Electrochemical Evaluation of Electrocatalysts for Fuel Cell Applications:A Practical Approach

摘要

The application of various electrochemical techniques to evaluate the activity of supported nano-size electrocatalysts for the oxidation of a specific fuel for fuel cell applications is examined. Cyclic voltammetry (CV) on both static and dynamic (rotating disc elec-trode, RDE) electrodes, and fuel cell station tests were the main electrochemical techniques used in this study. It was found from both static and dynamic CV and the fuel cell station tests that the most active catalyst is the one that shows the most negative oxidation peak potential. According to the Tafel equation, a lower anodic/cathodic overpotential is clear evidence of higher catalytic activity. This can be achieved for a specific current load by an electrocatalyst that exhibits as low a Tafel slope, and as high an exchange current density, as possible. RDE and fuel cell station tests show that the best performance was recorded for those electrocatalysts which have values of the Tafel slope (ba) and the exchange current density (io) that, on balance, give rise to the lowest overpotential. Therefore, CV and RDE are the recom-mended electrochemical techniques for a reliable assessment of electrocatalysts prior to performing a "real" fuel cell test.