DFT calculations, molecular simulations, and electrochemical investigations of Nature-inspired phytochemical attributes of Achillea Millefolium plants for the construction of effective zinc-based organic anti-corrosion layer on carbon steel

Carbon steel is an important industrial material; its corrosion and protection are attracting more attention from researchers. The use of advanced corrosion inhibitors is widespread due to their accessibility, convenience, and high-efficiency characteristics. In this account, for the first time, the leaves of Achillea Millefolium were extracted using ultrapure water, and the synergistic action of Achillea Millefolium Extract (AME) with zinc ion for carbon steel corrosion in 3.5% NaCl solution was evaluated. Polarization and electrochemical impedance spectroscopy (EIS) experiments were utilized to assess the suggested mixture's inhibition activity. Surface characterizations were carried out using ultraviolet-visible (UV-Vis) analysis, scanning electron microscope (SEM) equipped with EDX, Fourier transmission infrared (FTIR) spectroscopy, contact angle (CA) examination, and grazing incidence X-ray diffraction (GIXRD). Furthermore, DFT and molecular dynamics (MD) simulations were used to explain the inhibition mechanism at the atomic or molecular level. A combined protection attitude was identified, and for 500 ppm Zn + 500 ppm AME, the inhibition effectiveness was 93.49%. Polarization results suggest that the complex behaves as a mixed-type inhibitor, which simultaneously suppresses cathodic and anodic reactions. Surface analysis confirms the protective hydrophobic film formed on the steel surface, all of which demonstrate the outcomes of the electrochemical examination. Our work can provide a theoretical reference for further research on metal-organic-based corrosion inhibitors.