Advanced Materials Research Vols. 554-556

Abstract: Scattering spheres-embedding three-dimensional ordered macroporous (3DOM) titania(TiO₂) was fabricated, by the route of colloidal spheres self-assembly, infiltration and template removal. The procedures of 3DOM structure preparation were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD). The silica@PMMA core-shell spheres were prepared and self-assembled into colloidal crystal template. Solid material was deposited in the colloidal crystal template by spin-coating of titania nanoparticle dispersions. Subsequently, the samples were heated to 400 °C to form anatase TiO₂ and to remove the polymer of template, which resulted in macroporous structure with a silica sphere in each lattice pore. The conventional TiO₂ film, 3DOM TiO₂ photoanodes were also fabricated. It was found that SiO₂-embedding 3DOM photoanode has the higher photocurrent efficiency than both of TiO2 film and 3DOM, because there are scattering spheres in its lattice pores which enhance the light scattering and improve the light harvest of the dye.

Abstract: High tap-density Li_0.99W_0.01FePO₄/C composite have been synthesized via a simple and low-cost solid state-carbothermal reduction method, using Fe₂O₃ and citrate ferric as the Fe³⁺ precursors and citric radical containing in citrate ferric as both carbon source and reducing agent. The structure, morphology, and physicochemical properties of Li_0.99W_0.01FePO₄/C composite were characterized by XRD, SEM, laser diffraction and scattering measurement, and tap-density testing. It is observed the particle distribution of the Li_0.99W_0.01FePO₄/C composite is bimodal distribution. Because of the smaller particles filling in the space between the larger particles, the Li_0.99W_0.01FePO₄/C composite exhibits less vacancy, which resulted in a high tap density of 1.50 g•cm^-3. The Li_0.99W_0.01FePO₄/C composite also shows good rate capability and cycle performance. At current densities of 0.2, 0.5, 1.0 and 1.5 C, the composite material has initial discharge specific capacity of 141, 133, 130 and 125 mAh•g^-1, respectively.

Abstract: Solid oxide components such as electrolyte for solid oxide fuel cell require chemical stability and high conductivity. Substituting Zr for Ce in BaCe_0.8Nd_0.2O_3-δ improves the chemical stability but reduces conductivity. The objective of this work was to study the optimization of conductivity and chemical stability by changing the ratio of Ce to Zr in BZCN. Perovskite type BaZr_xCe_0.8-xNd_0.2O_3-δ (BZCN) powders were prepared by an EDTA–citric acid (EC) process. BaZr_xCe_0.8-xNd_0.2O_3-δ (x≥0.4) oxides show good chemical stability against carbon dioxide. The conductivities of sintered samples increased with the temperature and decrease with their Zr content. The good chemical stability and conductivity of BaZr_0.4Ce_0.4Nd_0.2O_3-δ is potential to be practically used with both high conductivity and good stability

Abstract: The efficiency of two Schiff base compounds namely (E)-N¹-benzylidene-N⁴-phenylbenzene-1,4-diamine (K1) and (E)-N¹-(4-methoxybenzylidene)-N⁴- phenylbenzene-1,4-diamine (K2) as corrosion inhibitors were compared with its parent amine namely N-phenyl-1,4-phenylenediamine (NPPD). Investigations have been made at 25 0C by electrochemical impedance spectroscopy (EIS) and polarization measurements in which the corrosion rates decrease and the percentage inhibition efficiencies and surface coverage degree increase with increasing additive concentration. The adsorption of inhibitors appears to follows Langmuir adsorption isotherm model. Results show K1 to have the highest inhibition efficiency among the three investigated compounds.

Abstract: The NiO/Co composite material was prepared by doping Co in the NiO, and the Co was prepared by chemical reduction. The structure morphology and performance were characterized by XRD, SEM, charge-discharge tests, cyclic voltammetry (CV), AC impedance and the behavior of lithium insertion-extraction was also be discussed. The results show that the conductivity of the NiO material was enhanced by doping Co, which would promote the decomposition of SEI during the charge process, and thus the cycle performance was improved obviously. The reversible specific capacity of NiO/Co composite material maintained 550 mAh g-1 after 30 cycles, and the capacity keep rate was 87.4% much higher than that of pure NiO material(343 mAh g-1 and 49.1%, respectively).

Abstract: The flotation performance of a complex lead and zinc ore were investigated by changing the grinding environments. Four groups of testing were conducted with different depressants or their combinations. Flotation results, size-by-size analysis, pulp potential (Eh) and dissolved oxygen (D0) were studied. It was found that the addition of depressants during grinding was beneficial to increasing the separation efficiency.

Abstract: A Schiff base, 3-(phenylimino)indolin-2-one, was successfully obtained from the condensation reaction of isatin and aniline in absolute ethanol with a yield of 72%. The ligand was successfully characterized via physical and spectroscopic techniques namely melting point, Elemental Analysis (C, H, N), 1H Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. The corrosion inhibiting property of the Schiff base and that of a mixture of its starting materials on mild steel in 1 M HCl solution was studied through Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR). The concentration of the Schiff base and the precursor molecules were varied from 1 x 10-3 M to 1 x 10-5 M. The results showed that the percentage of inhibition efficiencies increased with the increase of compound’s concentrations. Comparing the two sets of results for the Schiff base and the mixture of its starting materials, it was shown that the Schiff base was a much better inhibitor than the mixture of the starting materials, clearly indicating the importance of the presence of imine group (C=N) bearing lone pairs of electrons and π electrons in corrosion inhibition.

Abstract: A novel sensitive pH sensor was reported based on a carbon paste electrode modified (CPEM) with perovskite-type Li_0.31La_0.56TiO₃ (LLTO) and LLTO-xSrTiO₃ (x =0.05~ 0.15) in order to investigate the influence of the doping in the sensor response. The carbon paste proves the ability of this perovskite to detect the variation of pH 2 -13. The LLTO-xSrTiO₃ (x =010)-CPEM indicated that the best linear relationships. A variation of potential in different pH-buffers was obtained with a response maximum of 32.08 mV/pH unit at 25 ^◦C and 55.39 mV/pH unit at 70 ^◦C for the better responding electrode.

Abstract: Lithium vanadyl phosphate (β-LiVOPO₄) cathode material for lithium ion batteries was prepared via a novel solid state method. The microstructure and electrochemical properties of the sample were characterized by X-ray diffraction, scanning electron microscopy, galvanostatically discharge/discharge and cyclic voltammetry techniques, respectively. X-ray diffraction patterns showed that β-LiVOPO₄ has an orthorhombic structure with space group of Pnma. The discharge capacity of LiVOPO₄ sample is 89.9 mAh•g^-1 in the first cycle, and in the 50th cycle it is 76.2 mAh•g^-1 at the current density of 10 mA•g^-1 between 3.0-4.5 V. The chemical diffusion coefficient ( ) value determined from CV is about 10-11 cm² s^-1. Experimental results indicate that further efforts are needed to improve electrochemical performances of LiVOPO₄ material synthesized by solid state method; however, it has a higher discharge plateau around 3.9 V.

Abstract: Electrocatalytic oxidation of multi-nanostructured active electrode modified by platinum nanoparticles on glucose was examined. Based on 0.5mol/L KOH solution, we see a sensitive and good-shaped oxidation peak current near -0.77V (VS, SCE) by using differential pulse voltammetry method to scan in the range of -0.9~0.4V.The peak is regarded as the quantitative peak. There is a good linear relationship between glucose concentration and the peak current in the range of 1.0×10-2~1.0×10-5 mol/L. The linear correlation coefficient is 0.99864.The detection limit is 1.0×10-6mol/L. If added 0.06 m mol/L ascorbic acid or 0.3m mol/L uric acid (simulating human blood components), the determination of glucose is not interfered with. Results of the determination of glucose concentration in the blood are satisfactory.