Unraveling the corrosion inhibition mechanisms of Algerian Dryopteris filix mas leaf extract on A210C carbon steel in 1 M HCl: Comprehensive insights from electrochemical, morphological, XPS, and theoretical analyses

This study investigates the corrosion inhibition performance of Algerian Dryopteris filix mas L. (DFM) extract on A210C carbon steel in a 1 M HCl medium, addressing the critical demand for eco-friendly and sustainable corrosion inhibitors. The novelty of this work lies in its comprehensive approach, integrating experimental, morphological, and theoretical analyses to uncover the corrosion inhibition mechanisms of DFM extract. The extract's major components were characterized via Fourier Transform Infrared (FTIR) and UV-Vis spectroscopy, confirming the presence of key polyphenolic compounds, including Quercetin-3O-α-L-rhamnopyranoside (Q3Rha), consistent with previously reported data. Experimental methods, including weight loss, Open Circuit Potential (OCP), Electrochemical Impedance Spectroscopy (EIS), and Potentiodynamic Polarization (PDP), revealed a maximum inhibition efficiency of 88.50 % at 0.4 g/L concentration, with a significant reduction in corrosion current density. The Langmuir adsorption isotherm model described the adsorption behavior, yielding a free energy of adsorption (∆Gads°) of −18.31 kJ/mol, indicating spontaneous and stable physisorption. Morphological analyses using SEM, XPS, AFM, and Raman spectroscopy confirmed the formation of a protective organic-inorganic film on the steel surface, mitigating the corrosive effects of HCl. Computational studies provided additional insights: Density Functional Theory (DFT) calculations revealed an optimal HOMO-LUMO energy gap of 3.58 eV, while Molecular Dynamics (MD) simulations demonstrated a favorable interaction energy of −210 kJ/mol between the extract and Fe (1 1 0) surface. These results collectively highlight the dual mechanism of physical and chemical adsorption, showcasing DFM extract as a highly effective and environmentally benign corrosion inhibitor with promising industrial applicability.