Electrochemical Studies of Tin in the non-Cl~- [EMIm]BF4 Room Temperature Ionic Liquid

摘要

The electrochemistry of tin at platinum and glass carbon electrode was studied in the non-Cl~- [EMIm]BF4 ionic liquid at ambient temperature. The formal potential of the Sn(II)/Sn couple in the non-Cl~- [EMIm]BF4 is -0.64V vs. Ag/Ag(I). The results of cyclic voltammograms indicated that the reduction of Sn(II) on Pt electrode was quasi- or irreversible, the standard heterogeneous rate constant was estimated to be 3.61 x 10~(-4) cm s~(-1). The Stokes-Einstein product of Sn(II) in the non-Cl~- [EMIm]BF4 is, 11.8 x 10~(-10)g cm s~2 K~(-1), larger than that in free-Cl~- [EMIm]BF4, suggesting that Sn(II) may exists as bare cation in non-CF [EMIm]BF4 without complexing agents. The electrodeposition of Sn(II) at glass carbon electrode was complicated by nucleation. Experimental current-time transients are in good agreement with the theoretical model based on 3D nucleation. The morphology examined by SEM of the electrodeposit indicates that the Sn deposit is not a continuous plating film on Pt surface.