Electrocatalytic Activity of Nafion-Impregnated Pyrolyzed Cobalt Phthalocyanine: A Correlative Study Between Rotating Disk and Solid Polymer Electrolyte Fuel-Cell Electrodes

Carbon supported electrocatalysts for the reduction of oxygen can be screened quickly by using a rotating disk electrode (RDE) when an appropriate material is used as a binder to hold the catalyst on the disk electrode. The results obtained with the RDE in an oxygen-saturated H₂SO₄ solution mimic those measured for a full-cell H₂/O₂ solid polymer electrolyte setup. This result is demonstrated with a cobalt phthalocyanine-on-carbon black catalyst pyrolyzed at various temperatures ranging from 400 to 1100°C. When the catalyst is held on the disk electrode with electropolymerized pyrrole, a broad maximum of activity for the reduction of oxygen is observed for pyrolysis temperatures ranging between 600 and 900°C. When the catalyst is dispersed in a Nafion film on the disk electrode, a sharp maximum in its activity is observed at the pyrolysis temperature of 600°C, in agreement with its behavior in a full-cell setup.