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Yang M.,General Research Institute for Nonferrous Metals, China
Journal of Materials Chemistry | Year: 2011

Easy fabrication of nanostructured materials with high porosity and high specific surface area has been drawing much scientific interest. Here, we describe a direct electrodeposition of fern-shaped bismuth dendrites at hydrogen evolution overpotentials without any additive and foreign template. A predeposition step was adopted to adjust and control the nucleation and growth of hydrogen bubbles. Subsequently, the simultaneous electrochemical reductions of Bi 3+ and H + ions were performed at a constant overpotential. Scanning electron microscopy and transmission electron microscopy characterizations showed that the resultant microporous netlike films consisted of fern-shaped single-crystal bismuth dendrites. The formation mechanism was discussed and ascribed to a "stagnant" template effect of hydrogen bubbles, which limited the lateral growth of fern-shaped dendrites. Such a two-step electrodeposition could also be extended to the nanostructure fabrication of other metals and alloys with high hydrogen overpotentials. © The Royal Society of Chemistry 2011.

Yang M.,General Research Institute for Nonferrous Metals, China
Journal of Power Sources | Year: 2013

Spherical PtBi nanoparticles are electrodeposited from aqueous solution according to the preset composition. Their catalytic activities toward methanol electrooxidation are examined by cyclic voltammetry and chronoamperometry in acid media and first in alkaline media. Experimental results show that, methanol electrooxidation has lower onset potentials on PtBi than on Pt in either acid or alkaline media. The improved catalytic activities are due to the electronic effects of bismuth in PtBi. At higher overpotentials, the electrolyte acidity has produced different influences on the kinetics of methanol electrooxidation on PtBi and Pt. In acid media, PtBi is inferior to Pt for methanol oxidation at above 0.460 V, because that fewer continuous Pt sites on PtBi are not enough for the adsorption and dehydrogenation of methanol molecules. In alkaline media, the oxidation current on PtBi becomes much higher than that on Pt at above 0.768 V. The raised current can be credited to the bifunctional mechanism. Bi 2O5 sites on PtBi surface serve for OHad adsorption and Pt sites for methanol dehydrogenation. The better catalytic activity of PtBi nanoparticles in alkaline media suggests their promising application in alkaline direct alcohol fuel cells. © 2012 Elsevier B.V. All rights reserved.

Jia H.,Shandong University | Bai X.,General Research Institute for Nonferrous Metals, China | Zheng L.,Shandong University
CrystEngComm | Year: 2012

Gold nanochains were prepared at the air/water interface under the Langmuir monolayer of a long-chain ionic liquid 1-hexadecyl-3-methylimidazolium bromide (C 16mimBr) through the reduction of AuCl 4 - ions by UV-light irradiation. It is revealed that these nanochains are self-assembled from gold nanoparticles about an average diameter of 15 nm. The synthesis and assembly of the Au nanoparticles can be achieved in one step. It is found that the structures of the nanochains are mainly dependent on reaction temperature. Both the π-π interactions and the steric hindrance play important roles in the formations of the nanochains. The application of the thin film of Au nanochains as a substrate for surface-enhanced Raman scattering (SERS) was demonstrated. Interestingly, the enhancement property depended on the temperature. This means the effective "hot spot" of the metal nanochains are dependent on their lengths, which may be controlled by the temperature. © 2012 The Royal Society of Chemistry.

General Research Institute for Nonferrous Metals, China | Date: 2011-05-02

An electrochemical method for producing Si nanopowder, Si nanowires and/or Si nanotubes directly from compound SiX or a mixture containing a silicon compound SiX, the method comprises: providing an electrolysis cell having a cathode, an anode and an electrolyte, using the compound SiX or the mixture containing compound SiX as a cathode and immersing the cathode in an electrolyte comprising a metal compound molten salt, applying a potential between the cathode and the anode in the electrolysis cell, and forming one or more of Si nanopowder, Si nanowires and Si nanotubes on the cathode electrode. The method has advantages of: 1) shorter production processing, 2) inexpensive equipment, 3) convenient operation, 4) reduction of contaminate, 5) easily available feed materials, and 6) easy to achieve continuous production. This is a new field of using electrochemical method for producing one-dimensional Si nano material, and a new method of producing Si nanopowder, Si nanowires and Si nanotubes.

General Research Institute for Nonferrous Metals, China, Beijing Hengyuan Tianqiao Power Metallurgy Co. and Gripm Advanced Materials Co. | Date: 2012-09-28

According to the invention, there are disclosed a power metallurgy composite cam sheet and a fabrication method thereof. The power metallurgy composite cam sheet is constructed by combining a power metallurgy cam be composited on a surface of a matrix. The fabrication method of the power metallurgy composite cam sheet includes sinter welding, braze welding, argon arc welding, laser welding, hot pressing and other methods. The powder metallurgy composite cam sheet fabricated by the invention has merits of stable size, good impact toughness, good abrasion resistance, low cost and so on, so that it can replace an integral cam sheet that is currently fabricated by forging, drawing, power metallurgy or other process. It is suitable for the case where a hollow camshaft is prepared by mechanical assembly, hydraulic forming, welding or other process, so that the usage requirements of an assembled camshaft can be met.

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