Enhancing Proton Conduction of Poly(benzimidazole) with Sulfonated Titania Nano Composite Membrane for PEM Fuel Cell Applications

Abstract

Polybenzimidazole (PBI)-sulfonated nano titania (S-TiO2) polymer composite membranes have been prepared by solvent casting technique for high temperature polymer electrolyte membrane (HT-PEM) fuel cells. X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy was used to characterize the polymer structure and confirm the complexation of the sulfonated titania inside the polymer matrix. The highest proton conductivity obtained was 0.091 S cm−1 at 160 °C. The temperature dependent proton conductivity of the phosphoric acid doped proton conducting polymer electrolyte exhibits an Arrhenius relation and Grotthuss mechanism. Thermal gravimetric analysis (TGA) showed that all the prepared proton conducting polymer membrane exhibit good thermal stability. The morphological behaviors of the prepared proton conducting polymer electrolytes were depicted by scanning electron microscope (SEM) micrograph. The prepared composite membranes were characterized by proton conductivity, durability and mechanical strength. The acid uptake of the PBI-sulfonated titania blended membrane was found to be higher than that of the pristine PBI. The fabricated composite membrane with the highest conductivity exhibited a maximum current density of 0.89 A cm−2 through the high proton conductivity.