Proton-conducting membrane preparation based on SiO2-riveted phosphotungstic acid and poly (2,5-benzimidazole) via direct casting method and its durability

SiO2-riveted phosphotungstic acid (T–PWA–SiO2) was synthesized using the sol–gel method and thermally treated in a microwave synthesizer. The dissolving-detaching experiment shows that PWA in T–PWA–SiO2 exhibits better fastness than in the sample without thermal treatment (PWA–SiO2). The T–PWA–SiO2 samples were then combined with poly(2,5-benzimidazole) (ABPBI) to prepare ABPBI/(T–PWA–SiO2) composite membranes using the polyphosphoric acid direct-casting method. These composite membranes were characterized through X-ray diffraction and infrared spectroscopy. Then, the T–PWA–SiO2 particles were combined with ABPBI through hydrogen bonding between PWA and C=N in ABPBI. Membrane morphologies were investigated using scanning electron microscopy. Results of the thermogravimetric analysis indicate thermal stability of the composite membranes below 200 °C. The proton conductivity and durability between ABPBI/(T–PWA–SiO2) and ABPBI/(PWA–SiO2) composite membranes were also compared. The conductivity and life of the composite membranes were enhanced using T–PWA–SiO2. The conductivity of the ABPBI/(T–PWA–SiO2) (46 wt%) composite membrane was approximately 0.055 S/cm at 180 °C under 100% relative humidity.