Hybrid Nafion®-inorganic membrane with potential applications for polymer electrolyte fuel cells

Mixed Nafion®/silicon oxide membranes with non-uniform Si/S concentration ratio profile were prepared by allowing tetraethoxysilane (TEOS) and HF to diffuse simultaneously from isopropanol solutions located at opposite sides of the ionomer membrane. This was made possible by using a specially designed cell where the Nafion® membrane is used to define two different and non-contacting volumes containing the solutions. The presence of a Si/S intensity ratio profile with a maximum located near the center of the membrane is confirmed by point-by-point EDX measurements along the thickness of the membrane. These mixed Nafion®/inorganic membranes with unmodified surfaces are expected to have applications in polymer electrolyte fuel cells.