Nafion-TiO2 hybrid membranes for medium temperature polymer electrolyte fuel cells (PEFCs)

A nanocomposite re-cast Nafion hybrid membrane containing titanium oxide calcined at T = 400 oC 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 TiO2 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 TiO2 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 oC in humidified H2/air. The obtained results were compared with the commercial Nafion115 and a home-made recast Nafion membrane. Power density values of 0.514 and 0.256Wcm-2 at 0.56V were obtained at 110 and 130 oC, respectively, for the composite Nafion-Titania membrane. Preliminary tests carried out using steam reforming (SR) synthetic fuel at about 110 oC have highlighted the benefit of the inorganic filler introduction when PEFC operates at medium temperature and with processed hydrogen. © 2005 Elsevier B.V. All rights reserved.