Unusual dielectric properties of NaCl solutions within confined MoS2 monolayer nanochannels

Abstract

The dielectric behavior of NaCl solutions at varying concentrations within different types of MoS₂ nanochannels has been systematically investigated through molecular dynamics simulations. This comprehensive set of simulations aims to provide profound insights into the interplay among spatial dimensions, structural configurations, and electrolyte solution concentration on dielectric properties. The findings presented in this paper reveal that the dielectric constant of both aqueous and NaCl solutions in confined phases exhibits anisotropic behavior within MoS₂ confinement systems. Notably, as the concentration of NaCl solution increases, the axial dielectric constant in these confined environments decreases, while the radial dielectric constant experiences an increase, demonstrating a non-monotonic trend with critical points observed at 0.4 mol/L and 0.6 mol/L for NaCl solutions. This anomalous dielectric behavior can be attributed to the reorientation of water molecules at lower concentrations aimed at preserving the original hydrogen bonding network within the confined system, which leads to enhanced dipole fluctuations and an unusual increase in radial dielectric constants.