Ultra Low Pt Anodes for Polymer Electrolyte Fuel Cells

摘要

The reduction of the Pt catalyst loading in Polymer Electrolyte Fuel Cells (PEFC) is a premise for a broad introduction into the market, especially for the application in electric cars. In state of the art PEFCs, the Pt loading for the anode and the cathode varies between 50 to 100μg/cm~2 , and 300 to 500μg/cm~2 , respectively. In this work, ultra low platinum loadings in the range of 3 to 27μg/cm~2 were sputter deposited onto carbon cloth substrates. These sputtered electrodes were employed as PEFC anodes. Membrane electrode assemblies (MEAs) were prepared by hot pressing the sputtered anodes with Nafion 212 membranes and commercial cathodes with a Pt loading of 500μg/cm~2. We succeeded in reducing the Pt loading of PEFC anodes down to 27 μg/cm~2, without significant loss of fuel cell performance compared to commercial electrodes with 500 μg/cm~2 Pt loading. Even with anode loadings as small as 3 μgPt/cm2 we obtain a similar PEFC performance at low currents (<0.5 A/cm2). Longevity tests at constant current densities (0.5 A/cm~2; 27 μg/cm~2 Pt anodes) showed nearly stable voltages for at least 500 h. The Pt morphology of the sputtered electrodes was investigated by transmission electron microscopy.