Effect of Titanium Powder Loading in Microporous Layer on a Polymer Electrolyte Unitized Reversible Fuel Cell

Unitized reversible fuel cells (URFC) combine the functionality of a fuel cell and electrolyzer in one unitized device. For a URFC with proton exchange membrane, a titanium (Ti)-felt is applied to the gas diffusion layer (GDL) substrate at the oxygen electrode, and additionally titanium (Ti)-powders are loaded in the GDL substrate. The Ti-powder loading in the Ti-felt substrate yields hydrophobic meso-pores. The influence of this treatment is small for the electrolysis performance. In contrast, the change of pore-size distribution brings a significant improvement of fuel cell performance under fully humidification conditions. This fact indicates that the hydrophobic meso-pores in the GDL play an important role for mass transport.