Synergistic mechanism and synergistic effect of two structurally complex imidazole derivatives forming a double adsorption layer

The synergistic effect and mechanism of two complex imidazole derivatives (JMZ and WJN) on corrosion inhibition of Q235 steel in 1.0 M HCl were studied. The electrochemical results demonstrated that the corrosion inhibition efficiency of the mixed inhibitor was superior to that of a single inhibitor, reaching 98.74 % at a JMZ to WJN ratio of 4:4. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements revealed that the degree of corrosion on the carbon steel surface correlated with the concentration of the inhibitors. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) confirmed the effective adsorption of both JMZ and WJN on the Q235 surface. Molecular dynamics simulations suggest that the synergistic effect arises from a double adsorption layer, where JMZ preferentially adsorbs at a distance of 1.3 Å from the Fe (110) surface, while WJN fills the gaps in JMZ and continues to adsorb at 4.57 Å. At the 4:4 ratio, the adsorption energy reaches −4420.33 kcal·mol⁻¹, minimizing the diffusion rates of Cl^- and H₃O⁺ in the solution. These findings provide valuable insights into the synergistic effect of dual adsorption layers in developing effective corrosion inhibitors.