Jia Mei, Zhang Chao, Cheng Jun
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Department of Chemistry-Ångström Laboratory, Uppsala University, Lägerhyddsvgen 1, P.O. Box 538, 75121 Uppsala, Sweden.
J Phys Chem Lett. 2021 May 20;12(19):4616-4622. doi: 10.1021/acs.jpclett.1c00775. Epub 2021 May 11.
The structure of electric double layers (EDLs) dictates the chemistry and the physics of electrified interfaces, and the differential capacitance is the key property for characterizing EDLs. Here we develop a theoretical model for computing the differential Helmholtz capacitance of oxide-electrolyte interfaces using density functional theory-based finite-field molecular dynamics simulations. It is found that the dipole of interfacial adsorbed groups (i.e., water molecule, hydroxyl ion, and proton) at the electrified SnO(110)/NaCl interfaces significantly modulates the double layer potential which leads to the asymmetric distribution of . We also find that the dissociative water adsorption prefers the inner sphere binding of counterions, which in turn leads to a higher Helmholtz capacitance, compared with that of the nondissociative case at the interface. This work provides a molecular interpretation of asymmetric EDLs seen experimentally in a range of metal oxides/hydroxides.
双电层（EDL）的结构决定了带电界面的化学和物理性质，而微分电容是表征双电层的关键性质。在此，我们利用基于密度泛函理论的有限场分子动力学模拟，开发了一种计算氧化物 - 电解质界面微分亥姆霍兹电容的理论模型。研究发现，在带电的SnO(110)/NaCl界面处，界面吸附基团（即水分子、氢氧根离子和质子）的偶极显著调制了双层电位，这导致了[此处原文缺失具体内容]的不对称分布。我们还发现，与界面处非解离情况相比，解离性水吸附更倾向于抗衡离子的内球结合，这反过来导致更高的亥姆霍兹电容。这项工作为在一系列金属氧化物/氢氧化物中实验观察到的不对称双电层提供了分子解释。
