Bifunctional Sulfonatocalix[4]arene-MOF Fillers Enhance Proton Conductivity of Sulfonated Poly(Arylene Ether Ketone Sulfone) Membranes for Fuel Cells

Traditional proton exchange membranes (PEMs), such as Nafion, often rely on perfluorosulfonic acid, posing ecological risks. To address this, sulfonated poly(arylene ether ketone sulfone) containing amino group (Am-SPAEKS) membranes were created as an eco-friendly alternative. This study further innovates by incorporating sulfonatocalix[4]arene (SC4A)-functionalized UiO-66-NH₂ (SC4A@UiO-66-NH₂) into Am-SPAEKS to produce ASUS-X wt % hybrid membranes. This combination not only boosts proton conductivity without sacrificing mechanical properties but also leverages the unique functionalities of supramolecular macrocycles and metal–organic frameworks (MOFs) to create efficient proton transport channels. The resultant hybrid membrane ASUS-6 wt % exhibits remarkable properties, including a swelling ratio of 16.75% at 80 °C, tensile strength of 41.08 MPa, and proton conductivity of 163.11 mS cm^–1 at 80 °C and 100% RH, 89.13% higher than pristine Am-SPAEKS, with over 86% conductivity remaining after 432 h. Remarkably, the maximum power density reaches 392.73 mW cm^–2, twice that of pristine Am-SPAEKS. The unique properties of supramolecular macrocycles and MOFs can provide tailored functionalities to address key challenges in PEMs applications.