Pyrochlore Zirconium Gadolinium Oxide Nanorods Composite Membrane for Suppressing the Formation of Free Radical in PEM Fuel Cell Operating Under Dry Condition

Abstract

A proton exchange membrane fuel cell uses perfluorosulfonic acid polymers as a proton exchange membrane but exhibits poor performance and durability under dry operating condition. Herein, we develop a composite membrane by incorporating porous inorganic filler, Zr2Gd2O7, into a perfluorosulfonic acid, Nafion. Zr2Gd2O7 nanorods (ZrGdNR) are synthesized using an electrospinning process and subsequently calcination under air atmosphere at 500 °C. The Nafion-ZrGdNR composite (Nafion-ZrGdNR) and NRE-212 membranes exhibit power densities of 858 and 695 mW cm-2, respectively, at 0.6 V under 100% relative humidity at 80 °C. At 20% relative humidity, the maximum power density of the Nafion-ZrGdNR membrane (448 mW cm-2) is 3.8 times higher than that of a commercial NRE-212 membrane (119 mW cm-2), and moreover, the Nafion-ZrGdNR membrane exhibits a fluoride emission rate of 6.9 × 10-5 ppm h-1 cm-2, which is about 240 times lower that of than the NRE-212 membrane (1670 × 10-5 ppm h-1cm-2) for 120 h of open-circuit voltage testing. The composite membrane shows high proton conductivity, superior oxidative stability, and improved mechanical strength. The outstanding performance and remarkable durability of the Nafion-ZrGdNR membrane are due to its efficient water diffusion and stability against hydroxyl radical attack, resulting in low ohmic resistance and improved membrane degradation. Copyright © 2019 American Chemical Society.