Effect of titanium powder loading in gas diffusion layer of a polymer electrolyte unitized reversible fuel cell

► Polymer electrolyte unitized reversible fuel cell was investigated experimentally. ► The effect of structural properties of the oxygen-side GDL has been studied. ► Fuel cell operation has been influenced by the pore size distribution of GDL. ► The pore size distribution the GDL had no effect on the electrolysis performance. Polymer electrolyte-based unitized reversible fuel cells (URFCs) can be operated either as an electrolyzer to split water into hydrogen and oxygen using electric power or as a fuel cell to supply electric power when fed hydrogen and oxygen or air. In a URFC, titanium (Ti)-felt is used as a gas diffusion layer (GDL) in the oxygen electrode and typical carbon paper is used as a GDL in the hydrogen electrode. Here, first, Ti-powder was loaded into the Ti-felt GDL in URFCs to produce an effective pore distribution for water management in the membrane. Then, the effect of this Ti-powder loading on the cell performance was examined for both fuel cell and electrolysis operations. Experimental results revealed that the Ti-powder loading significantly improved the fuel cell performance under fully humidified conditions (relative humidity (RH) = 100%), but not under relatively dry conditions (RH = 66%). In contrast, the Ti-powder loading had no effect on the electrolysis performance.