Fundamental Research for Analysis of Electrode Reactions Involving Adsorption of Electroactive Species

采用二维准晶格模型，考虑吸附物种间的相互作用和配位数，对吸附在电极表面的电活性物种的氧化还原-电极反应进行了统计力学处理。得到了单电子转移阶段的电位扫描伏安法和交流伏安法的理论电流-电位曲线。此外，理论处理已扩展到两步单电子转移反应。为了建立一种分析吸附物种的电极过程的方法，需要有一个合适的模型系统，它可以被看作是一个原型。研究发现，某些紫精离子甚至以+2态吸附在汞电极上，并且在单分子层上的吸附物种呈现一对尖锐的尖峰状波，这可能是由于吸附物种的氧化还原-电极反应涉及吸附层的相变。这些波表现出很好的重现性，它的结论是，紫精汞系统可以被视为一个模型系统。详细研究了紫精的吸附和电化学行为。模拟实验的电流-电位曲线，使用推导出的理论结果已被尝试，考虑到电极过程的动力学参数和吸附物种之间的相互作用能。虽然理论曲线和实验曲线之间还没有完全一致的结果，但已证实理论结果可用于分析电流-电位曲线，并能解释某些复杂的曲线形状。

Redox-electrode reactions of adsorbed electroactive species on the electrode surface have been statistical mechanically treated using two-dimensional quasi-crystalline lattice model and taking into account the interactions among adsorbed species and coordination numbers. Theoretical current-potential curves have been obtained for potential sweep voltammetry and AC voltammetry for one electron transfer step. Furthermore, the theoretical treatment has been extended to two step one-electron transfer reactions. In order to establish a method of analysis of electrode processes of adsorbed species, it is required to have a suitable model system which can be regarded as a prototype. It has been found that some viologen dications adsorb on mercury electrode even in the +2 state and that the adsorbed species in a monolayer exhibits a pair of sharp spike-like waves which may be attributed to the redox-electrode reaction of the adsorbed species involving a phase transition of the adsorbed layer. These waves show very good reproducibility and it is concluded that the viologen-mercury systems can be regarded as a model system. The adsorption and the electrochemical behavior of the viologens has been studied in detail. Simulation of experimental current-potential curves using the derived theoretical results has been tried, taking into consideration the kinetic parameters of electrode processes and interaction energies among adsorbed species. Although a completely satisfactory agreement between the experimental and theoretical curves has not been obtained so far, it has been confirmed that the theoretical results obtained here can be applied to the analysis of current-potential curves can can explain some involved shapes of such curves.