Why Are Carbon Nanotubes Fast Transporters of Water?

作者：Sony Joseph, N. R. Aluru · 发表于：Nano Letters · 年份：2008 · DOI：10.1021/nl072385q · 被引用次数：837 · 研究领域：Nanopore and Nanochannel Transport Studies、Carbon Nanotubes in Composites、Microfluidic and Capillary Electrophoresis Applications

Extraordinarily fast transport of water in carbon nanotubes (CNTs) in recent experiments has been generally attributed to the smoothness of the CNT surface. Using molecular dynamics simulations we investigate water flow in (16,16) CNTs and show that the enhanced flow rates over Hagen-Poiseuille flow arise from a velocity "jump" in a depletion region at the water nanotube interface and that the water orientations and hydrogen bonding at the interface significantly affect the flow rates. For nanotube with the same smooth wall structure but with more hydrophilic Lennard-Jones (LJ) parameters of silicon, the enhancement is greatly reduced because it does not have "free" OH bonds pointing to the wall as in CNTs that would reduce the number of hydrogen bonds in the depletion layer. Roughness in the tube walls causes strong hydrogen-bonding network and no significant flow enhancement is attained in rough tubes.