Corrosion inhibition of copper in sulfuric acid by Leonurus japonicus Houtt. extract as a green corrosion inhibitor: Combination of experimental and theoretical research

Based on the consideration of green and safety in industrial production, the demand and desire for green corrosion inhibitors are increasingly strong. In this study, we selected Leonurus japonicus Houtt. leaves extract (LLE) extracted by water. Electrochemistry experiments and morphology characterization showed excellent anti-corrosion performance of LLE for copper in 0.5 mol∙L1 H2SO4. The chemical bond information measured by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that LLE adsorbed on Cu/H2SO4 interface by chemical bonding. Through quantum chemical calculation and molecular dynamics simulation analysis, the adsorption reaction mechanism was profoundly studied. Electrochemical test data showed that the inhibition efficiency of 400mg/L LLE arrived at 90% at 298 K, 308K and 318 K. After processing the data, it is concluded that LLE protective film belonged to Langmuir adsorption. By calculating thermodynamic and kinetic parameters of corrosion, it is found that the activation complex is formed by the binding of Cu+ and LLE in the adsorption layer.