Mechanistic Insight Into the Sustainable Management of Acid‐Induced Corrosion of Mild Steel by Bioactive Phytochemicals of Tropical Kudzu: Electrochemical, Theoretical, and Biomolecular Identification Studies

Abstract

The aqueous leaf extract of an invasive plant Pueraria phaseoloides (Pp) was valorized as a sustainable corrosion inhibitor for mild steel in 0.5 M HCl. Corrosion studies were carried out using both non‐electrochemical and electrochemical methods. After 24 h immersion in 0.5 M HCl, EIS, and PDP analyses revealed an inhibition efficiency of approximately 97%, while the corrosion current density decreased to 0.0980 mA/cm 2 . Polarization studies indicated that TKL acts as a mixed‐type inhibitor. Adsorption studies demonstrated that the inhibition process is spontaneous (∆ G 0 ads = −18.2635 kJ/mol at 298 K), follows the Langmuir adsorption isotherm, and is predominantly controlled by physisorption. Surface characterization was carried out using SEM and AFM and XPS analysis. HRLCMS confirmed the presence of 50 metabolites in TKL and molecular level mechanistic insights derived qualitatively using theoretical studies. The synergistic adsorption of phytochemicals forms a protective film that suppresses charge transfer and metal dissolution. This work demonstrates a sustainable approach for valorizing an invasive weed species into a high‐performance green corrosion inhibitor and provides molecular‐level insight into its inhibition mechanism.