应用扫描电化学显微镜研究了室温离子液体(Omim·Tf2N)与1,2-二氯乙烷(DCE)混合溶液/水界面上的电子转移反应.在保持共同离子(Tf2N^-)的浓度比恒定及异相电子转移反应由界面电势差所决定的条件下,研究了离子液体和DCE混合溶液中二茂铁(Fc)与水相中亚铁氰化钾[K4Fe(CN)6]之间异相电子转移反应.探讨了混合溶液中离子液体的体积分数(xRTIL)的变化对混合溶液/水界面上电子转移反应的影响.结果表明,随着xRTIL的减小(从1减小到0.1),Fc在混合溶液中的扩散系数单调递增(从2.730×10^-7cm^2·s^-1增加到9.131×10^-6cm^2·s^-1);而异相电子转移反应速率常数(k)则先逐渐减小(从8.0mol^-1·cm·s^-1减小到0.32mol^-1·cm·s^-1),之后又略有增大(从0.32mol^-1·cm·s^-1增大到0.48mol^-1·cm·s^-1).对这种现象可能的原因进行了较详细探讨.
The kinetic behavior of electron transfer(ET) reactions at the interface between room-temperature ionic liquid( RTIL, Omim · Tf2N) + 1,2-dichloroethane(DCE) solutions and water was studied by scanning electrochemical microscopy (SECM). The tip was positioned in the top RTIL + DCE solutions containing ferrocene(Fc) , and potassium ferroeyanide[ K4Fe(CN)6 ] was employed as the mediator in water( bottom phase). The effects of RTIL with different volume fractions (xRTIL ) in the mixtures on the apparent heterogeneous ET rate constants (k) were investigated at the same concentration ratio of the common ion (Tf2N^- ) by fitting the experimental approach curves to the theoretical values. The results showed that with XRTIL decreasing from 1 to 0. 1, the diffusion coefficient of Fc(DFc) in the mixtures increased from 2. 730 × 10^-7 to 9. 131 × 10^-6 cm^2 · s^-1 monotonously, but k decreased ( from 0. 32 to 0. 48 mol ^-1 · cm · s^-1 in details. firstly(from 8.0 to 0. 32 mol^-1 · cm · s^-1), and then increased a little ( from 0. 32 to 0. 48 mol^-1·cm · s^-1 ). The possible reasons for observation of these behavior were discussed in details.