The Surface Activity of the Hydrated Proton Is Substantially Higher than That of the Hydroxide Ion
The Surface Activity of the Hydrated Proton Is Substantially Higher than That of the Hydroxide Ion
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DOI：
10.1002/anie.201908420
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
Sudipta Das;M. Bonn;E. Backus
中科院分区：
文献类型：
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作者：
Sudipta Das;M. Bonn;E. Backus
摘要 氢氧根和水合质子（水的自电离产物）在表面的行为对于广泛的应用和学科都很重要。然而，尚不清楚这些离子在什么浓度下开始在水-空气界面上变得具有表面活性。在这里，我们报告了使用表面敏感振动和频发生（SFG）光谱测定的过量 D+ hyd/OD− hyd 存在下 D2O-空气界面的变化。 D2O 表面扰动的开始发生在本体浓度低至 2.7±0.2 mm D+ hyd 时。相反，改变 D2O 表面需要数百 mm OD− hyd 的浓度。因此，水合质子在水-空气界面上的表面活性比氢氧化物高几个数量级。
Abstract The behavior of hydroxide and hydrated protons, the auto‐ionization products of water, at surfaces is important for a wide range of applications and disciplines. However, it is unknown at which bulk concentration these ions start to become surface active at the water–air interface. Here, we report changes in the D2O–air interface in the presence of excess D+ hyd/OD− hyd determined using surface‐sensitive vibrational sum‐frequency generation (SFG) spectroscopy. The onset of the perturbation of the D2O surface occurs at a bulk concentration as low as 2.7±0.2 mm D+ hyd. In contrast, a concentration of several hundred mm OD− hyd is required to change the D2O surface. The hydrated proton is thus orders of magnitude more surface‐active than hydroxide at the water–air interface.