technologies. [1] The fuel cell (FC) is a device that, as an internal combustion engine, uses a kind of chemical fuel as a source of energy. However, such as a battery, the chemical energy is directly converted to electrical energy, [2] in a very simple and efficient way, overcoming the limitations in outcome imposed by a thermal machine cycle, in which the chemical energy is first converted to heat, and only then to electrical or mechanical energy.The current scenario arose once again investors' and researchers' interest for this technology in the last ten years. The expectation fed by the current world energy outlook is that this next century be of gradual transition from a "Hydrocarbon Economy" to a "Hydrogen Economy," with intense decrease of fossil fuel reserves. From the environmental point of view, the substitution of automobiles with internal combustion engines for those moved by hydrogen, for example, can promote air quality and climate conditions improvements, as well as in population health, by the elimination of exhaust gases Hybrid organic-inorganic membranes based on sulfonated poly(ether ether ketone) (sPEEK), zirconium oxide, and the protic ionic liquid (PIL) diethylmethylamine triflate ([dema][T f OH]) have been synthesized. Their structure has been investigated by X-ray diffraction and smallangle X-ray scattering and correlated to their electrical and thermomechanical properties. The membranes present good mechanical and chemical stabilities, as well as thermal stability over 300 °C. Zirconia contents up to 5 wt% (10 wt% PIL) lead to the formation of isolated zirconia-rich aggregates dispersed in the polymer matrix, constituted of spatially correlated zirconia nanoparticles. This segregation of zirconia species in nanodomains, interacting with sulfonic groups of sPEEK, inhibits conductivity. Differently, zirconia content of 6 wt% (10 wt% PIL) induces a conductivity much higher than pristine sPEEK, due to the formation of an extended fractal structure in the whole sample, constituted of connected zirconia-rich aggregates. Interaction of PIL molecules with the zirconia aggregates along this extended structure shall form new conducting channels for ion transport, favoring conductivity.

Concerns about environmental preservation instigate new investigations on alternative energy sources, such as proton exchange membrane fuel cells (PEMFCs). In order to avoid efficiency loss in PEMFC systems, at temperatures above 100 °C and minimize catalyst poisoning, anhydrous conditions are proposed, with substitution of water molecules by protic ionic liquids (PILs) as conducting medium for ions. PILs also feature excellent thermal stability. In this work, poly(ether sulfone) (PES), diethylmethylamine triflate ([dema][TfOH]) and titania (TiO2) or zirconia (ZrO2) based membranes were obtained and characterized, so that the filler effect on ion conductivity and polymer/PIL compatibility could be evaluated. XRD and TGA results indicated higher PES chain organization induced by the oxide networks, with thermal stability over 200 °C. These networks also contribute to better PIL retention in the membranes, as shown by TD‐NMR, and help improve ion conductivity, reaching values 160% higher than those found in samples containing just PIL.