  An external electric field changes the physical properties of polar-liquids
due to the reorientation of their permanent dipoles. For example it should
affect significantly the physical properties of water confined in a
nanochannel. The latter effect is profoundly enhanced, if the field is applied
along the nanochannel. Using molecular dynamics simulations, we predict that an
in-plane electric field applied parallel to the channel polarizes water
molecules which are confined between two graphene layers, resulting in
distinct-ferroelectricity and electrical hysteresis. We found that electric
fields alter the in-plane order of the hydrogen bonds: reversing the electric
field does not restore the system to the non-polar initial state, instead a
residual dipole moment remains in the system. Our study provides insights into
the ferroelectric state of water when confined in nanochannels and shows how
this can be tuned by an electric field.
