Development of a Hydrophobic Coating for the Porous Gas Diffusion Layer in a PEM-based Electrochemical Hydrogen Pump to Mitigate Anode Flooding

Anode flooding is one of the critical issues in developing a proton exchange membrane (PEM)-based electrochemical hydrogen pump. Improving the hydrophobicity of the gas diffusion layer (GDL) has been studied as an approach to mitigating anode flooding in electrochemical pumps. A mixture of Nafion™ and oxidized carbon nanotubes (O-CNT) has been applied to the porous gas diffusion medium in the hydrogen pump cell. The coating renders the GDL 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 in about 100 s.