Study on sulfonated MXene/halloysite nanotube composite-modified SPI proton exchange membrane: proton transport mechanism and durability enhancement

Proton exchange membranes (PEMs) attract attention for their tunable proton-conducting channels, but building effective transport networks and improving long-term stability in composites remain key challenges. In this study, a novel SPI composite PEM reinforced with 1,3-propane sultone-modified MXene/halloysite nanotube (SMH) fillers was successfully prepared. Systematic material characterization and performance tests revealed that the incorporation of SMH fillers significantly improved the physicochemical properties of the membrane. Moreover, the –SO 3 H groups on SMH and the –NH 2 groups on APTES can form hydrogen bonds and acid–base pairs with the –SO 3 H groups on SPI, thereby enhancing the tensile strength and proton conductivity of the composite film. The composite membrane exhibited a tensile strength of 80.3 MPa and a proton conductivity of 313.9 mS cm −1 (80 °C, 100% RH), representing 26.2% and 29.5% enhancements compared to the pristine SPI membrane, respectively. It assembled fuel cell with the SPI-2SMH composite membrane demonstrated a maximum power density of 259.1 mW cm −2 . More importantly, the radical scavenging effect of the variable-valence metal ions in MXene endowed the composite membrane with improved long-term stability under fuel cell operating conditions, extending the open-circuit voltage decay time to 3.3 times that of the pure SPI membrane. This study provides a new strategy for developing PEM materials with both high proton conductivity and enhanced durability for fuel cell applications. Graphical abstract