A PFSA Composite Membrane with Sulfonic Acid Functionalized TiO2 Nanotubes for Polymer Electrolyte Fuel Cells and Water Electrolysers

Titanate nanotubes (TiO2‐NT) were functionalized with sulfonic acid functional groups and characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD). Results confirmed that sulfonic acid groups were grafted onto TiO2‐NT with a uniform distribution. When the functionalized titanate nanotube (F‐TiO2‐NT) was incorporated in perfluorosulfonic acid membranes, the membrane conductivity and water uptake were improved. Polymer electrolyte membrane (PEM) fuel cells using 5 wt.% F‐TiO2‐NT incorporated composite membrane exhibited a peak power density of 429 mW cm–2 with non‐humidified O2 at 90 °C, which is about four times higher than that with Nafion 117 membrane at identical conditions. PEMWE with 5 wt.% F‐TiO2‐NT incorporated composite membrane achieved 1,000 mA cm–2 current density at voltages below 1.6 V at 90 °C without back pressurizing.