ROBERTA ALVARENGA ISIDORO
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Artigo IPEN-doc 27152 Properties and DEFC tests of Nafion2020 - MATOS, B.R.; GOULART, C.A.; TOSCO, B.; SILVA, J.S. da; ISIDORO, R.A.; SANTIAGO, E.I.; LINARDI, M.; SCHADE, U.; PUSKAR, L.; FONSECA, F.C.; TAVARES, A.C.Nafion based composites are promising materials to improve the performance of direct ethanol fuel cells. In this work, composite membranes of Nafion and titanate nanotubes functionalized with sulfonic acid groups were prepared by melt-extrusion and tested in a direct ethanol fuel cell. Far and mid infrared spectroscopies evidenced the formation of ionic bridges between the sulfonic acid groups of both functionalized nanoparticles and the ionomer. Small angle X-ray scattering measurements revealed that the melt-extrusion method leads to an uniform distribution of the inorganic phase in the ionomer matrix. Such structural analysis indicated that the improved the proton conduction properties of the composites, even with the addition of a high concentration of functionalized nanoparticles, are an outcome of the synergistic ionic network due to the hydrid organic/inorganic proton conducting phases. However, an improvement of the fuel cell performance is observed for 2.5 wt% of functionalized titanate nanotubes, which is a result of the lower ethanol crossover and the plasticizing effect of the aliphatic segments of the organic moieties grafted at the surface of the titanate nanoparticles.Artigo IPEN-doc 20706 Performance enhancement of direct ethanol fuel cell using Nafion composites with high volume fraction of titania2014 - MATOS, B.R.; ISIDORO, R.A.; SANTIAGO, E.I.; FONSECA, F.C.The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 C with Nafion-titania composite electrolytes prepared by solegel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.