Sulfonated Polysulfone/TiO2(B) Nanowires Composite Membranes as Polymer Electrolytes in Fuel Cells.

New proton conducting membranes based on sulfonated polysulfone (sPSU) reinforced with TiO2(B) nanowires (1, 2, 5 and 10 wt.%) were synthesized and characterized. TiO2(B) nanowires were synthesized by means of a hydrothermal method by mixing TiO2 precursor in aqueous solution of NaOH as solvent. The presence of the TiO2(B) nanowires into the polymer were confirmed by means of Field Emission Scanning Electron Microscopy, Fourier transform infrared and X-ray diffraction. The thermal study showed an increase of almost 20 °C in the maximum temperature of sPSU backbone decomposition due to the presence of 10 wt.% TiO2(B) nanowires. Water uptake also is improved with the presence of hydrophilic TiO2(B) nanowires. Proton conductivity of sPSU with 10 wt.% TiO2(B) nanowires was 21 mS cm-1 (at 85 °C and 100% RH). Under these experimental conditions the power density was 350 mW cm-2 similar to the value obtained for Nafion 117. Considering all these obtained results, the composite membrane doped with 10 wt.% TiO2(B) nanowires is a promising candidate as proton exchange electrolyte in fuel cells (PEMFCs), especially those operating at high temperatures.