Nanofiber Electrodes with Low Platinum Loading for High Power Hydrogen/Air PEM Fuel Cells

Membrane-electrode-assemblies (MEAs) were fabricated with electrospun nanofiber electrodes containing Johnson-Matthey (JM) HiSpec 4000 catalyst and a Nafion 212 membrane. MEA performance was evaluated in a hydrogen/air fuel cell, where power output was correlated with cathode Pt loading (0.029–0.107 mg Pt /cm 2 ) and changes in fuel cell temperature (60°C and 80°C), pressure (up to 3.0 atm), and feed gas flow rates. In all experiments, the nanofiber anode had a fixed Pt loading of 0.10 mg/cm 2 . The mass activity (0.16 A/mg Pt at 0.9 V) and electrochemical surface area (∼41 m 2 /g) of nanofiber cathodes were very high and more power was generated from nanofiber electrode MEAs than from a conventional MEA with decal electrodes. Thus, the maximum power density for H 2 /air fuel cell operation at 80°C, 1 atm (ambient) pressure, 125 sccm H 2 , and 500 sccm air was 437 mW/cm 2 for a nanofiber cathode at 0.065 mg Pt /cm 2 vs. 400 mW/cm 2 for a decal MEA with cathode/anode Pt loadings of 0.104/0.40 mg/cm 2 . Similarly, an electrospun cathode with a Pt loading of 0.055 mg/cm 2 produced a maximum power density of 906 mW/cm 2 at 80°C and 3 atm pressure with 2000 sccm fully humidified air and 500 sccm H 2 .