Electrochemical Reduction of Oxygen in Some Hydrophobic Room-Temperature Molten Salt Systems

The electrochemical reduction of oxygen was investigated in some hydrophobic room-temperature molten salt systems (ionic liquids) consisting of bis(trifluoromethanesulfone)imide anion with trimethyl- n -hexylammonium 1-butyl-1-methylpyrrolidinium 1-ethyl-3-methylimidazolium or 1,2-dimethyl-3-propylimidazolium cation. The oxygen dissolved in these melts was reduced to the superoxide ion on a gold electrode. The superoxide ion was stable against the aliphatic and alicyclic organic cations and but reacted with the aromatic ones and suggesting that nucleophilic reagents attack the melts consisting of imidazolium cations. The acceptor number of these -based molten salt systems was estimated to be comparable to those of acetonitrile and dimethyl sulfoxide from the comparison of the redox potential of The superoxide ion was further reduced, presumably to the peroxide, on a gold electrode in the melts consisting of the aliphatic or alicyclic organic cation. © 2003 The Electrochemical Society. All rights reserved.