Han Tianyi, Xu Wanxing, Han Jie, Adibnia Vahid, He Hongjiang, Zhang Chenhui, Luo Jianbin
State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, People's Republic of China.
School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
Nano Lett. 2024 Aug 28;24(34):10443-10450. doi: 10.1021/acs.nanolett.4c01230. Epub 2024 Aug 14.
Counterion adsorption at the solid-liquid interface affects numerous applications. However, the counterion adsorption density in the Stern layer has remained poorly evaluated. Here we report the direct determination of surface charge density at the shear plane between the Stern layer and the diffuse layer. By the Grahame equation extension and streaming current measurements for different solid surfaces in different aqueous electrolytes, we are able to obtain the counterion adsorption density in the Stern layer, which is mainly related to the surface charge density but is less affected by the bulk ion concentration. The charge inversion concentration is further found to be sensitive to the ion type and ion valence rather than to the charged surface, which is attributed to the ionic competitive adsorption and ion-ion correlations. Our findings offer a framework for understanding ion distribution in many physical and chemical processes where the Stern layer is ubiquitous.
抗衡离子在固液界面的吸附影响众多应用。然而，斯特恩层中抗衡离子的吸附密度一直评估得很差。在此，我们报告了对斯特恩层与扩散层之间剪切平面处表面电荷密度的直接测定。通过对不同水性电解质中不同固体表面的格拉姆方程扩展和流动电流测量，我们能够获得斯特恩层中的抗衡离子吸附密度，其主要与表面电荷密度相关，但受本体离子浓度的影响较小。进一步发现电荷反转浓度对离子类型和离子价敏感，而不是对带电表面敏感，这归因于离子竞争吸附和离子 - 离子相关性。我们的研究结果为理解许多物理和化学过程中离子分布提供了一个框架，其中斯特恩层无处不在。
