MAURO C. SANTOS
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Artigo IPEN-doc 19114 Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation2013 - GERALDES, ADRIANA N.; SILVA, DIONISIO F. da; SEGURA PINO, EDDY; HAMMER, PETER; SPINACE, ESTEVAM V.; OLIVEIRA NETO, ALMIR; LINARDI, MARCELO; SANTOS, MAURO C. dosCarbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beamirradiation. The obtainedmaterials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd:Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3ā5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd:Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown thatthe mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 90 ā¦C, and the best performance of 44 mWcmā2 in 2.0 mol Lā1 ethanol was obtained at 85 ā¦C for the Pd:Au 90:10 catalysts. This superior performance is mostlikely associated with enhancement of ethanol adsorption on Pd, oxidation ofthe intermediates,the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support.