Continuous Water Filling in a Graphene Nanochannel: A Molecular Dynamics Study

Low dimensional materials especially carbon materials hold high promise in the fields of water purification, mineral separation, energy harvesting/conversion, and so on. The fluidic devices fabricated by direct synthesis, lithography, or selfassembly of low dimensional materials provide opportunities for exploring the novel properties and applications of nanoconfined transport. Here, continuous filling of water and acetone molecules into a graphene nanochannel is investigated. A stairlike nonlinear dependence of the number of filling water molecules on interlayer distance d is found when d < 1 nm due to the existence of outplane layered and in-plane ordered monolayer structure, while near-linear dependence is found for acetone because of the freely rotating configurations along with varying d during the filling process. The entropy, potential energy, and free energy of the confined system during the continuous filling are analyzed to understand the structural evolution of water. The energy-costs are discussed depending on the structure evolution of water during the filling, which is crucial to understanding the swelling and capillary condensation widely existing in the angstrom/nanometer-scale separation membranes.

Automated summary

Low dimensional materials, especially carbon materials, show high potential in various fields including water purification and energy conversion. The study investigates the filling of water and acetone molecules in graphene nanochannels, revealing different filling behaviors based on the interlayer distance d. Analysis of entropy, potential energy, and free energy during continuous filling helps understand the structural evolution of water and discuss the energy costs associated with it.