AN EXAMINATION OF THE ELECTROCHEMICAL-BEHAVIOR OF PALLADIUM IN BASE

This survey of the electrochemistry of palladium in base is a continuation of a related investigation of the same metal in acid. Both dc and in-phase ac cyclic voltammograms for palladized palladium in base gave even more marked indications that, as compared with the behavior at low pH, the active metal can undergo premonolayer oxidation. Incipient hydrous oxide formation (positive sweep) was assumed to occur in the same region where thick Pd(IV) hydrous oxide films reduce, i.e., in the region on the negative sweep extending from below the monolayer oxide reduction peak right into the hydrogen adsorption region. Incipient hydrous oxide species were again assumed to be involved, as mediators, in the electrocatalytic oxidation of reductants such as hydrazine. Anomalous oxidation, which was reported recently, in quite independent work, for metal cluster/oxygen gas reductions, together with super-Nernstian potential/pH shifts, appear to be an intrinsic part of noble metal electrochemistry.