Composite membranes of quaternary ammonium cationic grafting poly(benzimidazole) modified by molybdenum clusters with enhanced proton conductivity

Developing novel, low-cost, and high-performance proton exchange membranes (PEMs) to replace commercial Nafion is of great significance. By grafting quaternary ammonium cations onto the side chains of polybenzimidazole, abundant charge carriers and proton hopping sites are provided for proton transport, accelerating proton migration and thereby enhancing the proton conductivity of composite membranes made from this material. Furthermore, polyoxometalates (POMs) are introduced through electrostatic interactions, and their exceptional proton-conducting properties further improve the proton conductivity of the composite membranes, with the maximum proton conductivity reaching 0.123 S·cm⁻¹. This work demonstrates that POM-based materials can serve as excellent proton carriers, expanding the selection of active materials for composite membranes and providing new references for the fabrication of novel proton exchange membranes.