Unveiling the influence of furan and thiophene on the corrosion inhibition capabilities of novel hydrazones derivatives in carbon steel/HCl interface: A dual experimental-theoretical study

The use of corrosion inhibitors is a critical measure in the preservation of metals. In this research, the performance of two hydrazone derivatives, N '-[(E)-furan-2-ylmethylidene]- 2-(6-methoxynaphthalen-2-yl)propanehydrazide (NFH) and 2-(6-methoxynaphthalen-2-yl)-N '-[(E)-thiophen-2-ylmethylidene]propanehydrazide (NTH), was evaluated for their ability to inhibit corrosion of carbon steel in a 1.0 mol/L HCl solution. Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP), and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX) were employed to assess the compounds' inhibition performance. The experimental results demonstrated that the efficiency of the inhibitors improved with increasing concentration. NFH reached a 90% threshold, while NTH peaked at 93%. This superior performance of NTH was attributed to its thiophene group, in contrast to the furan moiety in NFH. PDP data revealed that both compounds acted as mixed inhibitors, inhibiting both anodic and cathodic reactions. The EIS results indicated a significant increase in polarization resistance, accompanied by a reduction in the values of effective double-layer capacitance, due to the adsorption of inhibitor molecules. The adsorption of inhibitor molecules conformed to the Langmuir isotherm model, suggesting a combined physicochemical mode of interactions with the carbon steel, which was corroborated by potential of zero charge (PZC) analysis. SEM-EDX analysis confirmed the thiazole derivatives' capacity to protect the metal against corrosion. Quantum Chemical Calculations (QCCs) along with Molecular Dynamics (MD) simulations elucidated the reactivity descriptors and the optimal adsorption configurations on the Fe(110) surface. This exploration underscores the significance of the thiophene moiety in enhancing the adsorptive and corrosion inhibitory properties of the hydrazones, thus providing strategic insights for their future refinement and application.