Hydration Structures at Charged Surfaces

带电表面的水合结构

• 批准号: 452731703
• 负责人: Professorin Dr. Angelika Kühnle
• 金额: --
• 依托单位: Department of Applied Physics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452731703?language=en
• 关键词: Hydration; Structures; Charged; Surfaces

In this project, we aim for investigating the influence of an applied potential on the interfacial hydration structure of a range of metal and insulator surfaces. An emphasis will be on elucidating the competition between the alignment of the water dipole in the electrostatic field and specific binding towards the surface, e.g., via hydrogen bonds. Furthermore, as water forms an extended hydrogen bonded network, also cooperative effects will govern the resulting hydration structure. Moreover, added ions might or might not concentrate at the interface as a function of the applied potential. In the classical picture, an electrical double layer forms, with ion concentrations that can be calculated based on continuum theory. While the presence of the ions will impact the hydration structure, a clear understanding of the effect of specific ions in a molecular-scale picture is still lacking. Here, we will develop a setup that allows for high-resolution hydration layer mapping under potential control. This development will build upon the existing modified atomic force microscopes in the group that have been proven to allow for three-dimensional hydration layer mapping. For this project, we will add an electrochemical cell with potential control to an existing instrument. As a first benchmark for testing the new setup, we will investigate inert metal surfaces such as gold (111) and platinum (111) in de-ionized water, to validate our results against existing theoretical calculations and experimental findings. In a next step, we will benefit from the fact that atomic force microscopy is not limited to electrical conducting samples. Therefore, we will investigate well-studied insulator surfaces such as calcium fluoride (111) and silica as well as calcite (10.4). These studies will allow for elucidating the interplay between specific binding of water molecules to the surface, e.g., via hydrogen bonds, and the impact of the electrostatic potential on the molecule’s electric dipole. Due to the fact that these samples are transparent, they are accessible to vibrational sum frequency generation spectroscopy. This is extremely helpful as it enables the comparison of the spatially resolved structural data from the hydration layer mapping with the averaged information on the orientation from the sum frequency generation spectroscopy. Finally, we will investigate the impact of added ions on the hydration structure under potential control. Here, we will systematically investigate the effect of ions as a function of both ionic charge and ion size on the resulting hydration structure in presence of an applied electric potential. The project will, therefore, provide detailed insights into the driving forces that govern the hydration structure formation at charged interfaces.

在这个项目中，我们的目标是调查的影响，一系列的金属和绝缘体表面上的界面水合结构的施加电位。重点将是阐明水偶极子在静电场中的排列和对表面的特异性结合之间的竞争，例如，通过氢键。此外，由于水形成扩展的氢键网络，因此协同效应也将控制所得的水合结构。此外，添加的离子可能会或可能不会集中在界面处作为所施加的电位的函数。在经典图像中，双电层形成，离子浓度可以根据连续介质理论计算。虽然离子的存在会影响水化结构，但仍然缺乏对分子尺度图像中特定离子的影响的清晰理解。在这里，我们将开发一个设置，允许高分辨率的水化层映射下潜在的控制。这一发展将建立在现有的修改后的原子力显微镜组已被证明允许三维水化层映射。在这个项目中，我们将在现有的仪器上增加一个带有电位控制的电化学电池。作为测试新设置的第一个基准，我们将研究惰性金属表面，如金（111）和铂（111）在去离子水中，以验证我们的结果对现有的理论计算和实验结果。在下一步中，我们将受益于原子力显微镜不限于导电样品的事实。因此，我们将研究已被充分研究的绝缘体表面，如氟化钙（111）和二氧化硅以及方解石（10.4）。这些研究将允许阐明水分子与表面的特异性结合之间的相互作用，例如，以及静电势对分子电偶极子的影响。由于这些样品是透明的，因此它们可用于振动和频产生光谱。这是非常有帮助的，因为它使得能够将来自水化层映射的空间分辨结构数据与来自和频产生光谱学的关于取向的平均信息进行比较。最后，我们将研究在电位控制下添加的离子对水化结构的影响。在这里，我们将系统地研究离子作为离子电荷和离子尺寸的函数对所产生的水合结构的影响，在存在施加的电势的情况下。因此，该项目将提供详细的见解，在带电界面的水化结构形成的驱动力。