Catalyst Layer Architectures with Supportless Pt Hollow Spheres for Polymer Electrolyte Fuel Cells (PEFCs)

Supportless Pt black is an attractive oxygen reduction reaction (ORR) catalyst for polymer electrolyte fuel cells (PEFCs) due to its merits such as no concern of support corrosion at high potentials and high durability against Pt dissolution at frequent potential change conditions. However, when the Pt black catalysts were fabricated as MEAs the performance is still lower than the current Pt/C catalysts and they have difficulty in reducing Pt content in the MEAs. In the present study, we have prepared sub-micron size Pt hollow spheres as an alternative catalyst layer architecture for PEFC MEAs. The big Pt spheres were employed to make 3-dimensional catalyst layer architectures and to enhance oxygen transport in catalyst layers, and hollow type Pt was made to reduce Pt content and to facilitate water management. 200 nm Pt hollow spheres with 10 nm shell thickness were prepared using carbon sphere templates. The Pt hollow spheres revealed comparable ORR performance with commercial Pt/C catalyst in a half cell test. Catalyst layer fabrication was also performed using the catalysts by optimizing the catalyst slurries and its fuel cell performance at different operating conditions and durability will be discussed based on single cell test results.