Ag/ZnO纳米纤维的制备及光催化性能

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维, 然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面. 利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 能量色散X射线光谱(EDX)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征. SEM结果表明, 直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构. 以常见的有机污染物甲基橙、 亚甲基蓝和罗丹明B等为降解底物, 对Ag/ZnO纳米纤维的光催化性能进行了表征. 结果表明, 负载银纳米颗粒后, 复合催化剂的光催化性能明显提高.     

Three-Dimensional Hierarchical Superstructures of CuO Nanoflowers: Facile Synthesis and Applications for Enhanced Photocatalytic Activity of Dyes

A new nano-flower shaped material of CuO (3D CuONFs) with three-dimensional (3D) hierarchical superstructures were synthesized using mild experimental conditions, which showed high-efficiency and conveniently recyclable for five degradation including methylene blue (MB), methyl orange (MO), methyl violet (MV), bromocresol green (BG) by visible light irradiation. The structure of 3D CuONFs was important to improve the photo-degrading efficiency, due to the large specific surface area. The 3D CuONFs was characterized by various techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms, and powder X-ray diffraction (XRD), which evidently support the mentioned mechanism.

     

Dopant-stimulated CuO Nanofibers for Electro-oxidation and Determination of Glucose

We described the preparation of copper oxide composite nanofibers doped with carbon nanotubes (CuO/C-NFs) or nickel oxide(CuO/NiO-NFs) by electrospinning for direct glucose determination. The interest in exploring practical CuO/C-NFs and CuO/NiO-NFs electrode materials for sensor application was fascinated by the possibility of promoting electron transfer for kinetically unfavorable glucose oxidation reactions at a lower overpotential and thus improving the selectivity of the electrode for glucose in electroanalysis. The morphologies of CuO/C-NFs and CuO/NiO-NFs were characterized by scanning electron microscopy(SEM) and X-ray powder diffraction(XRD). The electrocatalytic performances of glucose were evaluated in detail by cyclic voltammetry(CV) and chronoamperometry. Facile charge transport, enhanced current response(at a lower overpotential of +0.35 V), improved stability and selectivity, as well as excellent resistance towards electrode fouling were observed at CuO/ C-NFs electrode in direct glucose electroanalysis. These merits are attributed to the highly porous three-dimensional network film structure of CuO/C-NFs electrode materials and the potential synergic catalytic effect of CuO and carbon nanotubes in composite nanofibers. This study may provide a new insight into metal oxide-based composite nanofibers obtained via electrospinning for fabricating novel and high performance sensors and devices.     

ZnO在CuO基甲醇合成催化剂还原过程中的作用(英)

用一步并流共沉淀法制备了一系列具有不同组成的ＣｕＯ基样品，并测试了它们在合成甲醇反应中的活性。利用ＴＧ ＤＴＧ手段，对各ＣｕＯ基样品的还原过程进行了考察，结果表明，ＺｎＯ组分对催化剂ＣｕＯ ＺｎＯ Ａｌ２Ｏ３的还原行为有重要影响。依据Ｃｏａｔｓ Ｒｅｄｆｅｒｎ 处理方法获得了ＣｕＯ基样品的还原动力学参数     

合成ZnO纳米阵列及刺突状CuO/ZnO异质结

采用低温水热法在掺氟SnO₂ (FTO)导电玻璃表面制备ZnO纳米阵列, 研究了前驱体溶液浓度摩尔配比对ZnO纳米阵列形貌、光学性能及其生长机理的影响. 研究发现, 随着前驱体溶液浓度摩尔配比的增加, ZnO纳米阵列形貌及光学性能也随之变化. ZnO纳米阵列高度逐渐降低, ZnO纳米阵列直径和光学带隙值大体上出现先增大后降低的趋势. 而当前驱体溶液(Zn(NO₃)₂:环六亚甲基四胺(HMT, C₆H₁₂N₄))浓度摩尔配比为5:5时, 其光学禁带值(3.2 eV)接近于理论值. 结果显示制备ZnO纳米阵列的最优浓度摩尔配比为5:5. 随后选用最优浓度摩尔配比下制备的ZnO纳米阵列为基底, 通过一种两步溶液法成功在其表面制备刺突状CuO/ZnO异质结.从场发射扫描电镜(FE-SEM)结果中可以清楚看见, 大量的CuO纳米粒子沉积在ZnO纳米阵列表面形成刺突状异质结结构.研究发现该CuO/ZnO纳米异质结相对于纯ZnO纳米阵列在紫外光下光催化性能明显增加. 最后, 讨论了CuO/ZnO纳米异质结光催化机理.     

Preparation and Ethanol Sensing Properties of ZnO Nanofibers

ZnO nanofibers with an average diameter of about 90 nm were prepared by an electrospinning method combined with a calcination process. The as-electrospun nanofibers before and after calcination were characterized by means of differential thermal analysis(DTA), thermal gravimetric analysis(TGA), X-ray diffraction(XRD) and scanning electron microscopy(SEM). The fibers after calcination at 600 °C belong to the hexagonal wurtzite structure. The sensor based on ZnO nanofibers exhibited excellent ethanol sensing properties at 206 °C such as good linear dependence in the low concentration(1―100 μL/L), high response, and good selectivity. Fast response(less than 2 s) and recovery(about 16 s) were also observed in our investigations.     

Advanced Nanoscale Surface Characterization of CuO Nanoflowers for Significant Enhancement of Catalytic Properties

In this work, advanced nanoscale surface characterization of CuO Nanoflowers synthesized by controlled hydrothermal approach for significant enhancement of catalytic properties has been investigated. The CuO nanoflower samples were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), selected-area electron diffraction (SAED), high-angular annular dark field scanning transmission electron microscopy (HAADF-STEM) with elemental mapping, energy dispersive spectroscopy (STEM-EDS) and UV–Vis spectroscopy techniques. The nanoscale analysis of the surface study of monodispersed individual CuO nanoflower confirmed the fine crystalline shaped morphology composed of ultrathin leaves, monoclinic structure and purified phase. The result of HR-TEM shows that the length of one ultrathin leaf of copper oxide nanoflower is about ~650–700 nm, base is about ~300.77 ± 30 nm and the average thickness of the tip of individual ultrathin leaf of copper oxide nanoflower is about ~10 ± 2 nm. Enhanced absorption of visible light ~850 nm and larger value of band gap energy (1.68 eV) have further supported that the as-grown material (CuO nanoflowers) is an active and well-designed surface morphology at the nanoscale level. Furthermore, significant enhancement of catalytic properties of copper oxide nanoflowers in the presence of H2O2 for the degradation of methylene blue (MB) with efficiency ~96.7% after 170 min was obtained. The results showed that the superb catalytic performance of well-fabricated CuO nanoflowers can open a new way for substantial applications of dye removal from wastewater and environment fields.     

Plasma-Induced Synthesis of Organic Compounds From Graphite and Aqueous Solution

Discharge experiments were performed to explore the synthesis between graphite and aqueous solution. It was found that atomic carbon was transferred from anode into the solution by arc-discharge experiments and various kinds of organic compounds were generated by synthetic reactions from graphite and water or ammonia water. Carboxylic acids and amino acids were identified in the products by GC-MS and HPLC analyses. It is well known that graphite can hardly combine with other substances under common conditions. So the reaction not only provided an interesting attempt for the chemical transformation from graphite to organic compounds but also served as a useful reference for the formation of organic compounds from atomic carbon under primitive earth conditions.     

The Kinetics of Plasma-Induced Degradation of Organic Pollutants in Sewage Water

The processes of treatment of actual surface water and model solutions in a low-temperature dielectric-barrier discharge (DBD) plasma were studied. The general evaluation of the efficiency of the plasma treatment procedure for sewage purification was made, and a conclusion on the reasonability of its use in combination with conventional treatment methods was drawn. Schemes of conversion processes for organic compounds upon DBD treatment of surface water were proposed, and the effective rate constants of corresponding reactions were estimated (for phenol, k = 0.46 × 10^–5 s^–1). It was found that the reaction of oxidation of pollutants in solutions modeling surface runoff occurs in the diffusion region.     

Synthesis and Magnetic Properties of Co3O4 Nanoflowers

Co3O4 nanoflowers were prepared through a sequential process of a hydrothermal reaction and heat treatment. The as-synthesized products were characterized by powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and infrared spectrum. These nanoflowers consist of numerous Co3O4 nanofibers, which have diameters of 20-40 nm, and lengths ranging from 100 nm to 500 nm. They have pore structures and Brunauer-Emmett-Teller surface area of ?34.61 m2/g. The temperature dependence curves of magnetization in zero-field-cooled conditions and field-cooled indicate mainly antiferromagnetism and weak ferromagnetism of Co3O4 nanoflowers at blocking temperature of ?34 K respectively.     

Toxicity of Nanoscale CuO and ZnO to Daphnia magna

The potential effects of nanoscale CuO(nCuO),nanoscale ZnO(nZnO)and their mixtures on Daphnia magna were investigated,including 48-h acute toxicity and 21-d chronic toxicity tests as well as a feeding ...     

Biogenic Synthesis of CuO,ZnO, and CuO–ZnO Nanoparticles Using Leaf Extracts of Dovyalis caffra and Their Biological Properties

Biogenic metal oxide nanoparticles (NPs) have emerged as a useful tool in biology due to their biocompatibility properties with most biological systems. In this study, we report the synthesis of copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO–ZnO) prepared using the phytochemical extracts from the leaves of Dovyalis caffra (kei apple). The physicochemical properties of these nanomaterials were established using some characterization techniques including X-ray diffraction analysis (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The XRD result confirmed the presence of a monoclinic CuO (Tenorite), and a hexagonal ZnO (Zincite) nanoparticles phase, which were both confirmed in the CuO–ZnO composite. The electron microscopy of the CuO–ZnO, CuO, and ZnO NPs showed a mixture of nano-scale sizes and spherical/short-rod morphologies, with some agglomeration. In the constituent’s analysis (EDX), no unwanted peak was found, which showed the absence of impurities. Antioxidant properties of the nanoparticles was studied, which confirmed that CuO–ZnO nanocomposite exhibited better scavenging potential than the individual metal oxide nanoparticles (CuO, and ZnO), and ascorbic acid with respect to their minimum inhibitory concentration (IC₅₀) values. Similarly, the in vitro anticancer studies using MCF7 breast cancer cell lines indicated a concentration-dependent profile with the CuO–ZnO nanocomposite having the best activity over the respective metal oxides, but slightly lower than the standard 5-Fluorouracil drug.     

Hydrothermal Synthesis of Ce-doped ZnO Heterojunction Supported on Carbon Nanofibers with High Visible Light Photocatalytic Activity

Ce/ZnO decorated carbon nanofibers(CNFs) heteroarchitectures(Ce/ZnO/CNFs) have been synthesized using electrospinning technique followed hydrothermal method, which have a high visible light photocatalytic activity. The samples were characterized by means of SEM, FTIR and XRD. The photocatalytic performance of Ce/ZnO/CNFs was tested with the methylene blue in the presence of visible light irradiation. In this work, we have analyzed the effects of Ce doping amount, initial methylene blue(MB) concentration and dosage of Ce/ZnO/CNFs on photocatalytic efficiency of the composite. The results showed that the photocatalyst containing 1.0% Ce in molarity(CZC1) obtained by autoclaving at 150℃ has the best photocatalytic degradation of MB than other as-synthesized samples. Ce/ZnO/CNFs catalysts exhibit a good stability and reusability, which would be an economical and environmentally friendly photocatalyst for various practical applications.     

Response kinetics of doped CuO/ZnO heterocontacts

In this work, the effects of doping on hydrogen sensitivity and sensor response of CuO/ZnO heterocontacts were examined. Both current-voltage and current-time measurements were utilized in hydrogen/air and hydrogen/nitrogen atmospheres at 400 degrees C. The addition of Ni to p-type CuO and Ga to n-type ZnO were observed to enhance the sensor properties. Through analysis of the time-dependent current data, it was shown that the sensor response of the heterocontact can be modeled via a two-site Langmuir adsorption model. The response times of the two sites were calculated using this model. While one of the sites showed a significant decrease in response time when the p-side was doped with Ni, the response time of the other site changed only slightly. The highest sensitivity was obtained by doping the n-side with Ga at the expense of the response rate. The fastest response times were achieved when both sides of the heterocontact were doped. This suggests that carrier density may play a significant role in the sensor response.     

Reduction of CuO-containing catalysts: CuO/ZnO

CO reduction of CuO in CuO/ZnO samples at 423 K isnot retarded by the support and occurs with no evidence of Cu₂O formation as reported (Porta et al. 1989). The positive order with regard to CO concentration varies with the precise range of CO partial pressure.

---

CuO CO CuO/ZnO 423 Cu₂O , (Porta etal Solid State Ionics 32–33, 1019, (1989)). CO CO.

     

Selective Synthesis of 2D Mesoporous CuO Agglomerates by Pulsed Spark Discharge in Water

Metal oxide nanomaterials, including copper oxide, have attracted great attention due to their unique physical and chemical properties that are dependent on particle size and morphology. In this study, we propose an alternative technique for the synthesis of 2D mesoporous CuO agglomerates that is both efficient and ecological. This technique is based on the use of pulsed spark discharges between copper electrodes immersed in deionized water. Detailed TEM analyses show that the synthesized CuO nanostructures are composed of elementary nanocrystals with sizes in the order of a few nanometers. Assessments of the effects of applied voltage (5 and 20 kV) and discharge pulse width (100 and 500 ns) demonstrate that the latter parameter influences the size and density of nanocrystals in a nanostructure. Moreover, voltage and pulse width may both be used to finely control the direct optical band gap energy of CuO nanostructures between 3.0 and 3.4 eV. The efficient and ecological technique developed in this study produces 2D mesoporous CuO agglomerates that can be readily used in other processes.

     

Synthesis and neel temperature determination of ferrites from the CuO−ZnO−Fe2O3 system

Conditions were established and individual and mixed ferrites with the general formula Cu_xZn_1?xFe₂O₄ (x=0; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 1.0) were synthesized from the CuO?ZnO?Fe₂O₃ system. X-ray phase analysis, Mössbauer spectroscopy and microscopic examinations revealed that the obtained ferrites are monophase samples. A magnetic device was attached to the Q-Derivatograph (MOM, Hungary) and successfully used for sample investigation in a magnetic field, and in particular for Curie (Neel) temperature determination. The ferrite composition and the thermal treatment conditions were shown to correlate with the Neel temperature of the synthesized ferrites.     

浆态床合成甲醇CuO/ZnO/Al2O3催化剂的表面性质

采用并流共沉淀法制备了不同Cu/Zn摩尔比的CuO/ZnO/Al2O3催化剂,考察了其浆态床CO加氢合成甲醇的催化性能.通过N2吸附-脱附、X射线衍射、程序升温还原及X射线光电子能谱等方法对催化剂表面性质进行了表征.结果表明,催化剂具有体相和表面高分散两种不同还原性质的CuO,表面CuO的含量及其与ZnO的相互作用使催化剂活性增大.当催化剂中Cu/Zn≤1时,随着铜含量的增加,表面高分散的CuO量增加,CuO和ZnO之间相互作用增强,催化剂的活性也随之增大;当催化剂Cu/Zn>1时,增加的铜量主要体现为体相CuO含量的增加,且ZnO结晶度提高,CuO和ZnO之间的相互作用减弱,催化剂的活性随铜含量增大而减小.     

Solvent‐free Synthesis of Hexagonal Iron Sulfide Nanoflowers

Employing green and economic solvent‐free synthesis route, hexagonal iron sulfide (Fe₇S₈) nanoflowers were successfully synthesized for the first time. In the experiment, ferric hexadecylxanthate was used as the precursor, and hexagonal iron sulfide (Fe₇S₈) nanoflowers were obtained by thermal decomposition of the precursor at 260°C without any additional solvent or inert gas protection. The as‐prepared iron sulfide nanoflowers were characterized by means of X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The characterization results indicated that the nanoflowers had uniform size distribution with an average size of about 160 nm. The proposed strategy provides a possible general route for the synthesis of other metal chalcogenide nanostructures.     

Improvement in the light conversion efficiency of silicon solar cell by spin coating of CuO,ZnO nanoparticles and CuO/ZnO mixed metal nanocomposite material

Synthesis of pure Zinc oxide (ZnO), Copper oxide (CuO) nanoparticles (NPs) and their (ZnO/CuO) nanocomposites (NCs) in 1:1 M ratio were successfully prepared by co-precipitation method. The structural properties of the as synthesized nanoparticles and nanocomposite materials were investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. Optical band-gap studies were done using UV–Visible absorption spectroscopy. Photovoltaic properties of pure ZnO NPs, CuO NPs and ZnO/CuO NCs coated over a single-crystalline silicon solar cell were carried out to compare improvement of light-conversion efficiency in coated solar cell. The maximum light conversion efficiencies were found to be of 8.02% for CuO (3 mg/ml concentration) and 7.28% for ZnO NPs (3 mg/ml concentration), whereas that of mixed metal nanocomposite CuO/ZnO NCs was found to be 7.62%. at very low concentration of 1 mg/ml. This indicates with low concentration of mixed metal NCs an improvement in light efficiency can be obtained. The enhancement in efficiency could be due to formation of p - n heterojunction by CuO/ZnO NCs composites which enhances the number of electrons and holes participating in conduction on the surface.