Amino- and Sulfonate-Functionalized Metal–Organic Framework for Fabrication of Proton Exchange Membranes with Improved Proton Conductivity

Metal–organic frameworks (MOFs) are emerging as highly promising candidates for the next-generation proton conductors. Particularly, the amine-containing as well as various acid-functionalized MOFs and coordination polymers have been well explored. In anticipation of producing an alternate proton-conducting material with superior proton conductivity, both amine and sulfonates were incorporated in a MOF (Cu-SAT). It exhibits high stability in water, stability to dilute hydrochloric acid, and a remarkable proton conductivity of 0.53 × 10–3 S cm–1 at 353 K and 98% RH. As a step toward the practical application of the material in proton exchange membrane fuel cells (PEMFCs), the composite membranes of Cu-SAT and poly(vinylidene fluoride) (PVDF)−poly(vinylpyrrolidone) (PVP) matrix have been further fabricated. These PEMs display a proton conductivity as high as 0.80 × 10–3 S cm–1 at 353 K and 98% RH.