Patterning the Cathode Catalyst Layer - Membrane Interface of a PEMFC for Elevated Power Density

Nafion patterned by electron beam lithography coupled with dry etching was tested for electrochemical performance in a proton exchange membrane fuel cell. Bare (neither patterned nor etched) and blanket etched Nafion membranes were also tested for comparison. Membrane electrode assemblies (MEA) were formed by sputtering Pt onto both sides of a membrane using a shadow mask to selectively expose 1 cm2 of geometric area. The blanket etched membrane produced the best performance with a power density of ~170 mW/cm2. The maximum power density for the patterned MEA was smaller compared to the bare and blanket etched Nafion membranes. Furthermore, the etched MEA initially displayed low open circuit potential. Its diminished performance was attributed to contamination artifacts from the fabrication process. A post fabrication hydrogen peroxide wash prior to MEA assembly led to a higher open circuit potential and improved performance.