Platinum oxidation in alkaline electrolyte under potentiostatic conditions

• Rate of Pt electrode oxidation depends on the order of applied oxidation potentials.
• Stability of Pt oxides depends on the sequence of applied oxidation potentials.
• Thick Pt oxides are stable at potentials lower than those of their formation.

Oxidation of a polycrystalline Pt electrode under potentiostatic conditions is examined in an aqueous 0.1 M KOH electrolyte at potentials lower than the oxygen evolution onset. When a potential step is applied, the kinetics of the oxidation and stability of the oxidised layer formed depend on the potential applied during the first oxidation step. The results also show that Pt surfaces with a high degree of surface coverage with an oxide are stable at potentials significantly lower than applied for the oxide formation.