Advanced Materials Research Vols. 399-401

Abstract: In order to reduce production cost of making H₂, one of the key points was to reduce Pt loading in Pt/C catalytic electrode. In our study, a new type of Pt/C membrane electrodes, PtCuLaO_x/C heterogeneous structure, in which with developing different flow of O₂, on the surface of carbonaceous substrates were manufactured by Ion Beam Sputtering (IBS) technology. These membrane electrodes were treated by annealing in vacuum furnace, and by different time in different concentration H₂SO₄ solution. The hydrogen evolution properties of these electrodes were tested by tri-electrode system, and were calculated results of their exchange current density (i₀), decomposition voltage (E_d) and active specific surface area (ESA). It was found that PtCuLaO_x heterogeneous membrane electrodes with Pt loading less than 0.041mg•cm^-2 (the electrode area) undergone treatment, whose E_d, i₀ and ESA was -0.223(V vs SCE), 4.562mA•cm^-2 and 46.2811m2•g^-1 respectively in balanced condition.

Abstract: The photocatalytic activity of Bi₂O₃ photocatalyst towards decolorization of Methyl Orange (MO) was studied by employing several reagents. The influence of H2O2 on the decolorization efficiency was investigated in detail. Addition of ions such as CO₃²⁻, Cl⁻, and SO₄^2- inhibits the photocatalytic efficiency.

Abstract: The layered LiNi_1/2Mn_1/2O₂ cathode materials were synthesized by a sol gel method. The effects of calcination temperature and time on the structural and electrochemical properties of the LiNi_1/2Mn_1/2O₂ were investigated. The prepared samples were characterized by X-ray diffraction (XRD) and electrochemical analysis. The results revealed that the layered LiNi_1/2Mn_1/2O₂ material could be optimal synthesized at temperature of 900°C for 10h. The sample prepared under the above conditions has the highest initial discharge capacity of 151 mAh/g and showed no dramatic capacity fading during 20 cycles between 2.5-4.5V at a current rate of 20mA/g.

Abstract: A new two-step synthesis of composite electrode based on carbon nanotubes (CNTs) and cobalt oxide (Co₃O₄) by electrophoretic deposition of CNTs on Ni foam followed by electrodeposition of cobalt hydroxide on CNTs electrode and heat treatment to form Co₃O₄/CNTs composite electrode was developed. The structure and morphology of the electrodes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their electrochemical performances were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). Experimental results indicated that the nanocomposite electrodes exhibitd excellent pseudocapacitive behavior. In the potential range of 0.1- 0.45 V(vs SCE), the nanocomposite electrode showed a high specific capacitance of 867 F•g-1 in 6 M KOH electrolyte and a capacity retention of 90% after 1000 cycles at a current density of 1 A•g^-1.

Abstract: A three-dimensional dendritic Sn-Co anode was prepared on the porous Ni substrate via pulse current electrodeposition methond, and characterized by means of scanning electron microscope (SEM), energy dispersive (EDX) analyzer. Then its electrochemical property were studied by means of charging-discharging (C-D) test. The influences of the current density and eletrochemical technique has been studied. Besides this, the importance of annealing for the cycling performance of the as-prepared electrode had been dicussed.

Abstract: The melt-spinning technique is applied to the preparation of the nanocrystalline and amorphous Mg₂Ni-type alloys with nominal compositions of Mg_2-xLa_xNi (x=0, 0.2, 0.4, 0.6). The as-spun alloy ribbons possessing a continuous length, a thickness of about 30 μm and a width of about 25 mm were prepared. The structures of the as-spun alloy ribbons are characterized by XRD, SEM and TEM. The electrochemical performances of the as-spun alloy ribbons are measured by an automatic galvanostatic system. The results show that no amorphous structure is detected in the as-spun Mg₂Ni alloy, whereas the as-spun alloys substituted by La display a nanocrystalline and amorphous structure, confirming that the substitution of La for Mg notably intensifies the amorphous forming ability of the Mg₂Ni-type alloy. For La content x≤0.2, the substitution of La for Mg brings to the formation of LaMg₃ and La₂Mg₁₇ phases without changing the Mg2Ni major phase. But as La content is increased to x≥0.4, such substitution changes the major phase of the alloys to (La, Mg)Ni₃+LaMg₃. The discharge capacity of the as-cast alloys grows with the increasing amount of La substitution, whereas that of the as-spun alloys yields a maximum value with variation of La content. Furthermore, the substitution of La for Mg remarkably enhances the cycle stability of the as-cast and spun alloys. And the high rate dischargeability (HRD) of the as-cast and spun alloys first mounts up then falls with rising La content.

Abstract: Tin nano-spheres film was synthesized by electrodeposition based on the copper-nickel nano-pillars which were prepared by electrochemical method on the copper foil in an aqueous solution containing Cu (II) and Ni (II) at room temperature. The morphology, structure and composition of the as-prepared copper-nickel nano-pillars and tin nano-spheres were characterized by SEM, XRD, and EDS. The tin nano-spheres film anode features the large surface area, good electronic conductivity, and adhesion with the current collector, leading to the enhanced performance in lithium-ion batteries.

Abstract: Dry water (DW) is a powder-like, solidified form of water, where water droplets are surrounded by silica nanoparticles. DW is considered to be an effective medium for gas storage because it can slurp up gases which combine the water molecules to form clathrate hydrate. In this paper, DW was prepared by mixing water and hydrophobic silica particles (H18) at high speeds, and based on which, dry water methane hydrates (DW-MH) were synthesized under certain conditions. The characteristics of DW and DW-MH were investigated by Raman spectroscopy. The results show that DW-MH is a typetical sI clathrate hydrate with hydration number around 5.9. The storage capacity in clathrate hydrate prepared with methane and four different materials, i.e. DW, powder ice, Sodium Dodecyl Sulfate (SDS) solution and liquid water, was measured by volumetric method. The results showed that DW is prospective medium for gas storage that can increase much higher of the storage capacity compared to other materials.

Abstract: n-ZnO thin films doped In with 2 atm.% were deposited on p-type silicon wafer with textured surface by Ion Beam Enhanced Deposition method, after annealing and prepared front and back electrodes, the n-ZnO/p-Si heterojunction samples were fabricated. The photoelectric property of the sample were measured and compared with silicon solar cell. The result indicated the saturated photocurrent of n-ZnO/p-Si heterojunction was 20% greater than one of the Si solar cell. It means the ZnO/Si heterojunction has a higher ability of produce photoelectron then one of silicon solarcell. The result of the photovoltaic test of n-ZnO/p-Si heterojunction show The open circuit voltage and short-circuit current of the n-ZnO/p-Si heterojunction was 400mV and 5.5mA/cm2 respectively. It was much smaller than the one of silicon solar cells. The reason was discussed

Abstract: Tris(8-hydroxyquinoline-5-sulfonic acid) iron(III) complex (Fe(HQS)₃) was prepared and characterized by elemental analysis, infrared, nuclear magnetic resonance and Raman spectrum. The results indicated that the Fe atom was located at the center of the Fe(HQS)₃ complex and the sulfonic groups did not present in the quinoline three-coordinate structure. The TGA analysis result showed that the three ligands were thermally stable within wide temperature range (364 °C, 512 °C, 628 °C,). According to XRD and UV-vis data, the nano-TiO₂ prepared by hydrothermal method was mainly in the form of anatase and brookite, and the Fe(HQS)₃ complex had single crystal structure. Neither Fe(HQS)₃ nor nano-TiO₂ has observable photocatalytic activity according to the result of our methyl orange degrading experiment. The Fe(HQS)₃-TiO₂ complex, however, demonstrated strong spectral response and photocatalytic activity under visible light.