AA-stacked bilayer square ice between graphene layers?

TL;DR

This study uses molecular dynamics simulations to explore the structure of water confined between graphene layers, revealing AA-stacked bilayer square ice with specific polarization properties and structural similarities to monolayer ice.

Contribution

It demonstrates the formation of AA-stacked bilayer square ice between graphene layers and characterizes its non-polar, non-ferroelectric nature, extending understanding of confined ice structures.

Findings

Bilayer ice forms an AA-stacked square lattice.

Each ice layer has a net dipole moment opposite to the other.

Three-layer ice retains monolayer-like crystal structure.

Abstract

Water confined between two layers with separation of a few Angstrom forms layered two- dimensional ice structure. Using large scale molecular dynamics simulations with the adoptable ReaxFF interatomic potential we found that flat monolayer ice with a rhombic-square structure nucleates between graphene layers which is non-polar and non-ferroelectric. Two layers of water are found to crystallize into a square lattice close to the experimental found AA-stacking [G. Algara- Siller et al. Nature 519, 443445 (2015)]. Each layer has a net dipole moment which are in opposite direction. Bilayer ice is also non-polar and non-ferroelectric. For three layer ice we found that each layer has a crystal structure similar to monolayer ice.