論文

EQCM (Electrochemical Quartz Crystal Microbalance) measurement during Sn(II)/Sn electrode reaction in a roomtemperature ionic liquid was conducted using an impedance method EQCM, which can measure the resonance resistance and frequency simultaneously. The mass increased during Sn deposition and decreased during Sn dissolution. The viscosity and density of the electrolyte near the electrode, ηLρL, can be estimated by monitoring the resonance resistance. The change of the ηLρL value during Sn(II)/Sn electrode reaction could be accounted for by the concentration profile of Sn(II) near the electrode.

The electrochemical reaction of Sn(II)/Sn was investigated in a room-temperature ionic liquid, 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI) at 25 °C. The anodic dissolution of Sn metal proceeded by a two-electron transfer reaction with a current efficiency of nearly 100%. Electrodeposition of Sn on a Cu substrate is possible in BMPTFSI containing Sn(II). The formal potential of the Sn(II)/Sn is -0.57 V vs. Ag/Ag(I). The diffusion coefficient of Sn(II) was estimated to be ∼ × 10-7 cm2 s-1 from chronoamperometric and chronopotentiometric techniques. The initial stage of nucleation of Sn on a polycrystalline Pt substrate was found to be classified into a three-dimensional progressive nucleation under diffusion control by chronoamperometry, suggesting the rate of nucleation is faster than that of crystal growth.