Experimental and theoretical studies of hexylmeythylimidazolium tetrafluoroborate ionic liquid as cathodic corrosion inhibitor for mild steel

[Display omitted] •The imidazolium based ionic liquid HMIM.BF4 is prepared by following the metathesis reaction.•On mild steel (MS) surfaces, HMIM.BF4 forms a superhydrophobic film.•The effectiveness of the prepared HMIM.BF4 is tested using electrochemical experiments.•In HCl, this ionic liquid showed 96 %IE against corrosion according to Langmuir and Temkin isotherms.•Analytical Fukui functions were used to calculate the HMIM.BF4’s electron transfer site. Ionic liquids (ILs) are principally investigated for their utilization and applications in electrochemistry and their prospective approach to corrosion prevention has attracted a lot of attention. This article explains the synthesis and utility of a room temperature imidazole-based ionic liquid namely 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIM.BF4) as an inhibitor of corrosion on the mild steel surface. The HMIM.BF4 showed the cathodic type of steel corrosion inhibition with both chemisorption and physisorption nature obeying Langmuir and Temkin adsorption isotherms. At concentrations greater than 100 ppm, the inhibition efficiency of HMIM.BF4 increases and was found to be 96.27% at 300 ppm. Quantum chemical studies (frontier molecular orbitals and analytical Fukui) have been used to locate the redox-active sites on the inhibitor.