Inhibition effect and adsorption behavior of Michelia alba leaf extract as corrosion inhibitors for Cu in 0.5 M H2SO4

Corrosion has become an increasingly serious hazard in modern industry and daily life, which makes the development of efficient and environmentally friendly corrosion inhibitors (CIs) extremely critical. In this study, the corrosion inhibition performance of Michelia alba leaf extract (MAE) on Cu in 0.5 M H2SO4 was investigated by polarization curve test (Tafel), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and theoretical calculations. The results of the EIS showed that the corrosion inhibition efficiency reached 94.72%. Tafel tests showed that the corrosion inhibition of Cu by MAE was reflected by a significant decrease in the corrosion current density and a significant increase in the charge transfer resistance. SEM showed that the number of corrosion pits on the Cu surface decreased and the depth of the pits became shallower with the addition of MAE. Theoretical calculations explained the adsorption mechanism between MAE and Cu surface, and the reduction of diffusion coefficient indicated that MAE could reduce the diffusion of corrosion ions. This study provides a theoretical basis for new green corrosion inhibitors.