Synergistic effect of 2-mercaptobenzimidazole and octylphosphonic acid as corrosion inhibitors for copper and aluminium - An electrochemical, XPS, FTIR and DFT study

Inhibitory action of 2-mercaptobenzimidazole (MBI) and octylphosphonic acid (OPA) and their binary combi-nations on copper and aluminium in 3 wt.% NaCl was investigated by electrochemical methods, whereas the bonding of inhibitors was scrutinized by XPS and FTIR spectroscopies, wettability measurements, and DFT calculations. MBI is a good inhibitor for Cu but not for Al, whereas OPA behaves complementary. Although OPA is not an inhibitor for Cu, it can synergistically boost corrosion inhibition of copper when added to MBI. Evidence suggests that OPA changes the bonding of MBI by making the copper surface more susceptible to MBI resulting in a thicker and more protective organic film.

Automated summary

The inhibitory action of 2-mercaptobenzimidazole (MBI) and octylphosphonic acid (OPA) on copper and aluminum in NaCl solution was investigated. While MBI was found to be a good inhibitor for copper but not for aluminum, OPA behaved complementarily. Evidence suggested that OPA changed the bonding of MBI on the copper surface, resulting in a thicker and more protective organic film.