Durability Aspects of Nanostructured Thin Film Catalysts for PEM Fuel Cells

Various durability properties of a nanostructured thin film based catalyst system (3M's NSTF) which does not contain carbon or additional ionomer, are compared with conventional carbon supported dispersed Pt catalysts. The NSTF catalysts are shown to have mass losses by TGA at 170oC that are two orders of magnitude less. The NSTF whisker support material in combination with the large-grained polycrystalline thin film catalysts that encapsulate the whiskers give significantly greater durability under normal fuel cell operating conditions and also under accelerated high voltage conditions, whether scanning between 0.6 and 1.2 volts at 20mV/sec under H2/N2, or under steady state conditions of 1.5 volts. At 1.5 volts, NSTF catalysts lose no surface area, specific activity or fuel cell performance over periods as long as 3 hours, whereas the Pt/C based electrodes lose both large amounts of surface area, activity and performance in just 30 minutes at 1.5 volts.