OXYGEN POLYLAYERS ON PLATINUM - KINETICS AND MECHANISM OF REDUCTION

A study into the reduction of phase-oxide (PO) polylayers and absorbed oxygen (AO) formed on platinum at high positive potentials is underta ken. The rate-determining steps are identified, the kinetic parameters are determined, and mechanisms for the reduction of POs and AO are pr oposed. It is shown that the rate-determining step for the reduction o f AO is electron transfer (E(H) > 0.4 V) or the migration of particles from the bulk of the electrode to the reaction zone (E(H) < 0.4 V). T wo reduction mechanisms, realized at E > 0.6 V and E < 0.5 V, are prop osed for POs. In the this region, the process presumably evolves via t he formation of oxygen adatoms emitted by PO globules to ionization si tes. At potentials more cathodic than 0.6 V, the reduction process shi fts directly into PO globules.