Adsorption and inhibition mechanism of (Z)-4-((4-methoxybenzylidene)amino)-5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione on carbon steel corrosion in HCl: Experimental and theoretical insights

Although the number of reported corrosion inhibitors has increased steeply in recent years, global corrosion damages raised the need for highly effective, new promising compounds for corrosion protection of metals and their alloys. Herein, chemical and electrochemical testing methods like weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) measurements were applied to evaluate the inhibition performance and adsorption mechanism of (Z)-4-((4-methoxybenzylidene)amino)-5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione (2C) against carbon steel (CS) corrosion 1.0 M HCl. Together, electrochemical results and morphological evidence from scanning electron microscope (SEM) demonstrated that, in the presence of 2C, the inhibition efficiency reaches a maximum of 86% at 10−3, forming a compact protective layer on CS surface. On the other hand, corrosion inhibition decreases a little with the rise of the temperature. The investigated compound was classified as a mixed class inhibitor, affecting both anodic and cathodic reactions, while its adsorption followed the Langmuir adsorption isotherm. Molecular dynamics (MD) simulations and quantum chemical calculations were used to give further insights into the inhibiting action of 2C and to explain its mechanism of action. Scanning electron microscopy (SEM) reveals an enhanced surface morphology of carbon steel after the addition of the tested compound to the electrolyte.