Experimental and computational study of newly synthesized benzimidazole derivatives as corrosion inhibitors for mild steel in 1.0 M HCl: Electrochemical, surface studies, DFT modeling, and MC simulation

Two newly synthesized benzimidazole compounds, 1-(Cyclopent-1-en-1-yl)-3-(prop-2-yn-1-yl)-1H-benzimidazol-2(3H)-one (IMD1) and 1-allyl-3-(cyclopent-1-en-1-yl)-1H-benzimidazol-2(3H)-one (IMD2), were evaluated for corrosion inhibition on mild steel (MS) in 1.0 M HCl solution. Techniques such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and weight loss (WL) analysis were employed. EIS analysis indicated increased resistance with compound concentration, suggesting the formation of a protective film at the MS/HCl interface. The formation of this protective coating was further confirmed through SEM-EDX analysis. PDP plots suggested a mixed-type inhibition mechanism. At 10⁻⁴ M concentration, IMD1 and IMD2 showed significant inhibition efficiencies of 98.1 % and 95.6 %, respectively. DFT gives insights into charge-sharing (donor–acceptor) interactions between inhibitor molecules and metallic surfaces. Monte Carlo simulation (MCS) confirmed these results, indicating that the molecules studied adsorbed almost parallel to the Fe (1 1 0) surface.