Water flow through a carbon nanotube: A comparison between static and terahertz electric fields

Abstract

Electric field regulates the structures and dynamics of confined water in nanochannels, because it directly affects the water dipole orientation. In this work, through a series of molecular dynamics simulations we find that the water flow through a carbon nanotube exhibits thoroughly different behaviors in static and alternating (terahertz) electric fields. In static electric fields, the water flow shows a monotonous and almost linear decay with the increase in field strength because of the overall stiffening of hydrogen bond network and reduced water diffusion. However, in terahertz electric fields, the water flow displays an interesting maximum behavior with the field strength because of the competition between resonant effect and reduced water occupancy. Furthermore, with the increase in field frequency, the water flow demonstrates two maxima because of the frequency resonance. As a result, tuning the strength and frequency of terahertz electric fields, the water flow can be enhanced by an order of magnitude, compared to the static electric fields. These findings provide basic physical insights into the effect of alternating electric fields on the confined water dynamics and should have great implications for the design of novel high-flux nanofluidic devices.