A combined electrochemical, molecular dynamics, quantum mechanics and XPS analysis of the mild steel surface protected by a complex film composed of neodymium (III) and benzimidazole

A mixture of Neodymium (III) nitrate (Nd) and Benzimidazole (Bi) was used for effective mild steel corrosion rate reduction in the sodium chloride solution. Results of electrochemical investigations revealed that the mixture of Bi and Nd significantly decreased both iron dissolution and oxygen reduction reactions rates and exhibited a mixed-type inhibition behavior and the best inhibition performance (about 98%) was achieved using 500 ppm Bi + 500 ppm Nd. Results of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and contact angle test confirmed that the chelation between the organic and inorganic inhibitors resulted in the protective film deposition on the steel substrate. The mechanism of organic and inorganic inhibitors adsorption over the steel surface was examined by Molecular Dynamic (MD) simulation and Quantum Mechanics (QM) calculation.