In situ, real-time imaging of redox-active species on Al/Cu galvanic couple and corrosion inhibition with 2-mercaptobenzimidazole and octylphosphonic acid

In situ localized electrochemical activity in the Al/Cu galvanic pair at the corrosion potential in an aggressive chloride electrolyte was investigated, along with the effect of the organic inhibitors 2-mercaptobenzimidazole (MBI) and octylphosphonic acid (OPA) on arresting the corresponding corrosion processes. Scanning electro-chemical microscopy (SECM) and the scanning vibrating electrode technique (SVET) were used to discern local anodic and cathodic sites at the surface. The electrochemical activity in the galvanic pair was greatly reduced when the copper surface was covered with an MBI-containing film. SECM was successfully applied to visualize spatially resolved differences in local electrochemical activity related to the inhibitor action.