Development of Hydrophobic Coating for Gas Diffusion Media in PEM-Based Electrochemical Hydrogen Pump

Abstract

Anode flooding is one of the critical issues in proton exchange membrane (PEM)-based electrochemical hydrogen pump. One way to to mitigate it is to make the gas diffusion media highly hydrophobic. The coating mateirals much be compatible with other critical materials in the PEM electrolyzer.. It was discovered that a mixture of Nafion™ and oxidized carbon nanotubes (O-CNT) coated onto the porous gas diffusion medium can render it hydrophobic with an effective contact angle of 130°. Electrochemical pump testing has shown that, with the help of the coating, the flood-recovery performance of the hydrogen pump was greatly improved. A hydrogen pump cell with an uncoated GDL was not able to recover from a flooded state, while a hydrogen pump cell with a coated GDL was able to recover its performance within 100 secs.