Kinetics of Aging of the Oxygen Monolayer on Platinum under a Complex Potentiodynamic Perturbation Program

Abstract

The dynamic aging of the oxygen‐containing species electrosorbed on platinum in sulfuric acid solutions in the region of the monolayer produces three energetically different Pt(O) species, which are revealed by running cathodic potentiodynamic scans. The dynamic aging process is described by a second‐order rate equation. It depends on the perturbation frequency and on the number of potential scans related to the aging process. The results also show a possible penetration of oxygen into the metal to the depth of the first and second crystallographic layers. A reaction scheme is proposed to explain the existence of the different species. The kinetic behavior is interpreted through a model where all the reacting particles are dynamically coupled to the fast electrochemical perturbation.