Contribution to the corrosion inhibitors of copper-nickel (Cu-30Ni) in 3% NaCl solution by two new molecules of triazole: Electrochemical and theoretical studies

Abstract

This study aimed to investigate the inhibitory effects of two triazole derivatives, 4-amino-3-methyl-1,2,4-triazole-5-thione (MTSNH) and 3-methyl-1,2,4-triazole-5-thione (MTS), as corrosion inhibitors for Cu-30Ni in a 3% NaCl solution. The examination involved the use of various experimental and numerical techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), density functional theory (DFT), Monte Carlo (MC), and molecular dynamic simulations (MD). Additionally, a scanning electron microscope (SEM) coupled with energy-dispersive X-ray analysis (EDX) was utilized to examine the surface morphology of the copper-nickel alloy with and without inhibitors. The results of both stationary and transient tests showed that both derivatives exhibited a good inhibitory effect on the Cu-30Ni surface, with MTSNH demonstrating better inhibition than MTS. The theoretical calculations suggested that both inhibitors were flatly adsorbed, providing better coverage of the copper-nickel surface. As such, the compounds were identified as mixed types since they slowed both anodic and cathodic processes, with anodic predominance. The free adsorption energies of MTSNH and MTS were -40.4 and -35.6 Kj.mol−1, respectively, indicating that both derivatives were adsorbed through chemisorption on the copper-nickel surface. Furthermore, the adsorption data obtained from the EIS of these compounds corresponded well to the Langmuir adsorption isotherm.