Promotion of PEM self-humidifying effect by nanometer-sized sulfated zirconia-supported Pt catalyst hybrid with sulfonated poly(ether ether ketone)

A self-humidifying membrane based on low-cost sulfonated poly (ether ether ketone) (SPEEK) hybrid with sulfated zirconia (SO42-/ZrO2, SZ)-supported platinum catalyst (Pt-SZ catalyst) was investigated for fuel cell applications. The SZ particle, a solid-state superacid with hygroscopic and high proton conductivity properties, was employed as the catalyst support. The SPEEK/Pt-SZ self-humidifying membrane was characterized by TEM and SEM coupled with EDX. FT-IR was conducted to verify the effect of SPEEK/Pt-SZ membrane on catalytic combination of crossover hydrogen and oxygen. To display the advantages of Pt-SZ catalyst as the additive, the IEC, water uptake, proton conductivity, single-cell performance, and areal resistance measurements were compared between the plain SPEEK membrane, SPEEK/Pt-SiO2 membrane, and the SPEEK/Pt-SZ membrane. The SPEEK/Pt-SZ membrane exhibited the highest IEC value, proton conductivity, single-cell performance, and the lowest areal resistance relative to the plain SPEEK and SPEEK/Pt-SiO2 membranes. The SPEEK/Pt-SZ self-humidifying membrane exhibited peak power density of 1.0 W/cm(2) under dry operation condition compared with 0.89 W/cm(2) and 0.58 W/cm(2) of SPEEK/Pt-SiO2 and plain SPEEK membranes, respectively. The incorporation of the catalytic, hygroscopic and proton conductive Pt-SZ catalyst in the SPEEK/Pt-SZ self-humidifying membrane facilitated water balance and proton conduction, and accordingly improved its single cell performance under dry operation. In addition, the enhanced OCV and the decreased areal ohmic resistance confirmed the promotion effect of Pt-SZ catalyst in the self-humidifying membrane on suppressing reactant crossover and the membrane self-humidification.