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Li J.,Kunming University of Science and Technology | Huang H.,Kunming University of Science and Technology | Guo Z.-C.,Kunming Hendera Science and Technology Co.
Gongneng Cailiao/Journal of Functional Materials | Year: 2013

Using ascorbic acid as reducing agent and poly (ethylene glycol) 4000 as dispersant, the ultra-fine silver powder for solar cell grid electrode was prepared by chemical reduction. The morphology, size and purity of silver powder were analyzed by scanning electron microscopy (SEM) laser particle analyzer and X-ray diffraction (XRD). The influences of reducing concentration of poly (ethylene glycol) 4000, silver nitrate, ascorbic acid, and pH value on the particle size and morphology were researched. The results show that the particle size of the silver powders decreases to be more stable with increasing dispersant concentration. The optimal reductive condition is: the pH value equals to 4, the concentration of ascorbic acid and silver nitrate is 2.0 and 0.5 mol/L and m(PEG4000)/m(AgNO3) is 0.10. Spherical silver powder with 5.32 μm of particle size is good dispersion, high purity, face-centered cubic lattice. The paste prepared with ready-made silver powder was printed on the silicon, and the square resistance of the sintered film tested by four-point probe is 4.27 mΩ/□, indicating the electrical property of the prepared silver is qualified for solar cell. Source


Hui H.,Kunming University of Science and Technology | Ju-kang L.,Kunming University of Science and Technology | Zhongcheng G.,Kunming Hendera Science and Technology Co.
Advanced Materials Research | Year: 2012

Conductive polyaniline/boron carbide (PANI/B 4C) composites have been synthesized by in-situ polymerization of aniline in the presence of B 4C particles. The structure and thermal stability of obtained composites were characterized by FTIR, XRD and TGA. The results showed that PANI and B 4C particles were not simply blended, and a strong interaction existed at the interface of B 4C and PANI. In the PANI/B 4C composite, the degree crystalline of PANI increased and diffraction pattern of B 4C was all but of amorphous. And that the composites were more thermally stable than that of the pure PANI. Electrical conductivity measurements indicated that the conductivity of PANI/B 4C composites was much higher than that of the pure PANI and the maximum conductivity obtained was 35.6 S·cm-1 at 20 wt% of B 4C. © (2012) Trans Tech Publications, Switzerland. Source


Yang J.,Kunming University of Science and Technology | Chen B.-M.,Kunming University of Science and Technology | Hang H.,Kunming University of Science and Technology | Guo Z.-C.,Kunming University of Science and Technology | And 2 more authors.
International Journal of Minerals, Metallurgy and Materials | Year: 2015

The objective of this work was to study the effect of different rolling technologies on the properties of Pb-0.06wt%Ca-1.2wt%Sn anodes during copper electrowinning and to determine the relationship between the properties of the anodes and rolling techniques during copper electrowinning. The anode process was investigated via anodic polarization curves, cyclic voltammetry curves, electrochemical impedance spectra, and corrosion tests. The microscopic morphology and phase composition of the anodic oxide layers were observed by scanning electron microscopy and X-ray diffraction, respectively. Observable variations in the electrocatalytic activity and reaction kinetics of anodes during electrowinning indicated that the electrochemical behavior of the anodes was strongly affected by the rolling technology. An increase in the rolling number tended to decrease the oxygen evolution overpotential and the corrosion rate of the anodes. These trends are contrary to that of the apparent exchange current density. Furthermore, the intensities of diffraction peaks associated with PbO, PbOx, and α-PbO2 tended to increase with increasing rolling number. In addition, the rolled anodes exhibited a more uniform microstructure. Compared with one-way rolled anodes, the eight-time cross rolled anodes exhibited better electrocatalytic activity and improved corrosion resistance. © 2015, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg. Source


Hui H.,Kunming University of Science and Technology | Ren-Chun F.,Kunming University of Science and Technology | Zhongcheng G.,Kunming Hendera Science and Technology Co.
Advanced Materials Research | Year: 2012

Polyaniline/tungsten carbide (PANI/WC) composite was synthesized by chemical oxidative polymerization of aniline using ammonium persulfate as the oxidant and thermal treated in air at 150°C, 250°C, 350°C and 450°C to 2 hours. The changes of structure, crystalline and conductivity were investigated by Fourier Transformed Infrared (FT-IR), Fourier Transformed Raman (FT-Raman), X-Ray Diffraction (XRD) and four-probe technique. The results showed that PANI/WC composite showed much-improved thermal stability compared to pure PANI. But the conductivity of PANI/WC is reduced to some extent (1.73 S/cm, the conductivity is reduced by about 82%) after thermal treated at 250°C, and dropped by 6 orders of magnitude (3.25×10-6S/cm) at 350°C. This may be explained by that only a fraction of dopant losses during thermal treatment at 250°C, but after thermal treatment at 350°C, along with cross-linking, chain scission and oxygen, resulting in destruction of crystal structure, decrease of the emeraldine sequence. © (2012) Trans Tech Publications, Switzerland. Source


Huang H.,Kunming University of Science and Technology | Guo Z.-C.,Kunming University of Science and Technology | Guo Z.-C.,Kunming Hendera Science and Technology Co.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2012

A series of molybdic oxide/ceria (MoO 3/CeO 2) composite catalysts with different MoO 3 concentrations (0, 5wt%, 7.5wt%, 10wt%, 12.5wt%, 15wt% and 20wt%) were prepared by hydrolysis of ammonium molybdate and the supports of CeO 2 at 70°C. The crystal structure, the morphology and interaction between MoO 3 and CeO 2 on the surface of the prepared MoO 3/CeO 2 composite catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), respectively. The catalytic activities of the prepared catalysts were evaluated by the electrolysis sulfuric acid solution. Results show that the catalytic activity of MoO 3/CeO 2 composite catalysts are superior compared with that of pure CeO 2, and the optimal concentration of MoO 3 is 12.5wt%. The MoO 3 content threshold value of composite catalysts is between 12.5wt% and 15wt%, and it is identified that the Mo-O-Ce bond forms at the interface of MoO 3 and CeO 2 in the composite catalysts. Moreover, more surface Mo-O-Ce bond over the MoO 3/CeO 2 composite catalysts will further benefit the improvement of the catalytic activity. Source

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