Putting together the puzzle of ion transfer in single-digit carbon nanotubes: mean-field meets ab initio
Putting together the puzzle of ion transfer in single-digit carbon nanotubes: mean-field meets ab initio
复制标题
整理个位数碳纳米管中离子转移的难题：平均场满足从头开始
DOI：
10.1039/d1nr08073c
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发表时间：
2022
期刊：
影响因子：
6.7
通讯作者：
Freger, Viatcheslav
中科院分区：
文献类型：
--
作者：
Neklyudov, Vadim;Freger, Viatcheslav
大自然利用通道蛋白选择性地使水穿过细胞膜，这激发了对生物模拟类似物的研究。碳纳米管孔蛋白（CNTPs）是一种有趣的水通道模拟物，但CNTPs中的离子传输仍然存在问题。作为连续介质模型的替代，在这里我们提出了一个分子平均场模型，它透明地描述了离子耦合，但与连续介质模型不同的是，它从头计算了KCl盐和水中存在的H+和OH−离子所需的所有热力学量。该模型从水迁移出发，考虑了自由离子的迁移，沿着离子对的形成，作为非平均场离子-离子相互作用的代表。实验表明，对氢氧化物的高亲和力使其成为CNTPs中的主要电荷载体，揭示了KOH对的异常有利的转移。然而，自由离子，与较少的移动的离子对共存，显然控制离子的运输。该模型很好地解释了盐浓度和pH值对电导率、迁移数、阴离子渗透及其活化能和电流整流的影响。所提出的方法可扩展到其他亚纳米通道，并有助于设计新的渗透材料和设备。
Nature employs channel proteins to selectively pass water across cell membranes, which inspires the search for bio-mimetic analogues. Carbon nanotube porins (CNTPs) are intriguing mimics of water channels, yet ion transport in CNTPs still poses questions. As an alternative to continuum models, here we present a molecular mean-field model that transparently describes ion coupling, yet unlike continuum models, computes ab initio all required thermodynamic quantities for the KCl salt and H+ and OH− ions present in water. Starting from water transfer, the model considers the transfer of free ions, along with ion-pair formation as a proxy of non-mean-field ion–ion interactions. High affinity to hydroxide, suggested by experiments, making it a dominant charge carrier in CNTPs, is revealed as an exceptionally favorable transfer of KOH pairs. Nevertheless, free ions, coexisting with less mobile ion-pairs, apparently control ion transport. The model well explains the observed effects of salt concentration and pH on conductivity, transport numbers, anion permeation and its activation energies, and current rectification. The proposed approach is extendable to other sub-nanochannels and helps design novel osmotic materials and devices.