Modulating Water Slip Using Atomic-Scale Defects: Friction on Realistic Hexagonal Boron Nitride Surfaces

Area of Science:

• Materials Science
• Nanotechnology
• Fluid Dynamics

Background:

• Atomic-scale defects are common in nanomaterials but their impact on fluid flow is not well understood.
• Hexagonal boron nitride (hBN) is a 2D material used in water purification and energy generation, but its pristine form has high water friction.
• Understanding defects is key to optimizing hBN for advanced applications.

Purpose of the Study:

• To investigate how atomic-scale defects in hexagonal boron nitride (hBN) affect water slippage.
• To quantify the friction coefficient and slip length of water on defective hBN surfaces.
• To explore the potential of engineered defects in hBN for fluid flow modulation.

Main Methods:

• Classical molecular dynamics simulations were employed to model water flow.
• Quantum-mechanical density functional theory was used to assist simulations.
• Friction coefficients were computed for hBN with various defects (vacancies and Stone-Wales defects) at different concentrations.

Main Results:

• Defects were found to significantly alter water slippage on hBN, with friction coefficients varying from 0.4 to 2.6 times that of pristine hBN.
• A maximum water slip length of 18.1 nm was achieved on hBN with nitrogen vacancies or Stone-Wales defects.
• The study identified specific defects that enhance water slippage on hBN.

Conclusions:

• Engineered defects in hBN can be used to tune water flow properties.
• Defective hBN presents a promising alternative to graphene as a high-slip surface for applications in desalination and osmotic power.
• This research provides insights into defect engineering for controlling fluid behavior at the nanoscale.