Vogel Yan B, Molina Angela, Gonzalez Joaquin, Ciampi Simone
Curtin Institute of Functional Molecules and Interfaces , Curtin University , Bentley , Western Australia 6102 , Australia.
Departamento de Quimica Fisica , Universidad de Murcia , Murcia 30003 , Spain.
Anal Chem. 2019 May 7;91(9):5929-5937. doi: 10.1021/acs.analchem.9b00336. Epub 2019 Apr 15.
The design of devices whose functions span from sensing their environments to converting light into electricity or guiding chemical reactivity at surfaces often hinges around a correct and complete understanding of the factors at play when charges are transferred across an electrified solid-liquid interface. For semiconductor electrodes in particular, published values for charge-transfer kinetic constants are scattered. Furthermore, received wisdom suggests slower charge-transfer kinetics for semiconductors than for metal electrodes. We have used cyclic voltammetry of ferrocene-modified silicon photoanodes and photocathodes as the experimental model system and described a systematic analysis to separate charge-transfer kinetics from diode effects and interactions between adsorbed species. Our results suggest that literature values of charge-transfer kinetic constants at semiconductor electrodes are likely to be underestimates of their actual values. This is revealed by experiments and analytical models showing that the description of the potential distribution across the semiconductor-monolayer-electrolyte interface has been largely oversimplified.
功能涵盖从感知环境到将光转化为电或引导表面化学反应的器件设计，通常取决于对电荷在带电固液界面转移时所涉及因素的正确且全面的理解。特别是对于半导体电极，已发表的电荷转移动力学常数数值分散。此外，普遍观点认为半导体的电荷转移动力学比金属电极慢。我们使用二茂铁修饰的硅光阳极和光阴极的循环伏安法作为实验模型系统，并描述了一种系统分析方法，以将电荷转移动力学与二极管效应及吸附物种之间的相互作用区分开来。我们的结果表明，半导体电极上电荷转移动力学常数的文献值可能低估了其实际值。实验和分析模型表明，对半导体 - 单分子层 - 电解质界面电位分布的描述在很大程度上被过度简化，这揭示了上述情况。
