Surfactant-assisted perovskite nanofillers incorporated in quaternized poly (vinyl alcohol) composite membrane as an effective hydroxide-conducting electrolyte

Perovskite LaFeO₃ nanofillers (0.1%) are incorporated into a quaternized poly(vinyl alcohol) (QPVA) matrix for use as hydroxide-conducting membranes in direct alkaline methanol fuel cells (DAMFCs). The as-synthesized LaFeO₃ nanofillers are amorphous and functionalized with cetyltrimethylammonium bromide (CTAB) surfactant. The annealed LaFeO₃ nanofillers are crystalline without CTAB. The QPVA/CTAB-coated LaFeO₃ composite membrane shows a defect-free structure while the QPVA/annealed LaFeO₃ film has voids at the interfaces between the soft polymer and rigid nanofillers. The QPVA/CTAB-coated LaFeO₃ composite has lower methanol permeability and higher ionic conductivity than the pure QPVA and QPVA/annealed LaFeO₃ films. We suggest that the CTAB-coated LaFeO₃ provides three functions to the polymeric composite: increasing polymer free volume, ammonium group contributor, and plasticizer to enhance the interfacial compatibility. The composite containing CTAB-coated LaFeO₃ results in superior cell performance. A maximum power density of 272 mW cm^-2 is achieved, which is among the highest power outputs reported for DAMFCs in the literature.