title: Water transport inside carbon nanotubes mediated by phonon-induced oscillating friction.
abstract: The emergence of the field of nanofluidics in the last decade has led to the development of important applications including water desalination, ultrafiltration and osmotic energy conversion. Most applications make use of carbon nanotubes, boron nitride nanotubes, graphene and graphene oxide. In particular, understanding water transport in carbon nanotubes is key for designing ultrafiltration devices and energy-efficient water filters. However, although theoretical studies based on molecular dynamics simulations have revealed many mechanistic features of water transport at the molecular level, further advances in this direction are limited by the fact that the lowest flow velocities accessible by simulations are orders of magnitude higher than those measured experimentally. Here, we extend molecular dynamics studies of water transport through carbon nanotubes to flow velocities comparable with experimental ones using massive crowd-sourced computing power. We observe previously undetected oscillations in the friction force between water and carbon nanotubes and show that these oscillations result from the coupling between confined water molecules and the longitudinal phonon modes of the nanotube. This coupling can enhance the diffusion of confined water by more than 300%. Our results may serve as a theoretical framework for the design of new devices for more efficient water filtration and osmotic energy conversion devices.
authors.affiliation: 1] Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] London Centre for Nanotechnology, University College London, London WC1H 0AJ, UK [3] School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.affiliation: 1] London Centre for Nanotechnology, University College London, London WC1H 0AJ, UK [2] Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China [3] Department of Physics, Tsinghua University, Beijing 100084, China [4] Citizen Cyberscience Centre, CUI, University of Geneva, Carouge CH-1227, Switzerland.
authors.forename: François
authors.initials: F
authors.lastname: Grey
authors.affiliation: School of Civil Engineering, University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: Luming
authors.initials: L
authors.lastname: Shen
authors.affiliation: 1] School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel [2] XIN Center, Tsinghua University, Beijing 100084, China [3] XIN Center, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Urbakh
authors.affiliation: 1] Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Jefferson Zhe
authors.initials: JZ
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
authors.forename: Yilun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 1] Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China [2] Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China [3] XIN Center, Tsinghua University, Beijing 100084, China [4] XIN Center, Tel Aviv University, Tel Aviv 69978, Israel [5] Applied Mechanics Lab, and State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Quanshui
authors.initials: Q
authors.lastname: Zheng