Interfacial properties of water/heavy water layer encapsulate in bilayer graphene nanochannel and nanocapacitor

Abstract

Water through nanochannels of graphene (G) exposes the capillary pressure, calling fundamental understanding and predictive design of water within G nanochannels. Nanoconfinement induces switching behaviors at an atomic level, altering electronic and geometric structures. Herein, we study the single-layer water (SLW) and double-layer water (DLW) on monolayer G and encap-sulated in G layers and explore their diverse interfacial properties using a number of high level first principles calculations. By correlating the stability of adsorption, and interfacial properties such as intermediate pressure, charge transfer, structural deformation, one can decode various synergies in interaction properties of water on G nanocapillars. The external electric field (Eext) enhances polarization of system. More especially, changing the strength of Eext can effectively modulate the bandgap of monolayer G and bilayer graphene (BLG), and correspondingly causes a semimetal-semiconductor transition, i.e. Eg = 0.8 and 0.9 eV respectively. We also provide a comparison of phonon vibrational modes of water and heavy water (D2O) encapsulated within BLG, capturing their mobility as a key factor of separation mechanism. Moreover, we propose a nanocapacitor array of graphene-water-graphene composite, which electrodes has been separated by a water layer as a dielectric film. Nanometre-scale G capillaries open up a pathway to fabricate atomically channels walls for nanofluidic technology and nanocapacitor as a key device in integrated circuits (ICs).