Phosphoric Acid‐Immobilized Polybenzimidazole Hybrid Membranes with TiO₂ Nanowires for High‐Temperature Polymer Electrolyte Membrane Fuel Cells

Polymer electrolyte membrane fuel cells (PEMFCs) have attracted significant attention as next‐generation clean compact power sources. In this study phosphoric‐acid‐doped polybenzimidazole (PBI) membranes with added itanium dioxide nanowires are prepared to afford novel hybrid membranes that improve the performance and reliability of PEMFCs. Furthermore, the electrochemical and power generation properties of membrane‐electrode assemblies fabricated using the prepared hybrid electrolyte membranes are investigated. The swelling of the PBI membrane caused by phosphoric acid doping is suppressed by the titanium dioxide nanowires, thereby increasing the phosphoric acid concentration in the PBI membrane, even with very low dopant loadings. The increased proton conductivity and maximum power density are attributed to the increased phosphoric acid concentration in the membrane.