An improved hydrophobic coating for the porous gas diffusion layer in a PEM-based electrochemical hydrogen pump to mitigate anode flooding

•Anode flooding is a critical issue of PEM-based electrochemical hydrogen pump.•Coating the gas diffusion media with Ag-HDFT renders it super-hydrophobic.•The coating effectively eliminated the anode flooding issue. Anode flooding is a critical issue in proton exchange membrane (PEM)-based electrochemical hydrogen pumps. Water-proofing the gas diffusion layer (GDL) on the anode side is a highly effective approach to mitigate the flooding problem and to enhance hydrogen pump performance. In this study, we report a low-cost, wet chemical process for water-proofing a metallic GDL. Silver particles, used as roughening and bonding agents, were first deposited on the porous metallic gas diffusion medium, and then heptadecafluoro-1-decanethiol (HDFT) was applied as a hydrophobic surface modifier. The result was a super-hydrophobic porous metallic GDL. Real electrochemical pump cell tests under simulated flooding conditions revealed that the water management performance of the coated GDL was dramatically improved.