Electrochemical polymerization of aniline in a protic ionic liquid with high proton activity

Electrochemical polymerization of aniline in conventional protic ionic liquids (PILs) usually requires an exogenous proton source or the aniline monomer pre-protonation to obtain high quality polyaniline (PANI). In the present work, a proton functionalized ionic liquid pyrrolidinium hydrogenosulfate ([Pyrr][HSO4]), which has high proton activity, has been tried for the first time as an electrolyte for the aniline electropolymerization. It is shown that in this medium the electropolymerization of aniline is facile and the resulting PANI has porous structure and high electrode specific capacitance. The electropolymerization in pyrrolidinium nitrate ([Pyrr][NO3]) as control experiment demonstrates that the high efficiency of the electropolymerization in [Pyrr][HSO4] is due to the high proton activity of HSO4−. The present work is of significance for simplifying pre-existing ionic liquid media for aniline electropolymerization and further improving the electrochemical performance of PANI obtained in ionic liquid media.