Novel SPEEK-ZIF-67 Proton Exchange Nanocomposite Membrane for PEMFC Application at Intermediate Temperatures

In this study, nanocomposite membranes were prepared by mixing of 1, 3, and 5% wt cobalt-based zeolitic imidazolate framework (ZIF-67) with a sulfonated poly­(ether ether ketone) (SPEEK) matrix. The films named SPEEK, SPEEK-Z1, SPEEK-Z3, and SPEEK-Z5 were obtained by the casting method and then characterized by several techniques such as scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and electrochemical impedance spectroscopy (EIS). Ion-exchange capacity (IEC) and water uptake (WU) were also measured. Subsequently, the polymeric nanocomposite membranes were tested in a H2/O2 single cell to evaluate their performance. Our results show that the proton conductivity of nanocomposite membranes increased with the addition of ZIF, obtaining the best value of 0.014 S cm–1 for the SPEEK-Z1 membrane. Furthermore, the thermal stability of the nanocomposite membranes improved considerably with the ZIF addition. Polymer electrolyte membrane fuel cells (PEMFC) performance experiments showed promising results for these membranes working at intermediate temperatures above 100 °C, although a proper optimization process is still required.