Orientation-Induced Adsorption of Hydrated Protons at the Air-Water Interface
Orientation-Induced Adsorption of Hydrated Protons at the Air-Water Interface
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DOI：
10.1002/anie.201707391
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发表时间：
2017-12-11
影响因子：
16.6
通讯作者：
Bonthuis, Douwe Jan
中科院分区：
文献类型：
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作者：
Mamatkulov, Shavkat I.;Allolio, Christoph;Bonthuis, Douwe Jan
添加无机盐后，空气-水界面的表面张力增加，这意味着离子物质的负表面过量。然而，大多数酸会导致表面张力降低，表明水合质子的表面过量。结合动电实验得出的纯空气-水界面上明显的负电荷，这一实验观察结果自 19 世纪中叶以来一直是激烈争论的根源。在这里，我们通过经典的、热力学一致的分子动力学模拟计算了空气-水界面的表面张力和离子表面倾向。 NaOH、HCl 和 NaCl 溶液的表面张力与实验显示出出色的定量一致性。在所研究的离子中，只有 H3O+ 吸附到空气-水界面。这种吸附是通过界面电场中 H3O+ 偶极子的取向引起的深势阱来解释的，这已被 abinitio 模拟所证实。
The surface tension of the airwater interface increases upon addition of inorganic salts, implying a negative surface excess of ionic species. Most acids, however, induce a decrease in surface tension, indicating a positive surface excess of hydrated protons. In combination with the apparent negative charge at pure air-water interfaces derived from electrokinetic experiments, this experimental observation has been a source of intense debate since the mid-19th century. Herein, we calculate surface tensions and ionic surface propensities at air-water interfaces from classical, thermodynamically consistent molecular dynamics simulations. The surface tensions of NaOH, HCl, and NaCl solutions show outstanding quantitative agreement with experiment. Of the studied ions, only H3O+ adsorbs to the air-water interface. The adsorption is explained by the deep potential well caused by the orientation of the H3O+ dipole in the interfacial electric field, which is confirmed by abinitio simulations.