Investigation of facilitated ion-transfer reactions at high driving force by scanning electrochemical Microscopy
Investigation of facilitated ion-transfer reactions at high driving force by scanning electrochemical Microscopy
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DOI：
10.1021/jp037498m
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发表时间：
2004-03-11
影响因子：
3.3
通讯作者：
Shao, YH
中科院分区：
文献类型：
--
作者：
Li, F;Chen, Y;Shao, YH
用扫描电化学显微镜（SECM）研究了高驱动力下水/1，2-二氯乙烷（W/DCE）界面的易化离子转移（FIT）反应动力学。二苯并-18-冠-6（DB 18 C6）促进的锂离子和钠离子在极化W/DCE界面上的转移被选为模型系统，因为它们具有可外部控制的最大电位范围。通过选择合适的反应物浓度比（Kr c（M）+/c（DB 18 C6））并使用纳米移液管作为SECM尖端，我们获得了在各种驱动力（Delta（O）（W）phi（ML+）（0 '）- Es）下的一系列速率常数（k（f）），Delta（O）（W）phi（ML+）（O ′）是促进离子转移的形式电势，Es是在基底界面处外部施加的电势），基于三个-电极系统发现FIT速率常数k（f）依赖于驱动力。当驱动力较低时，1 n k（f）对驱动力的依赖性是线性的，传递系数约为0.3。它遵循经典的Butler-Volmer理论，然后达到最大值，然后当我们进一步增加驱动力时，它再次减小。这表明存在一个倒置区，这些行为已被马库斯理论解释。
The kinetics of facilitated ion-transfer (FIT) reactions at high driving force across the water/1,2-dichloroethane (W/DCE) interface is investigated by scanning electrochemical microscopy (SECM). The transfers of lithium and sodium ions facilitated by dibenzo-18-crown-6 (DB18C6) across the polarized W/DCE interface are chosen as model systems because they have the largest potential range that can be controlled externally. By selecting the appropriate ratios of the reactant concentrations (Kr c(M)+/c(DB18C6)) and using nanopipets as the SECM tips, we obtained a series of rate constants (k(f)) at various driving forces (Delta(O)(W) phi(ML+)(0') - Es, Delta(O)(W) phi(ML+)(0') is the formal potential of facilitated ion transfer and Es is the potential applied externally at the substrate interface) based on a three-electrode system. The FIT rate constants k(f) are found to be dependent upon the driving force. When the driving force is low, the dependence of 1n k(f) on the driving force is linear with a transfer coefficient of about 0.3. It follows the classical Butler-Volmer theory and then reaches a maximum before it decreases again when we further increase the driving forces. This indicates that there exists an inverted region, and these behaviors have been explained by Marcus theory.