Materiais nanoestruturados baseados em Pt e Sn para células a combustível de etanol direto / Nanostructured materials based on Pt and Sn for Direct Ethanol Fuel Cells

AUTOR(ES)

Júlio César Martins da Silva

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

17/09/2010

RESUMO

This work presents the synthesis, characterization and performance of different electrocatalysts for Direct Ethanol Fuel Cells (DEFC). As cathode applications in DEFC it was synthesized a Pt3Sn/C alloy (20% metal w/w on carbon) by the polymeric precursor method (PPM) with 90% of alloy degree and particle sizes lower than 10%. Its performance using Pt3Sn/C as cathode and anode was measured in a single direct ethanol fuel cell, showing without oxygen pressurization of the cell a performance 20 % higher than the one using Pt3Sn/C as anode and Pt/C E-tek as cathode.The best performance using P3Sn/C as cathode is suggested to be explained due to a minimizing of the negative effects of the ethanol cross-over, because this material is considered one of the best for ethanol electrochemical oxidation. As anode applications for DEFC the electrocatalyst was synthesized in a coreshell structure of SnO2@Pt/C (20% metal w/w on carbon). The formation of core-shell nanoparticles (SnO2@Pt/C) was charactherized by UV-Vis, X-ray diffraction and electrochemical techniques. The diameters of the core-shell particles structures measured using high-resolution transmission electron microscopy images were in the range of 3 to 16 nm. Experiments of cyclic voltammetry and chronoamperometry were performed to evaluate the electrocatalytic activity of the nanomaterial. The electrocatalyst SnO2@Pt / C had its electrocatalytic activity compared to Pt/C, PtSn/C E-tek and PtSnO2/C (20% metal w/w on carbon). The mass current density for ethanol oxidation on SnO2@Pt was to much higher than those ones obtained for the same process using the comparison materials as electrocatalysts. This fact is probably due to an electronic effect, once Pt shell changes its electronic structure in the presence of the foreign core with an additional advantage of using low Pt loading.

ASSUNTO(S)

eletrocatálise materiais nanoestruturados ethanol electrocatalysis sno2@pt/c pt3sn/c defc nanostructured materials fisico-quimica oxidação de etanol

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