Fluorinated strategy of node structure of Zr-based MOF for construction of high-performance composite polymer electrolyte membranes

Abstract

The dispersion and compatibility of metal–organic frameworks (MOFs) in polymeric matrices significantly influence the properties of composite membranes. However, the modification and functionalization of the node structures of MOFs to improve their dispersion in the polymeric matrix have been rarely studied. In this work, the node structures of UiO-66-NH2 frameworks were modified by the introduction of F species, and abundant Zr–F bonds and pore blocking effects were generated, which significantly affected the comprehensive performances of the composite membranes, including the dispersion, mechanical properties, proton conductivities, swelling ratios, and water uptake. Due to the good dispersion of the fluorinated MOF nanoparticles in the Nafion matrix, the composite membranes had high proton/methanol selectivity and low methanol permeability, which exhibited superior fuel cell performances in DMFCs (24.9–26.8 mW cm−2) to that of recast Nafion (20.4 mW cm−2). Notably, this was the first time that the node structures of MOF-based nanoparticles were fluorinated to improve their dispersion in a polymeric matrix, providing a simple strategy for developing high-performance composite membranes.