Investigation of electron transfer across the ice/liquid interface by scanning electro-chemical micr

The study of interfacial electron transfer (ET) reaction between ferricinium (Fc+) produced in situ in 1,2-dichloroethane (DCE) and ferrocyanide in ice matrix under low temperatures by the scanning electrochemical microscopy (SECM) is reported. Tetrabutylammonium (TBA+) is used as the common ion (potential-determining ion) in both phases to control the interfacial potential difference. The potential drop across the liquid/liquid interface can be quantitatively adjusted by changing the ratio of concentrations of TBA+ between the two phases. The apparent heterogeneous rate constants for Fc+ reduction by at the interface under different temperatures have been obtained by a best-fit analysis, where the experimental approach curves are fitted to the theoretical simulated curves. A sharp change has been observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition process.