Kinetic stability diagram for copper in borate buffer solution

Abstract The passivity of pure copper over a wide pH range has been explored using potentiodynamic and potentiostatic polarization, Mott–Schottky analysis, and electrochemical impedance spectroscopy (EIS). The study shows that the passive film is a p‐type semiconductor. The natural logarithm of the passive current density is found to linearly increase with the film formation potential. The passive state of copper is interpreted by optimizing the point defect model (PDM) on the EIS data. Kinetic stability diagrams are derived for pure copper in borate buffer based on the rate law for passive film growth in accordance with the PDM.