Inhibition performance of a novel quinoxaline derivative for carbon steel corrosion in 1 M HCl

In this work, the effect of a new quinoxaline derivative, 2-phenyl-3-(prop-2-yn-1-yloxy) quinoxaline (PYQX), was evaluated as a corrosion inhibitor for carbon steel (CS) in 1 M HCl electrolyte. Weight loss measurement, atomic absorption spectroscopy, potentio­dynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and UV-vis spectroscopy were employed to assess the inhibitory activity. The electronic properties of the interaction between the inhibitor molecule and the CS substrate were studied using molecular dynamics (MD) simulation, density functional theory (DFT), and Fukui functions. According to AC impedance experiments, the inhibitor under consideration showed a maximum level of 98.1 % inhibition efficiency at 1 mM and 30 °C. The Langmuir adsorption isotherm model explains the adsorption of PYQX on the CS surface. A slope of 1 denotes a strong molecule-substrate interaction, suggesting that the binding occurs at specific surface locations. To understand the functioning of the adsorption mechanism, various thermodynamic and activation parameters were evaluated. PDP tests demonstrated that PYQX functions as a mixed-type inhibitor. Computational correlations (DFT, MD, and Fukui indices) supported the experimental findings.