Gas-Sensing Activity of Amorphous Copper Oxide Porous Nanosheets

In this paper, the gas-sensing properties of copper oxide porous nanosheets in amorphous and highly crystalline states were comparatively investigated on the premise of almost the same specific surface area, morphology and size. Unexpectedly, the results show that amorphous copper oxide porous nanosheets have much better gas sensing properties than highly crystalline copper oxide to a serious of volatile organic compounds, and the lowest detection limit (LOD) of the amorphous copper oxide porous nanosheets to methanal is even up to 10 ppb. By contrast, the LOD of the highly crystalline copper oxide porous nanosheets to methanal is 95 ppb. Experiments prove that the oxygen vacancies contained in the amorphous copper oxide porous nanosheets play a key role in improving gas sensitivity, which greatly improve the chemical activity of the materials, especially for the adsorption of molecules containing oxygen-groups such as methanal and oxygen.     

Graphene Nanosheets Decorated with Copper Oxide Nanoparticles for the Photodegradation of Methylene Blue

Textile industries extensively use colorants, such as methylene blue, and if disposed off untreated, they contaminate the effluent streams, causing a severe impact on the environment and aquatic life. Photocatalytic degradation has been found as an inevitable approach to treat them. Herein, we decorated the copper oxide nanoparticles on graphene nanosheets during the reflux process. The resultant copper oxide/graphene nanocomposites were analyzed for structural and functional attributes. It was observed that on increasing the copper oxide contents, the z-average size of the resultant nanocomposites decreased. The X-ray diffraction analysis demonstrated the crystalline nature of the nanocomposite. The surface morphology of the copper oxide nanoparticles appeared to be spherical and that of the copper oxide/graphene composite somehow wrinkled. The infrared analysis indicated successful intercalation of precursors in the nanocomposite. The bandgap of copper oxide/graphene nanocomposites varied in the range of 1.03-1.30 eV, which indicated their effective photocatalytic activity. The results demonstrated that after 120 min of exposure, the methylene blue removal efficiency reached 94.0%, 92.2%, and 89.4%(mass fraction) on the copper oxide/graphene nanocomposite at copper oxide nanoparticles to graphene nanosheets ratios of 1:1, 1.5:1, and 2:1 (mass ratio), respectively. The photodegradation performance of the prepared nano-catalyst was found satisfactory even after five cycles.     

Interaction of Zinc Oxide and Copper Oxide Nanoparticles with Chlorophyll: A Fluorescence Quenching Study

The present study aims to investigate the interactions of zinc oxide nanoparticles and copper oxide nanoparticles with the major photosynthetic pigment chlorophyll using ultraviolet-visible, steady state, and time resolved laser induced fluorescence spectroscopy. The steady state fluorescence measurements show that zinc oxide and copper oxide nanoparticles quench the fluorescence of chlorophyll in concentration-dependent manner. The Stern-Volmer plot for the chlorophyll-zinc oxide nanoparticles is linear, and the value of quenching constant has been observed to increase with temperature indicating the possibility of dynamic quenching. A decrease in the lifetime of chlorophyll with increase in the concentration of zinc oxide nanoparticles confirms the involvement of dynamic quenching in the chlorophyll–zinc oxide nanoparticle interaction. In the case of copper oxide nanoparticles, the Stern-Volmer plot deviates from linearity observed in the form of upward curvature depicting the presence of both static and dynamic quenching. In addition, the lifetime of chlorophyll decreases with increase in the concentration of copper oxide nanoparticles displaying the dominance of dynamic quenching in the chlorophyll-copper oxide nanoparticle interaction. The decrease observed in the value of binding constant with increasing temperature and negative values of change in enthalpy, entropy, and Gibb’s free energy indicates that van der Waal and hydrogen bonding are the prominent forces during the interaction of chlorophyll with both zinc oxide and copper oxide nanoparticles and that the process is spontaneous and exothermic. The interaction of zinc oxide and copper oxide nanoparticles with chlorophyll occurs through electron transfer mechanism. The obtained results are useful in understanding the sensitization processes involving chlorophyll and zinc oxide and copper oxide nanoparticles.     

Das thermische Verhalten einiger “Prussiate”

The air oxidation of copper sheets was followed by thermogravimetry in order to establish the formation of copper(II) oxide and to determine the activation energy of the copper(I) oxide — copper(II) oxide transition. The results were compared with those obtained by using the isothermal procedure.     

Mechanistic features of reduction of copper chromite and state of absorbed hydrogen in the structure of reduced copper chromite

The review discusses the experimental data on the unusual mechanism of the reduction of copper cations from the copper chromite, CuCr₂O₄, structure. Treatment of copper chromite in hydrogen at 180–370°C is not accompanied by water formation but leads to absorption of hydrogen by the oxide structure with simultaneous formation of metallic copper as small flat particles which are epitaxially bound to the oxide. This process is due to the redox reaction Cu²⁺ + H₂ → Cu⁰ + 2H⁺; the protons are stabilized in the oxide phase, which is confirmed by neutron diffraction studies. The reduced copper chromite which contains absorbed hydrogen in its oxidized state and the metallic copper particles epitaxially bound to the oxide phase structure exhibit catalytic activity in hydrogenation reactions.     

Chlorination of copper-containing raw material by ammonium chloride

A new method of processing the copper-containing raw material to copper(II) oxide was suggested and examined based on the chlorination of copper-containing raw material with ammonium chloride followed by dissolution of copper chloride, precipitation of copper hydroxide from a solution and its calcining to copper(II) oxide. Thermogravimetric analysis of the process was conducted. Kinetics of chlorination of copper(II) oxide by ammonium chloride was experimentally investigated. Technological scheme of the copper-containing raw material processing with ammonium chloride was suggested.     

Copper oxides: kinetics of formation and semiconducting properties. Part I. Polycrystalline copper and copper-gold alloys

The anodic formation of Cu(I) and Cu(II) oxides on polycrystalline copper and copper-gold alloys (4 and 15 at% Au) in deoxygenated 0.1 M KOH was examined by voltammetry, chronoamperometry, and chronopotentiometry with a synchronous registration of photocurrent and photopotential, in situ spectroscopy of photocurrent as well as XPS and SEM measurements. The band gap of p-Cu₂O is 2.2 eV for indirect optical transitions independent of the concentration of gold in Cu-Au alloy. It grows on CuOH or n-Cu₂O underlayer. The increase of anodic potential results in a thickening of oxide film which is a mixture of Cu(I) and Cu(II) oxides. The latter is a p-type semiconductor with a low photosensitivity. The rate of oxide formation on the alloys is lower than on copper. The structure-dependent properties of the oxide phase on the alloys and copper are different. Copper is prone to corrosive oxidation even in deoxygenated alkaline solution by the traces of molecular oxygen. The corrosive growth of Cu(I) oxide film occurs according to the parabolic law. After the cathodic polarization, the surface of copper remains free of corrosive oxide no longer than 15–20 min. The preliminary anodic formation even of a thin Cu₂O film as well as the alloying of copper with gold suppresses the corrosive oxidation of copper.     

Dispersion and reactivity of copper catalysts supported on Al2O3-ZrO2

A series of CuO/Al(2)O(3)-ZrO(2) catalysts with Cu loadings varying from 1.0 to 20 wt % were prepared and characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD) of CO(2) and NH(3), electron spin resonance (ESR), and Brunauer-Emmett-Teller surface area measurements. The dispersion and metal area of copper were determined by the N(2)O decomposition method. XRD results suggest that the copper oxide is present in a highly dispersed amorphous state at copper loadings < 10 wt % and as a crystalline CuO phase at higher Cu loadings. ESR results suggest the presence of two types of copper species on the Al(2)O(3)-ZrO(2) support. TPR results suggest well-dispersed copper oxide species at low Cu loadings and crystalline copper oxide species at high Cu loadings. Well-dispersed copper oxide species were reduced more easily than large copper oxide species by H(2). The results of CO(2) TPD suggest that the basicity of the catalysts was found to increase with an increase of copper loading up to 5.0 wt % and decreases with a further increase of copper loading. The results of NH(3) TPD suggest that the acidity of the catalysts was found to decrease with an increase of copper loading up to 5.0 wt % and increases with a further increase of copper loading. The catalytic properties were evaluated for the vapor-phase dehydrogenation of cyclohexanol to cyclohexanone and correlated with the results of CO(2) TPD measurements and the dispersion of Cu on the Al(2)O(3)-ZrO(2) support.     

高温煤气脱硫剂(英文)

综述了用于整体煤气化联合循环发电（ＩＧＣＣ）技术中的高温煤气脱硫剂的研究和开发,对几类主要应用的脱硫剂的优缺点进行了比较总结,指出了脱硫剂在工业应用中最重用的几个特性,并对今后脱硫剂的改进方向提出了建议。     

铜及氧化铜对煤燃烧过程多环芳烃排放的影响

在实验管式炉上研究了金属铜和氧化铜对烟煤燃烧过程中PAHs生成的影响。采用气相色谱分析PAHs。实验结果表明，铜会促进PAHs的生成，而且主要是促进中高分子量PAHs的生成，这是由于铜为PAHs的合成提供了大量的活性反应中心。另一方面氧化铜对PAHs的合成和裂解具有双重催化效果，从而显著增加了中分子量PAHs的排放。在800 ℃以下，添加铜和氧化铜都减小了PAHs排放的毒性当量。在900 ℃以上，添加铜增大了PAHs排放的毒性当量。添加氧化铜时与添加铜时的规律类似，但是在1100℃以上，PAHs排放的毒性当量要比不添加时小。     

使用变温原位X射线衍射技术认识氧化铜在氢气和一氧化碳气氛下的物相变化*

实验与理论相结合是化学专业教与学的原则。通过运用原位X射线衍射技术(in-situ XRD)探究氧化铜在氢气和一氧化碳气氛下的还原,结果发现无论在氢气或一氧化碳气氛下,从300 ℃开始,氧化铜逐渐被还原为氧化亚铜和铜单质,且该3种物相同时存在。直至温度升至450~500 ℃时,所有的氧化铜和氧化亚铜全部变为了铜单质。实验结果表明氧化铜的还原并非是一个由CuO → Cu2O → Cu逐步还原的单一过程,理论上可以得到的纯氧化亚铜物相在实验过程中并未得到,对此结果进行了分析。另外,将大型仪器尤其是原位表征技术推广到本科教学中具有重要意义。     

Biofouling resistant polyethylene cage aquaculture nettings: A new approach using polyaniline and nano copper oxide

Biofouling in cage aquaculture netting causes clogging of meshes, increased stress and retards the growth of fishes. This paper describes a new method of protecting polyethylene cage nettings from biofouling using polyaniline and nano-copper oxide. Polyaniline was synthesized in-situ over polyethylene cage netting material and subsequently treated with nano copper oxide. The modified netting material exposed to estuarine environment exhibited excellent fouling resistance. FTIR characterization confirmed the formation of polyaniline and adsorption of nano copper oxide over the netting material. SEM and AFM evaluation showed uniform coating of polyaniline and nano copper oxide on the polyethylene-polyaniline (PE-PANI) matrix. The results highlight the potential application of polyaniline plus nano copper oxide coated polyethylene nettings in controlling biofouling in cage aquaculture.     

Electrospun copper oxide nanoparticles as an efficient heterogeneous catalyst for N-arylation of indole

The N-arylation of indoles with a variety of aryl bromides is reported using copper oxide nanoparticles as a heterogeneous catalyst. These copper oxide nanoparticles, which were produced in a novel, facile, and scalable fashion via an electrospinning technique, resulted in an excellent product yield under mild conditions. Moreover, the catalyst was easily recovered and reused several times without significant loss of activity.     

钙硼对CuO/Al_2O_3催化剂结构及醋酸仲丁酯氢解性能的影响

以经氧化钙和氧化硼改性的氧化铝为载体,采用浸渍法制备了负载型CuO/Al2O3催化剂,采用XRD、BET、TPR和NH3-TPD技术对催化剂CuO/Al2O3进行了表征.结果表明,氧化硼既可以作为结构性助剂提高铜在催化剂表面的分散度,又可以作为电子性助剂有利于催化剂表面氧化铜物种的稳定;氧化钙的引入降低了催化剂表面酸性,有利于催化剂的选择性提高.采用氧化硼和氧化钙改性的Cu10B20Ca30为催化剂,醋酸仲丁酯转化率可达99.5%,生成仲丁醇和乙醇的选择性分别达98.9%和97.8%.     

Enrichment,incorporation and oxidation of copper during anodising of aluminium–copper alloys

Porous anodic oxides generated on copper‐containing aluminium alloys are less regular than anodic oxides generated on pure aluminium. Specifically, a porous oxide morphology comprising layers of embryo pores, generated by a cyclic process of oxide film growth and oxygen evolution, is generally observed. In this work, the relation between the oxidation behaviour of copper during anodising and the specific porous oxide film morphology was investigated by electrochemical techniques, transmission electron microscopy and Rutherford backscattering spectroscopy (RBS). It was found that the anodising potential determines the oxidation behaviour of copper, and the latter determines the porous oxide morphology. At low voltage, relatively straight pores with continuous cell walls were obtained on Al? Cu alloys, but selective oxidation of aluminium atoms resulted in the occlusion of copper‐containing metallic nanoparticles in the anodic film. At higher potentials, copper oxidation promoted oxygen evolution within the barrier layer, and generation of a less regular film morphology. RBS, performed on Al? Cu alloy specimens, revealed a high volume fraction of copper atoms in the anodic films generated at low potentials and a reduced amount of copper atoms in the anodic oxide films generated at high potentials. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation of Ultra-Fine CuO: Comparison of Polymer Gel Methods and Conventional Precipitation Processes

Different ways of preparing ultra-fine copper oxide were examined. Polymer precursor techniques using polyvinyl alcohol and acrylamide were compared with the conventional precipitation of copper salts and further calcination. Thermal analysis, XRD and TEM were employed to monitor polymer degradation and the phase transformations leading to copper oxide and to characterise particle size. Copper oxide obtained by precipitation from copper nitrate has smaller particles size meanwhile that obtained by acrylamide combustion method agglomerates in lower extension. Differences between XRD crystallite size calculations and TEM observations of particles size were checked.     

Concise and diversity-oriented synthesis of ligand arm-functionalized azoamides

Azoamides, previously established as bioactive intracellular GSH-depleting agents, were decorated with a terminal alkyne moiety to 4 and then were transformed, by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), into different ligand-arm functionalized azoamides 6. Azides 5 having ligand-arms amenable for binding to platinum(II) were selected for this study. Because, for the fragile azoamides 4, the typically employed reaction conditions for CuAAC failed, several alternative solvents and copper catalysts were tested. Excellent results were obtained with copper(II) sulfate pentahydrate/metallic copper and especially with heterogeneous catalysts, such as copper-in-charcoal, cupric oxide, and cuprous oxide. The heterogeneous catalysts were employed to obtain the desired products in almost quantitative yields by a simple three-step "stir-filter-evaporate" protocol with no or negligible contamination with copper impurities. This is of particular importance because compounds 6 have been designed for coordination.     

Extraction of lead(II) and copper(II) from salicylate media by tributylphosphine oxide.

Tributylphosphine oxide (TBPO) is proposed as an extractant for the extraction of lead(II) and copper(II) from salicylate media. The optimum conditions were evaluated by varying the experimental parameters, such as the pH, sodium salicylate concentration, tributylphosphine oxide (TBPO) concentration, shaking period and various diluents. The probable extracted species, deduced from log-log plots were Pb(HSal)2.2TBPO and Cu(HSal)2.2TBPO. The extraction took place through a solvation mechanism. The method permits the binary separation of lead(II) and copper(II) from commonly associated elements as well as the mutual separation of lead(II) and copper(II). The method is applicable to the determination of lead(II) and copper(II) in various alloys as well as environmental and pharmaceutical samples.     

Copper uptake by silica and iron oxide under high surface coverage conditions: surface charge and sorption equilibrium modeling

A sorption modeling approach based on surface complexation concepts was applied to predict copper uptake and its effects on the surface electrostatic potential of ferric oxide and silica colloids. Equilibrium modeling of copper uptake by ferric oxide using the traditional surface complexation model (SCM) was reasonably successful with some discrepancies especially in the acidic pH ranges and high colloid concentration cases. Good predictions of the ferric oxide charge reversals during uptake were obtained from the modeling. Based on the SCM predictions, copper removal from solution is due to the outer-sphere complexation of the first hydrolysis product, resulting in the surface-metal complex SO(-)CuOH(+). The SCM was found to be insufficient to describe copper uptake by silica particles. To address discrepancies between experimental data and SCM predictions, the SCM was modified to include attributes of the surface polymer model (SPM), which incorporates sorption of the dimeric copper species Cu(2)(OH)(2)(2+). The continuum model (CM) was also studied as a second modification to the SCM to include formation of surface precipitates. Both the SPM and the CM were successful in modeling copper uptake and zeta potential variations as a function of pH at various solution conditions and colloid concentrations. From the SPM and CM predictions, it was concluded that for systems with high surface loadings, copper removal from solution occurs due to the formation of both monomeric and dimeric surface complexes, as well as through precipitation mechanisms.