Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

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 reacti on can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfac ial potential difference. In our case, the potential determining ions are t etrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effe cts of the concentrations of TBA(+) and TPAs+ in two phases and other param eters have been studied in detail. The apparent heterogeneous rate constant s(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) fo r both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential d ifferences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.