Passive film of nano-grained pure copper was examined for semiconducting behavior in comparison to annealed pure copper. Mott–Schottky analysis revealed the vacancies behavior through the passive layer, and the Point Defect Model (PDM) put an accurate interpretation on the survey data. The findings clarify that the vacancy of copper is the main in the passive layer on both annealed and nano-grained pure copper formed anodically in 0.1 M KOH electrolyte. Also, calculations based on PDM showed that the diffusion coefficient of the copper vacancy for nano-grained sample reached to 17.11×10-17 cm2/s from 12.05×10-17 cm2/s of the initial annealed one.
