Characterization of Pt-​based catalyst materials by voltammetric techniques

Catalyst materials in inks, in half-​MEAs and in a polymer electrolyte membrane (PEM) fuel cell were characterized by cyclic voltammetry.  Lab.-​made Pt inks were modified with Ru, Os and Ru+Ir and the MeOH oxidn. activity of the created surfaces was tested.  A novel electrode, which enables the study of the O redn. reaction on the cathode was introduced.  With this measuring device it was possible to vary the O content on the ink side and the p activity of the electrolyte on the membrane side of a half-​MEA.  Catalyst layers based on Pt, Pt-​Ru and Pt-​Co inside a PEM-​unit cell were also characterized in situ by cyclic voltammetry.  The active surface areas are linearly dependent on the Pt mass d. in the catalyst layers.  Approx. 30​% of the Pt loading in the MEA was electroactive.