二茂铁衍生物L-B膜在CdSe/Fe(CN)_6^((3-)/(4-))界面的中介催化作用

MEDIATED ELECTROCATALYSIS OF FERROCENE DERIVATIVE L-B FILMS AT CdSe/Fe ( CN )_6^(3-/4-) INTERFACE

测定了CdSe薄膜电极及硬脂酸二茂铁酯L—B膜修饰后在Fe(CN)_6^(3-/4-)溶液中于白光和650nm单色光下的阻抗行为。用计算机非线性曲线拟合求出了等效电路中的元件参数值。进一步计算了CaSe薄膜电极光氧化还原反应速度常数。结果表明,修饰在CdSe薄膜电极上的硬脂酸二茂铁酯L—B膜在光诱发的CdSe/Fe(CN)_6^(3-/4-)界面电荷转移中加速电荷的传递起中介催化作用。

The impedance behaviors of CdSe thin film electrode and long alkyl chain derivative of ferrocene FcOCOC17H35 modified CdSe thin film electrode were measured in Fe(CN)63-/4- solutions under dark and illumination. CdSe thin film electrodes were prepared on Ti plates using painting method. Surface modification of ferrocene derivative in monolayer or multilayer assemblies were performed by L-B technique.The impedance measurements were carried out using lock-in amplifier over a frequency range of 7 Hz-2 kHz. Complex impedance, spectra of CdSe thin film electrodes before and after surface modification were obtained. The corresponding equivalent circuits consist of series resistance of solution and electrode Rs, charge transfer resistance Rct and capacitance Cp which is a combination of space charge Csc and Helmholtz layer CH. The estimation of element parameter values occurring in equivalent circuit was performed by using computer curves fitting. In comparison with the element parameter values obtained from CdSe thin film electrodes before surface modification, a large value of Cp observed in the case of modified electrodes indicated a contribution from the modified L-B films CF. The decrease in Rct after surface modification revealed that the rate of charge transfer at irradiated CdSe/Fe (CN)63-/4- interface was increased obviously. The electrode reaction rate constant K can be calculated directly from Rct. Significant increase in K value was obtained in thin film electrodes modified with monolayer and 3 layers of FcOCOC17H35 L-B film. This result provided strong evidence that ferrocene derivative molecules mediated interfacial charge transfer electrocatalytically. It functioned as fast charge transfer mediator at irradiated CdSe/Fe ( CN)63-/4- interface.