Characterization of High-Surface-Area Electrocatalysts Using a Rotating Disk Electrode Configuration

A newly developed method is presented which allows the characterization of the electrocatalytic properties of high-ly dispersed electrocatalysts in a true rotating disk electrode (RDE) configuration by attaching the catalyst powder on a glassy carbon electrode via a thin Nafion film. Complete utilization and high reproducibility of both the electrode prepa-ration and the catalyst loading could be shown via voltammetry and CO stripping voltammetry. Furthermore, RDE mneas-urements on the electro-oxidation of hydrogen on Pt/Vulcan showed that the effect of diffusion through the Nafion film can be avoided by proper electrode preparation. Therefore, the electrode kinetics for fuel cell relevant reactions under continuous flow conditions can be measured directly without mathematical modeling. Infroduction Platinumsupported on high-surface-area substrates (e.g., Vulcan XC72) is a commonly used electrocatalyst in low-temperature polymer electrolyte fuel cells (PEM-FCs) for the anodic oxidation of H2 as well as for the cathodic reduc-tion of 02. 1,2 The development of new or modified catalysts with improved activity for fuel-cell applications require