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

Z Chen and JW Yang and CP Ma and K Zhou and SP Jiao, JOURNAL OF PHYSICAL CHEMISTRY B, 125, 9824-9833 (2021).

DOI: 10.1021/acs.jpcb.1c05658

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.

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