DFT and electrochemical studies of tris(benzimidazole-2-ylmethyl)amine as an efficient corrosion inhibitor for carbon steel surface

The corrosion inhibition properties of tris(benzimidazole-2-ylmethyl)amine (TBMA) were analyzed by DFT and electrochemical techniques such as polarization curves and electrochemical impedance spectroscopy (EIS). DFT results clearly show that TBMA posses corrosion inhibition properties by having a delocalization region (N1double bond; length as m-dashC2double bond; length as m-dashN3) in the benzimidazole ring that gives up their ? electron density through its HOMO orbital to the metal LUMO to form a adsorption layer over the metallic surface; this has been proved by interacting the TBMA and its protonated structures with the surface of Fe13 cluster, showing that the protonated moiety adsorbs strongly on the iron surface than that of the neutral structure. Electrochemical impedance data demonstrate that the interface between the electrode and the TBMA solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of adsorption layer over the iron surface.