Spray-coated cerium-loaded crown ether layers on expanded PTFE for reinforced composite fuel cell membranes with improved durability

초록

This study presents the preparation of a reinforced composite membrane (Nafion-Ce@15C5-ePTFE) by spray coating a cerium-based radical scavenging layer immobilized with 15-crown-5 (15C5) (Ce@15C5) onto an expanded polytetrafluoroethylene (ePTFE) reinforcement, followed by bilateral impregnation with a Nafion ionomer. The coordination structure of the crown ether stably captures cerium ions, suppressing leaching, and also contributes to improving the surface hydrophilicity of ePTFE, thereby promoting Nafion impregnation. By systematically controlling the number of spray coating cycles, a uniform Ce@15C5 layer was achieved without pore blockage at two coating cycles, ensuring continuous ion conduction pathways. The resulting composite membrane exhibits enhanced mechanical integrity originating from the reinforced architecture, together with improved chemical durability against radical attack. Notably, the fluoride emission in Fenton's test decreases to 0.018 ppm, confirming effective suppression of Nafion degradation. In single-cell evaluation, the composite membrane maintains performance comparable to that of a commercial Nafion membrane (N211) while showing reduced hydrogen crossover, and it sustains a stable voltage during an accelerated OCV hold for 250 h. This work demonstrates a practical membrane design strategy that integrates an ePTFE-reinforced structure with an immobilized cerium-based radical scavenger to achieve both performance and durability. © 2026 Elsevier B.V.

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