Proton exchange membranes were prepared and characterized for utilization in high-temperature proton exchange membrane fuel cells, HT-PEMFCs. 1-vinylimidazole (1-VIm) and 4-vinylpyridine (4VP) monomers were simultaneously grafted onto pre-irradiated ETFE (ethylene-co-tetrafluoroethylene) films which were prepared using γ-rays with a dose of 100 kGy, as a robust substrate to prepare acid−base composite membranes. The grafting reaction was performed at 60°C for 24 h followed by protonation via phosphoric acid doping in the subsequent step. The effect of adding ferrous salts as promoters in grafting was investigated by characterization of resultant membranes via thermal gravimetric analysis and mechanical tests. The fuel cell tests were conducted under different relative humidities (RHs) and applied temperatures. Membranes prepared with salt addition exhibited superior proton conductivities. Results including up to 80 mS cm −1 conductivity at 110°C in 60% RH and excellent thermal stability, even at 300°C, suggest these membranes are promising for HT-PEMFC applications.

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The need for the development of new materials and strategies to enhance the performance of the PEM fuel cell at low humidity and platinum (Pt) loadings is becoming increasingly crucial. Due to this fact, the current study presents the fabrication of electrospun sulfonated silica (S-SiO 2 ) as a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE))-based, flexible, freestanding, and highly porous novel cathode structure for PEM fuel cells. The developed fiber-based P(VDF-TrFE)/Pt/C/S-SiO 2 cathodes are compared with electrospun PVDF/Pt/C/S-SiO 2 , PVDF/Pt/C/Nafion, and conventionally sprayed electrodes to evaluate the utility of a new (carrier) P(VDF-TrFE) polymer in electrode structure. Morphological analyses revealed that S-SiO 2 and Pt/C particles were homogeneously distributed along the fibers without any significant agglomerations. The MEAs prepared by fiber-based P(VDF-TrFE)-Pt/C/S-SiO 2 cathodes with low Pt loadings (0.1−0.15 mg cm Pt −2) demonstrated promising fuel cell performance recording up to 417.7 mW cm −2 . It also exhibited a remarkable power output retention (98.2%) under partially humidified conditions. In situ electrochemical measurements reveal that enhanced particle distribution and Pt/S-SiO 2 surface contact results in the cathode performance surpassing that of conventional sprayed and fiber-based PVDF/Pt/C/Nafion cathodes. The fiber-based P(VDF-TrFE)/Pt/C/S-SiO 2 cathodes exhibited a promising durability record retaining up to 86.5% of their maximum power output after 30 000 cycles of a Pt-dissolution accelerated stress test (AST). Furthermore, P(VDF-TrFE)-Pt/C/S-SiO 2 cathodes with high S-SiO 2 loadings exhibited a 2.7% gain in maximum power density after 1000 cycles of a carbon corrosion durability test.

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