Understanding the Mechanism of 2-mercaptobenzimidazole Adsorption on Fe (110), Cu (111) and Al (111) Surfaces: DFT and Molecular Dynamics Simulations Approaches

Density functional theory (DFT) was carried out in order to establish which of the two forms of 2-mercaptobenzimidazole (2-MBI) (designated as 2-MBIthione and 2-MBIthiol) is actually responsible for the performance of 2-MBI as effective corrosion inhibitor for mild steel, copper, and aluminum. In this regard, geometrical parameters, electronic densities, global reactivity descriptors, electrostatic potential surfaces, and Mulliken charges on active atoms of the two tautomeric forms of 2-MBI on Fe (110), Cu (111) and Al (111) surfaces were computed and compared. The results indicate that the thione form of 2-MBI has the most reactive centers, has the highest electron donor capacity, lowest energy gap, highest fraction of electron transfered to the metal surfaces, carries a negative charge on its S atom and should be the most stable on the metal surfaces under investigation. According to molecular dynamics (MD) simulations the binding energy of the thione form of 2-MBI (2-MBIthione) on t