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Zhaoqing, China

Wu Y.-N.,University of California at Riverside | Guo H.-F.,Zhao Qing University | Hu P.,Zhao Qing University | Xiao X.-P.,Zhao Qing University | And 2 more authors.

Three types of ternary low-platinum nanocatalysts, alloy PdPtIr/C, core–shell PdPt@PtIr/C and Pd@PtIr/C, have been prepared, and their catalytic behaviors toward methanol oxidation reaction (MOR)/oxygen reduction reaction (ORR) are comparatively investigated via cyclic voltammetry and chronoamperometry analysis in an acidic medium. Through a two-step colloidal technique, the synthesized core–shell structured catalyst PtPd@PtIr/C with alloy core and alloy shell show the best catalytic activity toward MOR and the best poisoning tolerance. The alloy PdPtIr/C catalyst prepared via a one-step colloidal technique exhibits the best performance toward ORR among the three catalysts. All the three catalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and other characterization techniques. © 2016 World Scientific Publishing Company Source

Wu Y.-N.,Zhao Qing University | Liao S.-J.,South China University of Technology | Guo H.-F.,Zhao Qing University | Hao X.-Y.,Zhao Qing University
Journal of Power Sources

A high-performance, low platinum loading catalyst for the anodic oxidation of methanol, Pd@PtRu/C, is prepared by a two-step colloidal approach. The activity of the Pd@PtRu/C catalyst is 1.67 times and 1.81 times that of PtRu/C and PtRuPd/C catalysts, respectively. The catalysts are characterized by TEM, XPS, and XRD. The active components are dispersed on the surface of the carbon support very well, yielding a particle size of ca. 4.7 nm and a shell thickness of ca. 0.25 nm. The catalyst's high activity may be attributed to the high exposure and dispersion of PtRu, as well as the interaction of PtRu in the shell layer with Pd in the core, resulting from the catalyst's core-shell structure. © 2012 Elsevier B.V. All rights reserved. Source

Wu Y.-N.,Zhao Qing University | Liao S.-J.,South China University of Technology | Guo H.-F.,Zhao Qing University | Hao X.-Y.,Zhao Qing University
Journal of Power Sources

Shortened carbon nanotubes (SCNTs) obtained by ball milling of carbon nanotubes (5-10 μm) with the assistance of ethanol are used as supports for fabrication of core-shell structured PdPt@Pt/SCNTs via a successive colloidal reduction approach. The catalysts are characterized by X-ray diffraction (XRD) analysis, Transmission electron microscopy, and X-ray photoelectron spectroscopy. The active particles are found to disperse on the shortened carbon nanotubes with an average particle size of 3.1 nm. PtPd nanoparticles, rather than single Pd nanoparticles, are used as core materials for prevention of possible agglomeration and better dispersion. Using this catalyst, we investigate methanol oxidation reactions (MOR) and oxygen reduction reactions (ORR). The catalysts show excellent activity to anodic MOR, 2.87 times higher than that of commercial Johnson Matthey 40 wt.% Pt/C catalyst. The ratio of forward current Ifto backward current Ib is as high as 1.41 for the oxidation of methanol relative to that of 0.74 for the commercial Pt/C catalyst, an indication of better CO tolerance of the former. In the ORR, the reaction is found to proceed via an overall four-electron transfer process. © 2013 Elsevier B.V. All rights reserved. Source

Wu Y.-N.,Zhao Qing University | Wu Y.-N.,South China University of Technology | Liao S.-J.,South China University of Technology | Zeng J.-H.,South China University of Technology
Journal of Power Sources

Small nanoparticles offer high surface areas and are certainly desirable for electrocatalytic reactions and fuel cells. However, the drawback of using small nanoparticles is their tendency towards particle aggregation. This paper aims to inhibit platinum agglomeration by adding silicon oxide to a carbon support for enhanced catalytic activity in low-temperature fuel cells. The catalysts are characterized by X-ray diffraction and transmission electron microscopy. Physical characterization and cyclic voltammetry techniques at room temperature are used to assess the effects of silicon oxide amount, post-heating temperature, and holding time on particle size and dispersion of active components, and the catalysts' activity towards the methanol oxidation and oxygen reduction reactions. It is found that using a support of carbon powder with 3 wt.% silicon oxide can enhance the electrochemically active surface area of Pt catalysts and their activity towards the anodic oxidation of methanol and reduction of oxygen. The active components are also more resistant than Pt/C to agglomeration upon heating. © 2010 Elsevier B.V. Source

Wu Y.N.,South China University of Technology | Wu Y.N.,Zhao Qing University | Liao S.J.,South China University of Technology | Su Y.L.,CAS Institute of Chemistry | And 2 more authors.
Journal of Power Sources

A palladium decorated Pt/C catalyst, Pt@Pd/C, is prepared by a colloidal approach with a small amount of platinum as core. It is found that the catalyst shows excellent activity towards anodic oxidation of formic acid at room temperature and its activity is 60% higher than that of Pd/C. Decoration of palladium shell on the platinum core is supported by XPS results. Due to the use of platinum as core, active components are dispersed very well and the particle sizes are smaller than those of Pd/C. The cyclic voltammetry measurement clearly shows synthetic electro-oxidation effects of formic acid on Pt@Pd/C. It is speculated that the high performance of Pt@Pd/C may result from the unique core-shell structure and synergistic effect of Pt and Pd at the interface. The preparation method for Pt@Pd/C reported in this work will provide additional options for the design of catalysts for direct formic acid fuel cell (DFAFC). © 2010 Elsevier B.V. All rights reserved. Source

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