This study aims to investigates the protective performance of three benzimidazole derivatives, namely, benzimidazole (B1), 2-methylbenzimidazole (B2) and 2-mercaptobenzimidazole (B3), on the corrosion of mild steel in 1.0 M HCl medium.
Density functional theory (DFT) and molecular dynamics (MD) simulations were employed alongside complementary analyses, including non-covalent interaction (NCI) index, mean square displacement (MSD) calculations, fractional free volume (FFV) and radial distribution function (RDF). Furthermore, global reactivity parameters, including (HOMO-LUMO) energies, energy gap (ΔE), global softness (σ), electronegativity (χ), electrophilicity index (ω), global hardness (η) and electron transfer (ΔN) were calculated and analyzed using various basis sets [3-21G, 6-31G, 6-31G++ and 6-31G++(d,p)].
MSD and FFV analyses showed a decrease in the mobility of corrosive species, suggesting a more restricted diffusion environment. Meanwhile, the RDF analysis revealed mixed adsorption behavior, with chemisorption being the dominant interaction mode for all three inhibitors. The simultaneous contribution of weak non-covalent and strong electrostatic interactions defines the interaction framework of the studied systems. The binding energy values follow the order B3 (1193.52 kJ·mol-¹) > B2 (1104.67 kJ·mol-¹) > B1 (964.63 kJ·mol-¹), indicating that B3 exhibits the strongest interaction with the metal surface. The corrosion inhibition performance of the benzimidazole derivatives increases in the following order: B3 > B2 > B1.
This work investigates the link between the corrosion inhibition performance of benzimidazole derivatives on mild steel and their theoretical assessment using DFT and MD simulations.
