Water-soluble fullerene derivatives as radical scavengers for highly durable proton exchange membrane fuel cells
Ratna Balgis, Hibiki Ohashi, Kazuhira Miwa, Yoshiki Ono, S. Suyama, T. Yanai, Miftakhul Huda, Takashi Watanabe, Tsutomu Aoki, Toshikazu Ogino, Chunyan Li, Masaya Kawasumi, Yutaka Matsuo
Abstract
Efforts to improve proton exchange membrane fuel cell (PEMFC) durability are crucial for a hydrogen-based society, but their widespread adoption, especially in heavy-duty vehicles, is limited by membrane degradation from radical attacks. Herein, we report polar-solvent- and water-soluble fullerene derivatives C60(C6H3(OH)2-3,4)5(OH)n and C60(C6H4COOH)5(OH)n (n = 0–13) as radical scavengers which are homogeneously dispersed into the Nafion membranes. The hydroxy and carboxylic acid functional groups in the fullerene derivatives not only improved water solubility but also facilitated proton conductivity and chelating scaffold for Ce ions as co-scavengers. The fabricated Nafion membrane with functionalized fullerene derivatives and the chelation of Ce significantly enhanced durability, delaying membrane degradation for 1050 h compared to pristine Nafion membrane, which degraded with 100 h. It also reduced the F⁻ ion release rate to 10% of that of the reference Nafion membrane. These findings highlight the potential of functionalized fullerenes and their derivatives as effective PEMFC additives, enhancing both performance and durability for wider hydrogen energy system adoption. The limited lifetime of proton exchange membranes, due to radical attacks, hinders the broader adoption of hydrogen energy in heavy-duty vehicles. Here, membrane durability is enhanced by incorporating water-soluble fullerene derivatives and Ce ions, extending lifespan and reducing degradation.