Innovative benzo[d]imidazole-oxadiazole derivative for corrosion inhibition of C38 steel in hydrochloric acid: experimental and theoretical insights

In this work, a novel benzo [d]imidazole-oxadiazole derivative (OXDZ2) was synthesized and comprehensively evaluated as a corrosion inhibitor for C38 steel in 1 M hydrochloric acid, using a combination of advanced experimental and theoretical approaches.The structure and purity of OXDZ2 were confirmed by FTIR, 1 H and 13 C NMR, and high-resolution mass spectrometry.Electrochemical measurements, including Tafel polarization and electrochemical impedance spectroscopy, demonstrated that the addition of OXDZ2 led to a substantial decrease in corrosion rate, achieving a maximum inhibition efficiency of 96.97% at the optimal concentration.This high efficiency was reflected by a significant reduction in corrosion current density and an increase in charge transfer resistance.Surface morphology analysis using scanning electron microscopy revealed the formation of a homogeneous and compact protective film on the steel surface in the presence of OXDZ2.Theoretical investigations, based on density functional theory calculations and molecular dynamics simulations, provided molecular-level insights into the adsorption behavior and interaction mechanisms of OXDZ2 on the Fe (110) surface.Quantum chemical descriptorsincluding HOMO-LUMO energies, energy gap, electronegativity, hardness, electrophilicity index, and fraction of electrons transferredhighlighted the electronic reactivity of the inhibitor and the donor-acceptor interactions with the metal.Adsorption studies confirmed that OXDZ2 follows the Langmuir isotherm, with thermodynamic parameters indicating that chemisorption is the dominant mechanism.