Instability of Pt∕C Electrocatalysts in Proton Exchange Membrane Fuel Cells

Equilibrium concentrations of dissolved platinum species from a electrocatalyst sample in 0.5 M at 80°C were found to increase with applied potential from 0.9 to 1.1 V vs reversible hydrogen electrode. In addition, platinum surface area loss for a short-stack of proton exchange membrane fuel cells (PEMFCs) operated at open-circuit voltage was shown to be higher than another operated under load . Both findings suggest that the formation of soluble platinum species (such as ) plays an important role in platinum surface loss in PEMFC electrodes. As accelerated platinum surface area loss in the cathode (from 63 to in ) was observed upon potential cycling, a cycled membrane electrode assembly (MEA) cathode was…