Boosting the Proton Conductivity and Overall Stabilities of Nafion via the Swelling-Filling Modification of MoO₂ Nanosheets

Enhancing the proton conductivity and oxidative stability of perfluorosulfonic acid membranes, represented by the Nafion membrane, is critical for improving the performance and lifetime of proton exchange membrane fuel cells (PEMFCs). In this study, molybdenum dioxide (MoO2) nanosheets are successfully incorporated into the Nafion membrane via a nondefective swelling-filling strategy since MoO2 can act as an effective free radical scavenger and form hydrogen bonding with Nafion chains. The Nafion-MoO2 composite membrane, therefore, exhibits a significant enhancement in both oxidative stability with a 56.7% improvement and proton conductivity with a 26% increase compared with the pristine Nafion membrane. As a result, a PEMFC equipped with the Nafion-MoO2 membrane achieves a 40% increase in maximum power density. This work provides a facile and scalable approach to improving the overall performances of the Nafion membrane for practical PEMFC application.