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

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 − .