Electrochemical and DFT study on corrosion inhibition of aluminum by imidazolium type ionic liquid

Organic compounds, especially those containing polar functions with oxygen, nitrogen and/or sulfur in a conjugated system, have been frequently reported to inhibit the corrosion of metals in aggressive environments. In recent decade investigations, ionic liquids (ILs) have been pro-posed as green inhibitors to control corrosion of different metallic substrates exposed to corrosive media, particularly acid solutions. Utilizing ILs is one of the goals of green chemistry because of their tempting properties such as negligible vapor pressure, large liquids range, high thermal stability, high ionic conductivity and large electrochemical window [1-3]. In the present work, different imidazolium type ionic liquid was synthesized and their inhibiting action on the corrosion of stainless aluminum in HCl was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of the investigation show that the newly synthesized compounds show excellent inhibition efficiencies against the corrosion of Al in acidic solution. The adsorption of ionic liquid ions onto the Al surface followed the Langmuir adsorption model. Electronic properties such as highest occupied molecular orbital (HOMO) energy, lowest unoccupied molecular orbital (LUMO) energy and frontier molecular orbital coefficients for inhibitors have been calculated.