabrication of visible-light-responsive Cu{sub 2}O porous nanosheet arrays. The synthesis involved the growth of Cu(OH){sub 2} nanosheet arrays on Cu mesh by solution-based corrosion and thermal transformation of Cu(OH){sub 2} nanosheet to Cu{sub 2}O porous nanosheets on Cu mesh. Benefiting from the one dimensional array structure and porous structure, the as-prepared Cu{sub 2}O porous nanosheet arrays exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation.

  13. Light-Induced Reduction of Cuprous Oxide in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Cavalca, Filippo Carlo; Laursen, Anders Bo; Wagner, Jakob Birkedal


    . Environmental transmission electron microscopy (ETEM) makes it possible to obtain insight into the local structure, composition and reactivity of catalysts in their working environment, which is of fundamental interest for sustainable energy research and is essential for further material optimization. Herein...

  14. Enormous excitonic effects in bulk, mono- and bi- layers of cuprous halides using many-body perturbation technique (United States)

    Azhikodan, Dilna; Nautiyal, Tashi


    Cuprous halides (CuX with X = Cl, Br, I), intensely studied about four decades ago by experimentalists for excitons, are again drawing attention of researchers recently. Potential of cuprous halide systems for device applications has not yet been fully explored. We go beyond the one-particle picture to capture the two-particle physics (electron-hole interaction to form excitons). We have deployed the full tool kit of many-body perturbation technique, GW approximation + Bethe Salpeter equation, to unfurl the rich excitonic physics of the bulk as well as layers of CuX. The negative spin-orbit contribution at the valence band top in CuCl, compared to CuBr and CuI, is in good agreement with experiments. We note that CuX have exceptionally strong excitons, defying the linear fit (between the excitonic binding energy and band gap) encompassing many semiconductors. The mono- and bi- layers of cuprous halides are predicted to be rich in excitons, with exceptionally large binding energies and the resonance energies in UV/visible region. Hence this work projects CuX layers as good candidates for optoelectronic applications. With advancement of technology, we look forward to experimental realization of CuX layers and harnessing of their rich excitonic potential.

  15. Oxidation of metals and alloys in controlled atmospheres using in situ transmission electron microscopy and Auger spectrography (United States)

    Rao, D. B.; Heinemann, K.; Douglass, D. L.


    Single-crystalline thin films of copper were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of .005 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. Results show that neither stacking faults nor dislocations are associated with the Cu2O nucleation sites. The growth of Cu2O nuclei is linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  16. Bi2Sr2CaCu2O8+δ ウィスカー ニオケル ボルテックス ダイナミクス ノ ケンキュウ


    菅原, 恵美子


    本研究は,層状性の強いBi2Sr2CaCu2O8+δを用い,色々な磁場印加角度の下での磁束状態の研究を,以下のことに留意して行うことを目的とする。(i)試料としては,良質なBi2Sr2CaCu2O8+δ単結晶にコルビノ形状電極をつけたものを用い,面内抵抗測定における試料端のピン止め効果の影響を除去する。(ii)面内抵抗(Rab)とC軸方向抵抗(Rc)測定を行い比較する。(iii)これより,磁場印加角度をc軸から傾けた場合の,パンケーキ磁束格子とジョセフソン磁束格子の共存する場合についての相図の全貌を実験的に研究する。(iv)特に磁場印加角度がab面方向近傍におけるジョセフソン磁束状態の相転移と相図の解明もする。 ・・・...

  17. 溶剂热合成Cu2O微球及其对高氯酸铵热分解的催化作用%Solvo-Thermal Synthesis of Cu2O Micro-Spheres and Their Catalytic Performance for Thermal Decomposition of Ammonium Perchlorate

    Institute of Scientific and Technical Information of China (English)

    罗小林; 韩银凤; 杨德锁; 陈亚芍


    以聚乙烯吡咯烷酮(PVP)为添加剂,利用溶剂热法合成了Cu2O微球.考察了PVP用量以及反应温度对产物形貌的影响,并在反应时间为2.5与4.5 h时分别合成了直径为100-200 nm和1 μm的Cu2O微球.同时,利用差热分析(DTA)技术考察了不同直径的Cu2O微球对高氯酸铵(AP)热分解的催化效果,结果表明:添加2%(w)的直径为100-200 nm和1μm的Cu2O微球使得AP的高温分解温度分别降低了116和118℃,AP在低温阶段的分解量也明显提高.%Cu2O micro-spheres were fabricated by a solvothermal method using poly vinylpyrrolidone (PVP) as an additive. The influences of PVP dosage and reaction temperature on the morphologies of the products were investigated. CuzO micro-spheres with diameters of 100-200 nm and about 1 um were synthesized with reaction time of 2.5 and 4.5 h, respectively. Meanwhile, differential thermal analysis (OTA) was used to determine the catalytic performance of these Cu2O micro-spheres with different diameters for thermal decomposition of ammonium perchlorate (AP). Adding 2% (w) CujO micro-spheres with diameters of 100-200 nm and about 1 um into AP decreased the maximum temperature of AP decomposition by 116 and 118 °C, respectively, and increased the amount of AP decomposed at lower temperature.

  18. Engineering nanomaterials with a combined electrochemical and molecular biomimetic approach (United States)

    Dai, Haixia

    Biocomposite materials, such as bones, teeth, and shells, are created using mild aqueous solution-based processes near room temperature. Proteins add flexibility to these processes by facilitating the nucleation, growth, and ordering of specific inorganic materials into hierarchical structures. We aim to develop a biomimetic strategy for engineering technologically relevant inorganic materials with controlled compositions and structures, as Nature does, using proteins to orchestrate material formation and assembly. This approach involves three basic steps: (i) preparation of inorganic substrates compatible with combinatorial polypeptide screening; (ii) identification of inorganic-binding polypeptides and their engineering into inorganic-binding proteins; and (iii) protein-mediated inorganic nucleation and organization. Cuprous oxide (Cu2O), a p-type semiconductor, has been used to demonstrate all three steps. Zinc oxide (ZnO), an n-type semiconductor, has been used to show the generality of selected steps. Step (i), preparation of high quality inorganic substrates to select inorganic-binding polypeptides, was accomplished using electrochemical microfabrication to grow and pattern Cu2O and ZnO. Raman spectroscopy and x-ray photoelectron spectroscopy were used to verify phase purity and compositional stability of these surfaces during polypeptide screening. Step (ii), accomplished in collaboration with personnel in Prof Baneyx' lab at the University of Washington, involved incubating the inorganic substrates with the FliTrx(TM) random peptide library to identify cysteine-constrained dodecapeptides that bind the targeted inorganic. Insertion of a Cu2O-binding dodecapeptide into the DNA-binding protein TraI endowed the engineered TraI with strong affinity for Cu2O (Kd ≈ 10 -8 M). Finally, step (iii) involved nonequilibrium synthesis and organization of Cu2O nanoparticles, taking advantage of the inorganic and DNA recognition properties of the engineered TraI. The

  19. Antimicrobial activity of metal oxide nanoparticles supported onto natural clinoptilolite. (United States)

    Hrenovic, Jasna; Milenkovic, Jelena; Daneu, Nina; Kepcija, Renata Matonickin; Rajic, Nevenka


    The antimicrobial activity of Cu(2)O, ZnO and NiO nanoparticles supported onto natural clinoptilolite was investigated in the secondary effluent under dark conditions. After 24h of contact the Cu(2)O and ZnO nanoparticles reduced the numbers of viable bacterial cells of Escherichia coli and Staphylococcus aureus in pure culture for four to six orders of magnitude and showed consistent 100% of antibacterial activity against native E. coli after 1h of contact during 48 exposures. The antibacterial activity of NiO nanoparticles was less efficient. The Cu(2)O and NiO nanoparticles showed 100% of antiprotozoan activity against Paramecium caudatum and Euplotes affinis after 1h of contact, while ZnO nanoparticles were less efficient. The morphology and crystallinity of the nanoparticles were not affected by microorganisms. The metal oxide nanoparticles could find a novel application in the disinfection of secondary effluent and removal of pathogenic microorganisms in the tertiary stage of wastewater treatment.

  20. Influence of electron storing, transferring and shuttling assets of reduced graphene oxide at the interfacial copper doped TiO2 p-n heterojunction for increased hydrogen production (United States)

    Babu, Sundaram Ganesh; Vinoth, Ramalingam; Praveen Kumar, Dharani; Shankar, Muthukonda V.; Chou, Hung-Lung; Vinodgopal, Kizhanipuram; Neppolian, Bernaurdshaw


    Herein we report simple, low-cost and scalable preparation of reduced graphene oxide (rGO) supported surfactant-free Cu2O-TiO2 nanocomposite photocatalysts by an ultrasound assisted wet impregnation method. Unlike the conventional preparation techniques, simultaneous reduction of Cu2+ (in the precursor) to Cu+ (Cu2O), and graphene oxide (GO) to rGO is achieved by an ultrasonic method without the addition of any external reducing agent; this is ascertained by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. UV-visible diffused reflectance spectroscopy (DRS) studies (Tauc plots) provide evidence for the loading of Cu2O tailoring the optical band gap of the photocatalyst from 3.21 eV to 2.87 eV. The photoreactivity of the as-prepared Cu2O-TiO2/rGO samples is determined via H2 evolution from water in the presence of glycerol as a hole (h+) scavenger under visible light irradiation. Very interestingly, the addition of rGO augments the carrier mobility at the Cu2O-TiO2 p-n heterojunction, which is evidenced by the significantly reduced luminescence intensity of the Cu2O-TiO2/rGO photocatalyst. Hence rGO astonishingly enhances the photocatalytic activity compared with pristine TiO2 nanoparticles (NPs) and Cu2O-TiO2, by factors of ~14 and ~7, respectively. A maximum H2 production rate of 110 968 μmol h-1 gcat-1 is obtained with a 1.0% Cu and 3.0% GO photocatalyst composition; this is significantly higher than previously reported graphene based photocatalysts. Additionally, the present H2 production rate is much higher than those of precious/noble metal (especially Pt) assisted (as co-catalysts) graphene based photocatalysts. Moreover, to the best of our knowledge, this is the highest H2 production rate (110 968 μmol h-1 gcat-1) achieved by a graphene based photocatalyst through the splitting of water under visible light irradiation.