The graphene materials can be applied as the protective layers of metallic materials against hostile conditions. However, the 2-dimensional graphene materials suffer from the high defect densities formed in the edges and boundaries of graphenes. The sophisticated control on defective sites is required to eliminate the possibility of preferential corrosion at those sites. In the current work, the 2-dimensional graphene materials were combined with atomic layer deposition of oxide materials in order to improve the corrosion resistance of metallic substrates against aggressive conditions. The presence of the graphene layer on copper foils hinders the dissolution of the metallic copper elements in the corrosive electrolyte where there is formed an interface between the ionic electrolyte and electronic graphene/copper materials. The atomic layer deposition of Al₂O₃ materials were performed onto the as-grown graphene materials which are formed on copper substrates. The anti-corrosive protection of graphene materials is enhanced through the defect-curing function of Al₂O₃ deposited through atomic layer deposition. Frequency-dependent impedance spectroscopy was employed in order to quantitatively monitor the quality of the graphene materials grown on metallic copper substrates without involving time-consuming transfer processes. The electrochemical impedance spectroscopy was combined with the Tafel analysis in association with the potentiodynamic measurements. The impedance-based quality control is demonstrated for optimized corrosion protection.