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AbstractAbstract
[en] Pt-rare earth/C electrocatalysts (rare earth = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, and Lu) were prepared (20 wt.% and Pt-to-RE atomic ratio of 50:50) by an alcohol reduction process using H2PtCl6.6H2O (Aldrich) and rare earth (III) chlorides (Aldrich) as metal sources, ethylene glycol as solvent and reducing agent, and Vulcan XC72 as support. The electrocatalysts were characterized by Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffractometry (XRD) and Transmission Electron Microscopy (TEM). The energy dispersive x-ray spectroscopy analysis showed that the Pt-Rare Earth atomic ratios obtained for all electrocatalysts were similar to those used in the preparations. In all diffractograms, it was observed a broad peak at about 25 degree which was associated to the Vulcan XC72 support material and four peaks at approximately 28=40 degree, 47 degree, 67 degree and 82 degree, which were associated to the (111), (200), (220), (311), and (222) planes, respectively, of the face-centered cubic (fcc) structure characteristic of platinum and platinum alloys. For the Pt-Rare Earth/C electrocatalysts, it was also observed peaks related to the rare earth oxides on the X ray diffractograms. PtLa/C electrocatalysts were prepared at different atomic ratio. Transmission electronic microscopy micrographs of electrocatalysts showed a reasonable distribution of the Pt particles on the carbon support with some agglomerations, which is in agreement with x-ray diffractometry result. The performance for CO, methanol and ethanol oxidation was investigated by cyclic voltammetry, chronoamperometry and Fourier transform infrared spectroscopy spectroscopy. The electrocatalytic activity of the Pt-Rare Earth/C electro catalyst, specially PtLa/C, were higher than that of the Pt/C electrocatalyst. Fourier transform infrared spectroscopy studies for ethanol oxidation on Pt-Rare Earth/C electrocatalyst showed that acetaldehyde and acetic acid were the main products. The PtLa/C (30:70) electrocatalyst presented the best results for oxygen reduction reaction, methanol and ethanol oxidation and for carbon monoxide oxidation at temperatures higher than 30 degree C.
Original Title
Preparacao e caracterizacao de eletrocatalisadores PT-terras raras/C para celulas a combustivel do tipo PEMFC
Primary Subject
Source
2009; 125 p; Tese (Ph.D.)
Record Type
Miscellaneous
Literature Type
Thesis/Dissertation; Numerical Data
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Country of publication
ALCOHOLS, CATALYSTS, COHERENT SCATTERING, DATA, DIFFRACTION, DIRECT ENERGY CONVERTERS, ELECTROCHEMICAL CELLS, ELECTRON MICROSCOPY, ELEMENTS, FUEL CELLS, HYDROXY COMPOUNDS, INFORMATION, METALS, MICROSCOPY, NONMETALS, NUMERICAL DATA, ORGANIC COMPOUNDS, PLATINUM METALS, SCATTERING, SOLID ELECTROLYTE FUEL CELLS, SPECTROSCOPY, TRANSITION ELEMENTS
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