-
[show abstract]
[hide abstract]
ABSTRACT: Nanocomposites consisting of the bimetallic carbide Co(6)Mo(6)C(2) supported on graphitic carbon ((g)C) were synthesized in situ by an anion-exchange method for the first time. The Co(6)Mo(6)C(2)/(g)C nanocomposites were not only chemically stable but also electrochemically stable. The catalyst prepared by loading Pt nanoparticles onto Co(6)Mo(6)C(2)/(g)C was evaluated for the oxygen reduction reaction in acidic solution and showed superior activity and stability in comparison with commercial Pt/C. The higher mass activity of the Pt-Co(6)Mo(6)C(2)/(g)C catalyst indicated that less Pt would be required for the same performance, which in turn would reduce the cost of the fuel cell electrocatalyst. The method reported here will promote broader interest in the further development of other nanostructured materials for real-world applications.
Journal of the American Chemical Society 02/2012; 134(4):1954-7. · 9.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Graphitic carbon (GC) is prepared using an ion-exchange resin as carbon source at 600 °C. A Co salt is selected as the graphitization catalyst and is pre-exchanged onto the resin during the ion-exchange process. The GC is characterized by transmission electron microscopy, x-ray diffraction, Raman spectroscopy, and thermogravimetry. Analysis of the crystallization shows that graphitization can occur at a temperature of as low as 600 °C, compared to the usual temperature of above 2000 °C in industry and above 1000 °C in literature. Different carbon structures have been found for different pretreatments of the resin and different heat treatment temperatures. This energy-saving method is an important breakthrough for the economic mass production of GC.
Journal of Materials Research. 12/2011; 26(24):3083 - 3090.
-
[show abstract]
[hide abstract]
ABSTRACT: Pt nanowires (PtNWs) have been controllably synthesized on carbon powders by the reduction of H(2)PtCl(6) with HCOOH. By adjusting the pH value of the solution, PtCl(6)(2-) can be controllable reduced into particles or nanowires. The Pt nanowires are single crystals growing along the <111> direction with a diameter of 3 nm and a length of 10 nm. The dispersion of Pt nanowires on the surface of carbon powders can be controlled by changing the loading of Pt. The PtNWs/C is evaluated as the catalyst for methanol oxidation. The PtNWs/C with 20 wt% Pt has a larger electrochemical active surface area and much higher mass activity for methanol oxidation than that of commercial Pt/C catalyst. The PtNWs/C catalyst shows significant improvement in the kinetics for methanol oxidation and mass transfer property due to the single crystal structure of the Pt nanowires. The PtNWs/C catalyst holds promising potential applications in energy converting devices and environmental protection.
Nanoscale 11/2011; 3(12):5041-8. · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have developed a general ion-exchange method of preparing a composite of low nanometre size carbide particles with controllable size less than 10 nm on carbon foams. The nanoarchitectures of the carbide nanoparticles on carbon foam are used to load Pt nanoparticles as electrocatalysts which show enhanced activity for the oxygen reduction reaction.
Nanoscale 08/2011; 3(9):3578-82. · 5.91 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The adsorption and electrooxidation pathways of ethylene glycol (EG) on polycrystalline palladium surfaces have been investigated in both alkaline and acidic media by in situ FTIR spectroscopy in conjunction with cyclic voltammetry. Palladium exhibits a high electrocatalytic activity in alkaline solution with low onset oxidation potentials and high current densities, depending on the pH, as well as on the supporting electrolyte. Higher potentials are required for EG oxidation in acidic solutions, where the catalytic performance decreases with increasing the pH. The products and intermediates of EG oxidation on Pd are influenced by the pH. In alkaline media, both C(2) species (glycolate, glyoxal, glyoxylate and oxalate) and C(1) species (formate and carbonate) are formed in mutual concentrations depending on the pH. In contrast, CO(2) is selectively produced in acidic aqueous solution.
Physical Chemistry Chemical Physics 02/2011; 13(7):2667-73. · 3.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tungsten carbide nanocrystals on carbon (W2C/C) and tungsten carbide nanocrystals and Pt on carbon (Pt-W2C/C) composite electrocatalysts were prepared by the intermittent microwave heating (IMH) method and tested for the electroreduction of oxygen in the acidic media for the first time. The results revealed that the tungsten carbide nanocrystal promoted Pt/C electrocatalyst was very active for ORR with the onset potential of 1.0 V vs SHE at ambient temperature that is over 100 mV more positive compared with that of traditional Pt/C electrocatalyst. The kinetic parameters were determined. The exchange current densities at both high and low overpotential regions are two orders higher for ORR on Pt-W2C/C than that on Pt/C, showing a synergetic effect to improve the activity for ORR. The novel electrocatalysts show a poisoning resistant property toward methanol.
The Journal of Physical Chemistry B 01/2006; 109(48):22705-9. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tungsten carbide nanocrystal modified Pt catalysts have been prepared by an intermittent microwave heating (IMH) method and show an improved activity for oxygen electroreduction in alkaline media.
Chemical Communications 10/2005; · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel three-dimensional electrode has been fabricated using polypyrrole (Ppy) coated polystyrene spheres (PS) covered by a platinum catalyst. This new type of porous structured electrode allows liquid alcohol to penetrate the catalyst layer quite easily thereby reducing the liquid sealing effect. The chosen approach results in an increased active surface area for electrochemical reactions. Preliminary studies show an improved performance for methanol oxidation on a three-dimensional electrode compared to a conventionally prepared electrode with the same platinum loading.
Journal of Power Sources.
