ELECTROCHEMICAL REDUCTION OF OXYGEN ON SMALL PALLADIUM PARTICLES SUPPORTED ON CARBON IN ALKALINE-SOLUTION

The electrocatalytic behaviour of highly dispersed Pd/carbon catalyst prepared by ion preadsorption method for oxygen reduction in alkaline solution was investigated with soft-embedded rotating disk electrode a nd soft-embedded microelectrode method. The results showed that this c atalyst has high catalytic activity both for oxygen and for HO2- reduc tion in alkaline solution. The occurrence of the peak current on the p olarization curves of oxygen reduction on the catalyst when potential was scanned negatively, and the occurrence of the negative slope of ID N/I-R vs. omega(-1/2) relation were analyzed. It is proved that the co mpetition of Pd and support surface for oxygen molecules during oxygen reduction was the main cause for this new phenomenon.