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 H-2/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 degrees C and 1 atm backpressure was 154 mW/cm(2). 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/cm(2) and then decreased to 106 mW/cm(2) at 500 cycles.