Scale Effect on Simple Liquid Transport through a Nanoporous Graphene Membrane

Area of Science:

• Materials Science
• Nanotechnology
• Computational Chemistry

Background:

• Understanding fluid transport through nanoporous materials is crucial for applications like filtration and energy storage.
• Graphene membranes offer unique properties for nanoscale fluid manipulation.
• Accurate modeling of nanoscale flow requires careful consideration of boundary effects.

Purpose of the Study:

• To investigate the liquid transport mechanism through nanoporous graphene membranes (NPGMs) with varying pore diameters.
• To analyze the influence of pore size on flow dynamics, density profiles, and pressure drop.
• To optimize boundary conditions for molecular dynamics (MD) simulations of nanoscale flow.

Main Methods:

• Nonequilibrium molecular dynamics (NEMD) simulations were employed.
• Pressure-driven flow was simulated using a moving specular reflection wall.
• Three boundary approaches and local nanoscale variants were implemented to analyze velocity profiles.
• Comparison with slip-viscosity-modified Sampson's prediction was performed.

Main Results:

• Local density peaks and pressure drop were found to be dependent on pore diameter.
• An optimized pore boundary definition was identified, minimizing deviation from theoretical predictions.
• Pore center velocity and slip velocity increased with decreasing pore size due to van der Waals interactions.
• Slip velocity, interfacial viscosity, and boundary effects decayed exponentially with increasing pore diameter.

Conclusions:

• The study provides insights into the complex interplay of pore size, fluid-wall interactions, and boundary conditions in nanoscale transport.
• An optimized simulation approach was established for accurate prediction of liquid flow through NPGMs.
• Findings contribute to the design and optimization of graphene-based membranes for various applications.