LAUSR

This study examines the corrosion inhibition of Schiff base (SB) and its copper complex (CSB) on API 5 L XC52 steel in 1 M HCl. Characterization using FTIR, UV–Vis, NMR, SEM–EDX, TGA, and XRD confirmed the successful synthesis and stability of the compounds. Electrochemical methods, including weight loss, Tafel polarization, and electrochemical impedance spectroscopy (EIS), assessed inhibition efficiency and revealed that both SB and CSB act as mixed‐type inhibitors. At 10−3 M, SB and CSB achieved maximum inhibition efficiencies of 93% and 97%, respectively. Tafel polarization revealed a marked reduction in corrosion current density from 0.0231 (blank) to 0.0012 μA·cm−2 and 0.0013 μA·cm−2 at 10−3 M of SB and CSB, respectively. A slight anodic shift in corrosion potential was observed, particularly for CSB, which shifted from −706 (blank) to −661 mV at 10−3 M. Electrochemical impedance spectroscopy (EIS) results showed an increase in charge transfer resistance from 0.276 (blank) to 2.033 KΩ·cm2 for SB and 3.2676 KΩ·cm2 for CSB at the same concentration. Meanwhile, the double‐layer capacitance decreased significantly from 0.3225 (blank) to 0.0685 μF/cm2 for SB and 0.0676 μF/cm2 for CSB, indicating effective adsorption of inhibitor molecules onto the steel surface. Adsorption followed the Langmuir isotherm (R2 = 0.999), indicating monolayer adsorption. Gibbs free energy values (−38.658 kJ/mol for SB, −39.921 kJ/mol for CSB) suggest chemisorption. Monte Carlo simulations confirmed strong inhibitor‐Fe(111) interactions, with CSB exhibiting superior adsorption energy (−2405.6740 kcal/mol). These findings highlight CSB's enhanced efficacy as an eco‐friendly corrosion inhibitor for steel in acidic environments.