Electrochemical and theoretical investigations to comprehend the adsorption of new pyrazole derivative on mild steel in 1 M HCl

The adsorption performance of 4-((1H-pyrazol-1-yl)methyl)-4-methyl-2-phenyl-4,5-dihydrooxazole [Pyr-H2] and 4-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-4-methyl-2-phenyl-4,5-dihydrooxazole [Pyr-(CH3)2] was evaluated for mild steel in 1 M HCl solution. The current examination was carried out using weight loss measurements, electrochemical techniques (polarization curves and electrochemical impedance spectroscopy), surface morphology analysis, and theoretical approach. Before the experimental test, in-silico environmental toxicity was evaluated, indicating the eco-friendly behavior of the concentration used as corrosion inhibitors. The experi-mental findings showed that these chemicals acting as mixed-type inhibitors, preventing both anodic and cathodic reactions. Moreover, the mild steel surface was also examined using scanning electron microscopy coupled with EDX analysis. These chemicals adsorbed onto the mild steel surface following Langmuir isotherm. In addition, DFT calculations at B3LYP 6-311G (d,p) was used to estimate the reactivity of these molecules by linking their electronic characteristics with their experimental outcomes, whereas Monte Carlo simulation confirms the parallel approach of the studied pyrazole into the steel surface. Finally, it can be concluded that the existence of two methyl group in [Pyr-(CH3)2] inhibitor augmented the covered surface area compared to [Pyr -H2] molecule.