Matos, B.R.; Goulart, C.A.; Tosco, B.; da Silva, J.S.; Isidoro, R.A.; Santiago, E.I.; Linardi, M.; Schade, U.; Puskar, L.; Fonseca, F.C.; Tavares, A.C.: Properties and DEFC tests of Nafion - Functionalized titanate nanotubes composite membranes prepared by melt-extrusion. Journal of Membrane Science 604 (2020), p. 118042/1-7

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.