Advanced Materials Research Vols. 785-786

Abstract: The uniform hierarchical and microspheric copper oxide (CuO) nanostructures, which have been successfully prepared via a simple one-pot method. The detailed morphology and structure of the synthesized hierarchical and microspheric nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and UVvisible spectroscopy. The morphology of CuO particles depends on the ammonium dihydrogen phosphate (ADP) used in the synthesis, the formation mechanisms were proposed based on the experimental results. The catalytic activity of as-synthesized CuO was demonstrated by catalytic oxidation of methylene blue in the presence of hydrogen peroxide (H₂O₂) and CuO with hierarchical nanostructures was found to be the best catalyst.

Abstract: This work demonstrated an approach of oil/water (O/W) microemulsion on preparation of hollow spheres with mesopores in the shell, in which a cationic surfactant was used as structural directing agent, alkane molecule as mesopore-swelling agent and oil droplets. The morphology and pore architecture of the obtained hollow spheres were characterized by SEM, XRD, TEM and N₂ adsorption/desorption isotherms. Cubic (Ia3d) mesopores are present in the shell and provide open channels for mass transport in between the hollow core and outer environment. The obtained hollow spheres with cubic mesoporous shell possess the potential of being used as nanoreactor and nanocontainer in the fields of catalysis and drug delivery.

Abstract: Ni-B amorphous alloy particle is a newly promising candidate of catalyst for methanol electrooxidation in Direct Methanol Fuel Cell (DMFC). For enhancing catalytic activity and increasing surface area, mesoporous Ni-B amorphous alloy nanoparticles was manufactured by chemical reduction of NiCl₂ and KBH₄ via surfactant hexadecyltrimethyl ammonium bromide (CTAB) as an soft template. The effects of the CTAB content and the feeding order on the phase evolution, microstructure, and surface area of the resulting products were investigated. Phase and structure of the samples were investigated using XRD, SEM and BET. Amorphous Ni-B nanoparticles with mesoporous structure were obtained in this study. The CTAB content great impacted the mesoporous structure of the resulting products, although the obviously effect on the phase was not found. The surface area, pore volume and pore diameter of samples improved with the increase of CTAB content. Compared to nanoparticles obtained by CTAB solution added to NiCl₂ solution, nanoparticles obtained by NiCl₂ solution added to CTAB solution exhibited better mesoporous structure.

Abstract: Carbon black supported Pd-Mo bimetallical nanoparticles are prepared by Strong Electrostatic Adsorption (SEA) method. A series of Pd-Mo catalysts were prepared by selective deposition of the [Pd (NH₃)₄]⁺² cationion onto the supported MoO₃ phase. The prepared materials are characterized by N₂-BET, powder XRD and STEM. The results showed that good dispersion of bimetallic nanoparticles on the carbon support is observed from STEM images. Oxygen reduction measurements performed by linear sweep voltammetry indicat the good catalytic activity of Pd-Mo by SEA compared to dry impregnation (DI) bimetallic catalysts since the SEA technique produced more well dispersed and intimately designed bimetallic particles after reduction.

Abstract: Zeta potential of micron-size tourmaline powders are studied using the laser granulometer and the Zeta potential analyzer. The result from the experiment shows, in the neutral condition, the micron-size tourmaline is negatively charged under water and Elbaite powder has the highest Zeta potential among all tested ones; the smaller the tourmaline powder is, the higher Zeta potential it has; heat-treated samples under reducing conditions have higher Zeta potential than those under oxidizing conditions by 4~5 mV; Dravites isoelectric point is 3.4, falling within the acid range.

Abstract: The nanimprint lithography technology was used on the optical glass substrate of organic light-emitting diodes (OLED). By optimizing nanoimprint process 2-dimensional micro-structures were fabricated on the substrate. The parameters of micro-structures such as period, diameter and length were optimized using Finite-difference time-domain (FDTD) and finally, the optical crystal micro-structure with 500nm period, 300nm diameter and 500nm length was fabricated. The basic structure of the devices fabricated on the micro-structure substrate is Glass/ LTO/photonic / ITO/ MoO3/NPB/Alq/LiF/Al. The light outcoupling efficiency can be increased effectively due to the photonic band gap effect produced by photonic crystal structures on the substrate of OLED. The measuring result showed that both the emission spectrum and the light intensity were increased.

Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality. We report the terahertz spectrum of Non-uniform graphene films based femtosecond probing with more than 6 THz spectral coverage and the 1 GHz resolution using high-speed asynchronous optical sampling, and it operates at 2 kHz scan rate without a mechanical delay stage. The overall waveform creates shock and the oscillation amplitude reached 0.37E-4 mV, main-peaks time delay is 151.83fs between graphene and substrate, frequency spectrum oscillatory fades at 2.8 THz and appeared obvious absorption peak.

Abstract: CP2 polyimide (prepd. from 6FDA and 1,3-bis (3-aminophenoxy) benzene) was blended with (1-50 wt.%) detonation nanodiamonds (DND, pristine, acetone-washed, and 4-(2,4,6-trimethylphenoxy) benzoic acid-functionalized), and the blends were evaluated as thin films for its potential utility in high-energy-density capacitors that would have stable dielectric properties over a wide temperature range (-55 to 300°C) and at frequencies up to or greater than 100 kHz. Both the dielectric storage and loss increased substantially with DND content. Surface functionalization (with the above benzoic acid derivative) significantly reduced the dielectric loss, while the use of acetone-washed DNDs had no effect on the dielectric loss. DND was also blended with CP2 via in-situ polymerization and found to have little effect on the dielectric properties.

Abstract: This paper reports the synthesis of CuO nanorods from Copper (II) sulphate (CuSO₄) aqueous solution under the hydrothermal condition variable concentration of NaOH (aq) at 160 °C for 12 h. The thin films of the nanorods on glass were prepared by dip-coating technique. The structure and chemical natures of the obtained materials were studied using powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). The optical properties of the nanorods were also studied by UV-visible spectra. The diffraction peaks were quite identical to those of pure CuO, which can be indexed as the monoclinic structure CuO. The diameters of CuO nanorods vary from 10 nm to 100 nm and the length is about several micrometers. The top-view SEM images be seen clearly that high-density, horizontally scattered nanorod were grown on the product prepared at concentration of NaOH (aq) 10 M at 160 °C for 12 h. The spectral of UV-vis data showed the strong cut off at 336 nm.

Abstract: A facile solution-phase process has been demonstrated for the selective preparation of single-crystalline Cu hexagons and flowers by reducing Cuprous iodide (CuI) with Sodium ascorbate (VCNa) in the presence of cetyltrimethyl ammonium chloride (CTAC) or cetyltrimethyl ammonium bromide (CTAB). The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). To study the formation process of Cu nanoparticles, samples obtained at various stages of the growth process were studied by XRD. UV-vis spectra of the Cu hexagons and flowers were recorded to investigate their optical properties, which indicated that as-prepared Cu nanostructures exhibited morphology-dependant optical property.