Hydrothermal Syntheses of CuO,CuO/Cu2O,Cu2O,Cu2O/Cu and Cu Microcrystals Using Ionic Liquids

In this paper, CuO, CuO/Cu₂O, Cu₂O, Cu₂O/Cu and Cu microcrystals were synthesized via a hydrothermal method by mixing Cu(NO₃)₂·3H₂O and NaOH together in the presence of an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate([BMIM]BF₄) or 1-butyl-3-methylimidazolium chloride([BMIM]Cl). The structures and the morphologies of the obtained products were characterized by means of X-ray diffractometer(XRD), field-emission scanning electron microscopy/energy-dispersive spectroscopy(FESEM/EDS), transmission electron microscopy/selected area electron diffraction(TEM/SAED) and Raman spectroscopy. The result of XRD indicates that Cu₂O and Cu microcrystals are cubic phase and the Raman spectra confirm the presence of carbon. The results of FESEM and TEM images show Cu₂O microcrystals as rule cubes of 2 μm in length and Cu particles of 5 μm in diameter. According to the difference between crystal structures, bi-component and single component products were synthesized by adjusting the reaction conditions. A possible formation mechanism of Cu₂O and Cu was proposed in[BMIM]BF₄.     

Cu2O/CuO Electrocatalyst for Electrochemical Reduction of Carbon Dioxide to Methanol

Herein, we report the controlled and direct fabrication of Cu₂O/CuO thin film on the conductive nickel foam using electrodeposition route for the electrochemical reduction of carbon dioxide (CO₂) to methanol. The electrocatalytic reduction was performed in CO₂ saturated aqueous solution consisting of KHCO₃, pyridine and HCl at room temperature. CO₂ reduction was carried out at a constant potential of −1.3 V for 120 min to study the electrochemical performance of the prepared electrocatalysts. Cu₂O/CuO shows better electrocatalytic activity with highest current density of 46 mA/cm². The prepared catalyst can be an efficient and selective electrode for the production of methanol.     

Controlled modification of multi-walled carbon nanotubes with CuO,Cu2O and Cu nanoparticles

Multi-walled carbon nanotubes (MWNTs) have been successfully modified with CuO, Cu₂O and Cu nanoparticles via a simple method, and the calcination temperature, the amount of NH₃·H₂O and soaking time play critical roles in controlling the final products. The modified MWNTs have been characterized by X-ray diffraction, infrared spectrum, scanning electron and transmission electron microscopies. Optical absorption of the obtained products has also been investigated, and the quantum confinement effect was illustrated in the absorption spectra.     

Enhanced Activity of CuCeO Catalysts for CO Oxidation: Influence of Cu2O and the Dispersion of Cu2O,CuO, and CeO2

CuCeO catalysts prepared by a hydrothermal method with subsequent calcination are tested for the catalytic oxidation of CO. This synthesis method leads to a homogeneous dispersion of Cu₂O, CuO, and CeO₂ in the catalysts. The composition of the catalysts is determined by the molar ratio of the metals, the hydrothermal process, and calcination temperature and influences the catalytic performance. The catalyst containing Cu₂O exhibits high catalytic activity with almost 100 % CO conversion at 105 °C and shows excellent stability with the conversion ratio not decreasing after four months of storage.     

Pt（Cu）-CdS／钛酸纳米管光催化转化CO2和H2O的研究

以商业P25为前躯体,用强碱水热超声法合成钛酸纳米管（TiNT）,以其为载体采用离子交换法制备CdS复合钛酸纳米管（CdS／TiNT）,再用浸渍法负载共催化剂Pt或Cu．对上述样品进行光催化转化CO2和H2O的实验研究,并采用透射电子显微镜（TEM）、X射线衍射（XRD）、紫外可见漫反射（UV—Vis DRS）、比表面...     

Synergistic effects of CuO and Au nanodomains on Cu2O cubes for improving photocatalytic activity and stability

Cu₂O is a promising photocatalyst, but it suffers from poor photocatalytic activity and stability, especially for Cu₂O cubes. Herein, we report the deposition of CuO and Au nanodomains on Cu₂O cubes to form dual surface heterostructures (HCs) to improve photocatalytic activity and stability. The apparent quantum efficiency of Au/CuO/Cu₂O HCs was ca. 123 times that of pristine Cu₂O. In addition, the Au/CuO/Cu₂O HCs maintained nearly 80% of its original activity after eight cycles in contrast to five cycles for the Au/Cu₂O material. Therefore, CuO and Au domains greatly improved the photocatalytic activity and stability of the Cu₂O cubes due to the synergistic effect of the HCs.     

锂 - 氧化铜电池及其反应机理

本文研究了Li/CuO电池和Li/CuO电池的一般放电行为,着重探讨了它们的反应机理。X射线衍射分析、ESR分析、XPS分析和循环伏安试验等结果表明,电池反应的实质是锂在正极内进行电化学嵌入反应,并在一定嵌入度后因Cu—O键断裂而析出金属铜。其化学反应式可表达为: xLi+CuO(Cu_2O)→Li_xCuO(Li_xCu_2O)(a) x_1Li+Li_xCuO(Li_xCu_2O)→ Li_(x+x_1)Cu_(1-y)O(Li_(x+x_1)CU_(2-y)O)+yCu (b) 用电化学暂态方法测得嵌入锂离子在正极内部的化学扩散系数约为2×10~(-12)cm~2·s~(-1)(室温),该值与在Li_xWO_3和Li_xTiO_2中的相近,与实际电池的放电速率是一致的。     

Comparison of CO2 Reduction Performance with NH3 and H2O between Cu/TiO2 and Pd/TiO2

The aim of this study is to clarify the effect of doped metal type on CO₂ reduction characteristics of TiO₂ with NH₃ and H₂O. Cu and Pd have been selected as dopants for TiO₂. In addition, the impact of molar ratio of CO₂ to reductants NH₃ and H₂O has been investigated. A TiO₂ photocatalyst was prepared by a sol-gel and dip-coating process, and then doped with Cu or Pd fine particles by using the pulse arc plasma gun method. The prepared Cu/TiO₂ film and Pd/TiO₂ film were characterized by SEM, EPMA, TEM, STEM, EDX, EDS and EELS. This study also has investigated the performance of CO₂ reduction under the illumination condition of Xe lamp with or without ultraviolet (UV) light. As a result, it is revealed that the CO₂ reduction performance with Cu/TiO₂ under the illumination condition of Xe lamp with UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:1:1 while that without UV light is the highest when the molar ratio of CO₂/NH₃/H₂O = 1:0.5:0.5. It is revealed that the CO₂ reduction performance of Pd/TiO₂ is the highest for the molar ratio of CO₂/NH₃/H₂O = 1:1:1 no matter the used Xe lamp was with or without UV light. The molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp with UV light was 10.2 μmol/g, while that for Pd/TiO₂ was 5.5 μmol/g. Meanwhile, the molar quantity of CO per unit weight of photocatalyst for Cu/TiO₂ produced under the illumination condition of Xe lamp without UV light was 2.5 μmol/g, while that for Pd/TiO₂ was 3.5 μmol/g. This study has concluded that Cu/TiO₂ is superior to Pd/TiO₂ from the viewpoint of the molar quantity of CO per unit weight of photocatalyst as well as the quantum efficiency.     

A controllable synthetic route to Cu,Cu2O,and CuO nanotubes and nanorods

Reducing Cu(OH)4(2-) with hydrazine hydrate and glucose in the presence of a structure-directing surfactant at room temperature gave Cu and Cu2O nanotubes/nanorods, respectively, whereas facile hydrothermal treatment of Cu(OH)4(2-) precursor resulted in CuO nanotubes/nanorods.     

Ferromagnetism in malonato-bridged copper(II) complexes. Synthesis,crystal structures,and magnetic properties of [[Cu(H2O)3][Cu(mal)2(H2O)]]n and [[Cu(H2O)4]2[Cu(mal)2(H2O)]][Cu(mal)2(H2O)2][[Cu(H2O)4][Cu(mal)2(H2O)2][(H2mal = malonic acid)

Three malonato-bridged copper(II) complexes of the formulas [[Cu(H2O)3][Cu(C3H2O4)2(H2O)]]n (1), [[Cu(H2O)4]2[Cu(C3H2O4)2(H2O)]] [Cu(C3H2O4)2(H2O)2][[Cu(H2O)4][Cu(C3H2O4)2(H2O)2]] (2), and [Cu(H2O)4][Cu(C3H2O4)2(H2O)2] (3) (C3H2O4 = malonate dianion) have been prepared, and the structures of the two former have been solved by X-ray diffraction methods. The structure of compound 3 was already known. Complex 1 crystallizes in the orthorhombic space group Pcab, Z = 8, with unit cell parameters of a = 10.339(1) A, b = 13.222(2) A, and c = 17.394(4) A. Complex 2 crystallizes in the monoclinic space group P2/c, Z = 4, with unit cell parameters of a = 21.100(4) A, b = 21.088(4) A, c = 14.007(2) A, and beta = 115.93(2) degrees. Complex 1 is a chain compound with a regular alternation of aquabis(malonato)copper(II) and triaquacopper(II) units developing along the z axis. The aquabis(malonato)copper(II) unit acts as a bridging ligand through two slightly different trans-carboxylato groups exhibiting an anti-syn coordination mode. The four carboxylate oxygens, in the basal plane, and the one water molecule, in the apical position, describe a distorted square pyramid around Cu1, whereas the same metal surroundings are observed around Cu2 but with three water molecules and one carboxylate oxygen building the equatorial plane and a carboxylate oxygen from another malonato filling the apical site. Complex 2 is made up of discrete mono-, di-, and trinuclear copper(II) complexes of the formulas [Cu(C3H2O4)2(H2O)2]2-, [[Cu(H2O)4] [Cu(C3H2O4)2(H2O)2]], and [[Cu(H2O)4]2[Cu(C3H2O4)2(H2O)]]2+, respectively, which coexist in a single crystal. The copper environment in the mononuclear unit is that of an elongated octahedron with four carboxylate oxygens building the equatorial plane and two water molecules assuming the axial positions. The neutral dinuclear unit contains two types of copper atoms, one that is six-coordinated, as in the mononuclear entity, and another that is distorted square pyramidal with four water molecules building the basal plane and a carboxylate oxygen in the apical position. The overall structure of this dinuclear entity is nearly identical to that of compound 3. Finally, the cationic trimer consists of an aquabis(malonato)copper(II) complex that acts as a bismonodentate ligand through two cis-carboxylato groups (anti-syn coordination mode) toward two tetraaqua-copper(II) terminal units. The environment of the copper atoms is distorted square pyramidal with four carboxylate oxygens (four water molecules) building the basal plane of the central (terminal) copper atom and a water molecule (a carboxylate oxygen) filling the axial position. The magnetic properties of 1-3 have been investigated in the temperature range 1.9-290 K. Overall, ferromagnetic behavior is observed in the three cases: two weak, alternating intrachain ferromagnetic interactions (J = 3.0 cm-1 and alpha J = 1.9 cm-1 with H = -J sigma i[S2i.S2i-1 + alpha S2i.S2i+1]) occur in 1, whereas the magnetic behavior of 2 is the sum of a magnetically isolated spin doublet and ferromagnetically coupled di- (J3 = 1.8 cm-1 from the magnetic study of the model complex 3) and trinuclear (J = 1.2 cm-1 with H = -J (S1.S2 + S1.S3) copper(II) units. The exchange pathway that accounts for the ferromagnetic coupling, through an anti-syn carboxylato bridge, is discussed in the light of the available magneto-structural data.     

Tailoring *H Intermediate Coverage on the CuAl2O4/CuO Catalyst for Enhanced Electrocatalytic CO2 Reduction to Ethanol

The direct electrochemical conversion of CO₂ to multi-carbon products offers a promising pathway for producing value-added chemicals using renewable electricity. However, producing ethanol remains a challenge because of the competitive ethylene formation and hydrogen evolution reactions. Herein, we propose an active hydrogen (*H)-intermediate-mediating strategy for ethanol electroproduction on a layered precursor-derived CuAl₂O₄/CuO catalyst. The catalyst delivered a Faradaic efficiency of 70 % for multi-carbon products and 41 % for ethanol at current density of 200 mA cm⁻² and exhibited a continuous 150 h durability in a flow cell. The intensive spectroscopic studies combined with theoretical calculations revealed that the in situ generated CuAl₂O₄ could tailor *H intermediate coverage and the elevated *H coverage favors the hydrogenation of the *HCCOH intermediate, accounting for the increased yield of ethanol. This work directs a pathway for enhancing ethanol electroproduction from CO₂ reduction by tailoring *H intermediate coverage.     

Surface chemistry of Cu in the presence of CO2 and H2O

The chemical nature of copper and copper oxide (Cu 2O) surfaces in the presence of CO 2 and H 2O at room temperature was investigated using ambient pressure X-ray photoelectron spectroscopy. The studies reveal that in the presence of 0.1 torr CO 2 several species form on the initially clean Cu, including carbonate CO 3 (2) (-), CO 2 (delta-) and C (0), while no modifications occur on an oxidized surface. The addition of 0.1 ML Zn to the Cu results in the complete conversion of CO 2 (delta-) to carbonate. In a mixture of 0.1 torr H 2O and 0.1 torr CO 2, new species are formed, including hydroxyl, formate and methoxy, with H 2O providing the hydrogen needed for the formation of hydrogenated species.     

Fabrications of hollow nanocubes of Cu(2)O and Cu via reductive self-assembly of CuO nanocrystals

In this work, a template-free synthetic approach for generating single-crystalline hollow nanostructures has been described. Using the small optical band-gap cuprous oxide Cu(2)O as a model case, we demonstrate that, instead of normally known spherical aggregates, primary nanocrystalline particles can first self-aggregate into porous organized solids with a well-defined polyhedral shape according to the oriented attachment mechanism, during which chemical conversion can also be introduced. In contrast to the spherical aggregates, where the nanocrystallites are randomly joined together, the Cu(2)O nanocrystallites in the present case are well organized, maintaining a definite geometric shape and a global crystal symmetry. Due to the presence of intercrystallite space, hollowing and chemical conversion can also be carried out in order to create central space and change the chemical phase of nanostructured polyhedrons. It has been revealed that Ostwald ripening plays a key role in the solid evacuation process. Using this synthetic strategy, we have successfully prepared single-crystal-like Cu(2)O nanocubes and polycrystalline Cu nanocubes with hollow interiors. For the first time, we demonstrate that nanostructured polyhedrons of functional materials with desired interiors can be synthesized in solution via a combination of oriented attachment and Ostwald ripening processes.     

Derivatives (Cu/CuO,Cu/Cu2O,and CuS) of Cu superstructures reduced by biomass reductants

Metallic Cu is considered as the promising functional material owing to its high conductivity and harmlessness. Here, metallic Cu which presents a unique interconnected and continuous structure (Cu superstructure) is prepared using Magnolia grandiflora leaves as the biomass reductant, a green process which avoided the release of harmful gases and massive energy consumption. What's more, Cu/CuO, Cu/Cu₂O, and CuS nanosheets with different sizes were fabricated using Cu superstructure as the substrate via facile methods, and the morphology is regulated by controlling the relevant factors. The electrochemical sensors based on the three derivations were fabricated to study the sensing performance of glucose. The unique structure of nanosheets encapsulating Cu superstructure guarantees the excellent conductivity of Cu/CuO and Cu/Cu₂O composites. Moreover, the electrochemical stability is improved owing to the nanosheet protective layer. Although no metallic Cu was maintained in CuS, the integrated multilayer nanosheets endow CuS with short channels for fast interlayer electronic transmission and with structural stability.     

Formation of tricuprotetraborate 3CuO · 2B2O3 · 6H2O in aqueous solutions

The reaction of copper sulfate, boric acid, and sodium hydroxide in an aqueous solution was studied in relation to the molar ratio and concentration of components, solution pH, temperature, and reaction duration. The conditions under which tricuprotetraborate hexahydrate 3CuO · 2B₂O₃ · 6H₂O is formed were determined.     

Flow reactor studies and kinetic modeling of the H2/O2/NOX and CO/H2O/O2/NOX reactions

Flow reactor experiments were performed over wide ranges of pressure (0.5–14.0 atm) and temperature (750–1100 K) to study H₂/O₂ and CO/H₂O/O₂ kinetics in the presence of trace quantities of NO and NO₂. The promoting and inhibiting effects of NO reported previously at near atmospheric pressures extend throughout the range of pressures explored in the present study. At conditions where the recombination reaction H + O₂ (+M) = HO₂ (+M) is favored over the competing branching reaction, low concentrations of NO promote H₂ and CO oxidation by converting HO₂ to OH. In high concentrations, NO can also inhibit oxidative processes by catalyzing the recombination of radicals. The experimental data show that the overall effects of NO addition on fuel consumption and conversion of NO to NO₂ depend strongly on pressure and stoichiometry. The addition of NO₂ was also found to promote H₂ and CO oxidation but only at conditions where the reacting mixture first promoted the conversion of NO₂ to NO. Experimentally measured profiles of H₂, CO, CO₂, NO, NO₂, O₂, H₂O, and temperature were used to constrain the development of a detailed kinetic mechanism consistent with the previously studied H₂/O₂, CO/H₂O/O₂, H₂/NO₂, and CO/H₂O/N₂O systems. Model predictions generated using the reaction mechanism presented here are in good agreement with the experimental data over the entire range of conditions explored. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 705–724, 1999     

均相还原法制备八面体氧化亚铜晶体

以CuSO4·5H2O和NaH2PO2为原料,采用化学还原法在均相体系中制备了八面体氧化亚铜晶体,其结构经IR,XRD和扫描电子显微镜表征.