Photocatalytically generated Pt/C-TiO2 electrocatalysts with enhanced catalyst dispersion for improved membrane durability in polymer electrolyte fuel cells

Platinum/carbon/titanium oxide (Pt/C-TiO2) electrocatalysts were prepared by a heterogeneous photocatalysis method wherein the semiconductor optoelectronic properties of TiO2 were exploited to facilitate photoreduction of a platinum precursor on the surface of the composite whole yielding excellent platinum dispersion. The TiO2 loading in the electrocatalyst was varied in the ranges: 5-10 wt % and the Pt content was varied from 5 to 50 wt %. The physical and electrochemical characteristics of these new-generation electrocatalysts were benchmarked against commercial Pt/C samples. Membrane electrode assemblies were prepared using these composite electrocatalysts and tested with hydrogen as fuel and oxygen/air as oxidants. The fluoride emission rate (in units of mu mol/h cm(2)) was estimated by condensate water analyses and found to be reduced by approximately an order of magnitude upon addition of TiO2. Implications of these data for optimization of polymer electrolyte fuel cells in terms of durability and performance are presented. (c) 2008 The Electrochemical Society.