Electrochemical Reactions of Some Metal Species in Amide-type Ionic Liquids

Some characteristic properties of the ionic liquids composed of bis(trifluoromethylsulfonyl)amide (TFSA(-)) have been discussed based on our experimental results on the electrochemical reactions of some metal species. Electrode potentials of metal species are affected by the coordination environment of the metal cations. The metal species coordinated by TFSA(-) is suitable for electrodeposition of the metal since the reduction potential of the species is the most positive in TFSA(-)-based ionic liquids. Diffusion of a charged species in TFSA(-)-based ionic liquids is determined not only by the size but also by the charge density of the species. Outer-sphere electron transfer reactions are sluggish due to slow dynamics of the ions of ionic liquids. On the other hand, the electrode reactions involving surface processes are considered affected by the electric double layer structure dependent on the electrode potential. The TFSA(-)-based ionic liquids are suggested to act as dielectric media.