Water in confined geometries exhibits unusual static and dynamic properties. Here, we revealed proton transport through water confined in distorted single-wall carbon nanotubes (SWCNTs) by means of molecular dynamics (MD) simulations. The proton transport properties of the confined water were found to be controlled by the distortion ratio of the SWCNTs, where the SWCNTs were uniaxially compressed in a direction perpendicular to the SWCNT axes. In the appropriately distorted SWCNTs, the confined water forms an ice nanoribbon with a finite width perpendicular to the tube axis. An excess proton was found to diffuse preferentially along the edge water molecules of the ice nanoribbon via the Grotthuss mechanism. The mobility of the excess proton sensitively depends on the structure, especially the O–O–O bond angle θ_OOO, of the edge water molecules in the ice nanoribbons, and it exhibits a maximum value when θ_OOO ∼ 146°. The mechanism of proton transport through the ice nanoribbons might have important implications for the development of novel proton exchange membranes for fuel cells, as well as for better understanding the mechanisms of proton transport through biological membranes.

中文翻译：

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通过冰纳米带的质子传输


受限几何形状中的水表现出不寻常的静态和动态特性。在这里，我们通过分子动力学（MD）模拟揭示了质子在扭曲单壁碳纳米管（SWCNT）中的水传输。研究发现，受限水的质子传输特性是由单壁碳纳米管的变形率控制的，其中单壁碳纳米管在垂直于单壁碳纳米管轴的方向上被单轴压缩。在适当扭曲的单壁碳纳米管中，受限水形成垂直于管轴的有限宽度的冰纳米带。发现过量的质子通过 Grotthuss 机制优先沿着冰纳米带的边缘水分子扩散。过量质子的迁移率敏感地取决于冰纳米带边缘水分子的结构，尤其是O-O-O键角θ _OOO ，当θ∼146°。通过冰纳米带的质子传输机制可能对开发用于燃料电池的新型质子交换膜以及更好地理解质子通过生物膜传输的机制具有重要意义。