Advanced Materials Research Vol. 669

Abstract: Abstract. This article reports the chemical deposition of silver shells on the surface of micro- carbon spheres. The structure, morphology and composition were characterized by scanning electron microscopy and X-ray diffraction. These result show that: concentrated nitric acid can transform the hydrophily of carbon surface; the application of promoting tin-or silver-containing agents that enhance metallic shell deposition by vigorous redox reaction between Sn2+or Ag+, is important to the site-selective deposition of silver. The resulting thickness of uniform silver shells on the surface of carbon and the crystal size of silver is 24.8nm. Amount of Ag-C core-shell structure composite can be systematically controlled through adding PVP and modest pH value

Abstract: Volatile organic compounds (VOCs), especially toluene as the typical indoor air pollutants, are toxic and environmentally persistent whose removal is undoubtedly becoming increasingly urgent matter over these years. Titania is one of the most promising photocatalysts for the degradation of organic compounds, whereas the large band gap of titania and massive recombination of photogenerated charge carriers limit its overall photocatalytic effciency. These defects can be tackled by modifying the electronic band structure of titania including various strategies like metal deposition, non-metal atoms substitution, transition metal ions doping, and coupling with a narrow band gap semiconductor, etc. This review encompasses several advancements made in these aspects, and also the influence factors such as physical morphologies changing, humidity, as well as the presence of O2 etc, are involved. To be practically considering, TiO2 photocatalysts require being fixed on the bulky supports like silica, alumina, clays and activated carbons. Moreover, photocatalytic coatings deposited on external building materials, like roofing tiles and corrugated sheets, is becoming the attractive application potentials to remove toluene from air.

Abstract: C(4×4) reconstruction on arsenic-rich GaAs(001) surface after phase transition has been investigated from the experiment and simulation. We found that the c(4×4) As-rich reconstruction structure of the GaAs (001) surface can be best depicted with the model which there are three As-As dimers without Ga-As dimers in a reconstructed unit cell, and these dimers are found to be aligned perpendicular to the As dimers on β2(2×4) surface.

Abstract: Polyaniline-modified nanocrystalline TiO₂ composites were successfully prepared by in situ chemical oxidative polymerization and used as an efficient photocatalyst for the degradation of methyl orange under natural light. The nanocomposites were characterized by Transmission electron microscope (TEM), Scanning electron microscope (SEM), Fourier transform infrared spectra (FT-IR), X-ray diffraction and UV-Vis spectra. Results show that polyaniline-modified nanocrystalline TiO₂ composites exhibit significantly higher photocatalytic activity than that of neat TiO₂ on degradation of methyl orange under natural light. In addition, the conductivity of polyaniline-modified TiO₂ nanoparticles was also investigated and has reached 2.65 × 10^-1 S cm^-1 at room temperature.

Abstract: Silicalite-2 zeolite was hydrothermally synthesized and Mn0.2Co0.8Fe2O4 magnetic nano-particle based on the Silicalite-2 zeolite carrier was prepared by a coprecipitation-impregnation method. The morphologies and microstructures of synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The heterogeneous catalytic oxidation electrolysis system of Mn0.2Co0.8Fe2O4/silicalite-2 was built by dispersing the catalysts in glass reactor for treating cationic brilliant red X-5GN wastewater. The SEM images showed that the structure of silicalite-2 zeolite remained its original after the introduction of Mn0.2Co0.8Fe2O4 magnetic particle. The XRD patterns revealed that Mn0.2Co0.8Fe2O4 oxides could not be observed on the surface of the silicalite-2 zeolite carrier. The experimental results showed that the dye wastewater with a satisfied decolorization rate (79.1%) was obtained when the initial pH was 6, the magnetic catalyst dosage was 0.4g/L, the electrolysis voltage was 2V, electrolytic time was 45min, respectively.

Abstract: A certain multi-metallic lead-zinc oxide ore contains 1.09%Pb，8.39%Zn． The oxide rate of lead and zinc is 96.34% and 98.15% respectively．In order to recover valuable minerals from the oxide ore comprehensively, the authors adopted priority flotation processing in this experimental research. At last, the lead concentrate with Pb grade of 27.41% and the zinc concentrate with Zn grade of 24.14 % were respectively achieved. The overall recovery of lead was 93.66%，and the overall recovery of zinc was 90.74%.

Abstract: The electronic and reaction properties of natural sphalerite containing seven typical kinds of impurities is studied by the density-functional theory (DFT). Mn and Ga impurities result in the Mulliken charge of the Zn atom reduced and consequently might decrease the ionicity of sphalerite; while Fe, Cd, In, Ge and Tl impurities lead to the increase in the Mulliken charge of the Zn atom. The frontier orbital calculations show that Mn impurities might lead to the over-oxidization of sphalerite, which may cause the further oxidation of lead xanthate, and thus are unfavorable for the flotation of sphalerite.

Abstract: The crystallographic structural characteristics and magnetic properties of Ho₃Fe_29-xT_x (T=V and Cr) compounds have been investigated by using Rietveld refinement analysis of X-ray diffraction (XRD) pattern and magnetic measurements. The calculated results indicate that among the 11 different kinds of Fe sites in these Ho-Fe compounds the preferential sites of the stabilizing elements V and Cr are quite different. The refined lattice parameters of these compounds are in good agreement with the experimental data. Spin reorientations of easy magnetization direction (EMD) are observed at around 150 K for Ho₃Fe₂₇V₂ and Ho₃Fe_25.5Cr_3.5. At the around 1.7 T critical fields (HCR) first order magnetization process (FOMP) occurs in magnetization curves at 4.2 K for the magnetically aligned samples of Ho₃Fe₂₇V₂ and Ho₃Fe_25.5Cr_3.5.

Abstract: This paper states how to prepare Pt-Ni alloy nanotubes in PC spray gold template using electrical deposition method, modify it to the glassy carbon electrode and make into dopamine sensor. It compares that cyclic voltammetry behavior of the bare glassy carbon electrode and Pt-Ni alloy nanotubes modified glassy carbon electrode. The conditions that glassy carbon electrode is modified by Pt-Ni alloy nanotubes for determination of dopamine were optimized. Under the optimized conditions, the test linear is in the range of 1.0×10-6 ~ 1.0 × 10-3 mol/L, detection limit is 4.0×10-7 mol/L, the recovery rate is 95.2%. This method has the advantages of simple operation, little amount of sample, high sensitivity and good reproducibility.