Experimental and detailed DFT/MD simulation of α-aminophosphonates as promising corrosion inhibitor for XC48 carbon steel in HCl environment

Corrosion is a pervasive issue in several industries, causing safety hazards and substantial economic losses. α-aminophosphonate substances have recently garnered attention for their ability to inhibit corrosion. In this study, two specific α-aminophosphonate molecules, namely diethyl(furan-2-yl(phenylamino)methyl) phosphonate (AMP1) and diethyl((2methoxyphenyl) amino) (thiophene-2-methyl) phosphonate (AMP2) were evaluated for their potential as anticorrosion agents for XC48 carbon steel under acidic conditions. Their corrosion inhibition was examined towards XC48 carbon steel under 1.0 M HCl solution utilizing the electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscope (AFM), scanning electron microscope (SEM), contact angle, Density functional theory (DFT), molecular dynamics (MD), and atoms in molecule (AIM). Results showed that AMP1 and AMP2 had inhibition efficiencies of 83.34% and 63.82% for EIS and 82.70% and 74.57% for PDP, respectively. The inhibition mechanism involved adsorption of the additives onto the metal surface via Langmuir isotherm. The study also demonstrated the influence of temperature on inhibition efficiency, with nearly 70% inhibition observed at 298 to 323 K. AFM and SEM analyses revealed chemisorption coating formation inhibiting acid attack, and contact angle analyses showed the surface to be hydrophobic. Theoretical analyses using DFT, MD, and AIM were used to clarify the inhibitors' adsorption effect on XC48 steel, showing a high agreement with experimental findings.