Mesoporous ZrO₂/C and ZnO/C nanocomposites derived from MOFs for SPEEK-based proton exchange membrane

The metal–organic framework (MOF) incorporation in sulfonated poly(ether ketone) (SPEEK) membranes improves the performance of proton exchange membrane fuel cells (PEMFC) that use this filler in the electrolyte. Mesoporous ZrO₂/C and ZnO/C nanocomposites derived from the respective MOFs, Zr-BDC-MOF and Zn-BDC-MOF, were used as fillers in SPEEK to determine the influence of the metal (Zr or Zn) and ligand (terephthalic acid (BDC) or carbon (C)) on the proton conductivity and oxidative stability of proton exchange membranes (PEMs). At a temperature of 100 °C, the results show that adding 7 wt% of Zr-BDC-MOF to SPEEK resulted in 2.5-fold higher proton conductivity than pristine SPEEK. However, water uptake and oxidative stability studies reveal that this membrane loses its chemical stability. The data set shows that the inclusion of 7 wt% ZrO₂/C to SZrC(7) membrane resulted in the best proton conductivity, ca. 2.2-fold higher than SPEEK at 100 °C, making it attractive for application in PEMFC at high temperatures. Our findings show that the influence of the metal used as a filler (Zr or Zn) is lower than that of the ligand (BDC or C) on the oxidative stability and proton conductivity of PEMFC.