Understanding the mechanism of corrosion inhibition of N-decyl-3-amino-1,2,4-triazole on Cu-Ni alloy: Combining electrochemical methods, morphological evaluation, DFT-electronic studies, complexation modes and molecular dynamics simulations

In this study, N-decyl-3-amino-1,2,4-triazole (TN10) was investigated as an eco-friendly corrosion inhibitor for copper-nickel alloy in a 3 % NaCl solution. A combination of experimental techniques, including open-circuit potential (E_OCP) measurements, Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), as well as theoretical approaches such as Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations, was employed to provide a comprehensive understanding of TN10′s inhibitory behavior and interaction mechanisms. The results revealed that TN10 exhibited excellent corrosion inhibition efficiency, achieving up to 99.17 % at a concentration of 1 mM. PDP curves demonstrated that TN10 acts as a mixed-type inhibitor with predominant anodic behavior. Adsorption studies following the Langmuir isotherm model indicated that TN10 adsorbs onto the metal surface primarily through chemisorption. SEM and EDX analyses confirmed that TN10 forms a protective barrier layer on the Cu-Ni alloy surface. Theoretical investigations using the B3LYP/6–311G++(d,p) provided insights into the electronic properties of TN10. Optimized geometries of TN10-metal complexes were obtained using the DFT/B3LYP/LANL2DZ method. Analysis of binding energies confirmed that these complexes formed strong interactions with the Cu-Ni surface, supporting TN10’s high adsorption potential and its effectiveness as a corrosion inhibitor. MD simulations further corroborated the experimental findings and DFT calculations, showing that TN10 adsorbs favorably on Cu-Ni (111) and Cu-Ni (110) surfaces. Radial distribution function (RDF) analysis pointed to a strong chemisorption interaction between TN10 and the metal surfaces (i.e., Cu-Ni (111) and Cu-Ni (110)), reinforcing the inhibitor's efficacy in corrosion protection.