自组装金团簇电极库仑台阶现象和电化学阻抗谱研究  

Coulomb Staircase Phenomena and Electrochemical Impedance Spectroscopy Study of Monolayer Protected Gold Clusters Self-assembled on Gold Electrode

作　　者：文莉[1] 林仲华[2] 翁少煌[1] 周剑章[2] 

机构地区：[1]化学化工学院化学系,厦门361005 [2]厦门大学固体表面物理化学国家重点实验室

出　　处：《高等学校化学学报》2008年第2期350-355,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20433040);福建省自然科学基金(批准号:Z0513002)资助

摘　　要：采用示差脉冲伏安法研究了自组装单层保护金纳米团簇（C8AuMPC）在常温下二氯甲烷溶液中的量子化电容充电效应．研究结果表明，该团簇在-0．8～0．8V电位范围内有4对明显的量子化电容充电峰．同时采用电化学阻抗谱对C8AuMPC修饰金电极体系的界面结构进行了表征，研究结果表明，MPC自组装层存在两个界面，即金电极-MPC层界面和MPC层一溶液界面；这两个界面的界面电容在MPC的零电荷电位（ca．-0．2V）附近均基本保持不变，随着电位正移或负移到一定程度，界面电容发生变化．进一步利用双隧道结金属岛库仑阻塞效应理论讨论了已有报道中对MPC量子化电容充电的理论分析结果，并证明电化学阻抗谱也是研究MPC量子化电容充电效应的有效方法．另外，用示差脉冲伏安法及循环伏安法研究了电活性物种二茂铁对C8AuMPC量子化电容充电的影响，发现溶液中的电活性物种对MPC层-溶液界面的电子传递的贡献可以忽略，表明该界面的电子传递主要发生在纳米粒子之间．Quantized capacitance charging was observed for octanethiolate self-assembled monolayer protected gold clusters（CsAuMPC） self-assembled on a gold electrode surface. The result from differential pulse voltammetry（DPV） shows that four pairs of well-defined quantized capacitance charging peaks appeared within the potential range from -0. 8 V to ＋ 0. 8 V. Electrochemical impedance spectra（EIS） of the monolayer protected clusters（MPC） modified electrode show that the electrode interfaces with adsorbed MPC consisted of two components, namely, the electrode-MPC interface and the MPC-solution interface. The interracial capacitances of the electrode-MPC interface（ COL1 ） and the MPC-solution interface（CDL2） almost had no change near the potential of zero charge（ ca. -0.2 V） , then CDL1 and COL2 both changed along with increasing or decreasing the electrode potentials. Quantized capacitance charging of MPC was further theoretically analyzed by using the theory of Coulomb blockade in normal metal two tunnel junctions, confirming that EIS method was an effective method for studying quantized capacitance charging of MPC. In addition, the effect of the electroacrive species-ferrocene on quantized capacitance charging of CsAuMPC was studied. The results show that the electroactive species in the solution almost made no contribution to the electron transfer of the MPC-solution interface, which mostly occurred between the nanoparticles.

关 键 词：自组装金纳米粒子 量子化电容充电 电化学阻抗谱 界面结构 

分 类 号：O647.11[理学—物理化学]