Electrochemistry of Cd(II) in the basic 1-ethyl-3-methylimidazolium chloride/tetrafluoroborate room temperature molten salt

The electrochemistry of cadmium species was investigated at glassy carbon, polycrystalline tungsten and platinum electrodes in a basic 1-ethyl-3-methylimidazolium chloride/tetrafluoroborate room temperature molten salt. Amperometric titration experiments suggest that Cd(II) chloride is complexed as [CdCl₄]^2- in this melt. [CdCl₄]^2- could be reduced to cadmium metal via a single-step quasi-reversible electron transfer process. On the other hand, effective dissolution of cadmium to Cd(II) is effected by the presence of sufficient chloride ions. The electrodeposition of cadmium proceeds via three-dimensional progressive nucleation with diffusion-controlled growth. The average Stokes-Einstein product for [CdCl₄]^2- is (2.3±0.1)×10^-10 g cm s^-2 K^-1. The cadmium electrodeposits are found to be very pure and adhere well on the tungsten substrate.