Investigation of self-humidifying membranes based on sulfonated poly(ether ether ketone) hybrid with sulfated zirconia supported Pt catalyst for fuel cell applications

A self-humidifying membrane based on sulfonated poly(ether ether ketone) (SPEEK) hybrid with sulfated zirconia (SO₄²⁻/ZrO₂, SZ) supported platinum catalyst (Pt-SZ catalyst) was synthesized for fuel cell applications. The SZ, a solid state superacid with hygroscopic properties and proton-conductive properties, was employed to synthesize the Pt-SZ catalyst. The self-humidifying membrane (SPEEK/Pt-SZ) was characterized by TEM, FT-IR, TGA and SEM coupled with EDX. The SPEEK/Pt-SZ membrane exhibited higher water uptake and proton conductivity than the plain SPEEK membrane. Consequently, the SPEEK/Pt-SZ self-humidifying membrane under dry operation showed a higher open circuit voltage (OCV) of 1.015 V and a maximum power density of 0.95 W cm⁻², relative to 0.96 V and 0.54 W cm⁻² for the plain SPEEK membrane. The incorporation of the catalytic, hygroscopic and proton-conductive Pt-SZ catalyst in the SPEEK matrix facilitated water balance and proton conduction, accordingly improved the single cell performance under dry operation. In addition, the enhanced OCV and the decreased area ohmic resistance confirmed the effect of Pt-SZ catalyst in the self-humidifying membrane on suppressing reactant crossover and the membrane self-humidification.