Nafion–TiO 2 hybrid membranes for medium temperature polymer electrolyte fuel cells (PEFCs)

Abstract

A nanocomposite re-cast Nafion hybrid membrane containing titanium oxide calcined at T = 400 °C as an inorganic filler was developed in order to work at medium temperature in polymer electrolyte fuel cells (PEFCs) maintaining a suitable membrane hydration under fuel cell operative critical conditions. Nanometre TiO 2 powder was synthesized via a sol–gel procedure by a rapid hydrolysis of Ti(OiPr) 4. The membrane was prepared by mixing a Nafion–dimethylacetammide (DMAc) dispersion with a 3 wt% of TiO 2 powder and casting the mixture by Doctor Blade technique. The resulting film was characterised in terms of water uptake and ion exchange capacity (IEC). The membrane was tested in a single cell from 80 to 130 °C in humidified H 2/air. The obtained results were compared with the commercial Nafion115 and a home-made recast Nafion membrane. Power density values of 0.514 and 0.256 W cm −2 at 0.56 V were obtained at 110 and 130 °C, respectively, for the composite Nafion–Titania membrane. Preliminary tests carried out using steam reforming (SR) synthetic fuel at about 110 °C have highlighted the benefit of the inorganic filler introduction when PEFC operates at medium temperature and with processed hydrogen.