Explanation of the Quinoxaline Analog’s Adsorption and Inhibition Mechanism for Carbon Steel Corrosion in 1 M HCl Based on Experiments and Theoretical Calculations

In this work, we tested the effectiveness of phenyl-1-propyl quinoxaline-2(1H)-one (PRQX), a novel quinoxaline analog, as a corrosion inhibitor for carbon steel (C-S) in a 1 M HCl electrolyte. Incorporating numerous techniques, such as scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopy (EDX), and UV-visible spectroscopy, we examined the inhibitory properties of PRQX. PRQX maximum anti-corrosion efficiency was determined to be 97.7% at 10-3 M dose at 303 K temperature. PRQX displayed a mixed-type inhibitor effect, slowing anodic and cathodic corrosion processes, as indicated by PPD tests. The PRQX molecule binds to the C-S surface in compatibility with the Langmuir adsorption model. UV-visible analysis of the inhibited electrolyte clearly reveals the complexation of the Fe2+ with the PRQX molecule. Additionally, using density functional theory (DFT) and molecular dynamics simulation (MDS), conceptual analysis of the PRQX molecule’s most reactive sites and its adsorption process were carried out.