Electroosmotic Flow in Nanotubes with High Surface Charge Densities

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• 作者：Yunfei Chen ; Zhonghua Ni ; Guiming Wang ; Dongyan Xu ; Deyu Li
• 刊名：Nano Letters
• 出版年：2008
• 出版时间：January 2008
• 年：2008
• 卷：8
• 期：1
• 页码：42 - 48
• 全文大小：269K
• 年卷期：v.8,no.1(January 2008)
• ISSN：1530-6992

文摘

The ion distribution and electroosmotic flow of sodium chlorine solutions confined in cylindrical nanotubes with high surface charge densitiesare studied with molecular dynamics (MD). To obtain a more practical physical model for electroosmotic driven flow in a nanoscale tube, theMD simulation process consists of two steps. The first step is used to equilibrate the system and to obtain a more realistic ion distributionin the solution under different surface charge densities. Then, an external electric field is acted to drive the liquids. The simulation resultsindicate that with the increase of the surface charge density, both the thickness of the electric double layer and the peak height of thecounterion density increase. However, the phenomenon of charge inversion does not occur even as the surface charge density increases to-0.34 C/m², which is rather difficult to reach for real materials in practical situations. This simulation result confirms the recent experimentalobservation that monovalent ions of sufficiently high concentrations can reduce or even cancel the charge inversion occurred in the case ofmultivalent ions [F. H. J. van der Heyden et al. Phys. Rev. Lett. 2006, 96, 224502].