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Cui J.,Central South University | Yang Y.,Central South University | Yang Y.,Cleaner Metallurgical Engineering Research Center | Yi P.,Central South University | And 2 more authors.
Journal of Power Sources | Year: 2014

In this paper, the effect of p-n junction additives via blending p-type semiconductors (NiO and CuI) with n-type TiO2in polymer electrolyte on quasi-solid-state DSSCs is studied. The conduction mechanism of DSSCs modified with random p-n junctions has been investigated by FTIR, SEM, UV-Vis and electrochemical analysis. The results indicate that the CuI-TiO2p-n blend modified polymer electrolyte reaches the maximum ionic conductivity of 6.44 mS cm-1, which is almost twice over than that of pure-TiO2modified one. From photovoltaic study, it is found that introducing CuI-TiO2and NiO-TiO2p-n blends in polymer electrolyte can obviously improve electron recombination and light-to-electric conversion efficiency of DSSCs. The conversion efficiency of CuI-TiO2p-n blend modified DSSC is 3.34%, which is much higher than that of pure TiO2modified device (1.76%). It is also demonstrated that the photovoltaic properties of DSSCs directly depends on the ratio of p-type CuI and n-type TiO2in the p-n blends and the optimal conversion efficiency of 4.27% is obtained at CuI:TiO2ratio of 4:1. © 2014 Elsevier B.V. All rights reserved. Source

Tian Q.,Central South University | Tian Q.,Cleaner Metallurgical Engineering Research Center | Li Y.,Central South University | Li Y.,Cleaner Metallurgical Engineering Research Center | And 4 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2015

Spherical ultrafine silver powders were prepared by liquid-phase reduction method with continuous feeding mode using silver nitrate as raw silver source, aqueous ammonia as complexing agent, ascorbic acid as reducing agent. The properties of the ultrafine silver powders were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) absorption spectrum analyzer. The effects of different dispersants, initial pH value of ascorbic acid solution, reaction temperature and feeding speed on the morphology, mean particle size, dispersity and tap density of ultrafine silver powders were investigated. The results showed that the gum arabic had better dispersity than other dispersants, and the mechanism of dispersion was discussed. The initial pH value of ascorbic acid solution had a great influence on particle size and distribution of silver powders, the particle size was about 0.6 μm and the distribution was narrow with pH≤4.0, while the particle size was about 0.7 μm and the distribution was wide with pH>4.0. The feeding speed had a great influence on the particle size and tap density, the particle size of silver powder decreased and the tap density of silver powder increased at first then decreased with the feeding speed increasing. Spherical silver powder with good dispersibility, particle size of 0.73 μm and tap density of 4.3 g·cm-3 could be obtained under conditions with the pH of 2.45, the temperature of 30℃ and the feeding speed of 133.3 ml·min-1. ©, 2015, Editorial Office of Chinese Journal of Rare Metals. All right reserved. Source

Guo X.-Y.,Central South University | Guo X.-Y.,Cleaner Metallurgical Engineering Research Center | Xu Z.-P.,Central South University | Xu Z.-P.,Cleaner Metallurgical Engineering Research Center | And 4 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2015

The valuable metals were separated from copper anode slime (CAS) by low-temperature alkaline smelting process. The effects of the mass ratio of NaOH, smelting temperature, smelting time, leaching temperature, leaching time and liquid-solid ratio on the leaching efficiency of metals were investigated. The results show that the optimum conditions are determined as follows:m(NaOH)/m(CAS) is 0.5, smelting temperature is 600 ℃, smelting time is 60 min, leaching temperature is 70 ℃, leaching time is 60 min and liquid-solid ratio is 12.5 mL/g. Under the optimum conditions, leaching efficiencies of Se and As are 95.79% and 96.83%, while the leaching efficiencies of Cu, Pb, Sb and Te are 0.16%, 3.36%, 1.02% and 0.05%, respectively, leading to the separation and enrichment of valuable metals from copper anode slime relatively. ©, 2015, Central South University of Technology. All right reserved. Source

Guo X.-Y.,Central South University | Guo X.-Y.,Cleaner Metallurgical Engineering Research Center | Deng D.,Central South University | Deng D.,Cleaner Metallurgical Engineering Research Center | And 4 more authors.
Fenmo Yejin Cailiao Kexue yu Gongcheng/Materials Science and Engineering of Powder Metallurgy | Year: 2015

The ultra-fine silver powder was prepared using silver ammonia solutioin with a certain pH value prepared by adding stronger ammonia water in AgNO3 solution as feed solution, and adding hydrogen peroxide as reducer. The effects of the feeding mode, pH value, dispersants, concentration of AgNO3 and H2O2 on the morphology and particle size of silver powder were investigated. The results show that the optimal dispersive silver powder can be prepared by positive rapid addition of H2O2. The Zeta potential of silver particles can be tuned by changing pH value of silver ammonia, then influence the silver powder dispersity. Silver particle size first increases then decreases with increasing H2O2 concentration, while it increases with increasing the AgNO3 concentration. The dispersants have great effect on the morphology of silver powder. The optimal spherical like and dispersive silver powder with mean particle size of 1.9~2.3 μm can be prepared with the AgNO3 concentration of 0.1~0.3 mol/L, the pH value of 10.0~11.0, H2O2 mass fraction of 3% with the absence of dispersants. © 2015, Central South University. All right reserved. Source

Guo X.,Central South University | Guo X.,Cleaner Metallurgical Engineering Research Center | Liu J.,Central South University | Qin H.,Central South University | And 5 more authors.
Hydrometallurgy | Year: 2015

An efficient alkali fusion-leaching-separation process is developed to recover metals in crushed metal enrichment (CME) which originated from waste printed circuit boards (PCBs). Impacts of fusion parameters on metals conversions were systematically investigated. In the fusion-leaching process, amphoteric metals such as tin, lead, zinc and aluminum in the CME were leached out, while leaving copper and precious metals in the residue. Subsequently, metals in solution were further extracted via precipitation processes, and metals in the residue were recovered using an acid leaching-electrowinning process. Cathode copper, nano-Cu2O, CaSnO3/CaSn(OH)6 crystal and mixture of PbS-ZnS were obtained as the final products of this process. By optimizing the experimental conditions, recoveries of 98.66% for Cu, 91.08% for Sn, 91.25% for Zn, 78.78% for Pb were achieved, respectively. And all precious metals were enriched in the final residue with grades of Au 613 g/t, and Ag 2157 g/t. © 2015 Elsevier B.V. All rights reserved. Source

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