Metal-organic framework anchored sulfonated poly(ether sulfone) nanofibers as highly conductive channels for hybrid proton exchange membranes

In this study, a novel MOFs-anchored-nanofiber framework (UiO-66-NH 2 @NFs) is designed via electrospinning. To hybridize with Nafion matrix , UiO-66-NH 2 @NFs/Nafion membranes with acid-base pairs are fabricated. In the framework, sulfonated poly(ether sulfone) (SPES) nanofibers with effective –SO 3 H groups serve as bonding platforms and UiO-66-NH 2 with –NH 2 groups act as co-reinforcement units tethering in nanofibers. As systematically studied and compared in membrane performance , the homogeneous UiO-66-NH 2 @NFs/Nafion membrane with a moderate UiO-66-NH 2 filler amount of 8 wt% present excellent performance on elevating proton conductivity of 0.27 S cm −1 (80 °C, 100% RH) and inhibiting methanol permeability of 7.54 × 10 −7  cm 2  s −1 , respectively. The above superiorities can be attributed to the unique MOFs-anchored-nanofiber framework with balanced acid-base pairs. The interconnected UiO-66-NH 2 @NFs framework with hydrophilic SPES nanofibers and UiO-66-NH 2 offer consecutive proton transfer channels, making protons easily transfer via the hydration channels. Moreover, –NH 2 groups in UiO-66-NH 2 and –SO 3 H groups in matrix interact via acid-base pairs, which synergistically conducts protons via proton hopping channels in the membranes. Meanwhile, the good compatibility of UiO-66-NH 2 @NFs with Nafion matrix resulting from the tight electrostatically interactions between –NH 2 and –SO 3 H groups endow the hybrid membranes with suppressed methanol permeation and strengthened mechanical properties .