温和条件下氧化铜纳米片层的制备与电化学催化性质研究

为实现特定形貌CuO纳米材料的温和可控合成,增强该材料作为电化学催化剂的催化活性,利用亚铜离子在碱性溶液中的氧化沉淀反应,制备了形貌均一稳定的CuO纳米片层。采用粉末X射线衍射、扫描电子显微镜、透射电子显微镜、X射线光电子能谱与电化学催化反应等手段,研究了不同合成参数对产物的形貌、价态与电化学催化性能的影响。研究结果表明:当产物投料比为0.01 g CuCl/10 mL TBAOH时,产物的电化学催化性质最好;在200℃下煅烧后,催化性能得到进一步提高。利用具有特殊分子结构的四丁基氢氧化铵作为模板剂,能够实现CuO纳米片层的简单、快速、温和制备;同时,产物中低价态Cu离子的存在可提高催化剂的电化学催化活性。通过煅烧提高产物的结晶性,能够进一步增强材料的电化学催化活性。     

Facile sonochemical synthesis of hierarchical porous CuO nanotablets

Hierarchical semiconductor CuO nanotablets with pores have been fabricated on a large scale by a facile and one-pot sonochemical process using the copper acetate and ammonia aqueous solution as precursor in the absence of surfactants or additives. The as-synthesized products were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and N2 physisorption. The results reveal that porous tablet-shaped CuO nanostructures composed of nanoribbons possess a monoclinc phase CuO with the average diameters about 200 nm and around 50 nm in thickness. The Brunnauer-Emmett-Teller (BET) specific surface area and the single point adsorption total pore volume were measured to be 26.8 m2/g and 0.083 cm3/g, respectively. The band-gap energies were estimated to be 2.52 eV from a UV-vis absorption spectrum, which showed the quantum size effects of the nanosized semiconductors. A possible mechanism for porous CuO nanotablets was discussed.     

Facile synthesis and characterization of urchin-like CdSe nanostructures

CdSe nanostructures with urchin-like shape were successfully synthesized in water-in-oil (W/O) microemulsion. The phase structure, morphology, optical property, and specific surface area of the CdSe products were characterized. The X-ray powder diffraction pattern of the product showed that it is pure CdSe in zinc blende structure rather than thermodynamically favored wurtzite structure. It is found that numerous one-dimensional CdSe nanorods radiate from the center of the agglomerate to form urchin-like nanostructures and grow along the (111) crystal planes. The photoluminescence spectrum of the urchin-like nanostructures indicated that there is a blue-shift as compared with that of the bulk CdSe. Additionally, these interesting urchin-like nanostructures showed an increased specific surface area.     

Hydrogen peroxide-assisted hydrothermal synthesis of hierarchical CuO flower-like nanostructures

Hierarchical CuO nanostructures were synthesized through a hydrogen peroxide-assisted hydrothermal route in which Cu(OH)₂ was the copper source. The CuO nanostructures were composed of numerous nanobelts that radiated from the center of the nanostructure and formed a flower-like shape with a diameter of 5-10 μm. The nanobelts had lengths of 2.5-5 μm and widths of 150-200 nm. The H₂O₂ concentration directly influenced the product morphology. As the concentration of H₂O₂ increased, the length and width of the nanobelts increased and the quantity of the nanobelts decreased. The possible formation mechanism of hierarchical CuO flower-like nanostructures was presented.     

Facile synthesis of Pr(OH)3 nanostructures and their application in water treatment

By means of a facile electrochemical approach, Pr(OH)₃ nanostructures consisting of nanosheets amorphous were successfully constructed on Cu substrates, and their morphologies can be readily tuned by simply adjusting the current density. Moreover, these Pr(OH)₃ nanostructures exhibit a good performance to remove Congo red in wastewater treatment.     

Microwave-assisted synthesis and characterization of flower shaped zinc oxide nanostructures

A microwave-assisted solution-phase approach has been applied for the synthesis of zinc oxide nanostructures. The synthesis procedure was carried out by using two reagents: hydrazine hydrate and ammonia. Flower shaped particles were obtained with hydrazine hydrate whereas mainly spherical agglomerated particles were observed with ammonia. The nanostructures were influenced by microwave irradiation time, reagent concentration and molar ratio of the precursors. High crystalline materials were found without the need of a post-synthesis treatment. The average crystalline size of ZnO nanostructures has been analyzed by X-ray Diffraction (XRD) pattern and estimated to be 18 nm. The presence of flower shaped zinc oxide with nanorods arranged has been confirmed from Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) micrographs. The samples were further analyzed by Fourier Transform InfraRed (FT-IR), Thermogravimetric Analysis (TGA) and photoluminescence spectroscopic techniques.     

Green and facile synthesis of hierarchical cocoon shaped CuO hollow architectures

Hierarchical cocoon shaped CuO hollow nanostructures have been synthesized on a large scale by a facile green microwave-assisted aqueous process at reflux in the absence of templates and additives. The as-prepared products were investigated by FESEM, TEM, HRTEM, XRD and UV-vis absorption optical properties. The results reveal that cocoon shaped structures, that is ellipsoids, possess a monoclinc phase CuO with the long and short diameters of about 300 nm and 150-200 nm, respectively. The walls of hollow cocoons with around 50 nm in thickness are self-assembled by nanorods with diameters of 6-8 nm. A possible mechanism for the hollow CuO structures was proposed, in which CO₂ bubbles act as soft-template to aggregate the primary monomers. The band gap energies were estimated to be 2.03 eV, which showed the quantum size effect of the nanosized semiconductors.     

Facile co-precipitated synthesis of NdFeO3 perovskite nanoparticles for lithium-ion battery anodes

In this report, NdFeO₃ perovskite nanoparticles were facilely prepared by co-precipitation of Nd³⁺ and Fe³⁺ cations in hot water, followed with the pyrolysis process in atmospheric conditions. Morphology and crystal structure of NdFeO₃ perovskite were determined with appropriate methods, revealing orthorhombic lattice with size distribution from 40 to 180 nm. Functioning as anode lithium-ion batteries (LIBs), NdFeO₃ exhibited great electrochemical performance such as high retention capacity, excellent cyclability, and high current rate. Such enhanced electrochemical efficiency was evidently ascribed to the perovskite structure of NdFeO₃ due to short lithium-ion diffusion pathway and volume expansion control of working material during lithiation/delithiation operation. By demonstrating a capacity value of 475 mAh g^?1 even through 450 cycles at 0.1 A g^?1, NdFeO₃ perovskite nanoparticles proved itself a competitive anode material for the coming generations of LIBs. In addition, this novel synthesis method is suitable for mass production of perovskite materials for long-life lithium-storage facilities.

     

Facile shape-controlled synthesis of palladium nanostructures on copper for promising Surface-enhanced Raman scattering

In this letter, size-controlled Pd nanocubes, hexagonal prism and Pd dendrites nanostructures were synthesized by a simple galvanic displacement process between Pd ion and Cu. The sizes and morphology of Pd nanostructures could be controlled by simply regulating the reaction parameters, such as concentration of palladium dichloride, reaction time and types of surfactant. A possible formation mechanism of Pd nanocubes was also briefly discussed. Furtherly, Surface-enhanced Raman scattering (SERS) investigation demonstrated the nanostructures on copper foils were SERS-active by using 4-aminothiophenol (PATP) as probe molecule. We believe the unique Pd nanostructures on copper foils would be a flexible and promising SERS substrate.     

Facile synthesis of three-dimensional porous graphene nanostructures from coordination complexes for supercapacitor electrode

Fabrication of hierarchical nanostructures is an important way for performance improvement and application expansion of nanomaterials. It is still a great challenge to synthesize three dimensional hierarchical graphene nanostructures with controlled secondary structures and primary building units, because it is difficult to realize effective control of graphene layer morphology and necessary arrangement of graphene. In this work, a “complex-directed” strategy has been successfully developed for the synthesis of three dimensional graphene nanostructures. Especially, the obtained three dimensional graphene nanostructures are quite regular in morphology, they can be nanorods or regular particles, composed of hollow graphene nanospheres with different layers. The morphology and the structure of these nanostructures, including primary building units and secondary structures are strongly dependent on the amount of HCl solution. The obtained three-dimensional graphene nanostructure can serve as an excellent candidate for electrode material of electric double layer capacitors (EDLCs) and present outstanding electrochemical behaviors. This is mainly due to the excellent electrical conductivity of graphene hollow nanospheres and the porous structures conducive to ion diffusion and electron transport.     

Controlled synthesis of CuO nanostructures on Cu foil, rod and grid

CuO nanowires are synthesized by heating Cu foil, rod and grid in ambient without employing a catalyst or gas flow at temperatures ranging from 400 to 800 °C for a duration of 1-12 h. Scanning electron microscopy (SEM) investigation reveals the formation of nanowires. The structure, morphology and phase of the as-synthesized nanowires are analyzed by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). It is found that these nanowires are composed of CuO phase and the underlying film is of Cu₂O. A systematic study is carried out to find the possibilities for the transformation of one phase to another completely. A possible growth mechanism for the nanowires is also discussed.     

Facile and large-scale synthesis of single-crystalline manganese oxyhydroxide/oxide nanostructures

On basis of the redox reaction between MnO₄⁻ and Mn²⁺, a facile hydrothermal method combined with the adjustment of pH value in the reaction system has been employed to synthesize single-crystal γ-MnOOH nanorods, and square-like Mn₃O₄ nanoparticles. Additionally, single-crystalline β-MnO₂ and Mn₂O₃ nanorods can be obtained after subsequent calcinations of the as-prepared γ-MnOOH nanostructures at 300 °C and 600 °C, respectively. Furthermore, electrochemical property of as-obtained β-MnO₂ is also studied.     

Facile synthesis of ZnO nanostructures and investigation of structural and optical properties

ZnO nanostructures were synthesized by chemical bath deposition method, using zinc nitrate [Zn(NO₃)₂] and hexa-methylene-tetra-amine [(HMT),C(H₂)₆N₄] as precursors. Controlled size and shape evolution of ZnO nanostructures were achieved by changing the HMT concentration from 0.025 M to 0.1 M, whereas Zn(NO₃)₂ concentration kept constant. X-ray diffraction (XRD) and Raman study confirmed the formation of single crystalline, hexagonal wurtzite ZnO structure. Sharp peaks in Raman spectra, corresponding to E₂(low) and E₂(high) referred to wurtzite structure with higher order of crystallinity. Transmission electron microscopy (TEM) revealed that the shape and size of the nanostructures reduced, with increasing concentration of HMT. Further, effect of structure's size was observed in the band gap (shift). Photoluminescence study showed two peaks at ~ 380 nm and ~ 540 nm corresponding to the band to band transition and defect transitions. Modifications of properties are explained in detail on the basis of shape and size change of the structures and possible mechanism is discussed.     

磺基水杨酸钠辅助下CuO纳米结构的维度可控合成与表征

以磺基水杨酸钠(SS)作为形貌调控剂,采用水热方法可控合成了各种不同形貌和维度的CuO纳米材料。结果表明,通过简单调节SS/CuCl2的摩尔比,分别合成了CuO纳米棒,纳米枝晶和海胆状球形分级结构。如果体系中不引入SS,产品则是CuO纳米片。紫外-可见光谱显示了各种CuO纳米结构与尺寸和形貌相关的吸收现象,为了探索CuO各种形貌的影响因素,我们进行了系统的实验观察。     

Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications

A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response-recovery characteristics, good selectivity and long-term stability.     

Facile synthesis of SnS nanostructures with different morphologies for supercapacitor and dye-sensitized solar cell applications

Journal of Materials Science: Materials in Electronics - In this paper, tin Sulfide (SnS) nanoparticles are synthesized with three different solvents through hydrothermal method and characterized...     

Hot-filament CVD synthesis and application of carbon nanostructures

We have reported the catalyst-assisted hot-filament chemical vapor deposition (HFCVD) of various carbon nanostructures, such as carbon nanotube (CNT), nanoparticle (CNP), and nanofiber (CNF), and their application examples. In the case of CNT, vertically aligned high-density growth has been investigated in detail using in-situ optical reflectivity measurement. For CNF showing large field-emission currents, adsorbate-related emission behavior and the emission from patterned cathodes have been studied. Regarding CNP, the performances of a series of triode field emitters with CNP cathodes have been compared, and the application of CNP triode to miniature time-of-flight mass spectrometer has been discussed.     

HEPES-mediated controllable synthesis of hierarchical CuO nanostructures and their analogous photo-Fenton and antibacterial performance

Owing to the strongly morphology and size-dependent properties of nanomaterials, developing a simple and eco-friendly approach for controlling synthesis and assembly of hierarchical CuO nanostructures plays a critical role. In this work, we successfully developed an eco-friendly and facile hydrothermal route for controllable synthesis of various morphologies CuO nanostructures, where traditional and toxic additives were replaced by biocompatible 4-(2-hydroxyethyl)-1-piperazineethane-sulfonic acid (HEPES). The growth rate and orientation of CuO nanoparticles were tuned through adjusting the concentration and pH value of HEPES. The XRD pattern, SEM, UV-DRS, and BET indicated CuO nanostructures maintained high purity and excellent crystalline nature and showed more regular morphology and size with enhanced visible light absorption. The analogous photo-Fenton assay demonstrated that the as-prepared CuO nanostructures present enhanced dye removal capability when compared with CuO synthesized in pure water. Furthermore, the antibacterial assay on S. aureus was also investigated, and CuO nanoparticles with smallest size displayed the best antibacterial performance. These results reveal that HEPES shows a remarkable influence on the possible application of as-prepared CuO nanostructures which having great potential in pollutant removal.