Coalescing theoretical and experimental approaches for Schiff base and its copper complex as high-performing corrosion inhibitors for XC52 alloy

This study explores the corrosion inhibition properties of a newly synthesized Schiff base (HL) and its copper complex (CHL) on API 5 L XC52 steel alloy in HCl, integrating advanced electrochemical techniques, and computational modeling for a thorough evaluation of inhibition mechanisms. Comprehensive characterization of HL and CHL were conducted using Scanning Electron Microscopy (SEM), Ultraviolet-Visible (UV–Vis) Spectroscopy, Fourier-transform infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), and Nuclear Magnetic Resonance (NMR) Spectroscopy. CHL exhibits a superior inhibition efficiency of approximately 94 %, exceeding HL's 89 %, attributed to its capability to form a robust, protective film on the steel surface. Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements reveal CHL's substantial enhancement in polarization resistance and its pronounced reduction of both anodic and cathodic corrosion rates. Adsorption studies highlight CHL's improved chemisorption, following the Langmuir isotherm model, with a significantly higher adsorption affinity. Monte Carlo simulations further corroborate CHL's greater adsorption stability, with an adsorption energy of −2405.67 kcal/mol compared to HL's − 2087.95 kcal/mol. Overall, these findings position CHL as an exceptionally effective corrosion inhibitor with enhanced adsorption affinity and durable protective properties, establishing both HL and CHL as strong candidates for industrial steel protection applications.