Avaliação de catalisadores à base de platina-paládio suportados em carbono para a oxidação de etanol em eletrólitos ácido e básico
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2018-08-09
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Universidade Federal de Goiás
Resumo
The management of the world energy matrix needs to be rethought, and in this context, the
energy sector is, over all, the focus of this discussion, and the present, depends more and
more on new strategies for energy production. In this way, the advances in the development
of technologies about alternative sources of energy generation called Fuel Cells, mainly the
electrochemical devices which working with ethanol as fuel (DEFCs). This work, the carbon
supported Pt/C; Pd/C; Pt75Pd25/C; Pt75(PdOx)25/C; Pt50Pd50/C e Pt50(PdOx)50/C electrocatalysts
with 20wt% of metal on carbon were prepared by fast reduction with sodium borohydride
(NaBH4) followed by thermal treatment. The materials were characterized by X-ray diffraction
(XRD) Transmission electron microscopy (TEM) and High resolution transmission electron
microscopy (HRTEM), x-ray energy dispersive spectroscopy (EDS), cyclic voltammetry (VC)
and Chronoamperometry. The EDS spectra showed e, experimental compositions of
electrocatalysts are close to nominal, which suggest, high efficiency of the redactor agent
BH4(aq)
-
/OH-
(aq) for reducing the ions Pt+4 (H2PtCl6.6H2O) and Pd+2 (PdCl2.6H2O). The XRD
analysis indicate the nanoparticle arrangement of the Platinum-Paladium with different
content results in crystalline structure on carbon support, and the peaks assigned to
Pt75(PdOx)25/C and Pt50(PdOx)50/C were observed indicating oxide formation from metal
precursors Pt75Pd25/C e Pt50Pd50/C by thermal treatment method. The micrographs HRTEM
showed homogenies particle size distribution on high area Vulcan XC-72 Carbon support. The
particle size were determined as the maximum of Gaussian distribution of Pt/C; Pd/C e
PtxPdy/C which showed electrochemical activity toward ethanol oxidation reaction in both, acid
and alkaline, electrolyte. The exception is Pd in acid media. Moreover, the materials
Pt75Pd25/C; Pt75(PdOx)25/C; Pt50Pd50/C e Pt50(PdOx)50/C with high Pd content, showed more
better performance for ethanol oxidation reaction in alkaline media, with high anodic current
density registered in the cyclic voltammetry and chronoamperometry experiments, in
comparison with Pd/C e Pt/C catalysts.
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CARVALHO, L. L. Avaliação de catalisadores à base de platina-paládio suportados em carbono para a oxidação de etanol em eletrólitos ácido e básico. 2018. 112 f. Tese (Doutorado em Química) - Universidade Federal de Goiás, Goiânia, 2018.