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

Abstract

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 × 10^-4 cm s^-1. The Stokes-Einstein product of Sn(II) in the non-Cl^– [EMIm]BF₄ is, 11.8 × 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-Cl^– [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.