Effect of RTILs on the Hydrogen Evolution Reaction in Alkaline Media

Three 1-ethyl-3-methylimidazolium [Emim]-based room temperature ionic liquids (RTILs), namely [Emim][Ac] (acetate), [Emim][EtSO4] (ethylsulfate) and [Emim][MeSO3] (methanesulfonate), were tested as additives in alkaline solutions for hydrogen evolution reaction (HER). Electrochemical measurements were performed with a platinum foil working electrode at 25 oC in 8 M KOH solution and after adding 1-2 vol.% of each ionic liquid. From the polarization curves, Tafel plots were constructed and the main kinetic parameters were obtained for all different electrolytes. Higher currents were found after [Emim][MeSO3] addition. Electrochemical impedance spectroscopy measurements revealed a significant decrease of the overall impedance in the RTILs added electrolytes.