Electrospun Fiber Mat Cathode with Platinum‐Group‐Metal‐Free Catalyst Powder and Nafion/PVDF Binder

Electrospun nanofiber cathode mats were prepared with a metal‐organic framework (MOF)‐derived Fe−N−C catalyst and a blended binder of Nafion and polyvinylidene fluoride (PVDF). The electrodes were incorporated into H2/air fuel cell membrane‐electrode assemblies (MEAs) and compared with conventional sprayed‐cathode MEAs, in terms of power output and durability. The addition of hydrophobic PVDF into the electrode binder of nanofiber and sprayed cathodes produced a stable power output for 300 hours, whereas the sprayed‐electrode MEA with neat Nafion binder exhibited a 63 % power loss. The steady‐state maximum power density output of a PGM‐free nanofiber‐cathode MEA with a 1 : 1 Nafion : PVDF cathode binder at 80 °C and 1 atm backpressure was 154 mW/cm2. MEAs with a nanofiber cathode generated significantly more power than a sprayed cathode and the nanofiber cathodes continued to produce power throughout a carbon‐corrosion voltage cycling accelerated‐stress test. After 50 carbon corrosion‐voltage cycles, the maximum power density rose from 154 to 186 mW/cm2 and then decreased to 106 mW/cm2 at 500 cycles. Pt‐free catalyst nanofibers: Nanofibers with a Nafion/PVDF binder significantly improve the durability of proton‐exchange membrane fuel cells with platinum‐group‐metal‐free catalyst cathodes. This improvement is attributed to the increased hydrophobicity imparted by the PVDF and porosity of the nanofibers.