Huang Jun
Institute of Energy and Climate Research, IEK-13: Theory and Computation of Energy Materials, Forschungszentrum Jülich GmbH, 52425Jülich, Germany.
JACS Au. 2023 Jan 25;3(2):550-564. doi: 10.1021/jacsau.2c00650. eCollection 2023 Feb 27.
The double layer on transition metals, , platinum, features chemical metal-solvent interactions and partially charged chemisorbed ions. Chemically adsorbed solvent molecules and ions are situated closer to the metal surface than electrostatically adsorbed ions. This effect is described tersely by the concept of an inner Helmholtz plane (IHP) in classical double layer models. The IHP concept is extended here in three aspects. First, a refined statistical treatment of solvent (water) molecules considers a continuous spectrum of orientational polarizable states, rather than a few representative states, and non-electrostatic, chemical metal-solvent interactions. Second, chemisorbed ions are partially charged, rather than being electroneutral or having integral charges as in the solution bulk, with the coverage determined by a generalized, energetically distributed adsorption isotherm. The surface dipole moment induced by partially charged, chemisorbed ions is considered. Third, considering different locations and properties of chemisorbed ions and solvent molecules, the IHP is divided into two planes, namely, an AIP (adsorbed ion plane) and ASP (adsorbed solvent plane). The model is used to study how the partially charged AIP and polarizable ASP lead to intriguing double-layer capacitance curves that are different from what the conventional Gouy-Chapman-Stern model describes. The model provides an alternative interpretation for recent capacitance data of Pt(111)-aqueous solution interfaces calculated from cyclic voltammetry. This revisit brings forth questions regarding the existence of a pure double-layer region at realistic Pt(111). The implications, limitations, and possible experimental confirmation of the present model are discussed.
过渡金属（如铂）上的双层具有化学金属 - 溶剂相互作用和部分带电的化学吸附离子。化学吸附的溶剂分子和离子比静电吸附的离子更靠近金属表面。在经典双层模型中，内亥姆霍兹平面（IHP）的概念简洁地描述了这种效应。在此，IHP概念在三个方面得到了扩展。首先，对溶剂（水）分子进行了精细的统计处理，考虑了取向极化状态的连续谱，而非少数几个代表性状态，以及非静电的化学金属 - 溶剂相互作用。其次，化学吸附离子是部分带电的，而非像溶液本体中那样呈电中性或具有整数电荷，其覆盖度由广义的、能量分布的吸附等温线确定。考虑了由部分带电的化学吸附离子诱导的表面偶极矩。第三，考虑到化学吸附离子和溶剂分子的不同位置和性质，IHP被分为两个平面，即吸附离子平面（AIP）和吸附溶剂平面（ASP）。该模型用于研究部分带电的AIP和可极化的ASP如何导致与传统古依 - 查普曼 - 斯特恩模型所描述的不同的有趣双层电容曲线。该模型为最近通过循环伏安法计算得到的Pt(111) - 水溶液界面的电容数据提供了另一种解释。这次重新审视引发了关于实际Pt(111)上是否存在纯双层区域的问题。讨论了本模型的意义、局限性以及可能的实验验证。
