Yu YanZi, Fan JingCun, Xia Jun, Zhu YinBo, Wu HengAn, Wang FengChao
CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, CAS Center for Excellence in Complex System Mechanics, University of Science and Technology of China, Hefei, Anhui 230027, China.
Nanoscale. 2019 Apr 25;11(17):8449-8457. doi: 10.1039/c9nr00317g.
There has been long-standing academic interest in the study of ion transport in nanochannel systems, owing to its vast implications in understanding the nature of numerous environmental, biological and chemical processes. Here, we investigate ion transport through two-dimensional slits using molecular dynamics simulations. These slits with angstrom-scale height dimensions can be realistically replicated in the simulation, which leads to direct comparisons between simulations and experiments. In particular, this new confining geometry allows the size exclusion effect to be unambiguously decoupled from other mechanisms. As the slit size approaches the ultimate scale, dehydration at the entry impedes the ionic conductance significantly, and even induces a complete ion rejection. We demonstrate that energy barriers required to accomplish the ion permeation can be theoretically connected to the partial dehydration process. The proposed model is further validated by simulations. Our results offer insights into the atomistic details of ion permeation, which may also shed light on developing effective ways for water filtration and desalination.
由于离子在纳米通道系统中的传输对理解众多环境、生物和化学过程的本质具有广泛影响，因此长期以来一直受到学术界的关注。在此，我们使用分子动力学模拟研究离子在二维狭缝中的传输。这些具有埃级高度尺寸的狭缝可以在模拟中真实地复制，这使得模拟和实验之间能够进行直接比较。特别是，这种新的受限几何结构使得尺寸排阻效应能够与其他机制明确地解耦。随着狭缝尺寸接近极限尺度，入口处的脱水会显著阻碍离子传导，甚至导致完全的离子排斥。我们证明，实现离子渗透所需的能量屏障在理论上可以与部分脱水过程联系起来。所提出的模型通过模拟得到了进一步验证。我们的结果提供了对离子渗透原子细节的见解，这也可能为开发有效的水过滤和脱盐方法提供启示。
