New small gemini ionic liquids for intensifying adsorption and corrosion resistance of copper surface in sulfuric acid solution

Abstract In this study, three new gemini ionic liquids (GILs 1–3) were designed and prepared. The results showed that the GILs could undergo orderly molecular aggregation in sulfuric acid solution, which reached a steady aggregation state at 0.050 mM with 8 h evolving time. The tough chemical adsorption of the GILs aggregates on copper surface was confirmed by different means such as X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which could be formed by the Cu(I)-GILs coordination complexes. The yielded hydrophobic self-assembled monolayers (SAMs) adsorption of the GILs aggregates on copper surface were demonstrated by the measurements of spectroscopic ellipsometry and contacting angles (such as the GIL 3, the adsorption layer thickness, 5.70 nm, the contacting angle, 124.5 °). The copper corrosion inhibition effects of the GILs in sulfuric acid solution were measured by the electrochemistry analysis. The obtained results show the GIL 3 achieved over 96% corrosion inhibition efficiency at 0.050 mM based on electrochemical impedance spectroscopy (EIS). The decrease of charge transfer as well as the increase of double layer capacitance may make major contributions in copper corrosion resistance. The adsorption behavior of the GILs aggregates on the Cu surface was found to obey the Langmuir isotherm plots. In further consideration of the other advantages of the target GILs such as water solubility, negligible toxicity as well as easy preparation based on commercial starting materials, a large application potential could be expected.