Shi Rui, Cooper Anthony J, Tanaka Hajime
Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China.
Department of Fundamental Engineering, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
Nat Commun. 2023 Aug 7;14(1):4616. doi: 10.1038/s41467-023-40278-x.
Ions exhibit highly ion-specific complex behaviours when solvated in water, which remains a mystery despite the fundamental importance of ion solvation in nature, science, and technology. Here we explain these ion-specific properties by the ion-induced hierarchical dipolar, translational, and bond-orientational orderings of ion hydration shell under the competition between ion-water electrostatic interactions and inter-water hydrogen bonding. We first characterise this competition by a new length λ(q), explaining the ion-specific effects on solution dynamics. Then, by continuously tuning ion size and charge, we find that the bond-orientational order of the ion hydration shell highly develops for specific ion size and charge combinations. This ordering drastically stabilises the hydration shell; its degree changes the water residence time around ions by 11 orders of magnitude for main-group ions. These findings are fundamental to ionic processes in aqueous solutions, providing a physical principle for electrolyte design and application.
离子在水中溶剂化时表现出高度离子特异性的复杂行为，尽管离子溶剂化在自然界、科学和技术中具有根本重要性，但这一现象仍是个谜。在此，我们通过离子 - 水静电相互作用与水间氢键相互竞争下离子水化壳层的离子诱导分层偶极、平移和键取向有序化来解释这些离子特异性性质。我们首先用一个新的长度λ(q)来表征这种竞争，解释离子对溶液动力学的特异性影响。然后，通过连续调节离子大小和电荷，我们发现对于特定的离子大小和电荷组合，离子水化壳层的键取向有序性高度发展。这种有序化极大地稳定了水化壳层；其程度使主族离子周围水的停留时间变化了11个数量级。这些发现对于水溶液中的离子过程至关重要，为电解质设计和应用提供了物理原理。
