Thermal degradation of the support in carbon-supported platinum electrocatalysts for PEM fuel cells

The cathode catalyst layer in proton exchange membrane (PEM) fuel cells can contain nanometer-sized platinum particles dispersed on a high surface area carbon. In order to assess support stability, samples of carbon-supported catalysts were held at elevated temperatures under dry air conditions. The samples were weighed at regular intervals. These tests showed that the platinum particles were able to catalyze the combustion of the carbon support at moderate temperatures (125-195 °C). As the temperature increased, the rate of carbon combustion increased. The amount of carbon that was lost after extended oven exposure at a constant temperature was shown to depend on both the temperature and platinum loading. A simple first-order kinetic model was able to describe the results. With further work on a range of different carbon supports, this work is expected to help develop more stable catalyst supports for PEM fuel cells.