In-depth study of the adsorption mechanism of two synthesized triazole-pyrazole derivatives for corrosion inhibition of steel in 1M HCl: Electrochemical, XPS and computational approaches

Background: This work examined two newly synthesized triazole-pyrazole hybrids, 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1H-1,2,4-triazole (TzPz1) and 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1-methyl-1H-1,2,4-triazole (TzPz2), as prospective corrosion inhibitors for carbon steel in 1 M HCl. Methods: The inhibitory efficacy of TzPz1 and TzPz2 was evaluated by PDP and EIS to examine their electrochemical properties. The surface morphology and elemental composition were analyzed using SEM/EDX, while XPS and UV-visible spectroscopy were employed to investigate their chemical interactions with the steel surface. The adsorption behavior was assessed using the Langmuir isotherm, while theoretical investigations (DFT and MDS) elucidated the molecular-level adsorption process. Significant findings: The study demonstrated that TzPz1 and TzPz2 display concentration-dependent inhibition, with TzPz2 (95.2%) proving more efficacious than TzPz1 (92.6%) at 303 K and 10−3 M, as ascertained by PDP measurements. Both function as mixed-type inhibitors, adhering to the Langmuir isotherm and generating a chemisorbed protective layer, as shown by XPS and SEM-EDX analyses. DFT and MDS computations corroborated these findings, emphasizing robust interactions with the steel surface, consistent with experimental data.