Porous silicon-aluminium oxide particles functionalized with acid moieties: An innovative filler for enhanced Nafion-based membranes of direct methanol fuel cell

This paper investigates potentials of a porous silicon aluminum oxide particles obtained by heating NH4-X zeolite powder as an innovative filler to form composite Nafion membranes for direct methanol fuel cells. Results from XRD show the filler has an amorphous type structure whereas FTIR, BET and 27Al MAS-NMR analysis show zeolite-like cage structures still exist. The Nafion composite membranes are prepared by solvent casting with filler content equal to 1.25 wt%, 2.5 wt%, 3.75 wt% and 5 wt%, respectively. The composite membranes show performance promotion in water uptake, ion exchange capacity, proton conductivity and methanol permeability in comparison to pristine Nafion due to the synergistic effect of Nafion, SiOH and SiOSO3H groups, skeleton framework, and porous structure of the activated filler. Especially, the membrane with 3.75 wt% filler shows the highest selectivity and excellent performance in terms of peak power density. For example at 80 °C, it exhibits a peak power density of 217 mW cm−2 which is more than 4 times the value of the pristine Nafion membranes prepared in this work.