应用扫描电化学显微镜研究水/1,2-二氯乙烷界面上离子诱导的电子转移反应

摘要

In this work, we report the reverse electron transfer reaction between TCNQ in 1,2-dichloroethane(DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA+) and tetraphenylarsonium ion(TPAs+). The effects of the concentrations of TBA+ and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(kf) were obtained under different values of Kp(Kp=cwi/coi) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.%应用扫描电化学显微镜和微电极技术研究了水/1,2-二氯乙烷界面上的反向电子转移反应. 分别以K4Fe(CN)6和7,7,8,8-四氰代二甲基苯醌(TCNQ)作为水相和有机相的电活性物质, 通过选择合理的共同离子(TPAs+与TBA+)来控制界面电位差, 实现了这一在热力学上通常不可能实现的反向电子转移反应. 利用扫描电化学显微镜给出的正负反馈信息, 研究了界面电位差驱动的液/液界面上的电子转移反应, 并进一步得到了在不同的共同离子浓度比时, 此异相界面反应速率常数kf为1.3×10-3～1.8×10-2 cm/s(共同离子为TBA+)和2.5×10-3～2.8×10-2 cm/s(共同离子为TPAs+). 验证了此反应速率常数kf是由界面电位差所决定的. 在此实验条件下, 此反应速率常数kf与界面电位差的关系遵守Butler-Volmer公式.