Electrochemical Investigation for Cu ~(2+) Oscillatory Phenomena at the Liquid/Liquid Interface with a Specific Adsorption of Ion Pair Model

摘要

In this paper, a novel current oscillatory phenomenon for Cu ~(2+) at the water/1,2-dichloroethane interface is reported with cyclic voltammetry and potential-step chronoamperometry. The small irregular current spikes were only observed near the site of the oxidation peak of CuCl _2 - and were mainly related to the Cu ~(2+)concentration in the aqueous phase. Our experimental results demonstrated that the current oscillation is caused by specific adsorption of ion pairs at the W/DCE interface between Cu ~(2+) in the aqueous phase and TPB - in the organic phase. Therefore, a specific adsorption of ion pair model has been formulated for the current oscillation at the liquid/liquid interface. The DFT calculation method was used to explain the mechanism of ion pair formation. The calculation results suggested that the TPB -Cu ~(2+)TPB - ion pair has the lowest-energy state, thus providing qualitative support for the ion pair model. A probable mechanism for the observed current oscillation was also discussed in this paper. At the same time, a spectrophotometric experiment was performed to evidence a strong attractive interaction between Cu ~(2+(and TPB -.